# Micro-controller controlled Pneumatic Power Draw Bar



## jcdammeyer (Sep 15, 2021)

This is a more appropriate place to continue the thread that started out asking about coil springs.
https://canadianhobbymetalworkers.com/threads/coil-springs.3876/page-2#post-51519

Finally got around to casting the patterns today. 

Also since it appears that my AliExpress ordered pneumatic valves have been cancelled by the sender (waiting for credit now) I bit the bullet and went over to Princess Auto and picked up the 5 way 2 position valve to run the cylinder as I've not been able to get it to move while sharing air with the butterly impact wrench.  
PA 5 Way 2 Position 
The down side is it's truly binary in that when one coil is energized the valve moves over and stays there as does then the cylinder.  The other coil has to be energized to move it in the other direction.  So the coils don't need to have power continuously.  But it needs two outputs.


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## jcdammeyer (Sep 15, 2021)

It needs to be reduced in thickness by another 0.03" or so which will remove some more of the bigger imperfections but I'm still having issues with porosity.  It's not that it matters as the part is more than strong enough and I still have to mount and run the G-Code to profile it and drill the holes.




My source material is scrap extrusions and whatever aluminium I have lying around.  I use a degassing compound which creates lots of bubbles and brings a lot of crap to the surface of the silicon carbide crucible.  This was poured at 710C.    Surface was milled at 5 ipm, 400 RPM, 0.01 depth of cut with a 4 carbide insert facing mill.  And yet there's still the tiny little bubbles.

Silky smooth though.


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## Tom O (Sep 15, 2021)

What degassing compound are you using?


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## jcdammeyer (Sep 15, 2021)

Tom O said:


> What degassing compound are you using?


It's pink.  The container is marked "from Joe".  It's so long ago I don't even remember where I got it.  I did have a container of pool chlorine which is supposed to remove much of the dissolved hydrogen gas that expands as it cools.   But it sat and absorbed moisture and one day I noticed the plastic container had expanded, cracked and spread goopy white stuff all over the bench.  That's when I started also having more rust problems but that's another story.

My raw material is crap. As I said, extrusions that are also dirty.   Ideally I should probably first make ingots properly degassed and clean.  And then start with those.  This pour was a mix of ingots from 10 years ago and extrusions and an old sprue plus some stamped 1/8th sheet aluminium.

The material/casting is more than strong enough for what it's supposed to do.  But it would be nice to be able to take this crap and make a pristine, if soft and hard to machine, casting.


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## jcdammeyer (Oct 3, 2021)

Well after screwing up the casting because the X axis lost position between homing I've now converted the entire machine to Bergerda AC servos.  Now my zero position for the part is repeatable.
I had a small piece of 3/8" flat aluminium bar stock so I used that to make the part that was originally going to be cast.

Depth of each pass was 0.050" with 14.6 ipm and spindle RPM 1000 turning a 1/2" two flute center cutting end mill.    The two sloping sides were done with the full 1/2" cutter with the two vertical and the bottom was no more than about 1/8" or os.  I think the chatter and rough marks are due to backlash as it's following the slope. 

I really don't know.  This is where my amateur status shows through.  No idea if it's feeds, speeds, spindle rpm, cutter quality (Busy Bee Tools) or even spindle bearings.


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## Tom O (Oct 3, 2021)

Was it just a roughing tool path ( with .010 left for finishing ) or did you follow up with a finishing pass to smooth it out


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## jcdammeyer (Oct 3, 2021)

No I didn't do a finishing pass.  Have to figure out how to get the MecSoft CAM to do that.  Probably a separate G-Code operation.  

However the next step was facing off the bottom of the base casting which went really well.  After that the mounting slots.  And there you can see how the X axis gets pushed as the 1/4" end mill bites into the metal and then stays offset by the 0.027" backlash.  

Unfortunately on this mill there is no way to remove it.  I'd have to create a new bronze ACME anti-backlash adjustable nut.  I don't think it's worth the effort compared to fitting a proper ball screw.


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## jcdammeyer (Oct 23, 2021)

I added a comment about this in another thread.
https://canadianhobbymetalworkers.com/threads/dreaming-of-a-power-draw-bar.4094/


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## jcdammeyer (Oct 29, 2021)

Things are progressing.  Made the second spring collar tonight.  Really must refit the mill with ball screws.  It's always been find to position and drill using the DRO and scales but unless I somehow close the loop to the scales with LinuxCNC the open loop and terrible backlash leave a pretty ugly surface finishing holes don't line up as well because the CNC doesn't always approach from the same direction.  

Tomorrow the weather forecast is for no rain so I can finally cast the plate that the draw bar system will bolt onto.  

So here are a few more pictures.


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## jcdammeyer (Nov 2, 2021)

So I poured the milling machine spindle cover plate which will hold the drawbar assembly.  The original from House of Tools was just sheet metal made to look like a casting. 


 

One slight side effect.  Forgot how long the furnace had been on and reached under to pullout a metal ring that was in the exhaust flow.  Some cold water, a couple of bandaids and finished the pour.





Next some machining, trimming the edges to the correct width, creating the slots and holes and taking care of a bit of sag in the top part of the casting. This is the bottom and the slot is in the back to match up to the motor mount plate.





Next step is make a slightly longer draw bar with a single 9/16" hex nut at the top.  Enlarge the two mounting holes and tap them 6mm.  And drill the 4 holes for the 6mm hold down screws onto the head casting.  Might need to add a couple more hold downs too.





And then shorten the 1/2" copper pipe so the socket is just above the draw bar.  I may just have a power drawbar before Christmas...


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## Tom O (Nov 3, 2021)

Yep it’s definetly….


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## 6.5 Fan (Nov 3, 2021)

For a burn i keep vitamin E capsules in the fridge, smear some of the E liquid on burn as soon as possible. Otherwise project looks good.


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## jcdammeyer (Nov 3, 2021)

Thanks.  I was lucky.  The skin remained intact and each has a big bubble of skin covering fluid protecting the burn while it heals so as long as I keep it bandaged it should be fine.  I keep a pharmacist in house just for these sort of things.  She burns herself on the oven way more often than I do.  Been a long time since I grabbed a soldering iron incorrectly too.

The key thing is now that I have the system on the stand I can measure how much to remove from the two 1/2" rods and the water pipe spacers so the socket clears properly but also is down as it starts turning.  Although I can delay that now with software since I'm now controlling the cylinder separately from the butterfly wrench.   They switch off at the same time.  Or more precisely the up valve will go on at the same time as the air to the wrench is switched off.

But for the other direction I think I will introduce a delay so the socket goes down first and then is spun for 2 turns before the off event.


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## jcdammeyer (Nov 8, 2021)

Finished milling and threading the cylinder link.  


  That was an interesting exercise.  
It moves the butterfly wrench closer so I found a few short pieces of copper pipe.  There's just enough spring tension to push it back up and I plumbed it for now to use the same air for the cylinder and the wrench so it's not very predictable the way it will be when the micro-processor controls the cylinder and wrench separately.  

But holding the air hose against the open tube showed that it can do a decent job to push down and either tighten or loosen an R8 tool depending on how I arrange the tubes.  Still have to drill, tap and countersink the base casting (and clean up the edges so the wrench fits if I want to use it.
Baby steps.


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## jcdammeyer (Nov 14, 2021)

Made a U shaped bracket to hold the two pneumatic valves.  This will screw to the head side cover which I normally never remove.
Used the probe to find the corners and then move to the appropriate positions to spot and then drill the holes.  Same with the holes in the bottom for mounting to the cover.  Didn't use the power tapping because my 5mm spiral tap doesn't fit in the tap collet meant for a 5mm tap.  So just a pointed piece in the spindle guiding the tap.  Do like those spiral taps for aluminium.

Anyway.  Successful day.  Not nearly as many mistakes as I usually make.  The longer valve runs the Butterfly Wrench with a center CLOSED position.  The shorter one is a dual position latching valve because the type I wanted was not carried by Princess Auto.  Actually it was but what they have in stock is NORMALLY OPEN.  

So I had to add an extra output to move the cylinder up and down.  The springs therefore aren't really needed but help with keeping it up out of the way when air is shut off.


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## jcdammeyer (Nov 16, 2021)

Here's a link to a very short video showing the power drawbar progress. 

Press unload button and cylinder goes down first.  Then wrench turned on max 1 second.  Then both wrench turned off and up valve switched on to lift wrench out of the way.  Sure does move fast.  Might want some rubber stops to absorb some of the shock.

First test of pneumatically controlled power draw bar.

Only one tiny little problem happened when I put it all on the mill along with the RPM count sensor.  Nothing in the quill.  Just spinning the draw bar. 

I think I damaged the top part of the spindle from possibly the drawbar spinning around loose.  Most of my R8 tools will no longer slide up into position.  There have always been some that are a tad tighter than others and I put that off on tolerances in the far east R8 collets.  But now I can only find one that fits and it's tight.  

I put bluing on it and pressed it in and then pushed it out.  The photos show 3 different angles and that in some places the bluing has been pushed down and in others not touched.  Almost as if the end of the spindle where the collet goes in is not round.

Not sure how to fix this.

I knew I had to replace the draw bar anyway.  It's a bit smaller in diameter than the original and 5mm too short with the thick washer at the top.  And the impact wrench in no time loosened the double nuts (which I expected).  I wouldn't think that the drawbar threads can even touch the surface that registers the collets.  And the drawbar isn't marked up.  Threads look fine.

Ideally a reamer to clean it out.  But the registration pin is in the way so I think the spindle has to come out.


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## jcdammeyer (Nov 17, 2021)

I cleaned up the entrance to the parallel 0.950 diameter section of the spindle with a small drump sander held in an extension and manipulated by hand.  After that the collets all went in really easily.

Tried again with air on the impact wrench.  Litterly twisted a off roll pin that was through the nut and the drawbar shaft.  When it works, it works well.  But I'd say at the moment it works 1 of 5 tries.  Until it broke the pin.

Looks like I have to make a new drawbar.  Or somehow weld the nut on so it will stay.


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## kevin.decelles (Nov 17, 2021)

My draw bar on my 6x26 is in the same state.  Roll pin keeps breaking.  Going to take care of that by welding or solid draw bar.


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## jcdammeyer (Nov 17, 2021)

kevin.decelles said:


> My draw bar on my 6x26 is in the same state.  Roll pin keeps breaking.  Going to take care of that by welding or solid draw bar.


I used a pretty small roll pin (#40 drill for the hole) on the 9/16" nut.  At about 80 PSI the impact wrench had no trouble breaking it.  Also realized that the wrench didn't go down far enough so the draw bar climbed up and had trouble ejecting the R8.  I've adjusted that and had better success but if the socket sticks at all then the socket is left behind.  I do have a set screw in the socket that could clamp onto the driver but I think I should probably dimple the square driver so the set screw hooks it in place rather than holds it with pressure.

Not ready to do a video yet.


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## jcdammeyer (Nov 18, 2021)

One I realized by thinking outside the box that if I used the lathe with traveling steady I could reduce the drawbar enough so it would fit through the back of the rotary table since I didn't have a 14mm 5C collet for the spin indexer.  Not only that the drawbar isn't exactly straight so it binds a bit making it difficult to finger tighten.  The new thinner 13.5mm drawbar no longer binds and fits through the table so it can be clamped.

Easy then to index and cut the 6 flags from the 22mm square head into 19mm (18.6mm compared to 18.75 for a nut I had on hand) hex head.  

Problem though.  If the socket isn't perfectly lined up it just stops at the top and essentially jams.  I see nuts have a bit of a bevel.  What sort of shape do I need to put on the top so the socket is uncomfortable out of position and _wants_ to turn to line up with the nut.  Do I make it spherical?  Or angle from the center of the flat top edge in both directions towards the nut corners.  So the flat on the inside of the socket follows a ramp towards the corner.

If that makes sense?


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## jcdammeyer (Nov 18, 2021)

This is what I was thinking might work?  As the inside flats of the socket out of alignment by 30 degrees, will tend to slide down the curve in the direction of one of the edges.  The angle can't be too shallow or I suspect it would then still hang up on the surface.

Comments?


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## jcdammeyer (Nov 19, 2021)

jcdammeyer said:


> This is what I was thinking might work?  As the inside flats of the socket out of alignment by 30 degrees, will tend to slide down the curve in the direction of one of the edges.  The angle can't be too shallow or I suspect it would then still hang up on the surface.
> 
> Comments?


Update on this.  I first tested a 45 degree and then 60 degree angle on a 17mm bolt head.  Seemed to make it slip on more easily.  So I turned a 60 degree angle on the 19mm draw bar bolt head.  It does slip on more easily but still when off center the socket comes down so hard with the pneumatics that it hangs and I've seen the hardened impact socket actually leave a mark on the softer draw bar bolt.

I've ordered a 12 point socket.  And I'm going to take a dremel grinding tool to the inside sharp edges of the 6 point socket to round them so they won't hang up but will slide.  Won't affect the overall socket operation.  More when I've tried that.


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## jcdammeyer (Nov 19, 2021)

The newest problem.  I've ground the inside edges of the impact socket.  Since it's a 3/4" on a 19mm head (really 18.6mm) certainly loose enough to slip over easily when lined up.  On another group it was suggested perhaps giving the wrench a blip to spin it as it's pushed down that the spinning socket would self register.  It does.  And the few times it might not as soon as the power cycle starts the wrench, now with bevelled head on bolt and inside socket has no trouble going down.

Not tight to lift off either but, as an impact socket, is heavy.  And the air cylinder really moves up very fast and that results in the socket being left behind occasionally.  Worse is if as it goes up it pulls halfway off the wrench while the wrench is still turning.  Been hit in the chest and shoulder with a flying socket.  Not a good thing.  

A 3D printed guide/guard will help that.  But it looks like I will need some sort of better retention on the socket.  Not sure if the 3/8" drive is hardened.  Suspect it is.


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## jcdammeyer (Nov 25, 2021)

Just a quick update.  Turns out the replacement registration pin I made for the wrench was too short.  The finishing nail I trimmed looked like it protruded high enough above the gasket but I hadn't actually gotten it into the bottom hole deep inside the wrench.  So once the wrench was operated a few times the outer body, not held from turning by the pin, rotated enough to almost completely prevent CCW operation due to the blocked air passage.  I kept adjusting software not realizing it was mechanical.

So I now have a new pin made from a 0.104" diameter 2.5" finishing nail turned down to the correct 0.084".  The shorter nails were 0.071 and I didn't have a longer one that diameter.  So I center drilled the big end, turned off the point end and center drilled that too.  Then shaved it down on the little Unimat DB200.

Now I have full power back in both directions.  Everything is now on hold until KMS Tools delivers the 12 point deep socket.  I drilled a relief in the side of the 3/8" drive.  Ultimately I'll do as one of the other members and use locktite to prevent the socket from dropping but not enough to prevent that little bit of wiggle for guiding onto the nut.

Now the other issue was the socket spinning too fast once the draw bar was loose.  This is a standard operation of air tools.  So the guide plate demonstrates that a bit of resistance can slow it down along with PWM on the air valve.  Ultimately I think I'll add a brake of sorts to keep it from spinning too fast.   

And it looks like I will need a wrench down switch before I start turning.  I've found it does too much spinning on the top of the bar mangling it a bit. The 12 point will help but it may not be enough because if the socket doesn't go down then the magnet on the socket isn't picked up by the hall effect sensor and so it tends to over spin the wrench and I get way more than 2 turns on the draw bar.  Sometimes the R8 even drops out.

More when I have it.


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## Susquatch (Nov 26, 2021)

Dumb question - seems you are going to a lot of trouble trying to get a socket to mate up with the drawbar head. 

Why not leave it engaged permanently and just spin the drive with the drawbar? 

Alternatively, spin the socket with the drawbar but install a clutch between the socket and the drive? In fact, eliminate the socket and nut entirely and just put a clutch in. ???


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## jcdammeyer (Nov 26, 2021)

Not a dumb question at all.  
The bushings in the impact wrench are designed to be oiled with the supplied air.  As such spinning them without that oil might damage them.  Then there's also the tangs inside the wrench that under light load may well click back and forth making noise.

A clutch such as this: DC Clutch might well work but the size is prohibitive without a total frame redesign.

Eliminating the socket would then also require a redesign of the end of the draw bar.  At this point, aside from the redesign, there still needs to be a way to manually remove it if something fails with it tightly in place.

Again the big issue is for TTS tooling I want no more than 2 turns in the CCW and probably 3 seconds in the CW so the impact wrench can reach 15 to 25 ft-lbs of torque.  The other postings with various rotary power draw bar subjects all use R8 tooling and spin CCW until the R8 drops out.  Watch the videos  closely of the manually engaged versions and if the socket doesn't go down all the way there's a slight twist of the handle to blip the air wrench just enough to move it slightly without excess pressure on the nut.     And in one thread the need for the 12 point socket was emphasized.  So when a human is involved the slight behavior changes are handled without thinking.  

But I also want the ability to swap R8 tooling so mine is a dual operation draw bar.  So far I haven't seen any other threads or you tube videos that deal with that.

If I were to start over I'd look at a 300 oz-in stepper motor and probably a 20:1 planetary drive.  A few days ago the drives on Aliexpress were all in the $39 range.  Yesterday they were all in the $70 range.  In either case, a change to a fully electric version still runs up to $200 with drive etc.  And some major redesign. 

I've found one of the bigger issues is when the socket doesn't descend all the way and it starts to spin the magnet isn't lined up with the hall sensor so it defaults to timed turning which polishes or marks up the top of the draw bar even more.  I think a switch to detect fully down before turning might be the solution.   Then if it isn't down I can move it up, blip it to turn a tad, and try again.  With a 12 point socket likely it will drop into place quite quickly and then a 2 turn spin to undo it leaves the R8 in place and the TTS drops out.


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## Susquatch (Nov 26, 2021)

jcdammeyer said:


> Not a dumb question at all.
> The bushings in the impact wrench are designed to be oiled with the supplied air.  As such spinning them without that oil might damage them.  Then there's also the tangs inside the wrench that under light load may well click back and forth making noise.
> 
> A clutch such as this: DC Clutch might well work but the size is prohibitive without a total frame redesign.
> ...



I hear you. I'm just noodling the issues and asking myself what would I do. 

Maybe that helps, maybe it doesn't. But at a minimum it provides other ways of looking at things. Starting over or switching to Gen II is always an option. "A wise man changes his mind often."

Here is a smaller clutch to consider. It's a riding lawn mower PTO clutch for the blade deck. Plenty strong enough and can be made much smaller than it is if you turf the pulley. 



			Amazon.ca


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## jcdammeyer (Nov 26, 2021)

Susquatch said:


> I hear you. I'm just noodling the issues and asking myself what would I do.
> 
> Maybe that helps, maybe it doesn't. But at a minimum it provides other ways of looking at things. Starting over or switching to Gen II is always an option. "A wise man changes his mind often."
> 
> ...


Thanks.  Brings back memories of equipment I worked on in the early nineties.  It was a 30 Ton Flywheel press with a clutch and absolute encoder.   The clutch was engaged and as the flywheel rotated the micro-processor was interrupted on absolute locations.  It would then load the next location for an event until the revolution was completed.  Depending on what it was doing it would release the clutch or do another rev.

These events did thinks like engage air valves or tell stepper motors to move.  All to move IC lead frames under the press for trimming, bending and forming the leads of the ICs.

The issue of cost has to be factored.  A reduction drive and stepper/servo motor can, in addition to controlled speed and position can also control torque.   Assuming the curve says the motor has 288oz-in of torque then that's 1.5 ft-lb.  If I want between 12 and 20 ft-lbs then a 10:1 planetary gear box would create 15 ft-lbs.  If I set the current to create 12 ft-lbs and turn it slowly as it tightens then I get predictable torque.  If I set to 15 ft-lbs for unloading then I can turn it slowly at full torque for 1/2 a turn and then quickly for 1.5 turns.    But then it might be nice to close the loop and have an encoder on the back of the motor too.

That would allow fractional turns if the first try didn't move the socket all the way down.

Like you said, different ways of looking at things.  Since I've done this kind of computer controlled hard for many decades it's the way I tend to look at it.


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## Susquatch (Nov 26, 2021)

jcdammeyer said:


> Thanks.  Brings back memories of equipment I worked on in the early nineties.  It was a 30 Ton Flywheel press with a clutch and absolute encoder.   The clutch was engaged and as the flywheel rotated the micro-processor was interrupted on absolute locations.  It would then load the next location for an event until the revolution was completed.  Depending on what it was doing it would release the clutch or do another rev.
> 
> These events did thinks like engage air valves or tell stepper motors to move.  All to move IC lead frames under the press for trimming, bending and forming the leads of the ICs.
> 
> ...



When the gang first started doing automotive engine controls, they wanted to replicate the mechanical stuff in electronics. But how do you do things like timing advance (vac or speed) when the mechanical systems really are advanced ahead of the event? So some genius figured out we could delay from the previous point which would be the same as advanced from the current event. I argued that a lot could change in 90° of engine rotation. But the electronics guys won that round and we did it that way for a few years. It made their life easy when fast computer controllers only have to wait to act. Then the problems came home to roost and they started to listen a bit better. We switched to real time using position sensors and let the computers do what computers do best - a million calcs between counts. That works! Yup, those were the days.......


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## jcdammeyer (Nov 26, 2021)

My ELS still does awesome threading with 1PPR under the restriction that the spindle speed as to be solid.  Even then it did track variations on the smaller Sherline Lathe.  Not to say the larger PPR isn't better but at the time I designed the ELS an encoder pulleys and belts were more expensive than the entire ELS kit which included a micro-stepping driver for the Z axis.

I designed a CDI multi-point fuel injection ECU for Honda VTEC that were used in home built aircraft and hovercraft.    We only used two sensors: one at TDC and one at 20 degrees (I think) BTDC.  One one rev an engine just doesn't change speed that fast. 
Firewall Forward Engine Control


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## Susquatch (Nov 26, 2021)

jcdammeyer said:


> My ELS still does awesome threading with 1PPR under the restriction that the spindle speed as to be solid.  Even then it did track variations on the smaller Sherline Lathe.  Not to say the larger PPR isn't better but at the time I designed the ELS an encoder pulleys and belts were more expensive than the entire ELS kit which included a micro-stepping driver for the Z axis.
> 
> I designed a CDI multi-point fuel injection ECU for Honda VTEC that were used in home built aircraft and hovercraft.    We only used two sensors: one at TDC and one at 20 degrees (I think) BTDC.  One one rev an engine just doesn't change speed that fast.
> Firewall Forward Engine Control



Awesome stuff. I do agree that engine parameters don't *normally* change that much in one rev. Trouble is that these were mass produced engines used by consumers all around the world. Sometimes things don't work so smoothly in the real, world. Low speed operation, cold starts, and misfires can change engine speed dramatically in just a few degrees of rotation. It happened often enough that we had to fix it with a much more accurate system that knew exact crank position in real time. 

Funny that you mention lost spark. I was actually thinking about that when I wrote my previous note because it was another problem that came up for the same reasons. It was another one of those "it worked great in the lab" situations from the early days. Mechanical & vacuum advance systems moved the rotor plate as well as the spark timing signal via points, so rotor to cap position was compensated for almost automatically. But when they were replaced by a hall effect system (also before engine position control), that auto positioning advantage was lost and so was the spark! Unfortunately not lost well enough as it would sometimes go to a cylinder that wasn't at all ready for it! We found that one quite by accident looking for other things related to combustion emissions processes. I was on a cold trip up north looking at low temp performance of catalysts. I just happened to have a storage oscilloscope monitoring a lot of other functions and couldn't explain that one oddball signal that popped up at the oddest of times. Then the lightbulb went on! I wonder if.....


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## jcdammeyer (Nov 26, 2021)

The only major problem I had, and our engineer was in the cockpit logging data with the pilot doing a dead stick landing, was subtle.  Never showed up on the dyno so it may have been linked to a wiring/ground issue which of course we see a lot of in CNC systems too.  We caught this one with the logged data.  The system was doing A/D sensor acquisition on a periodic basis often enough so we could filter and get clean data.  Seems that if a conversion was done at the same time as a spark event the electrical noise caused MAP values to change and therefore that changed the mixture and that stalled the engine.  

A restart would have worked in this case and he could have flown it back under power.   Changed the code to hold off A/D conversions during spark events and no more problems.  The CD ignition was modeled after a SAAB patent and the coil I designed (in that one photo on the web page) could create as much as 300V even at 8V during very cold poor battery cranking.  

The original ignition system (no injection) used dual PIC controllers and sparked the exhaust stroke as well as the compression stroke which is why the one photo shows 4 ignition coils.  That was all a long time ago now when we still had to use UV Eraseable EPROMs.


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## Susquatch (Nov 26, 2021)

jcdammeyer said:


> That was all a long time ago now when we still had to use UV Eraseable EPROMs.



Hey, you say that like UV Eraseable EPROMS were a bad thing! They were AWESOME compared to the non-eraseable one-time ROMs and going back a bit further still the cold bootstraps that came before that! 

Ah yes, the memories......


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## jcdammeyer (Nov 26, 2021)

This was the precursor to what is now an Arduino.  Monitor program in Mask ROM.  Expansion bus with EEROM and 32K RAM added an RTOS I wrote and a Tiny PASCAL Interpreter written by the late Ian MacKay that could create tasks for the RTOS.  

But the ability to flash code via serial/USB to a processor with more memory wasn't available for 20 years.  We also had a 3 channel quadrature encoder card.  12 bit A/D card.  But made in Canada means it would never compete with made in China.


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## Susquatch (Nov 27, 2021)

jcdammeyer said:


> This was the precursor to what is now an Arduino. Monitor program in Mask ROM. Expansion bus with EEROM and 32K RAM added an RTOS I wrote and a Tiny PASCAL Interpreter written by the late Ian MacKay that could create tasks for the RTOS.



I can't believe you kept all that stuff. I pitched all mine about 20 years ago in a big fit of anti-nostalgia. Then I pitched again about 10 years ago when we moved to the farm. I think what hurt the most was the s100 boards - especially all the a/d & d/a stuff. But then again, now you can get an add-on package for a tablet or laptop that will do all that better and faster for much less.

Out with the old, in with the new?!?!


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## jcdammeyer (Nov 27, 2021)

Susquatch said:


> I think what hurt the most was the s100 boards - especially all the a/d & d/a stuff. But then again, now you can get an add-on package for a tablet or laptop that will do all that better and faster for much less.


I still have all the old S100 boards and a couple of boxes along with my PERSCI 8" drive.  An original 8" Turbo Pascal Disk etc.  Probably about 10 years ago I tried to boot once of the machines and the disks no longer read.   The graphics cards, including my wire wrapped video board are all worse than a Raspberry Pi or Beaglebone so the reality is I should really just put the stuff up on EBAY.  Hard to let go and yet I know I won't do anything with it.  

What I have on hand, like the dsPIC30F5011 based modules that I designed and built are way more powerful than an entire S100 mainframe.  Funny eh?  One of those to control my power draw bar.  Here are 3 of them.  The gold box xIM are the PIC based units.  BIM has analogue, PWM, CAN bus, RS485, Relay drivers, and is set up for 0-36V input measurement along with thermister measurement.  The B stands for Battery Interface Module and it started life as a BMS for large batteries.  The other one is a GIM for Generator interface and controlled an ONAN diesel Genset with a small plug in board and that's what I'm using for the Power Drawbar.    There is one more version not in the photo that has 6 more relay drivers and some I/O plus RS232 all on the RH connector instead of the A/D inputs.

Finally the white box (xMU) has another 16 bit processors (9S12) and has 5 CAN bus channels, 6 relay drivers, 6 dry contact to ground inputs, USB and an internal add on board with Real time clock and micro-SD for logging.  The xMU one was designed in 2009 and initially a Rings Management Unit for the 2010 Winter Games in Vancouver.  Now i use it for other projects to talk to other CAN devices like Motors, BMS, Solar Chargers.


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## Susquatch (Nov 27, 2021)

jcdammeyer said:


> I still have all the old S100 boards and a couple of boxes along with my PERSCI 8" drive.  An original 8" Turbo Pascal Disk etc.  Probably about 10 years ago I tried to boot once of the machines and the disks no longer read.   The graphics cards, including my wire wrapped video board are all worse than a Raspberry Pi or Beaglebone so the reality is I should really just put the stuff up on EBAY.  Hard to let go and yet I know I won't do anything with it.
> 
> What I have on hand, like the dsPIC30F5011 based modules that I designed and built are way more powerful than an entire S100 mainframe.  Funny eh?  One of those to control my power draw bar.  Here are 3 of them.  The gold box xIM are the PIC based units.  BIM has analogue, PWM, CAN bus, RS485, Relay drivers, and is set up for 0-36V input measurement along with thermister measurement.  The B stands for Battery Interface Module and it started life as a BMS for large batteries.  The other one is a GIM for Generator interface and controlled an ONAN diesel Genset with a small plug in board and that's what I'm using for the Power Drawbar.    There is one more version not in the photo that has 6 more relay drivers and some I/O plus RS232 all on the RH connector instead of the A/D inputs.
> 
> Finally the white box (xMU) has another 16 bit processors (9S12) and has 5 CAN bus channels, 6 relay drivers, 6 dry contact to ground inputs, USB and an internal add on board with Real time clock and micro-SD for logging.  The xMU one was designed in 2009 and initially a Rings Management Unit for the 2010 Winter Games in Vancouver.  Now i use it for other projects to talk to other CAN devices like Motors, BMS, Solar Chargers.


Pretty sure I still have a few old 8" drives too. But I knew even at the time that they would only be parts for other stuff. When you watch tape drives turn into way bigger 5.25 drives with 8" coming in the side door but never making it into the regular stuff because way bigger 3.5 stuff was arriving and then the first hard drives doubling every year and look where we are now! Omg! Bigger drives just empowered bloat ware. 

And here we are - two old dinosaurs lookin at the kids and sayin - if you only knew where I have all been....... 

Too bad the tree tops don't taste so good anymore......

I have no regrets. 

Do you really think you can sell that stuff on ebay? I may have to open some of those drawers and start selling some of it. Better that then the kids and wife just trashing it when I leave this playground.


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## jcdammeyer (Nov 27, 2021)

> Do you really think you can sell that stuff on ebay? I may have to open some of those drawers and start selling some of it. Better that then the kids and wife just trashing it when I leave this playground.



It's become a bit of a nostalgic hobby for some.  S100 Parts or from Bulgaria S100 in Bulgaria


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## YYCHM (Nov 27, 2021)

Susquatch said:


> Bigger drives just empowered bloat ware.



Boy... Ain't that the truth.


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## jcdammeyer (Dec 30, 2021)

I heated up the 3/8" drive part of the deep socket to yellow and then let it cool slowly.  No problem drilling and tapping now even if I did accidentally make the hole a bit too far down.  The socket did not discolour down to the 12 point drive part so I'm going to guess it's still reasonably hard.

Next step is a sensor for tool down so the wrench isn't started until the socket is all the way onto the drawbar bolt.  Then look at a new drawbar bolt head that can be hardened so it can't wedge the socket by deforming.  

More with pictures when I have them.


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## jcdammeyer (Jan 17, 2022)

No matter what I do to the top of the draw bar the 12pt socket still can jam onto the draw bar head.  The head is just too soft. 




And I now see that the head was either welded or glued or threaded onto the draw bar shaft.




The metal is very soft so I tried heating it to orange/yellow with the torch and quenching in water.  That didn't work.  Still soft.  I can pull down against the springs by hand (no air pressure attached) and just that action can jam the socket onto the head.  

To prevent rounding the nut and random carving of the head I added a second hall sensor on the other post and magnet attached to the cylinder body to sense when the draw bar socket is down all the way.  Tweaked the software to deal with that and if not all the way down then go back up and blip wrench and try again.  Problem there is now that the socket is sticking to the draw bar head it brings the unloaded draw bar up with it so that's not working.  If the drawbar is attached to a collet then the socket can be pulled really hard.  It was coming off but I've fixed the retainer so that works better.  

Next step is to somehow attach a 12mm bolt from Home Depot (with the 19mm head) onto the draw bar.  It's definitely harder than what's there.  If that doesn't work I'll look at some oil or water hardening stock and make something really hard.


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## jcdammeyer (Jan 17, 2022)

So I've cleaned up the draw bar head yet again to look as much as possible as a standard 12mm bolt and I also turned a spacer to bring the bolt up high enough so that the head is in reach of the draw bar at the lowest position.

Using the bolt and spacer I cannot, no matter how hard I try, get the bolt to stick in the socket.  On the third try once again the draw bar did get stuck.  The teeth in the socket just deform/deflect the metal enough to cause it to stick.

The spacer is aluminum.  (A piece of left over sprue from casting).  In real life it would be steel.  The problem is how to connect the draw bar to this bolt and the steel spacer.  

Ideally I'd buy a piece of 1" diameter water or oil hardening steel and create a combination bolt head and spacer like what appears to be on the original drawbar.  But something that is actually hard after heating and quenching.  I did try that with the original draw bar bolt but it didn't get any harder or softer after heating and quenching.  

It looks like the original was threaded onto the shaft but I can't see how they locked it on.  Heating to orange and quenching should have broken any sort of loctite bond.  

I don't want to weld directly onto the bolt head so that the hardness isn't changed.   One idea I had is to drill and tap say 5/16" through the middle of the bolt cutting off the 12mm threaded part.  Then take another drawbar I built and thread the end 5/16. to screw into the bolt.    Then slide on a spacer without the shoulder.  Maybe even with a V groove on the bottom.  Weld the junction between the bolt, the drawbar and the spacer and build it up enough so that when turned down becomes that shoulder to center the bar in the spindle.  That also allows the lathe to make the bottom face and shoulder of the drawbar concentric to the rest of the drawbar and spindle.

Suggestions?


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## Susquatch (Jan 17, 2022)

jcdammeyer said:


> So I've cleaned up the draw bar head yet again to look as much as possible as a standard 12mm bolt and I also turned a spacer to bring the bolt up high enough so that the head is in reach of the draw bar at the lowest position.
> 
> Using the bolt and spacer I cannot, no matter how hard I try, get the bolt to stick in the socket.  On the third try once again the draw bar did get stuck.  The teeth in the socket just deform/deflect the metal enough to cause it to stick.
> 
> ...



Maybe all dumb ideas, but.... 

Have you considered a bar and slot instead of a nut and socket? That would eliminate the jamming totally. No sensors required either. 

Another similar option would be an electric clutch. Again, no need for a nut and socket.


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## jcdammeyer (Jan 17, 2022)

Susquatch said:


> Maybe all dumb ideas, but....
> 
> Have you considered a bar and slot instead of a nut and socket? That would eliminate the jamming totally. No sensors required either.
> 
> Another similar option would be an electric clutch. Again, no need for a nut and socket.


Yes.  Been pondering that idea too if the socket solution isn't.   The clutch solution ends up being too expensive both in labour and parts.  

So I did a bit more work tonight.  The original Drawbar nut is threaded on but I was only able to break it free and turn it about 8mm before the other end looked like it was chewing up the thread.  Very difficult to put back together.

So I looked at my original replacement drawbar that had the WUT under it and decided to turn down the 3/8" threaded section to 5/16" and then thread it 5/16-18.  Do love my ELS for this.

I drilled first 1/8" then 'F' and tapped the 12mm bolt.  Boy that metal was hard.  Could tell by the clicking of the drill bit as the chips snapped off.  The tapping was like 1/8 or 1/16th of a turn and then back 1/2.  Once I had enough tapped I moved it out of the chuck, parted it off and back drilled 5/16" about half way.  Cleaned it up with counter sinks etc. and then threaded it onto the draw bar.

The idea here is that the next step is a bushing that is like the aluminum one but without the collar to center it in the spindle.  The 3rd photo shows the bolt head without a collar.  I was thinking that TIG welding the bolt head to the shaft and the collar to that with enough material built up and then turned down into being the centering collar.


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## Degen (Jan 18, 2022)

It looks (just from the picture)  like you are using mild steel for your draw bar and there are several issues with this.  First is your drive nut, too soft.  The second is elongation during use, this means it stretches when loaded and you bit holding suffers. The third with stretching it will fail, likely at the weakest point which is at the thread to shaft transition jambing the threaded portion in your R8 collet at best,  at worst doing it during a heavy milling operation and ejection holder, bit into the work piece and causing damage and potential injury in the process.

Heat treated 4140 would be a good choice after finishing.

The second thing is use a 6 point socket better fit and less damage to the nut.


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## Susquatch (Jan 18, 2022)

jcdammeyer said:


> Yes. Been pondering that idea too if the socket solution isn't. The clutch solution ends up being too expensive both in labour and parts.



I hear you. But you might be able to get a good used electric clutch at a lawnmower repair shop. The pulley belt drive system in most lawn tractors is usually clutched to the motor shaft.


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## Darren (Jan 18, 2022)

I am planning my own power drawbar setup. I'm going to get started if my linear bearings ever show up. Ive pondered a few ideas after looking at the various designs out there.

Kurt uses an E-Torx looking socket drive, with a male end on the drawbar, and a female socket on the gun. I'm sure they do this for positive engagement. When the drawbar wears, you replace it. Fairly spendy. I thought about making a new drawbar out of an 1/2" dr extension, or milling the hex nut portion to a 1/2" square and pinning a large 1/2" drive male torx bit socket  to it, then using an E-Torx socket on the gun, sort of replicating the Kurt setup, but with replaceable bits.  Something in the T55 range will easily take 40-50 ft-lbs all day and last for a long time. Snap On has a lifetime warranty...

I'm probably going to try a 12 point socket first, but if that doesn't work.


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## jcdammeyer (Jan 18, 2022)

Degen said:


> It looks (just from the picture)  like you are using mild steel for your draw bar and there are several issues with this.  First is your drive nut, too soft.  The second is elongation during use, this means it stretches when loaded and you bit holding suffers. The third with stretching it will fail, likely at the weakest point which is at the thread to shaft transition jambing the threaded portion in your R8 collet at best,  at worst doing it during a heavy milling operation and ejection holder, bit into the work piece and causing damage and potential injury in the process.
> 
> Heat treated 4140 would be a good choice after finishing.
> 
> The second thing is use a 6 point socket better fit and less damage to the nut.


This is the original draw bar that came with the House of Tools Mill.  Square head milled to be hex, 19mm.  Started with 6pt socket and it was even worse for lining up.  Consensus of the various users who have done this was that 12pt was better.  Seems 99% of the power draw bar systems used a manual lever to bring down the impact wrench onto the head of the draw bar and then pull the lever left or right for tighten or release.

They also don't care if they spin it too long since they either want the R8 tool to drop out or they want it to tighten with the impact wrench until it stops turning.  And if they are using TTS tooling then they use a much larger air cylinder to push down on the draw bar, compressing the springs enough so the draw bar moves down enough to let the TTS tool drop out.

In my case I want 1 or maybe two turns max for releasing TTS tools from the R8 collet leaving the collet loosely in place.  Tightening is the same as an R8.  

But I also want the option of holding the button down so that it turns long enough to drop or pull up a tool with R8.


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## jcdammeyer (Jan 18, 2022)

Susquatch said:


> I hear you. But you might be able to get a good used electric clutch at a lawnmower repair shop. The pulley belt drive system in most lawn tractors is usually clutched to the motor shaft.


If I went with a clutch system of sorts then I have to do a major redesign for connecting and holding all that.  And if I had to do that I'd rather replace the air wrench with a stepper motor and 25:1 planetary drive.  By my calculations 300 oz-in is 1.56 ft-lbs with 25:1 is 39 ft-lb.  From what I've read the max needed for R8 collets is about 20 ft-lb.   

So turn the stepper at slightly lower current until it stalls.  Then turn at same current much slower to do final tighten at a lower speed higher up the torque curve.  To loosen,  start with full current and turn slowly for 1.5 revs for TTS holders.  If I put an encoder on the back of the motor I can track by closing the loop.  Still use air to push it down.  If it doesn't go all the way down lift up, turn 1/24th of a turn and try again.  

If I close the loop with LinuxCNC I could ask LCNC to turn the spindle 1/24 of a turn since the spindle is run with a step/dir AC servo.  But I don't want to include LCNC in the tool change operation.... yet...

I think the stepper motor approach with 25:1 will operate very slowly thought.  But repeatably.


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## Susquatch (Jan 18, 2022)

jcdammeyer said:


> If I went with a clutch system of sorts then I have to do a major redesign for connecting and holding all that.  And if I had to do that I'd rather replace the air wrench with a stepper motor and 25:1 planetary drive.  By my calculations 300 oz-in is 1.56 ft-lbs with 25:1 is 39 ft-lb.  From what I've read the max needed for R8 collets is about 20 ft-lb.
> 
> So turn the stepper at slightly lower current until it stalls.  Then turn at same current much slower to do final tighten at a lower speed higher up the torque curve.  To loosen,  start with full current and turn slowly for 1.5 revs for TTS holders.  If I put an encoder on the back of the motor I can track by closing the loop.  Still use air to push it down.  If it doesn't go all the way down lift up, turn 1/24th of a turn and try again.
> 
> ...



I'm just throwing out ideas since you requested that.

The gist of my thinking revolved around your engagement issues. The easiest way to slaughter that problem is to eliminate it through permanent engagement. Its standard systems approach to solve problems by eliminating the steps or process that needs fixing. 

That said, it isn't where my heart is. I do have a 34 Yr career behind me primarily as an electronics systems guy. But in my bones, I am still an old fashioned DIY guy to the core. I'll just reach up and tighten the wrench however much I think it needs.


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## jcdammeyer (Jan 18, 2022)

Susquatch said:


> I'm just throwing out ideas since you requested that.


And I really do thank you for that.  

I too have been mostly in Electronics and Software for my career except for the 1 year at CJOI and 3 years at IBM repairing Selectric and other typewriters.  Back in Grade 8, Hillcrest Jr. High in Edmonton still had a decent shop class with lathes etc.  So different now for kids that age.

And it's true if I just had TTS and no R8 or only R8 and no TTS then this would be a simple project.  But in the long run I want an automatic tool changer just because I can. So the power draw bar has to be part of that.  That's why I'm also playing around with harmonic drives and planetary reduction systems for the various joints of a robot arm to handle the tool change.  Silly I know.  But something interesting to keep me busy.


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## Degen (Jan 18, 2022)

I've been thinking about your problem.  I suspect your problem is with the nut design in removing it without causing damage.

The nut should have a taper on it to allow the socket to slip on.

Additionally you may find most drawbars the nut is pinned onto the draw bar,  I suspect this is to ensure hardened nuts, further helping.

Finally consider doing a constant bleed through your draw bar drive system. Just spins the socket with no torque, power applied after full engagement.


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## jcdammeyer (Jan 18, 2022)

Degen said:


> I've been thinking about your problem.  I suspect your problem is with the nut design in removing it without causing damage.
> 
> The nut should have a taper on it to allow the socket to slip on.
> 
> ...


The nut on the drawbar that came with the mill is too soft.  Way too soft.  It's actually threaded onto the draw bar and then in some fashion, perhaps soldered or something.  I was able to back it off about 4 turns but then it jammed and the threads on the bottoms showed definite scraping.  But it's too soft anyway so doesn't matter.  A taper just makes the problem worse as it provides a nice ramp to jam into the socket and then hang there.  The 12mm bolt I bought at Home Depot is much much harder and there is no jamming.

I am now ready to take the updated draw bar assembly to a friend to TIG weld the pieces together.  Won't happen until tomorrow now.  The side effect of all this is I will end up with a nice shoulder that keeps the draw bar centered.

The constant bleed is an interesting idea although what I've found is if there isn't enough air, it just doesn't turn.  So it might be finicky.

If I handed control over to LCNC I could arrange to have a wrench push sideways onto the draw bar nut sensing if it's all the way on. If not have LCNC turn the spindle although there the problem is if there is nothing attached to the draw bar the wrench (like the socket does) holds the wrongly oriented nut still while the spindle turns.  Then use LCNC to twist the spindle to undo the draw bar.  A 2HP servo motor should be able to create more than enough torque, assuming the V belt doesn't slip.  

Might have to wait for toothed belt drive.  It never really ends does it.


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## Darren (Jan 18, 2022)

Thinking about this more, what about a dog clutch? Lovejoy coupler minus the rubber? Or even a beefy single tooth dog clutch?


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## jcdammeyer (Jan 18, 2022)

I still want the fall back ability to use a wrench.  And with my luck the dog clutch would also land tooth on tooth 50% of the time.   Ideally, an air cylinder pushes out a pin against the round part of the draw bar nut.  The spindle then turns slowly up to one rev until the pin locks in.  The the spindle turns as required to lock/unlock.  Not really a lot different then the larger tool holders that have that rectangular index to line up.  That's done gently too I think.

But it means I need access to the LCNC to use the system.  I was trying to keep in independent.  Also I haven't yet figured out, nor tried actually, the process of changing the spindle from a speed/direction with step/dir control to an absolute position control with step/dir.  Not even sure if the MESA 7i92H can do that easily.  I have the encoder and index on the spindle but...


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## Susquatch (Jan 18, 2022)

jcdammeyer said:


> Silly I know. But something interesting to keep me busy.



Absolutely not! I was NOT suggesting you should be happy with manual. I was just saying that would be my direction.

I am of the view that most of us do what we do because WE WANT TO! It doesn't have to make sense, be cost justified, etc etc. We can all justify things from time to time, but it need not be a requirement. We all ought to be able to say that we want to do something just because we do. No explanation required. Simple as that.

Ps - I have a few similar projects on the go. I'm doing them because I want to. No other reason. Nuff said.


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## jcdammeyer (Jan 18, 2022)

Susquatch said:


> Absolutely not! I was NOT suggesting you should be happy with manual. I was just saying that would be my direction.


I never took it that way.  Sorry if my reply gave that impression.


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## jcdammeyer (Jan 20, 2022)

A friend TIG welded on the spacer and bolt along with building up the shaft for the spindle register.  And then I machined it to size.  Since it had gone orange during welding and cooled slowly the hardness on the bolt head was gone which of course made the assembly easier to machine.  I then heated it up with my biggest oxy/acet torch and overheated it enough to actually distort the flats on the bolt head.  Stupid.  Once quenched and tempered the bolt head is quite hard but needed grinding to get rid of the melted distortion I caused.

I then played around with the drawbar.  Socket doesn't stick but for various reasons is tight enough to hold onto the bolt head and then pull the socket off the wrench.  I'll have to pin the socket to the wrench better.  This is starting to look like a lost cause.  

Have to take a few days and rethink this...  Very disappointed.


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## Susquatch (Jan 20, 2022)

I feel your pain.

If you are stepping back and rethinking, how about a whole new driver system that uses the hardware you have (assuming it fits or can be made to fit).

Instead of a nut and socket, make a dog clutch of your own. Either small like the ones on a mill spindle, or as big as you want. Personally, I prefer round pins in one plate and round holes in the other. Pins can be rounded at the ends to ride the plate smoothly and enter the holes easily at low speed. Your sensor system would still know when they are engaged. Lots of clearance in the size of pins and holes would make for easy engage/disengage action. Might need as few as 2  pin/hole pairs, but I'd go for 4 and keep it small.


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## Tom O (Feb 2, 2022)

Here’s a thought pick up a switch to control the air pressure and position it to allow air passage only after the nut is on the drawbar say at least 1/2 or fully engaged.


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## Degen (Feb 2, 2022)

jcdammeyer said:


> A friend TIG welded on the spacer and bolt along with building up the shaft for the spindle register.  And then I machined it to size.  Since it had gone orange during welding and cooled slowly the hardness on the bolt head was gone which of course made the assembly easier to machine.  I then heated it up with my biggest oxy/acet torch and overheated it enough to actually distort the flats on the bolt head.  Stupid.  Once quenched and tempered the bolt head is quite hard but needed grinding to get rid of the melted distortion I caused.
> 
> I then played around with the drawbar.  Socket doesn't stick but for various reasons is tight enough to hold onto the bolt head and then pull the socket off the wrench.  I'll have to pin the socket to the wrench better.  This is starting to look like a lost cause.
> 
> Have to take a few days and rethink this...  Very disappointed.


I might suggest you look at one of our other members work, why reinvent the wheel when its not going in the right direction https://canadianhobbymetalworkers.com/threads/darrens-active-projects.4418/post-65106


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## jcdammeyer (Aug 16, 2022)

Back in February I took a break from the power draw bar project once I realized the butterfly wrench wasn't suitable for slow release once the load is gone.

Today I picked up an electric 3/8" ratchet good to 22 ft-lbs from Princess Auto.



I tried it and it really does tighten up well and once loose since max speed is less than 4 revs per second it's easy to stop it bore the R8 collet drops out while I'm catching the TT holder.

But, it also tightens so well that I wasn't able to break it loose with my 1/2" torque wrench set to 22 ft-lbs because the spindle servo motor just can't handle that.   

I don't currently have a WUT under the nut so I can't hold back the turning of the spindle.  I think in the long run some sort of spindle lock is warranted.  Underneath this plate I have access to the splined spindle shaft and I believe if I make a pivoting toothed lever I can use a solenoid to push it into place which will lock the spindle and then be able to easily tighten/loosen the draw bar.

As before I'll have two options (I have them now but the butterfly doesn't listen well).  A quick press on the release or load button turns the nut a max of two times or until it stops turning.  A hold down on the button causes continuous operation for up to 5 second or when button is released.  This is to let the entire R8 assembly come out.  (Software is the easy part).

The hardest part is going to be the reversing.  The ratchet does that (being a ratchet) with a knob on the top.  I just want to change the direction of the motor so I may have to figure out a way of locking the ratchet so forward or back create the same motion.  However, the internal part of the electric ratchet sounds more like an impact wrench so it may not be the solution.

Works real nice right now for manual tool changes.


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## PaulL (Aug 16, 2022)

It feels like I'll be duplicating your setup.  I'm just too short to keep dealing with my drawbar manually.


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## jcdammeyer (Aug 16, 2022)

Here's my idea for a spindle lock.  I think if the gap is big enough between the plate and the spindle teeth the pivot point doesn't need to be too far away.  Mill out of 3/8" thick aluminum.


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## PaulL (Aug 16, 2022)

And throw a solenoid on the other end?


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## jcdammeyer (Aug 16, 2022)

PaulL said:


> And throw a solenoid on the other end?


Yup.  And an NC micro switch with the Spindle Enable signal in series with it.  So when the switch opens as the bar moves away it prevents the mill from turning but also release the hold the spindle motor has on the spindle (AC servo with step/dir so it stays put normally).  That allows whatever turns the draw bar but to rotate the spindle enough so it latches and then spindle drive is disabled.

I could rotate the spindle until the lock seats but the idea is to be able to use this manually without the CNC control if I need to.


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## jcdammeyer (Aug 16, 2022)

OK.  Spray glued the 1:1 print of the drawing onto cardboard.  Gee I hate spray glue.  Trimmed it to the lines and then started trimming away until it fit underneath.  Once I pulled the cover I found I'd have to do some more trimming but for now I just raised it above the recess.  I already had two holes in line with the spindle center line (approximately).







Then laid it back onto the mill.  Raised the quill back up and moved the cardboard back and forth to engage and disengage the lock.  I think an eccentric pivot might be useful to line it up perfectly.

Here's a top view with the cover laid in place and the lock pivoted into engagement.  Takes very little movement to pull it out and clear of the splines.






You can see how the entire lock mechanism could be shifted to the right a millimeter or so but then the spindle could also be turned a bit.  It's very close.  I think a spacer under the flying end so it sits proud.  Easier to attach spring and solenoid.

Anyway, just rambling out loud.


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## jcdammeyer (Aug 17, 2022)

Progress.  In the next few days I'll try a dry run and then cut out the part.  I've set it up to use a 6mm cutter and that will likely make the teeth too rounded but since I'm only making one a file will fix that detail.


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## Degen (Aug 17, 2022)

Great concept and idea, unfortunately this won't work on my mill.  But I'll keep watching as it might give me a good idea.


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## jcdammeyer (Aug 25, 2022)

Bit the bullet this evening and ordered a 25:1 planetary reduction drive.  With the DC motor I have on hand I theoretically should be able to apply the holding torque (25 NM) on a TT Holder in about 2 turns.





This should be reasonably easy because I've been there before.  This photo shows a CAN bus controlled DC Servo coupled through the 3D printed holder to a 100:1 reduction drive and then a worm drive to move the lever up in less than 30 seconds.  The key part here is that it moves in velocity mode but snugs up to the upper stop or the stowed stop using torque mode.  Just enough to press hard but not break anything.  The photo is of the simulator.  Sorry I can't show the real end product; only the simulator.





It's not that different from what I want to do.  Turn for a distance X at full speed and a specific torque value.  When it is no longer turning at torque Y then stop.  That's for tightening.  To loosen if it's a TT holder then set distance to 2 turns after the reduction drive and set torque to max.  Decelerate to a stop at distance 2 turns.  If it's an R8 tool then set distance to more like 16 or 18 turns. 

In the case of the draw bar I have the up down motion to deal with.  If it doesn't go all the way down then bring it back up, turn 1/12 of a turn and lower to line up with the flats on the draw bar.  Or something to that effect.

No idea when this will arrive.  Lots of projects on the go so no lack of anything to do.


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## jcdammeyer (Aug 25, 2022)

One of the sites I spend time on occasionally has a thread for supporting the UHU DC Servo drives.  A bit of background.  Uli Uber (sp?)  in Germany designed a DC servo drive driven by an 8 bit Atmel processor (around 2005)  He also published the schematic and circuit board layout and a number of people around the world built some boards.  I bought one from Manjeet in India.  To make the boards work you had to buy the processor and crystal from Uli for the price of a beer or thereabouts.    Here's mine.





It worked well enough that a guy with the id Kreutz took the design and redid it to handle much higher voltage and current along with both a continuous and max current setting.  Still used the same processor from Uli.  Requries 15V and of course whever high voltage you might want for the motor.  The encoder circuit was now also differential to combat noise.  I had two of these set up on my mill for X and Y until discovered that the X motor had issues and kept loosing steps.  Which is why it's nice to keep the DRO on the machine even if you go CNC.  The one mistake I made was using the wrong polarity on the DB-9 for terminal communications.  It's optically isolated too so it needs that USB connector for the PC side 5V.





The next step in this project was done by Henrik Olsson in Sweden.  He developed a little companion board with a PIC18 that had quadrature encoder support so that higher res encoders running at higher RPM could be used.  He wrote his own code which he claimed was less sensitive to encoder noise because of the hardware QEI.   Because of my X axis losing steps issue I bought a couple.






That cleaned up most of my problems but every once in a while the HP_UHU still had issues so eventually I moved to the Bergerda AC Servos since the cost of a replacement motor was the same as a 400W servo with drive and no power supply was needed.  And because I was in the market for a 3 phase spindle motor and VFD I checked the price of that verses a 1.8kW AC Servo and the two motors with drives ended up being cheaper.

So why the story?  Well Kreutz vanished for a while but recently returned to the UHU forum.  And chatting with him about my issues with wanting a constant torque mode for my Draw Bar he found this thread on the forum.





						Stepper-Driven Power Drawbar
					

Last night, thanks to some prodding from a friend, I finally got off my lazy a\\\$\\\$ and designed up the stepper-driven power drawbar I've been wanting



					www.cnczone.com
				




Seems this fellow, Ray Livingston,  has done the same thing that I wanted to do except he's using a 400 oz-in stepper, 55:1 planetary reduction, a Gecko stepper Drive with a relay to change motor current by adding in a resistor.  Way back in 2012.

From the video it appears to work quite well.  He's not posted anything since unfortunately.  I've only ordered a 25:1 planetary reduction but then he's got the potential of 110 ft-lbs which is a tad high.
ie.  400 oz-in divided by 16 oz/lbs and 12"/ft is 2 ft-lbs static torque.  With 55:1 that's a lot of static torque for a drawbar that doesn't need more than about 20 ft-lbs.

Finally to add one more thing to this story, Henrik Olsson is willing to help me update his code to a dsPIC that has hardware quadrature, PWM and CAN bus.  A new module will be built that will replace the comparators used for detecting over current.  With that, the ability to duplicate the german servo motor I used in that project I described in the previous posting will be possible.

Anyway.  That's about it on this for now.  Next step is to machine up a Size 23 mounting plate for the surplus PA motor in the first picture.  Then do some testing to see if it's got the torque to do what I want while I wait for the reduction drive.

edit:  The motor in the previous posting was French not German.  https://sonceboz.com/en/


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## Degen (Aug 26, 2022)

Learned a lesson a few days ago.....bruised thumb and ego, broken butterfly wrench, bent drawbar nut, and socket thrown across the shop.....

Phone call during tooling change, left butterfly wrench on nut on mill to answer important call...started machine after call....butterfly wrenches aren't balanced trying to get up to 3000rpm....

Lesson learned, nothing seriously broken or no major injuries.

Now I will build a drawbar wrench with prevent that from happening again.


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## jcdammeyer (Aug 27, 2022)

Here's a commercial version very similar to what I'm building.








						Power Draw Bar for Torus PRO
					

Increase the versatility of your milling machine by adding a Power Draw Bar (PDB). Exclusively designed for the Novakon mills, this device will quickly load and unload all of your QTC style tooling in a snap. No more spring washers and tools slipping. The uniquely designed motorized torquing...




					www.novakon.net


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## jcdammeyer (Aug 27, 2022)

So for now I've put the existing power draw bar aside while I wait for the planetary reduction and do some upgrades to the servo motor and drive.
Still need to be able to tighten and loosen the tools though.  And without a spindle lock which is in the works I'm back to using the WUT.
I enlarged it on the lathe to 16mm ID so the shoulder on the new draw bar nut would fit through.  Visible in this photo.  The actual drawbar hex head is a grade 8 bolt, annealed and drilled,tapped to thread onto the shaft.  Then welded onto the shaft along with the larger round base.




The original that came with the machine (square head now machined as hex) was so soft the impact wrench rounded it pretty quickly when it rammed on crooked.    This shows what I wanted before I made it out of steel and welded.




Now the rounded part was from 1" steel so too large for the 24mm wrench.  Thank goodness for carbide inserts.  The nut assembly after hardening was hard.  But now the 24mm wrench fits over that and anchors the WUT to prevent it from turning while the 19mm box end turns the draw bar. 





Now that I can mill again, I can cut out the spindle lock and make the DC Motor mounting plate.


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## jcdammeyer (Aug 27, 2022)

BTW, this is the sort of thing that was happening with the original draw bar and even now occasionally but with less force on the new one.  
The pneumatic force pushing it down was fast enough and hard enough to not make the draw bar or socket turn but instead just jam on.
Humans are far more gentle and they will subconsciously wiggle things to get them to slide together.


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## Degen (Aug 28, 2022)

I find using the butterfly wrench that I don't need to lock the spindle to turn the draw bar, current on some holder still need to give it a tap to get the holders to let go.

I'll address it with a nut stop which will not allow the nut to rise and forces the holders down.

I am going to keep the auto/manual wrench simple to avoid failure points.


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## jcdammeyer (Aug 28, 2022)

Degen said:


> I find using the butterfly wrench that I don't need to lock the spindle to turn the draw bar, current on some holder still need to give it a tap to get the holders to let go.
> 
> I'll address it with a nut stop which will not allow the nut to rise and forces the holders down.
> 
> I am going to keep the auto/manual wrench simple to avoid failure points.


I also find that with the AC Servo Motor holding the current position that the spindle is sort of locked for the butterfly.  But with wrenches the pulley spins in the V belt.  I imagine once I have toothed belts it will be better.  But the torque on a 2 HP motor is way lower than the 20 ft-lbs for an R8 Collet so it would still be easy to spin the motor.  Hence the need for a spindle lock.

Look at the WUT article in HSM by Rick Sparber what he did


			Drawbar with Integrated Spindle Lock
		


One option is capture the WUT onto the spindle and have a shoulder on the draw bar.  So now when you turn it CCW the drawbar can't go up so pushes the collet downwards.

I find if I center drill, pilot drill, tap drill, clearance drill and finally tap that I've done 5 tool changes.  And since my TT holder with the jacobs chuck is only good to 1/4" (should really order a 3/8") that the tool changes are more involved.
Tool #1 Center Drill
Tool #5 Jacobs chuck with pilot drill.
Tool #5 again for the other two drill bits although the clearance drill bit is often in a TT ER collet.
If the drill is too large then TT 0.75" R8 collet comes out and in goes the big ball bearing drill chuck.
Then out again for the 3/4" TT Holders and Tool #10 for the tap.

If I've done face milling on the part before I drill the holes then the 3/4" R8 TT Collet comes out for the R8 4 carbide cutter face mill.

Then the 3/4" R8 goes in again.

Now I'm really tired...


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## Susquatch (Aug 29, 2022)

jcdammeyer said:


> Look at the WUT article in HSM by Rick Sparber what he did
> Drawbar with Integrated Spindle Lock



My round column mill drill clone has the WUT arrangement on it. It looks original. I've had it since 2012 and it was well used when I got it. I think the idea is WAY WAY older than Sparber's article. 

I improved on mine by adding a centering locator button on the washer to reduce drawbar rattle. 

I also added the centering button to both BPorts I had here. It was a little tricky to do because the thread on the drawbar of both mills is rolled not cut. I solved that problem by threading the washer and button and then drilling out the threads to the OD of the bar so they thread on at the bottom of the bar and then slide on to the top. 

My draw bars don't rattle anymore. 

Of course, the BPort and its clones have a spindle brake. 

What does TT mean in your write up? 

Should WUT and TT be added to the Acronym thread or are they so rarely used as to suggest not using them at all?


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## jcdammeyer (Aug 29, 2022)

Susquatch said:


> My round column mill drill clone has the WUT arrangement on it. It looks original. I've had it since 2012 and it was well used when I got it. I think the idea is WAY WAY older than Sparber's article.
> 
> I improved on mine by adding a centering locator button on the washer to reduce drawbar rattle.
> 
> ...


His original article was in Home Shop Machinist.   The photo of mine is from 2007.

TT stands for "Tormach" Tool holder.  The shank is 0.75" and the R8 0.75" collet is ground flat instead of rounded.  The back end of the holder has a recess for the little bit of R8 collet that sticks out.  As the collet is pulled up into the spindle it seats the back of the TT holder against the spindle.  

This makes inserting a tool repeatable from a length perspective.  So on each tool change you don't have to change the Z axis zero position.  That's done once and the value entered into the tool table.

Now when I do a tool change for #1, the spot drill I use a feeler gauge or piece of paper to find the zero on the work piece.  Since #1 doesn't have a length I set the machine Z zero to that.  Then go ahead and spot drill the holes. 

Next tool change is #5.  I insert it and because there is a length in the table the machine Z zero had now been 'adjusted' for the longer drill bit so the g-code assumes Z is still set to the surface of the plate.
For example:  (I've added comments to describe what is happening)
(Standard 3mm Drill )
N2 T5 M06 G43  (Change to Tool #5 by moving to Tool Change position and use Tool Z offset)
N3 S2000 M3     ( Turn on Spindle motor to 3000 RPM).
N4 G0 Z2.4409   ( Move Z to 2.4409" (62mm) above work to avoid  and clamps.)
N5 X-1.1404 Y-0.6299 (Move X,Y to the first hole to drill)
N6 G83 X-1.1404 Y-0.6299 Z-0.4278 R0.0984 Q0.0965 F3.4  (Peck drill the hole)
N7 G80  (Cancel the canned drilling cycle)

The G83 parameters are explained here:


			G Codes
		

The G-Code was created automatically by AlibreCAM (AKA Mecsoft CAM)

When the power drawbar is working properly all I do when it pauses at the tool change position is tap the release button and catch the tool.  Then hit enter on the PC keyboard.  I think I posted a video showing that operation earlier spot drilling, drilling and tapping into a piece of oak.


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## Susquatch (Aug 29, 2022)

jcdammeyer said:


> His original article was in Home Shop Machinist. The photo of mine is from 2007.



The article you linked to was dated Nov 2006. My mill drill is way older than that. Just trying to say that Sparber didn't invent that idea. 

But it is a good idea. 

Your work is awesome. I'm jealous. Although my equipment will never be CNC, it's very cool to follow what you are doing.


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## jcdammeyer (Sep 10, 2022)

So time to make the two adapters for the stepper motor planetary drive so I can turn a socket.





Start with the raw materials.  In this case 2" steel bar.  Two pieces.   




Dew point has risen in the shop by one degree since it's also pretty warm outside.


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## jcdammeyer (Sep 10, 2022)

Since I'm getting forgetful I thought I'd make up a drawing that outlines the machining operations for turning the socket driver part of this hub.  (The blue one). 

If it seems like I'm doing something dumb please do let me know.


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## jcdammeyer (Sep 12, 2022)

This evening my wife threw the stuffies around so our dog was distracted and wouldn't cry at the shop door so I had a few hours to play.  This HRS sure tears and doesn't turn well.  I'm even using carbide and 0.025" deep cuts 

1. Flatten both sides of the disk I cut off.  
2. Turn a 9/16" hub and then mount in collet
3. Turn to the correct width and create the registration edge
4. Looks almost like the drawing.

The 14mm hole depression on the one side is just in case the motor shaft (also 14mm) has to protrude a tad.

Next chance to do something will maybe be Wednesday and then I can do the other hub which will have the 14mm hole and 5mm key.  Need to make a broach holder yet.

Final operations will be the 4 holes drilled 5mm in this hub and threaded for 5mm screws in the second hub and cutting the 9/16" round hub into the 3/8" socket driver.


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## Susquatch (Sep 13, 2022)

jcdammeyer said:


> Since I'm getting forgetful I thought I'd make up a drawing that outlines the machining operations for turning the socket driver part of this hub.  (The blue one).
> 
> If it seems like I'm doing something dumb please do let me know.



Sorry I didn't see this earlier. We had a nephews wedding this weekend. I just looked at your drawing now. It looks good to me. Very cool to do an order of ops like that. 

My only question is the shallow drilled hole. Why so shallow? Also, why did you choose to drill? For shallow holes like that, I'll often use an end mill because it creates a flat bottomed hole that can then be bored to size. 

Obviously, if the bottom of the hole doesn't matter, a drill is fine. I'm really only pointing out that an endmill can be used to achieve a flat bottomed hole.


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## jcdammeyer (Sep 13, 2022)

Susquatch said:


> Sorry I didn't see this earlier. We had a nephews wedding this weekend. I just looked at your drawing now. It looks good to me. Very cool to do an order of ops like that.
> 
> My only question is the shallow drilled hole. Why so shallow? Also, why did you choose to drill? For shallow holes like that, I'll often use an end mill because it creates a flat bottomed hole that can then be bored to size.
> 
> Obviously, if the bottom of the hole doesn't matter, a drill is fine. I'm really only pointing out that an endmill can be used to achieve a flat bottomed hole.


Shallow because I didn't want to take away strength from the 3/8" driver part.

Funny you should mention that.  After the drilling and realizing the boring wasn't going well, I took a 1/2" mill and made the initial hole deeper.  Then opened it out to 14mm.   It wouldn't have had that dimple.  I'll change my instruction sheet.  

Other part won't matter because the hole is all the way through.


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## jcdammeyer (Sep 14, 2022)

Haven't added the adapter or even a socket to the assembly yet but it's clear the current one for moving the impact wrench up and down is totally not what I need.

Going to have to rethink this I think.  Push the motor assembly up from the base rather than down from the top since the planetary mount face is at the other end of the butterfly wrench.

The attached pdf is the 3D type that you can click on and then rotate to look at it from all angles but you'll have to download it to get that feature.  Doesn't do it from the web browser.


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## jcdammeyer (Sep 23, 2022)

Back to this thread from the Broach and Broach guide examples.
The socket driver is complete




and fits onto the motor+planetary drive perfectly.




I tightened up the draw bar with a torque wrench to 220 inch-lbs which is about 18 ft-lbs.  That's about what I end up setting it to with a wrench.  I put a wood working clamp on the motor so I could hold onto it and then jogged counter clockwise.   The assembly had no trouble loosening it.

Max step rate from the ELS is 20,000 steps per second.    Set up to have 1600 steps per rev and turning the 25:1 drive means it takes 40,000 steps to make one turn of the socket.  That's two seconds per rev from the motor turning 750 RPM which is about max before a stepper starts to see torque drop off to the point of being useless.

But I think this will work.   
A few things though:
I made the 3/8" drive nub the same length as the torque wrench or ratchet I really should have made it longer.  The hole in the socket for capturing the drive isn't in the right place.  So it looks like I should make a new one with a longer piece.

Backlash on the mill is still an issue even though I  believe I have the correct amounts into LinuxCNC.   It doesn't locate the center of a part using my touch probe as well as I'd like.

Oh and cutting the soft steel nub was done at 1150 RPM,  F4 feed rate and 0.015 depth of cut over the length of the nub done with a 0.25" ball mill.  

Now to start on a new frame design that will hold this motor drive assembly.


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## jcdammeyer (Sep 24, 2022)

Turns out it wasn't only backlash.  I either forgot or assumed that my probe was calibrated.  Turns out after I went through the calibration procedure I found it was out by about 0.010".





Once I did that I put a 1-2-3 block into the vise and used the LinuxCNC VersBy screen to find the center of the 1-2-3 block.  From the LinuxCNC perspective the edges are now in the correct spot.  From the Shumatech DRO the Y is good but the X is still out about 0.002".  I'm guessing that the backlash adjustment for LinuxCNC is out a hair.

Time to do some more testing there but for now I've clamped a piece of casting sprue turned to just over 2" into the vise.  I'll see how the CNC approach works on this test piece.


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## jcdammeyer (Sep 25, 2022)

jcdammeyer said:


> Time to do some more testing there but for now I've clamped a piece of casting sprue turned to just over 2" into the vise.  I'll see how the CNC approach works on this test piece.


I did try the aluminum but this casting sprue is so soft and gummy and I was running the CAM generated for steel, so way too slow.  I still think it's easier to turn a hub on the lathe first and then square that.


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## jcdammeyer (Sep 25, 2022)

Because the 3/8" drive hub is a bit short it's been suggested that I just weld to the top of it and built it up a bit.  Then machine it back to size.  That should give me the support for the retaining hole and screw.

Today I just spent tidying up and vacuuming up chips.  The pile of steel ones on the lathe and mill were way to sharp to leave lying around.


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## PaulL (Sep 25, 2022)

jcdammeyer said:


> Because the 3/8" drive hub is a bit short it's been suggested that I just weld to the top of it and built it up a bit.  Then machine it back to size.  That should give me the support for the retaining hole and screw.
> 
> Today I just spent tidying up and vacuuming up chips.  The pile of steel ones on the lathe and mill were way to sharp to leave lying around.


Gotta say my world has been getting better through deeper shop cleaning.
Also, moving to better-machining steel has been helpful.  The difference between 12L14 and 1018 is night and day.  The 12L14 makes chips!  Just like the books claim!  I have some lovely 1018 razor slinkies from before figuring that out.


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## jcdammeyer (Oct 4, 2022)

A bit of progress last night.  I've spaced the guides further apart so the motor assembly fits between.  Flipped the air cylinder around so the ram will be fastened to the base rather than to the upper bracket.  Still need to design a new upper bracket to steady the guides and fit around the motor.


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## jcdammeyer (Oct 5, 2022)

Scale the drawing up by 1% to handle shrinkage.  Always a bit of a crap shoot, Add 3 degrees draft so it will pull from the sand.  Remove all the holes and slots. Then 3D print.

Still need to do the motor mount bracket pattern and print that.  Then fill, prime, sand and paint.  And wait for a bit damper weather before I pull the furnace out onto the driveway and cast.


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## Susquatch (Oct 6, 2022)

jcdammeyer said:


> And wait for a bit damper weather before I pull the furnace out onto the driveway and cast.



On the driveway??? 

I have this mental image of you on the driveway with the furnace running and the whole neighbourhood sitting across the street in lawnchairs watching, and wondering when you are gunna put the burgers on.


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## jcdammeyer (Oct 6, 2022)

Once I get the fume hood made (Project #42) I can go back to casting indoors.  For now the hose to the Natural Gas line is long enough for me to wheel the assembly outside the door.   The vehicle is parked in such a way and trees are along the driveway so that from the road nothing can be seen.
First photo is when the spark plug has ignited the gas but the fan is only turning slowly.
Second is after ignition the fan spools up to melting speed, the flame pulls into the furnace and spins around the crucible.
Third is pour is complete, ingots made from left over metal, furnace is closed and back on slow speed with gas solenoid now off.

Inside the shop that corner with the furnace is lined with the cement board used for shower stalls, then ceramic tiles.  That's also my welding corner.


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## Susquatch (Oct 6, 2022)

jcdammeyer said:


> Once I get the fume hood made (Project #42) I can go back to casting indoors.



You are truly a man of many talents. From S100 to ELS to casting. I am truly impressed. 

I enjoyed the neighbourhood image though......


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## Tom O (Oct 6, 2022)

You could pipe it outside like doubleboost has his giving you year round casting.


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## jcdammeyer (Oct 6, 2022)

That's the idea of the fume hood. Yhe vent is already there but things like insulation and vapor barrier and ceiling needs to be done first. Project #42.


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## 140mower (Oct 6, 2022)

jcdammeyer said:


> Project #42


Only #42?...... It's a long weekend coming up, what's keeping you back? .......... Slinking away to hide behind my own ever growing to do list.....


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## jcdammeyer (Oct 6, 2022)

140mower said:


> Only #42?...... It's a long weekend coming up, what's keeping you back? .......... Slinking away to hide behind my own ever growing to do list.....


I'm surprised no one has asked why every one of my projects is #42.


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## Doggggboy (Oct 6, 2022)

42 is THE answer to everything


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## 140mower (Oct 6, 2022)

jcdammeyer said:


> I'm surprised no one has asked why every one of my projects is #42.


...... I doubt many of us can count that high....


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## jcdammeyer (Oct 6, 2022)

140mower said:


> ...... I doubt many of us can count that high....


Try this then. 
A=1, B=2, C=3,... Z=26.  If you add together the numbers representing the letters MATH you get 42.


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## YYCHM (Oct 6, 2022)

jcdammeyer said:


> Try this then.
> A=1, B=2, C=3,... Z=26.  If you add together the numbers representing the letters MATH you get 42.



This was brought up before and I still don't get it.  What significant about MATH = 42?


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## jcdammeyer (Oct 6, 2022)

YYCHM said:


> This was brought up before and I still don't get it.  What significant about MATH = 42?


Math is the answer to life, the universe and everything.  At least according to "The Hitchhiker's guide to the galaxy".


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## PaulL (Oct 6, 2022)

jcdammeyer said:


> Math is the answer to life, the universe and everything.  At least according to "The Hitchhiker's guide to the galaxy".


And the question, apparently is "what is 6 x 9?"  The implication, then, is that god has 13 fingers.


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## Susquatch (Oct 6, 2022)

jcdammeyer said:


> I'm surprised no one has asked why every one of my projects is #42.



I noticed but just thought it was funny. Don't change. That's a joke that never gets old. I'll keep laughing.


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## jcdammeyer (Oct 6, 2022)

Anyway back to the draw bar...
Using the Alibre CAD I can create the parts and make sure there isn't any interference.  
Then take those parts, remove the holes, change a few dimensions and add taper so it will pull out of the sand for casting.
They are now 3D printed.  Next step is sand off the rough parts of the tapered posts.  Add filler and primer and make them smooth enough to pull.
Then cast.  Each plate is only just a tad thicker than 1/4"


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## Degen (Oct 9, 2022)

jcdammeyer said:


> Math is the answer to life, the universe and everything.  At least according to "The Hitchhiker's guide to the galaxy".


Throw yourself at the ground and miss.


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## jcdammeyer (Oct 9, 2022)

Degen said:


> Throw yourself at the ground and miss.


I do that all the time.  Doesn't everyone??????


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## 6.5 Fan (Oct 10, 2022)

The last time i threw myself at the ground i didn't miss. Damn it is still harder than my body.


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## jcdammeyer (Oct 31, 2022)

Found this video on a tool changer for a PCB drilling operation.  It's an upside down version of what I'm trying to do and has other features that don't apply to a draw bar.  

But overall the same idea that I'm pursuing now with the stepper motor and planetary drive for tightening/loosening.  And like his my plan is to change the amount of current to the stepper motor to change the torque so there is more for loosening and less for tightening.






John


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## jcdammeyer (Nov 29, 2022)

Yahoo.  My tool height setter arrived.  Not directly related to the drawbar project but for tool changing those few times where I need to use R8 instead of a TTS holder or if I put a different tool into a TTS holder and need to get the height of that into the LinuxCNC tool table.






Now to figure out where to wire it.


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## jcdammeyer (Nov 29, 2022)

Needless to say I almost dropped everything just so I could play with it.  Sensitivity is good.   The over travel N/C switch opens and could be put in series with the Z travel limit switch.

Here's it sitting on the mill table at the tool change position which is almost at the X and Y limit switches.


			http://www.autoartisans.com/mill/TouchProbe/TouchPosition-1.jpg
		


If I mount it there permanently I can see it will be constantly in the way.  Going to have to figure out some sort of fast attach method.


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