# Tool Post Grinder



## Susquatch (Dec 5, 2021)

I've always been leery of putting a tool post grinder on my lathe for fear of messing up my ways with grinding grit. But others here don't seem to be afraid of them so I may just swallow my fears and make one. 

I've seen lots of videos about how to do that from mounting a Dremel attachment to a CNC drive motor. 

Anyone here ever make one?

Favorite approach? 

Any advice regarding do's and don'ts, etc. 

Lathe is a 14x48 with BXA Series 200 tool holder. 

Love to hear what others think.


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## combustable herbage (Dec 5, 2021)

Dremel 395 Mount for MPCNC using Universal Tool-Mount Plate... by dintid
					

Mount for Dremel Multipro 395 ...for a MPCNC using the Universal Tool-Mount Plate I also made for it. With/out -Support The version with support in the filenames is with build-in supports. The other version is if you like to print without or use your own support system Parts There is the Dremel...




					www.thingiverse.com
				





I found this one on thingiverse you probably want something a bit more robust but with the drawing one could probably fashion something out of aluminum or help with the footprint.  I have been thinking a bit about this one a bit as well but I wasn't sure the dremel would be robust enough but maybe lighter grinds it would be ok.


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## Susquatch (Dec 5, 2021)

Ya, I think I mentioned the Dremel approach someplace. But I share your view of it. My Dremels are not all that great - especially as they wear and get older. I think the Dremel approach is just an easy way to go. 

I'm kind of favoring the cheaper cnc spindle drive motor approach.


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## combustable herbage (Dec 5, 2021)

Yes I had looked at some of those as well it maybe a better long term idea this one I had found has an er11 chuck.









						Machifit ER11 Chuck CNC 500W Spindle Motor with 52mm Clamps and Power Supply Speed Governor
					

Only US$85.99, buy best machifit er11 chuck cnc 500w spindle motor with 52mm clamps and power supply speed governor sale online store at wholesale price.




					www.banggood.com


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## Johnwa (Dec 5, 2021)

The workshop practice book Spindles by Harprit  Sandhu is a good read whether or not you want to build one from scratch.


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## gerritv (Dec 5, 2021)

Dremel's suck. Go for Proxxon instead. They have a proper mounting boss on the front.
https://www.proxxon.com/en/micromot/handheld-power-tools-12v-and-transformers.php 

Gerrit


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## RobinHood (Dec 5, 2021)

Stefan G has a 4 part video series on making a TPG starting with this one:





Ca Lem also made his own TPG here:


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## PeterT (Dec 5, 2021)

Sorry for cross referencing to another forum, but in the best interests of my typing fingers skim through these in particular for more links, resources & opinions to digest. 





						Grinding spindle.
					

Hullo, I looking for ideas really. I retired from precision engineering, college workshop technician and 30 years in a shipyard and now have a small Colchester student and similar size vertical mill. I have been making the Quorn t/c grinding machine, which has been a challenge but...




					www.homemodelenginemachinist.com
				








						Toolpost (or other) grinding in the lathe
					

I thought it might be beneficial to share information & experiences on this subject because it seems to come up often. The typical reason behind grinding in general is to achieve a high degree of accuracy as well as surface finish. Personally, I am interested in what you have achieved with...




					www.homemodelenginemachinist.com
				




I'm not being critical of Dremel type assemblies because IMO they have a role in hobbyist tool arsenal. But its important to set out what you want to achieve: A) making something 'shinier than a machined finish' is very different than B) hitting a tight tolerance with appropriate finish. In A) lots of reasonable options exist. In B) the spindle assembly, bearings (under load & temperature), machine stability, vibration, measurement feedback... all factor significantly & typically cost more. Also depends on what kind of mass you are working on. Small objects can get away with low HP. Bigger objects & higher removal rates can be power hungry.


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## whydontu (Dec 5, 2021)

Dremel is kind of useless, unless all you want is what I want, which is something to do final polishing. 

Here‘s my rig. Flex shaft, boring bar holder, a insert machined to fit the barrel of the flex shaft. Dremel make a Forti Flex with a metal barrel. ( the photo shows my regular Dremel flex shaft without the insert, my Forti Flex is at a job site.


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## Susquatch (Dec 5, 2021)

Wow! I love it all guys! It's looking like this project will be a LOT of fun!

I'll prolly have more questions shortly, but I feel like I have way more to chew on for right now than I ever anticipated. Please give me a while to do that.....


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## Susquatch (Dec 12, 2021)

Ok, so I've researched the crap out of this. I think I'm going to go with @combustable herbage suggestion but upgraded to a brushless motor. It has an ER11 Chuck, comes with a 1/8 collet to take Dremel size bits and is variable speed w a controller and best of all, can be easily adapted to my quick change tool post. There were too many complaints about overheating of the brushed version.

I have not ordered it yet, so last minute concerns are welcome.

[CA$173.21 47% OFF]Machifit 400W 12000rpm ER11 Chuck CNC Brushless Spindle Motor with Driver Speed Controller and Clamp Machine Tools & Accessories from Tools on banggood


			https://banggood.app.link/zSH1wXtAVlb
		



A leading alternative is a compressed air die-grinder......


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## PeterT (Dec 12, 2021)

I was looking at the 500 or 600w cousin of that (same brushless) for light duty messing around. If I recall, the higher watt versions have same/similar motor can diameter & ER#, so similar form factor with more power. I was fully expecting the bearings might be dubious quality, so just expect to upgrade and/or replace often. That's cheap & easy fix, treat it like a 'kit' etc. Attached video of brushed motor is a bit revealing. ~3:30 he shows the end bell disassembly with a rubber thingy to <ahem> centralize/float the bearing? Not good. 

So I'm not sure if the brushless and/or larger motor assemblies mean a better bearing system? Really there should be no correlation brush/brushless motor to bearing layout other than maybe the latter might be more predominant in hobby cnc machines? The end bells looks a bit meatier, maybe thicker can, maybe wishful thinking on my part. I've even seen encouraging runout claims in hobby CNC spindles. But haven't seen as many teardown/inspection links to see what's under the hood - if they have any kind of compensation. My gut feel is light duty; don't run it long/hot/hard. But if that fits the bill, its a cheap experiment. I had a bailout plan to use in a rudimentary pantograph but that project is far down the list.


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## gerritv (Dec 12, 2021)

The fact that he expects to do milling with a drill chuck, esp. mounted as it is on that shaft, tells me to ignore this particular video altogether.

Gerrit


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## Johnwa (Dec 12, 2021)

The motor on my little CNC router looks very similar to that one.  Mine came with an ER11 chuck already mounted.


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## PeterT (Dec 12, 2021)

_>The fact that he expects to do milling with a drill chuck, esp. mounted as it is on that shaft, tells me to ignore this particular video altogether._
I didn't even pay attention to that. I was just referring to the rubber bearing support washer on that particular model. 

Most of these hobby CNC motors look like they have an ER collet fixture that slides on the output shaft & retained with a set screw. Some are package deals where you can add the power supply if needed, select between different ER#, with/without clamp.. etc. Note, some power supplies are N-Am/Euro AC-IN voltage switchable, but some are dedicated one way or another, so check the fine print. Some of the brushless controllers look a bit different so maybe some variation to investigate. 

FWIW, most of these max at 12-15K max rpm which might seem high but in reality on small wheels works out to low-ish SFPM typically recommended for grinding (say 4-5K SFPM according to literature). Commercial TPGs can spin 45K for <1" wheels, but usually require wheels to step up the motor rpm. I'm not sure if these surface speeds are more for efficient material removal that we could overcome with patience & more/lighter passes, or if finish or heat is also factored. Precision grinding can be pretty specialized. I suspect these TPG add-ons is more like messing around but can still serve a hobby purpose.


			GRINDING FEEDS AND SPEEDS
		


We need to convince Gerrit to put his cnc VFD motor in the lathe with a wheel!


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## Susquatch (Dec 12, 2021)

All good stuff guys. The job at hand is a toolpost grinder. 

Today, I confirmed that the motor OD will work on my toolpost. I'll just need to dedicate and modify a BXA tool holder to the task for ease of attachment, and may have to overhang the compound for clamp clearance if needed.


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## DPittman (Dec 13, 2021)

Here is what I used for a tp grinder.  I wanted a more powerful and hopefully sturdier one than what I thought the little electric or air die grinders are so I bought a 700 watt variable speed electric die grinder from princess auto.  

I'm not sure yet how successful the grinder will be as I have only done a bit with it and the 1/4" shank stones I've bought ate terrible.

I really like the stones that @PeterT picture posted above.  Where did you get those done? I think that is what I need.


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## Tom Kitta (Dec 13, 2021)

I frequently just slammed one of these pencil air grinders into the tool post and ground away. For small tiny stuff it works great. Not sure how "accurate" that is but I bet that once nicely dressed it is no more then few tenths. 
This is not to remove a lot - just few thou runout on say chuck jaws or similar. 
I do have large tool post grinder but no belt. I finally have to take the stupid expensive thing out and add a belt to it. On the other hand this thing is massive so maybe I sell it and buy or make something more "tiny" with say 100w motor just to do little cuts not hog on things with its 1/2 hp or more motor.


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## RobinHood (Dec 13, 2021)

DPittman said:


> the 1/4" shank stones I've bought ate terrible.


It’s probably the bonding of the abrasive that is bad.

I would look for “mounted stones” online and go with a reputable name like a Norton, Radiac, Dumore, CGW, etc (not affiliated). You should also have a diamond dresser to true them up before use.


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## DPittman (Dec 13, 2021)

RobinHood said:


> It’s probably the bonding of the abrasive that is bad.
> 
> I would look for “mounted stones” online and go with a reputable name like a Norton, Radiac, Dumore, CGW, etc (not affiliated). You should also have a diamond dresser to true them up before use.


Yes the stones vary quite a bit on quality and some of them glued in so crooked they wouldn't be adequate in a hand drill. I did dress them all with a diamond dresser but the worse one practically were ground down to nothing and were so unbalanced until then.  I did buy a couple of mounted stones from kbc and they were not so bad.  The worse of the bunch I had were called 1/4" shank but were actually 6mm shank and of course unusable in a 1/4" collet.


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## Susquatch (Jan 3, 2022)

I ordered this spindle motor from bangood today. Just need to find an ER11 1/4" collet to accomodate better grinding stones. 

Gotta be better than a Dremel..... 









						[CA$116.92 45% OFF] Machifit ER11 Chuck CNC 500W Spindle Motor with 52mm Clamps and Power Supply Speed Governor Machine Tools & Accessories from Tools on banggood.com
					

Machifit ER11 Chuck CNC 500W Spindle Motor with 52mm Clamps and and Power Supply Speed Governor For CNC Machine, Air cooled 0.5kw Air cooled spindle ER11 chuck CNC 500W Spindle Motor + Power Supply




					m.banggood.com


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## Susquatch (Jan 3, 2022)

Actually, I found an ER11 imperial collet set for $12 on bangood too. So I bought that just now. It's hard to imagine a full 15 pc collet set being any good, but at that price we will see.


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## deleted_user (Jan 7, 2022)

Susquatch said:


> Actually, I found an ER11 imperial collet set for $12 on bangood too. So I bought that just now. It's hard to imagine a full 15 pc collet set being any good, but at that price we will see.


I'm going to watch how your project comes out. I am convinced more power is better here. I watched Cà Lem's build on youtube, he made a really fine spindle. We've elected to build Clough42's version. It is so well documented.


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## DPittman (Jan 7, 2022)

TorontoBuilder said:


> I'm going to watch how your project comes out. I am convinced more power is better here. I watched Cà Lem's build on youtube, he made a really fine spindle. We've elected to build Clough42's version. It is so well documented.


Very well documented, almost too well documented for me as I told myself I can't watch 24 episodes in their entirety! Of course if one was to be making the exact changes same project it would be well worth watching then.


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## DaveK (Jan 8, 2022)

Susquatch said:


> I ordered this spindle motor from bangood today. Just need to find an ER11 1/4" collet to accomodate better grinding stones.



Maybe a dumb question, and also a slight detour, but why not use a 6.5 mm collet ?  I have various ER sets, all metric, and since they have a reasonable clamping range  I have always found a metric size that works for an imperial shaft.  Is this a bad compromise ?

Dave


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## Susquatch (Jan 8, 2022)

DaveK said:


> Maybe a dumb question, and also a slight detour, but why not use a 6.5 mm collet ?  I have various ER sets, all metric, and since they have a reasonable clamping range  I have always found a metric size that works for an imperial shaft.  Is this a bad compromise ?
> 
> Dave



Not a dumb question at all. I'll prolly get a metric set when the price is right. 

But most of my existing stones have 1/4 inch or 1/8" shafts. So 1/4 & 1/8 are a must for now.


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## combustable herbage (Jan 10, 2022)

I'll throw this one into the mix as well 220 volt, down the vevor rabbit hole today.









						2.2kw Water-cooled Spindle Motor Engraving Grinding Milling Numerical Updated  | VEVOR CA
					

Buy 2.2kw Water-cooled Spindle Motor Engraving Grinding Milling Numerical Updated at cheap price online, with Youtube reviews and FAQs, we generally offer free shipping to Europe, US, etc.




					vevor.ca


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## Tom Kitta (Jan 10, 2022)

combustable herbage said:


> I'll throw this one into the mix as well 220 volt, down the vevor rabbit hole today.
> 
> 
> 
> ...



I like that fact they point out "German import bearing" and a cost per bearing (set?) of $150 while whole spindle is less then $150


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## combustable herbage (Jan 10, 2022)

Don't forget your pallet forks with your spindle motor, the shit they have is amazing.









						Clamp On Pallet Forks 1500lbs 30 Inch With Adjustable Stabilizer Bar For Loader  | VEVOR CA
					

Buy Clamp On Pallet Forks 1500lbs 30 Inch With Adjustable Stabilizer Bar For Loader at cheap price online, with Youtube reviews and FAQs, we generally offer free shipping to Europe, US, etc.




					vevor.ca


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## whydontu (Jan 10, 2022)

I’m not sure I’d buy pallet forks made from steel with a tensile strength of 3 psi, if my last set of Chinese bolts are any indication


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## DPittman (Jan 10, 2022)

Tom Kitta said:


> I like that fact they point out "German import bearing" and a cost per bearing (set?) of $150 while whole spindle is less then $150


Maybe what they mean is they spent $150 more for bearings for the entire production lot to "upgrade".   Hee hee.


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## Dabbler (Jan 10, 2022)

Tom Kitta said:


> I like that fact they point out "German import bearing" and a cost per bearing (set?) of $150 while whole spindle is less then $150





DPittman said:


> Maybe what they mean is they spent $150 more for bearings for the entire production lot to "upgrade". Hee hee.


Cheap bearings are made everywhere, even in Germany.  Since there is only one 'precision' bearing, and all you need is an ABEC3 bearing, it can be done for 5$ and the rear bearing can be almost anything, say a 60 cent one.  Yes these kind of bearings can be had from Germany for these prices.  You can even get FAG bearings to do this even cheaper, made in Canada.


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## thestelster (Jan 19, 2022)

These are what I built.  The first one I used was a Foredom Flex -Shaft unit with H25H hand piece.  (That huge block of steel was for a job I had to do years ago, I had to bore an 1 1/4" hole 6" deep into a 2" diameter stainless bar.)  The Foredom worked well enough but I wanted something a little better.  Plus because it was on that block of steel, taking the tool post off, putting the block on was a bit of a pain, plus the foot speed control was a pain as well.  The second one I made last year, which utilizes a Bosch Colt mini router.   This has worked wonderfully well.  Except that you can only go about 2" deep.  Most of the time is fine (rifle bolt faces for instance), lathe jaws, but deeper would be a really nice.  I will probably, eventually, rig up a unit using ER16 tool holder, and machine the shaft for bearings, etc, etc.


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## PeterT (Jan 19, 2022)

I'm impressed you got the Foredom to do that kind of work. I don't have one myself but was eyeing one more for conventional work. Was yours the 1/6 or 1/3 HP model? From what I could discern of the handpieces, its a pair of regular roller bearings inside the housing? Do you recall what kind of DOC/pass were you doing? Did things get toasty? Did you set your compound at shallow angle & feed that way or how did you monitor bore diameter progression?

Themac's have long reach ID spindles but the TPG's are stupidly expensive. Used ones can be had but vary in price & quality. I still want to build a good spindle cartridge one day with AC bearings & incorporate some specific features.


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## Ian Moss (Jan 19, 2022)

PeterT said:


> I'm impressed you got the Foredom to do that kind of work. I don't have one myself but was eyeing one more for conventional work. Was yours the 1/6 or 1/3 HP model? From what I could discern of the handpieces, its a pair of regular roller bearings inside the housing? Do you recall what kind of DOC/pass were you doing? Did things get toasty? Did you set your compound at shallow angle & feed that way or how did you monitor bore diameter progression?
> 
> Themac's have long reach ID spindles but the TPG's are stupidly expensive. Used ones can be had but vary in price & quality. I still want to build a good spindle cartridge one day with AC bearings & incorporate some specific features.


Hi Peter: I have a Foredom with a number of hand pieces I would part with if you are interested. I am just outside Edmonton (Sherwood Park)


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## thestelster (Jan 19, 2022)

Hi PeterT, the hand piece that I have uses 2 sets of ball bearings.  The motor drive unit is the HB, which is 1/3HP.  In the picture of grinding the chuck jaws, I am using the Bosch Colt router which is 1HP.  Depth of cut was .001" at a time, but I had to go in and out the length of the jaws with the power feed several times to spark out before I fed it in again.  I just used the cross-slide.  It didn't feel warm, but that's a huge piece of steel acting as a heat sink!


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## Susquatch (Jan 29, 2022)

I recently received the spindle motor I ordered to make a tool post grinder. As delivered with the standard mounting bracket, it sits just about perfect to be on my lathe centerline. 






Note that the vertical bar in the photo is my lathe tool centering fixture. To mount the spindle motor the best way, I think I need to make a special tool holder to mount to my tool post. I don't have a shaper so I'll either have to use my mill to make a special tool holder or find another way.

After looking at all the trouble @YYCHM is having to make the required dovetail, I am thinking I'll just buy a 60 degree dovetail end mill and make one on my mill. 

Any better ideas?


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## thestelster (Jan 29, 2022)

Have a look at this link. A ton of information about making a tool post holder.  Its on an Aloris.





__





						Aloris  dovetail dimensions
					

Hi all: Can anyone point me to a place where I can get the dimensions for the dovetail slot in BXA size tool holders?  I bought an original Aloris post and now need an assortment of tool holders to match.  Also, does anyone have any idea what the tolerance would be on the dovetail?  Thanks  Pete



					www.practicalmachinist.com


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## trlvn (Jan 29, 2022)

Unless you plan to do grinding a LOT, I wouldn't bother mounting it via the quick change tool post.  It looks like it would be easy to make a new tee-nut and bracket such that you would take the QCTP off and mount the tool post grinder in its place.  

Craig


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## combustable herbage (Jan 29, 2022)

I like that unit looks to be the perfect size for your lathe and nice length it should clamp down fairly rigid.
I think the mill is your best route, but no guarantee's of success without the right setup but with the 60 degree dovetail you maybe have an easier time of getting the two surfaces correct,


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## thestelster (Jan 29, 2022)

If I was to make a holder, it would be exactly like the Aloris #4D, boring bar holder with split clamping.


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## Susquatch (Jan 29, 2022)

trlvn said:


> Unless you plan to do grinding a LOT, I wouldn't bother mounting it via the quick change tool post.  It looks like it would be easy to make a new tee-nut and bracket such that you would take the QCTP off and mount the tool post grinder in its place.
> 
> Craig



Yes, I considered that. But notice how the spindle motor is already very close to the lathe center. 

To get some adjustment range, and still have the motor rigidly held, I had planned to hang the motor over the end of the compound taking advantage of the way a tool holder normally mounts. 

I have some "glorious" plans for that grinder. They are probably all beyond its capability but a fellow must dream. If even 20% of those plans get realized, the grinder will see a lot of use. So I'd also really like to retain the quick change feature.


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## ThirtyOneDriver (Jan 29, 2022)

I have a 60° end mill cutter that you can borrow @Susquatch.


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## Susquatch (Jan 29, 2022)

That sounds like a plan @ThirtyOneDriver ! I don't think I need one for anything else so borrowing one makes sense. If I break it, I'll replace it!


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## Susquatch (Jan 29, 2022)

I could do that. Heck, I'll even make yours first....... (insert evil grin here.....)


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## Tom Kitta (Feb 14, 2022)

OK, done. Main issue i am seeing is that the collet wobbles at over 6000 rpm. But otherwise great. I have speed control and even on off switch. 

You can see where I milled it thin. I hope now it's more clear.


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## Tom Kitta (Feb 14, 2022)

TorontoBuilder said:


> Is this the same 500 watt spindle as susquatch is using?
> 
> I was wondering what the TRO is with the er11 collet and if the larger spindle motors from vevor may be any better. I doubt it tho



Yes it's 500w. Feels like plenty of power. I need to play around with the spindle assembly and see what results I get. The 12000 rpm speed will be good for small internal stones while I need to run much slower for 3in stones.


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## Susquatch (Feb 14, 2022)

Tom Kitta said:


> Yes it's 500w. Feels like plenty of power. I need to play around with the spindle assembly and see what results I get. The 12000 rpm speed will be good for small internal stones while I need to run much slower for 3in stones.



That was my thinking too.

My spindle motor arrived a bit ago, but first I need to make a holder to fit my bxa quick change tool post. I already have an aluminium block to make it from. But I'm fussy so there is fair bit of planning and fabrication to do before I can actually run it. 

Where do you get high quality (ie safe) well balanced 3" stones? And are they marked with a safe rpm for them?


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## Susquatch (Feb 14, 2022)

TorontoBuilder said:


> norton abrasives, toolroom wheels, still only ~5500 rpm for 3 inch wheel
> 
> My question is how are you mounting anything that size in a ER11 collet



I haven't looked at the 3" wheel you referenced yet. But your question about ER11 collet is appropriate. I had assumed everyone was talking a 1/4" shaft designed to fit a motor with a 1/4" shaft holder of some kind. I was picturing a wheel somewhat like a cutoff blade just a bit thicker - say 1/4". But maybe I am not gunna be able to do outside grinding after all. Or perhaps only with a smaller stone held on an angle.

It's a good question. How would you answer it yourself?


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## YYCHM (Feb 14, 2022)

Susquatch said:


> My spindle motor arrived a bit ago, but first I need to make a holder to fit my bxa quick change tool post. I already have an aluminium block to make it from. But I'm fussy so there is fair bit of planning and fabrication to do before I can actually run it.


Why don't you want to modifying the holder that came with the motor?


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## Susquatch (Feb 14, 2022)

YYCHM said:


> Why don't you want to modifying the holder that came with the motor?



You have no idea how hard I tried to make that work. In the end, I simply gave up. The original doesn't have enough meat to take the dovetail and the through bolts end up interfering with the compound table. Lastly, a two part assembly would be difficult to assemble. An entirely new holder doesn't need bolts and can accommodate the dovetail. 

The bigger question is can I make a dovetail that fits my tool post well enough to handle the spindle motor.


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## Tom Kitta (Feb 14, 2022)

TorontoBuilder said:


> norton abrasives, toolroom wheels, still only ~5500 rpm for 3 inch wheel
> 
> My question is how are you mounting anything that size in a ER11 collet



I do not use ER11 I use ER20.


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## Tom Kitta (Feb 14, 2022)

Susquatch said:


> You have no idea how hard I tried to make that work. In the end, I simply gave up. The original doesn't have enough meat to take the dovetail and the through bolts end up interfering with the compound table. Lastly, a two part assembly would be difficult to assemble. An entirely new holder doesn't need bolts and can accommodate the dovetail.
> 
> The bigger question is can I make a dovetail that fits my tool post well enough to handle the spindle motor.



I should show you my design. No issues - used original aluminium. Less work. Just make it square and add an adapter plate to the bottom. The whole thing is very rigid. It is held with 3/8 bolt against T-nut. 

Basically I machined T-nut - simple - right?

I machined the original clamp square so its even. I measured how much higher it needs to be then my spindle - about 5.5mm. I machined adapter plate of 5.5mm. I added adapter plate to the bottom via 4 tiny cap screws - I think size 10-24. The 3/8 just holds the adapter plate against T-nut. Works great. Very rigid. Maybe I would not lift the whole lathe by it but I am sure it will work for the grind stones.


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## Tom Kitta (Feb 14, 2022)

Susquatch said:


> I haven't looked at the 3" wheel you referenced yet. But your question about ER11 collet is appropriate. I had assumed everyone was talking a 1/4" shaft designed to fit a motor with a 1/4" shaft holder of some kind. I was picturing a wheel somewhat like a cutoff blade just a bit thicker - say 1/4". But maybe I am not gunna be able to do outside grinding after all. Or perhaps only with a smaller stone held on an angle.
> 
> It's a good question. How would you answer it yourself?



I got some cheap Chinese wheels and norton wheels. 

I have these bad boys:








						PACK OF 5 NEW!!! NORTON SG RECESSED GRINDING WHEELS 3" X 1-1/4" X 5/8" 5SG46-KVS  | eBay
					

Recessed Grinding Wheels.



					www.ebay.com
				




I also have like 10 cup wheels in case someone wants them - good stuff, norton as well. I don't think I need 10 identical ones. https://www.ebay.com/itm/353890612374 

Not sure what is the RPM max. I assume 5500 or 6000 would be safe limit.


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## Tom Kitta (Feb 14, 2022)

TorontoBuilder said:


> I assumed not... I was referring to those who have the 500 watts spindle



I have 500w spindle with ER20 on her. You don't have to use supplied ER11.


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## PeterT (Feb 14, 2022)

Tom Kitta said:


> I also have like 10 cup wheels in case someone wants them - good stuff, norton as well. I don't think I need 10 identical ones. https://www.ebay.com/itm/353890612374


I might take you up on cup wheel. I need to figure out adaptability to my bench grinder. Is 1.25 the hole ID I assume?
NORTON ALUNDUM CUP GRINDING WHEELS 4"/3" X 1-1/2" X 1-1/4"


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## PeterT (Feb 14, 2022)

Tom, how is the ER collet holder attached to the shaft (like key or set screw on flat or?). 
How are you varying RPM on that motor? I guess I'm more wondering what happens to 500W rating when you go to 40% throttle or whatever?
Do you happen to know what it has for bearings or just give it a go?


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## Tom Kitta (Feb 15, 2022)

PeterT said:


> I might take you up on cup wheel. I need to figure out adaptability to my bench grinder. Is 1.25 the hole ID I assume?
> NORTON ALUNDUM CUP GRINDING WHEELS 4"/3" X 1-1/2" X 1-1/4"



Yes, 1 1/4 is I think standard for SG. You can always use adapter - my TC&G is 1 in and I have some adapters to use same wheels as on SG.


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## Tom Kitta (Feb 15, 2022)

PeterT said:


> Tom, how is the ER collet holder attached to the shaft (like key or set screw on flat or?).
> How are you varying RPM on that motor? I guess I'm more wondering what happens to 500W rating when you go to 40% throttle or whatever?
> Do you happen to know what it has for bearings or just give it a go?



Collet is attached via two set screws. Its a DC motor and you simply lower the voltage to get speed down. I do not think it will be a big deal, these grinders are usually not too powerful - I mean 6" pedestal grinders are usually 250w and they move two 6" stones doing far more cutting action then 3" or similar stone.


----------



## Tom Kitta (Feb 15, 2022)

TorontoBuilder said:


> AH. I see.
> 
> I'd heard that those ER11 chucks were impossible to remove from the shaft.
> 
> Did you buy or make a new er20 collet chuck? I may just buy a dedicated tool post grinder spindle



Yes the ER11 chuck was like .1mm smaller then the spindle. Same with the ER20. I could not have put them on, it was not even close to interference fit. So I reamed 8mm. Not sure whatever that was a great idea - I guess I see soon.


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## Susquatch (Feb 15, 2022)

Tom Kitta said:


> Not sure what is the RPM max. I assume 5500 or 6000 would be safe limit.



Seems fast to me.... Not for the stone itself but rather for my 1/4 shaft in an ER11 collet. 



Tom Kitta said:


> Yes the ER11 chuck was like .1mm smaller then the spindle. Same with the ER20. I could not have put them on, it was not even close to interference fit. So I reamed 8mm. Not sure whatever that was a great idea - I guess I see soon.



I would be too scared to try that mod. Basically, I am scared of high speed stones period. I use them just like everyone else, but I've seen 3 people in three separate accidents get chewed up bad by an exploding stone or wheel. I'm already ugly enough. 

I still use them but usually well off to the side and still scared. 

It may be perfectly safe, but I don't think I have the kind of guts it would take to make me modify a collet like that. Just me being a giant big sissy maybe but it is what it is. I don't like heights either.


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## Susquatch (Feb 15, 2022)

Funny that I'm so scared of modifying a collet. At the same time, I'm not scared of making a mandrel to hold a bigger 3 inch wheel (as was suggested by another member). That's my current plan so I can do external grinding without having to turn the spindle on an angle with all the side loads that creates.

For what it's worth, I'm also thinking about using cut-off wheels instead of stones. I think they will be just fine for the light loads I will put on them.


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## Tom Kitta (Feb 15, 2022)

You can either wear a face shield, put a shield on the grinder or both. We are not talking about a lot of energy here - 3in wheels are much smaller then 6in in your pedestal grinder. I can imagine the damage some of the 12", 2" thick weighting at around 20lbs+ wheels would do if they exploded at their 1800 rpm speed. That would be far more scary they a tiny 3" wheel weighting in at maybe 200 grams going off. Remember angular speed of the 12" wheel is same as the 3" wheel - i.e. similar SFM rating for cutting. 

I am thinking of adding a small collar with a tiny shield or something like that, maybe held in place by just a clamp to make it both light weight and low profile.


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## DPittman (Mar 8, 2022)

@Susquatch 
Any progress on your tpg?


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## Susquatch (Mar 8, 2022)

On hold while I setup the DRO.

Basically, I found myself thinking that a DRO would make the tool post grinder job a lot easier so I decided to do the DRO first. I'll probably do the Tool Post grinder before the two Z Axis DROs though. Almost certainly before the quill z DRO. 

I may post a drawing of my Tool Post Grinder plans for everyone to shoot at in the meantime.


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## Susquatch (Apr 3, 2022)

So now that I have a working XYZ DRO, it's time to pickup where I left off on this project. 

Here is my future grinder tool holder hiding inside this block of aluminium. The block is 4x4x4.5   It is all squared up and ready to machine in the features. It was an expensive block of aluminium by my standards so I want to save as much of it for future projects as I can. 






And this is what I think is hiding in there......






As I sit here noodling the machining sequence, I find myself realizing how green I am at this stuff and wondering how others would tackle this. 

Although I'd like to start right off cutting out the three blocks so I can save them for future projects, I think that might make it difficult to clamp and position the spindle holder for subsequent machining operations like boring the hole for the spindle motor, cutting the wedge for the tool post, slitting the holder to clamp the motor, and drilling and tapping the spindle clamp. 

Any suggestions? 

Design concept suggestions and criticisms are allowed too.


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## Dabbler (Apr 3, 2022)

Here is what I'd do:






I'd use a bandsaw to take out 1 and 2, then refine the faces on the mill.  You now have a good place to work hold.   This is also a good time to mill the dovetail. The rest of the details on the dovetail (the height adjuster) can be done later.

Then take out the remaining piece and mill the last face (behind the bore)  You can now hold it any which way, and be fine.


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## Susquatch (Apr 3, 2022)

Dabbler said:


> Here is what I'd do:
> 
> View attachment 22740
> 
> ...



YES! 

That's sort of what I had in mind but you added the details I hadn't thought about - specifically to square up the leftover sides from those first two blocks on the mill BEFORE doing anything else, and then doing the dovetail right away. 

Tomorrow! (I hope)


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## Susquatch (Apr 4, 2022)

Good progress today despite a few honey do's and a Kijiji run. 

I cut the two bars off above and below the wedge with the band saw, then cleaned it all up on the mill, then cut the wedge groove, then tried it on my tool post. Looks GREAT! 


















Tomorrow, I'll cut the right back off, drill out the motor hole,and maybe bore it to size.


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## YYCHM (Apr 4, 2022)

Gee, how did you manage to get that dovetail right the first time


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## Darren (Apr 4, 2022)

Nice work @Susquatch


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## Susquatch (Apr 5, 2022)

YYCHM said:


> Gee, how did you manage to get that dovetail right the first time



There are three ways to learn. 

From your mistakes, 
From watching others,
From the mistakes of others. 

I much prefer to put you in the second method. I am grateful to you for the learning opportunity. 

That said, I had my tongue between my teeth the whole time. It's an expensive block of aluminium and I really didn't want to have to cut it off and screw two pieces together. I used my tightest tool holder as the model because I figured aluminium might get loose over time. An elephant could not have licked the smile off my face when that sucker slipped over the toolpost dovetail perfectly with zero room to spare!


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## YYCHM (Apr 5, 2022)

Susquatch said:


> There are three ways to learn.
> 
> From your mistakes,
> From watching others,
> ...



Did you used the measure between pins technique to bracket the dovetail width?


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## Susquatch (Apr 5, 2022)

Today I tackled the 2 inch hole for the motor. First I cut off the big block on the right rear behind the motor.






Many thanks to @thestelster for the tip to use a machine leveler to balance the saw vise. 

Then I cleaned it up again on the mill. 






Still fits the lathe tool post perfectly! 






Next I used a two inch long by 1-7/8 annular cutter to rough out the motor mounting hole.


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## Susquatch (Apr 5, 2022)

Sorry, somehow I can't delete that last duplicate photo. 

Anyway, after I cut the hole I hit a snag. Apparently a 2" boring bar has a wart on it. That makes it 2-1/8 diameter 3/4 of an inch or so above the cutting edge. That won't work. I need 2.055 inches down the whole hole - not just the first 3/4 inch. 

So now I have to order a smaller boring bar which would delay the whole project a week or so, or cobble something up using a long bar in the 2" head. I don't like long tool stick outs.


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## YYCHM (Apr 5, 2022)

Set it up in the 4J on the lathe and bore it out.  How deep is the hole?


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## trlvn (Apr 5, 2022)

Rotary table on the milling machine and use a sufficiently long end mill to open up the hole to the desired size?

Craig in Oakville


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## DPittman (Apr 5, 2022)

Line bore it on the lathe, you already have the tool post holder made for it.


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## Susquatch (Apr 5, 2022)

@YYCHM & @trlvn, & @DPittman .

All three of those would have worked just fine. All very innovative solutions. Another member also privately volunteered to loan me the right size boring bar.

Before I saw your ideas, I went off line, sucked up some big air and went at it with a really long stick out on a honking big boring bar to clear the rest of the battle field. That worked just fine albeit slow to stop the chatter. Also had to slow down the mill a bit.

Here is the bored out holder.






And here it is with the motor inserted. I still have to slit it and then drill and tap for two clamp screws. I also want to reduce the thickness all the way around so it will bend more evenly as it tightens down around the spindle motor. Might even end up with another piece of scrap aluminium for future projects. 






Anyway, the CEO is starting to get antsy about how long I've been out here so that's it for today.

Tomorrow I'll get to those tasks and might even spin it up!


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## Dabbler (Apr 5, 2022)

Here's a trick.  locate or make an arbor that is the same diameter as your hole (or close, it doesn't have to be perfect)

Clamp the workpiece in the vice with the arbor resting on top of the jaws.  You can take successive cuts, making a concentric arc made of short lines that way - the result if very nice, and no thought or extra work to follow the inside circle...


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## Susquatch (Apr 5, 2022)

Dabbler said:


> Here's a trick.  locate or make an arbor that is the same diameter as your hole (or close, it doesn't have to be perfect)
> 
> Clamp the workpiece in the vice with the arbor resting on top of the jaws.  You can take successive cuts, making a concentric arc made of short lines that way - the result if very nice, and no thought or extra work to follow the inside circle...



Sorry @Dabbler ,  it isn't obvious to me what you mean. I did think about using a small fly cutter with a longer than normal tool stick out. Is that sort of the idea?

I know the job is done, but if there is something to learn, I want to learn it.


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## Dabbler (Apr 5, 2022)

This might not help much, but cuts are made across the part along the Y axis,  and the part is indexed (or rotated, if you will)  around the arbor, makinc a segmented OD cut in an arc to make very nice flexible clamping.....


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## Susquatch (Apr 5, 2022)

Dabbler said:


> This might not help much, but cuts are made across the part along the Y axis,  and the part is indexed (or rotated, if you will)  around the arbor, makinc a segmented OD cut in an arc to make very nice flexible clamping.....
> 
> View attachment 22848



At my daughters place. Just taking a short break. I see now. I thought you were describing another way to bore the hole. But you are telling me how to make a more flexible motor clamp.


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## Susquatch (Apr 5, 2022)

Dabbler said:


> This might not help much.....



I also have a rotary table. 

But I had originally planned a bit of an octogonal shape which would provide 4 bending locations. But the bored hole is a pretty good slip fit so a lot of bending is prolly not required.


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## ShawnR (Apr 5, 2022)

I have seen holes and slots drilled as flex points before. Don't know the names nor the application but it seems to me that this might be one, considering the amount of material you are flexing with..?


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## Susquatch (Apr 6, 2022)

ShawnR said:


> I have seen holes and slots drilled as flex points before. Don't know the names nor the application but it seems to me that this might be one, considering the amount of material you are flexing with..?



Although I like this idea, I was planning to cut off the bottom leaving a 1/4", trimming the far side, far bottom and far top at 45° to 1/4", but leaving a top flange for screws. That would leave 4 weaker spots for bending.

Question: how would you cut that inside slot?

A totally different approach but still viable is to cut it totally in half and make the far side a cap with 2 top and 2 bottom screws.


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## Susquatch (Apr 6, 2022)

Funny how you get locked into ideas by history. Here is the bracket that came with the motor.


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## ShawnR (Apr 6, 2022)

Susquatch said:


> Although I like this idea, I was planning to cut off the bottom leaving a 1/4", trimming the far side, far bottom and far top at 45° to 1/4", but leaving a top flange for screws. That would leave 4 weaker spots for bending.
> 
> Question: how would you cut that inside slot?


Milling down appears to result in a larger flexible or  "hinge" area. Nice.

lol...after posting, I was wondering the same thing! The only thing that came to mind was drilling the hole and then a hack saw....take the blade off, place it through the hole and back together again. But then I realized that you have or will have a slot already so no need to disassemble the hack saw or just use the band saw? Maybe a little crude for this project. But then, my tool post holder is half a piece of pipe, that fits my die grinder,  welded to a piece of keystock that fits my tool holder, and a pipe clamp to hold it together. 

I like the look of yours. Very nice. I might put it on the list of things to do.

edit-I just read Post #84. Disregard everything I said....


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## Susquatch (Apr 6, 2022)

ShawnR said:


> Milling down appears to result in a larger flexible or  "hinge" area. Nice.
> 
> lol...after posting, I was wondering the same thing! The only thing that came to mind was drilling the hole and then a hack saw....take the blade off, place it through the hole and back together again. But then I realized that you have or will have a slot already so no need to disassemble the hack saw or just use the band saw? Maybe a little crude for this project. But then, my tool post holder is half a piece of pipe, that fits my die grinder,  welded to a piece of keystock that fits my tool holder, and a pipe clamp to hold it together.
> 
> ...



No worries. All discussion is welcome. Discussion and brainstorming ideas results in improvements and also forms the basis of ideas for future projects. 

Ya, I had thought of taking the blade off too. Then also realized its all just order of operations. The real problem is that hacksaws and bandsaws leave a rough surface. So I had planned to make the top cut with a slitting saw. But the more I think about it, the more I think a cap with 4 Screws is actually the best option because all four mating surfaces can be milled. 

A separate cap can also be machined a bit easier. 

Just wish I had thought of that earlier. The block would have been easier. 

In fact, if the bracket that came with the motor was cut in half, I prolly didn't have to buy any stock at all. 

Lots of lessons learned in this little project. 

Heck, it may turn out that the spindle motor makes a very poor tool post grinder and the whole project was nothing but another failed experiment. 

I hope otherwise.


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## Rauce (Apr 6, 2022)

Susquatch said:


> Heck, it may turn out that the spindle motor makes a very poor tool post grinder and the whole project was nothing but another failed experiment.


I hope not, I just ordered one! 

A good backup project might be a pantograph engraver?


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## Mcgyver (Apr 6, 2022)

Dabbler said:


> Here's a trick.  locate or make an arbor that is the same diameter as your hole (or close, it doesn't have to be perfect)
> 
> Clamp the workpiece in the vice with the arbor resting on top of the jaws.  You can take successive cuts, making a concentric arc made of short lines that way - the result if very nice, and no thought or extra work to follow the inside circle...


I do most of them that way, quick and easy, after a few licks with a file, they look great.  Just don't take a heavy cut!


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## Susquatch (Apr 6, 2022)

Dabbler said:


> This might not help much, but cuts are made across the part along the Y axis,  and the part is indexed (or rotated, if you will)  around the arbor, makinc a segmented OD cut in an arc to make very nice flexible clamping.....
> 
> View attachment 22848



Sometimes it takes me a while to fully digest such things. 

It's a very cool idea that could be used for all kinds of things. 

I see why the arbour isn't critical at all. All it does is maintain the spacing between the ID of the hole and the end mill. One could take as many cuts as desired to make it round or multi faceted. 

I really like the possibility of a multi faceted result so I may try this. Unfortunately, my vice isn't deep enough to allow the bottom of the hole to be level with the top of the vice. Perhaps some bar stock on top of the vice just for spacing purposes. 

Thanks @Dabbler !


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## Susquatch (Apr 6, 2022)

Mcgyver said:


> I do most of them that way, quick and easy, after a few licks with a file, they look great.  Just don't take a heavy cut!



Why can't you take a heavy cut?


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## YYCHM (Apr 6, 2022)

Susquatch said:


> Sometimes it takes me a while to fully digest such things.
> 
> It's a very cool idea that could be used for all kinds of things.
> 
> ...


----------



## Janger (Apr 6, 2022)

DPittman said:


> Here is what I used for a tp grinder.  I wanted a more powerful and hopefully sturdier one than what I thought the little electric or air die grinders are so I bought a 700 watt variable speed electric die grinder from princess auto.
> 
> I'm not sure yet how successful the grinder will be as I have only done a bit with it and the 1/4" shank stones I've bought ate terrible.
> 
> ...


Don
I really like this approach. I have a die grinder and metal lying around. 
How did this turn out?


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## Mcgyver (Apr 7, 2022)

Susquatch said:


> Why can't you take a heavy cut?



Sometimes, depending on the part, there isn't much to hold onto, sometimes the part is long on the bore and short on width or its hanging down the side of the vise (not the best or strongest way to hold things), but the main reason is you don't know where along the work the clamping force is actually occuring.  It might be even, or there might be a spot on the work a few thou thicker (something small enought that you can see it) where the force is concentrated.  IF the later, when there is force on the work from the cutter, that creates a moment around where the clamping force is.  This is very common but doesn't matter and isn't noticed when the work is supported from the bottom by vise or parallels or notched out angle block, but it can mess you up when taking an unsupported cut.  I've have parts move using this technique when I was rushing (never a good idea).


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## Susquatch (Apr 7, 2022)

Mcgyver said:


> Sometimes, depending on the part, there isn't much to hold onto, or its hanging down side of the vise (not the best or strongest way to hold things), but the main reason is you don't know where along the work the clamping force is actually occuring.  It might be even, or there might be a spot on the work a few thou thicker (something small enought that you can see it) where the force is concentrated.  IF the later, when there is force on the work from the cutter, that creates a moment around where the clamping force is.  This is very common but doesn't matter and isn't noticed when the work is supported from the bottom by vise or parallels or notched out angle block, but it can mess you up when taking an unsupported cut.  I've have parts move using this technique when I was rushing (never a good idea).



Gotcha. Makes sense.


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## Susquatch (Apr 7, 2022)

Janger said:


> Don
> I really like this approach. I have a die grinder and metal lying around.
> How did this turn out?



I considered this approach long and hard. The problem for me was the attachment to the motor body. That is what drove me to a ring clamp. I could have just turned one and then screwed it to a bar from the inside, but I worked myself all up worrying about up and down vibration harmonics accompanied by the inherent danger of a high speed grinding stone. Besides, I really wanted to try my hand at cutting a dovetail tool holder and a one piece arrangement just made sense to me. Whether the motor has enough oomph or not remains to be seen. 

I'll prolly end up making an arbour for 3" outside stones, but where did you end up getting inside stones?


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## DPittman (Apr 7, 2022)

Janger said:


> Don
> I really like this approach. I have a die grinder and metal lying around.
> How did this turn out?


Well I think the idea has some potential but I think I should have started with a better die grinder.  The bearings in mine tend to be screechy so I wonder about their accuracy.  The die grinder has speed control which is nice and has a collet holder system (although an oddball one).  Mounting it on the tool post holder makes it easier to flip it to get it in different positions.  
My biggest hold back on the whole thing is not having much for decent mounted stones yet.  I haven't done much precision grinding with it because of that.


----------



## Susquatch (Apr 7, 2022)

DPittman said:


> My biggest hold back on the whole thing is not having much for decent mounted stones yet. I haven't done much precision grinding with it because of that.



Please let me know when you do find some decent stones. I'm on the same hunt and not finding much of anything but what I know is junk!


----------



## Susquatch (Apr 7, 2022)

YYCHM said:


> Did you used the measure between pins technique to bracket the dovetail width?



Somehow or another I missed this question Craig. My apologies. 

Yes, but I didn't go crazy. I used two pieces of stainless dowel that are about 0.2" in diameter. Nowhere near precision rod, but I reasoned that precision was not as important as consistency. I also only used a caliper to measure the gap. But again, I figured a caliper was more than enough for this job. 

Last but not least, I used my DRO to make sure I was taking off roughly the same amount on both sides. For some reason that I never took the time to figure out, I reasoned that equal amounts on both sides was important. I still don't know if that is true but my gut tells me that it is. Stupid Gut..... LOL!


----------



## DPittman (Apr 7, 2022)

I believe I ordered some 1/4" shaft mounted stones from kbc that were acceptable.  The typical die grinder stones in Princess Auto are pure garbage and I've had some that were called 1/4" shaft but in fact were 6mm (not useable in a 1/4" collet)


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## Susquatch (Apr 7, 2022)

DPittman said:


> I believe I ordered some 1/4" shaft mounted stones from kbc that were acceptable.  The typical die grinder stones in Princess Auto are pure garbage and I've had some that were called 1/4" shaft but in fact were 6mm (not useable in a 1/4" collet)



Thank you. I thought I looked there but lemme look again to see what I can find there.


----------



## Rauce (Apr 7, 2022)

I got some nice mounted stones from a supplier in Cambridge a few years ago. Can’t remember which one though, maybe Abrasive Supply & Service? I just walked in one afternoon, looked through their catalogue of shapes and left with a 20 or so and a wheel dressing stone for my bench grinder.


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## Susquatch (Apr 7, 2022)

Rauce said:


> I got some nice mounted stones from a supplier in Cambridge a few years ago. Can’t remember which one though, maybe Abrasive Supply & Service? I just walked in one afternoon, looked through their catalogue of shapes and left with a 20 or so and a wheel dressing stone for my bench grinder.



If you can remember, it would be appreciated. I get there every so often and that would be nice fruitful adventure!


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## Rauce (Apr 7, 2022)

Susquatch said:


> If you can remember, it would be appreciated. I get there every so often and that would be nice fruitful adventure!


Since I walked in I don’t have any emails to reference but I’m pretty sure it was Abrasive Supply and Service.


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## Susquatch (Apr 7, 2022)

Rauce said:


> Since I walked in I don’t have any emails to reference but I’m pretty sure it was Abrasive Supply and Service.



OK, I'll look them up. I will need a small supply of quality stones. If not for this tool, then for my air die grinder or my Dewalt 20V Rechargeable Die Grinder (which is an awesome piece of equipment).


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## Susquatch (Apr 7, 2022)

Rauce said:


> Since I walked in I don’t have any emails to reference but I’m pretty sure it was Abrasive Supply and Service.



Is this it? Across the street from a Toyota Dealer?


----------



## Rauce (Apr 7, 2022)

Susquatch said:


> Is this it? Across the street from a Toyota Dealer?
> 
> 
> View attachment 22867


Yup that’s the one!


----------



## Susquatch (Apr 7, 2022)

Rauce said:


> Yup that’s the one!



Awesome!  I'll drop by there next time I'm in K/W/C. 

THANK YOU!


----------



## Janger (Apr 9, 2022)

- Mounted Points
					

Shop our selection of Mounted Points from industry leading brands like Walter Surface Technology, Carborundum, and more! We carry a variety of styles and options to fit every application. ohcanadasupply.ca has all of your Mounted Point needs ready to ship anywhere in Canada. - ohcanadasupply.ca




					ohcanadasupply.ca
				




Grinding stones another option.


----------



## Susquatch (Apr 11, 2022)

Mac tools stopped by and had some small grinding stones on sale so I bought some. 

Still looking for 3 to 4 inch wheels for outside grinding. I can make my own arbour for them. 

Spin up the motor for the first time yesterday. Smooth as silk and "feels like" it will do the job! 

Need to finish the motor holder and also make a chuck jaw expander so I can use the grinder to true up my 3jaw chuck. I'll be doing before and after comparisons when I do.


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## DPittman (Apr 11, 2022)

Susquatch said:


> Mac tools stopped by and had some small grinding stones on sale so I bought some.
> 
> Still looking for 3 to 4 inch wheels for outside grinding. I can make my own arbour for them.
> 
> ...


I've kind of been bumping around looking for what's available in 3 and 4 inch grinding wheels also and haven't found much.  Most of the ones I come across are made for either angle grinder or a hand drill.  
Have you figured out that your motor will be adequately able to turn a 4" wheel without exceeding the rpm limit of the wheel?


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## PeterT (Apr 11, 2022)

Pretty sure I've seen wheels ~3" range (metric) on Ali or Ebay in various grits & compositions. You'd have to make your own arbor to suite but that's probably preferable.
I ran into this same issue. N-Am wheels are out there but not as prevalent to Canucks, meaning grit/material/thickness. The other thing to start thinking about f you haven already is a reliable/safe/clean way to dress stones in-situ because that has to occur regardless. I know I've posted my setup if you're looking for ideas.


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## Susquatch (Apr 11, 2022)

DPittman said:


> I've kind of been bumping around looking for what's available in 3 and 4 inch grinding wheels also and haven't found much.  Most of the ones I come across are made for either angle grinder or a hand drill.
> Have you figured out that your motor will be adequately able to turn a 4" wheel without exceeding the rpm limit of the wheel?



Not really. But it is variable speed, seems to work quite smoothly, and I can reliably measure the speed. 

I'm much more concerned about vibration explosion. 

At any rate, I'll pay close attention to what the maker says, I won't be buying junk wheels, and I won't be standing in line with them. As I said elsewhere, I've seen what can happen and I'd prefer to stay on the other side of the planet from that!


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## Susquatch (Apr 11, 2022)

PeterT said:


> Pretty sure I've seen wheels ~3" range (metric) on Ali or Ebay in various grits & compositions. You'd have to make your own arbor to suite but that's probably preferable.
> I ran into this same issue. N-Am wheels are out there but not as prevalent to Canucks, meaning grit/material/thickness. The other thing to start thinking about f you haven already is a reliable/safe/clean way to dress stones in-situ because that has to occur regardless. I know I've posted my setup if you're looking for ideas.



The problem with Ali and ebay is quality. I'd prefer to buy a wheel like that from an outfit at risk of being sued. Not that the Ali stuff is really any worse, just I feel safer with something from an outfit with a reputation.

I am quite happy to make my own arbour.

Good point on dressing. Hadn't crossed that bridge just yet. I will try and find your post on that.

I could always make an external dressing rig.


----------



## DPittman (Apr 11, 2022)

Susquatch said:


> Not really. But it is variable speed, seems to work quite smoothly, and I can reliably measure the speed.
> 
> I'm much more concerned about vibration explosion.
> 
> At any rate, I'll pay close attention to what the maker says, I won't be buying junk wheels, and I won't be standing in line with them. As I said elsewhere, I've seen what can happen and I'd prefer to stay on the other side of the planet from that!


Ya I'm just playing around with numbers dreaming up how I'm going to do my next tool post grinder and sfm, motor torque and safe wheel rpm seem to get all questionable once I get to the "larger" 3-4" wheels.  I'm just getting my head around it all now so could be mistaken about everything


----------



## Susquatch (Apr 11, 2022)

DPittman said:


> Ya I'm just playing around with numbers dreaming up how I'm going to do my next tool post grinder and sfm, motor torque and safe wheel rpm seem to get all questionable once I get to the "larger" 3-4" wheels.  I'm just getting my head around it all now so could be mistaken about everything



I suppose that's yet another reason to buy from a well known outfit. But in any event, I assume you know that rpm normally goes down as diameter goes up.


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## DPittman (Apr 11, 2022)

Susquatch said:


> I suppose that's yet another reason to buy from a well known outfit. But in any event, I assume you know that rpm normally goes down as diameter goes up.


Yes rpm goes down with an increase in diameter but power requirement goes up.  A motor than can spin a little 1" stone at 30000rpm may not be able to turn a 4" wheel at 7500 rpm. (And/or said wheel may not be safe at 7500rpm)


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## Susquatch (Apr 11, 2022)

DPittman said:


> Yes rpm goes down with an increase in diameter but power requirement goes up.  A motor than can spin a little 1" stone at 30000rpm may not be able to turn a 4" wheel at 7500 rpm. (And/or said wheel may not be safe at 7500rpm)



Agreed. I have no idea about the power or speed at power yet. 

About all I can say is that it's one hell of a fast response torquie little motor. We shall see.


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## PeterT (Apr 11, 2022)

Shop made wheel dresser example








						Toolpost grinding wheel dresser
					

I wanted something rigid & adaptable I could set up quickly on the lathe for wheel dressing in whatever orientation the wheel diameter happened to present. Then knock it down quickly without fuss but preserve the height setting if required again. The parts are just from scrap box metal on hand...




					canadianhobbymetalworkers.com


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## DPittman (Apr 11, 2022)

Susquatch said:


> Mac tools stopped by and had some small grinding stones on sale so I bought some.
> 
> Still looking for 3 to 4 inch wheels for outside grinding. I can make my own arbour for them.
> 
> ...


I forgot, Little Machine Shop has a nice selection of 80 mm diameter grinding wheels


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## Susquatch (Apr 14, 2022)

One of my many interests in a grinder was to true up the Jaws on my 3-Jaw chuck. It's been a while since I measured the run-out though. Since I am close to finishing the spindle motor based tool post grinder, I figured it was high time that I got a good baseline with a few baseline measurements. So I mounted a precision ground indictator rod this afternoon and checked it out.

As soon as I made the first rotation, I realized that my Asimeto tenths indicator had crapped the bed - hardly any runout at all. I've been waiting for that thing to die anyway so I took it off and mounted my good Mitutoyo Tenths. But wait a second..... Same thing! Maybe 3 tenths at worst. Axial concentricity brought that to 4 tenths at 5 inches out...... 

So much for grinding my jaws to improve concentricity...

More experimenting is obviously required. It shouldn't have been that good.......


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## 140mower (Apr 14, 2022)

Damn, I hate it when that happens, hoping for junk and stuck with quality, and no reason to complete the latest project...... I feel your pain friend.


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## thestelster (Apr 14, 2022)

Susquatch said:


> One of my many interests in a grinder was to true up the Jaws on my 3-Jaw chuck. It's been a while since I measured the run-out though. Since I am close to finishing the spindle motor based tool post grinder, I figured it was high time that I got a good baseline with a few baseline measurements. So I mounted a precision ground indictator rod this afternoon and checked it out.
> 
> As soon as I made the first rotation, I realized that my Asimeto tenths indicator had crapped the bed - hardly any runout at all. I've been waiting for that thing to die anyway so I took it off and mounted my good Mitutoyo Tenths. But wait a second..... Same thing! Maybe 3 tenths at worst. Axial concentricity brought that to 4 tenths at 5 inches out......
> 
> ...


Try it with different diameter rods.


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## Susquatch (Apr 15, 2022)

thestelster said:


> Try it with different diameter rods.



All the ones I have are all basically small ( 0.20000 (+/- 0.00001) to 0.50000). I don't have anything bigger than that. All the ones I have measured virtually the same.

I plan to make a bigger one myself today, but it won't be anywhere near that precise. But it will be good enough for this job. Even so, I expect that it will be worse. My jaws are in relatively good shape except at the very ends closest to the tool post. You can actually see the damage in one of the photos above. It isn't as bad as it looks though. The very end bevel is factory. But I probably made those tiny cuts somehow myself. I do not know how nor do I remember doing anything like that. I often grip threaded parts in my jaws and perhaps something held very short spun.

Which raises another question. Should I try facing off my jaws?

I plan to remove the chuck and re-install it today and check again. Back when I first got it I indexed it so it always goes on in the same place and it is a very tight fit, so I'm not expecting it to change.

But the odd thing is that I do not recall it ever being so good. In fact, I remember it being a fair bit worse. Very odd. Things don't usually get better with time. 

The other thing I plan to do today is to make a stepped rod/bar, then reverse it. That might be very telling because it will load the Jaws. I was not about to ruin a very expensive indicator rod by gronking on it.  It was tight, but not gronked. But a home made rod will definitely be suffering that fate.


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## ShawnR (Apr 15, 2022)

Susquatch said:


> gronked



learned a new word today 

ps...the smiley only worked caused I used : & )  so


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## 140mower (Apr 15, 2022)

ShawnR said:


> learned a new word today
> 
> ps...the smiley only worked caused I used : & )  so


...... perhaps your emojis are gronked too......


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## Susquatch (Apr 15, 2022)

I suppose I should be laughing at everything.

I just turned my own indicator rod. Well, more like an indicator bar given that it's 1" in diameter.

I just chucked a 6 inch shaft and cut 3" of it down smooth. Then I reversed it and cut the other end smooth. Then I reversed it again and measured the runout. About 3 tenths. So I started clocking it in the Jaws and retested about every 45 degrees to test for any coincidental concentricity. Turns out the worst I measured was 5 tenths and the best was 1 tenth. 

That's all with gronking on the chuck key.

Totally amazing and very hard to believe. So ya, I'm not gunna be messing with the Jaws on my 3 jaw chuck. They are good enough just the way they are!


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## thestelster (Apr 15, 2022)

Susquatch said:


> I suppose I should be laughing at everything.
> 
> I just turned my own indicator rod. Well, more like an indicator bar given that it's 1" in diameter.
> 
> ...


I suggest you never remove that chuck.  In fact I suggest paying homage, give offerings, or a sacrifice to the lathe gods.  Don't even cast a look at it in an ambivalent way!


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## Susquatch (Apr 15, 2022)

thestelster said:


> I suggest you never remove that chuck.  In fact I suggest paying homage, give offerings, or a sacrifice to the lathe gods.  Don't even cast a look at it in an ambivalent way!



Ya, I'm thinking the same thing. 

I'm torn. A big part of me wants to take the chuck off and try it again just for poops and giggles. The other part says: "ARE YOU CRAZY!"

But it has to come off. UNLESS I buy another lathe...... Hmmmm......

Honey, I need another lathe.....

Big noise far in excess of 90db, grass looks root white for some reason, and I suddenly have a dozen brand new sparkly clean lathes and a dozen matching mills, and I could swear I hear angels singing.......


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## PeterT (Apr 15, 2022)

I've noticed some +/- runout repeatability variations on my 3-jaw chuck too. Its a Bison 6", jaws & scroll in good shape, never abused or crashed or overtightened etc. Always mounted on same marked (lowest runout) D1-4 orientation. Same dowel which is hardened, known circular tolerance. The resultant indicator deviation range is typically 0.001 to 0.0015" runout which is pretty good for 3-jaw. So when I get a rogue reading like 0.003" it stands out for further investigation. Assuming all the obvious things like debris, I find I can usually make it revert to the mean by re-inserting & gradually tightening all the jaws in progressive succession and to the same (hand estimated) torque. Over-gronking or worse yet gronking on one jaw only is not good practice IMO. I know there is some kind of primary or dominant jaw, but I've found equal tightening to be better. Shorter length dowels that don't fully contact the jaws fully might be another discrepancy source. Measuring close or further from jaws is another variable. The dowel could be circular, but is it perfectly straight?

I think there a few subtleties to testing runout that people may not think of as important but may actually may be in the range. IE blaming the chuck, but it could be external factors. I've heard countless times something to effect:_ I chucked a shiny ground piece of O1 tool steel and_.... Hope this isn't stating the obvious but Tool steel in its typical annealed ready-to-machine form is no harder than most other common alloys, so may as well say I chucked a piece of stainless or 4140. The hardness only comes after heat treating. Also, every tool steel bar I've had varies by 0.0005"-0.001" across the axis (non circular) which is actually stated by specs if they can be found. So right off the bat there will be at least this runout to contend with in otherwise perfect jaws. But this eccentric shape will present itself differently to the 3 jaws as a function of shape & orientation. If you rotate it slightly & re-grip, runout will be different again. Insertion: if the jaws are wide open and you 'drop' the bar kind of in between 2 supporting jaws & start scroll tightening, the jaws could be squeezing up the bar OD differently until fully tangent contacted. VS. getting the jaws close to OD & lightly turning the dowel as you tighten. I do this spin thing routinely on drills as I tighten chuck. Its how I discovered the crazy raised stamped marks on the shank affecting grip It probably pays to have some known (hardened) dowel standard for testing, ideally of a few different diameter ranges. Maybe the jaws faces are OK but scroll is worn or distorted in different areas? Not sure what can be done about that but at least you aren't chasing your tail fixing the wrong perceived problem source.

I haven't actually purchased a set of jaws for a chuck yet, but I've heard of people who did & majority of headaches went away assuming that's all it was. May not be the answer but something to compare as baseline cost to alternatives assuming the chuck body, scroll & slide ways are good. I'm a fan of Set-True type chucks where you can tweak the chuck axis relative to spindle axis. Unfortunately the backplate adapters & chucks themselves can add considerable cost. This discussion is related to repeatability issues of typical 3-jaw. Many will advocate getting a collet chuck for precision work. That may be helpful, but maybe not, depends on quality of chuck, collets & same axis orientation issues. And a 5C or ER collet chuck wont do us much good if we need repeatability on parts outside the typical range of collets.


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## RobinHood (Apr 15, 2022)

As far a buying replacement parts for chucks: it depends on the quality/value of the chuck, IMHO. If a set of jaws are $700 for a 10” Röhm then one has to compare that to the new price of $2000+. It may be a good purchase. Not so much for a $400 import. Oh, btw, for Röhm chucks, any replacement jaws need to be ground in situ once they are installed to achieve the very tight tolerance that Röhm work holding tooling is known for.

Agree with “twisting in” a part as you tighten the jaws. I also use all available key holes to get it tight, with the final torque on the “master” key (as per Röhm [and other high quality] operating instructions).


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## Janger (Apr 15, 2022)

Pete alluded to this but I'll spell it out specifically. The dowel can be round and straight - but is it in the chuck straight? Measure the run out at 1" out from the chuck and then again at say 3" out from the chuck. If it's different it's not in straight (assuming it is a straight bar). The texan guy has a video on this. Joe Pieczynski but I can't seem to find it.


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## Susquatch (Apr 15, 2022)

Janger said:


> Pete alluded to this but I'll spell it out specifically. The dowel can be round and straight - but is it in the chuck straight? Measure the run out at 1" out from the chuck and then again at say 3" out from the chuck. If it's different it's not in straight (assuming it is a straight bar). The texan guy has a video on this. Joe Pieczynski but I can't seem to find it.



That's the concentricity measurement I spoke of earlier. I measured it at the chuck and out 3 inches for my homemade indicator bar and at 5 inches with my precision ground rod. 

But I'm more inclined to believe that the majority of any of this error is due to non-concentric or belled jaws that need grinding than it is to not putting the part in straight.


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## Tom O (Apr 16, 2022)

This guy shows his grinding setup and mentions other setups on his channel


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## Dabbler (Apr 17, 2022)

Max has a completer video series on OD grinding, ID grinding and taper grinding using a TPG.  The series begins here:


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## PeterT (Apr 17, 2022)

Dabbler said:


> Max has a completer video series on OD grinding, ID grinding and taper grinding using a TPG.  The series begins here:



Good score @Dabbler I've come across his channel but missed these. Kind of hard to see from this angle perspective but demonstrates the potential tailstock vs spindle competing real estate issue I was mentioning. The only way to work around TS support is if the spindle housing is smallish OD and the grinding wheel biggish OD & part is not too smallish ID. His setup is similar to typical Dumore/Themac/Maximat TPG layout where the spindle is compact OD & larger diameter motor is back up out of the way (and belt driven). Versus if its a direct drive motor, the HP dictates rotor diameter, so you need a proportionately larger wheel to clear. Some lathes can accommodate this if wheel extends outboard of cross slide, but kind of depends. 

Grinding angles (with TS support) can also be a bit tricky as the compound can only swing out of the way, not into the lathe axis path. Some parts like the R8 arbors can be flipped end to end to accommodate, but not all parts lend themselves to this.


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## Susquatch (Apr 21, 2022)

Well, big day today. I fired up the new spindle motor based tool post grinder.

Excuse the fancy drop cloth. Didn't want grit on my ways.

The video is huge so I uploaded it to dropbox. I'm no youtube creator.









						20220421_143819.mp4
					

Shared with Dropbox




					www.dropbox.com
				




The lathe isn't as Noisy in person as it is in the video, and the spindle motor is the opposite and much quieter in person. The grinding noise is much quieter in person too. It's probably the way my phone normalizes sound. 

It didn't take long at all to grind down that last 1/4 inch to get the bar round. It doesn't bounce unless you push it which isn't in any of my planned uses.

Wish I had a bigger wheel, but not yet. Need to make or buy a wheel dresser too.

In any event, it works. So I'm happy for now. Best of all, I learned a lot along the way with lots of learning yet to come.

Next phase is an enclosure for the control box, a stone dressing system, a proper height adjuster for the holder, some proper stones, and prolly a few stone arbors too. Then I'll try to use it to make something since grinding my jaws as originally planned would be stupid.


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## Susquatch (Apr 21, 2022)

Here is the "almost finished" tool holder. Still needs the height adjuster but the relief for it is cut. 

I decided to go with two halves. Didn't have a sharp slitting saw and figured a 2 part clamp would be better anyway. So I just cut it in half on the band saw and then cleaned up the surfaces on the mill. 

Drilling, countersinking, and even tapping was a piece of cake with the DRO. No idea how I lived my life so long without one. Like it enough that I might even splurge and put one on the lathe too.


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## DPittman (Apr 21, 2022)

Looking good.  That spindle motor seems VERY quiet! What rpm was that running at?  Most tool post grinding recommendations say to run work piece in opposite direction of grinder spindle but you were probably just trying things out as you didn't have a dressed stone either.  
Nice machining on the holder.


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## Susquatch (Apr 21, 2022)

DPittman said:


> Looking good.  That spindle motor seems VERY quiet! What rpm was that running at?  Most tool post grinding recommendations say to run work piece in opposite direction of grinder spindle but you were probably just trying things out as you didn't have a dressed stone either.
> Nice machining on the holder.



Actually, you are being kind. I totally missed the opposite direction thing. In any event, I had thought the spindle motor was reversable but it isn't. At least not that I know of. I have not tried simply reversing the power leads. My lathe is reversable though. So that one is an easy fix either way. 

I don't know what the spindle motor speed was. It's variable but the reostat isn't calibrated. That was running about 1/3 throttle. I have not even tried to measure it yet. 

However, I did try running the motor a bit faster maybe 1/2. Given the unknown pedigree of the stone, i didn't want to go too fast. At 1/2 throttle it was even smoother.


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## Susquatch (Apr 22, 2022)

DPittman said:


> Most tool post grinding recommendations say to run work piece in opposite direction of grinder spindle but you were probably just trying things out as you didn't have a dressed stone either.



I reversed the power wires on the spindle motor. That does indeed reverse its direction.

I should have been a little more confident of that given that the wires are polarized - a red wire and a black one.

This just means I need a double pull double throw switch in the motor power circuit so I can easily choose direction in the final setup.

I rigged up something temporary to measure speed with too. I put two counterbalancing pieces of black tape and reflective strips on the output shaft at different distances so only one triggers the tach and that seemed to be pretty stable at between 500 and 15,000 rpm. The setting I had it on in the previous video appears to have been around 5000 rpm. Prolly give or take 1000 or so. Although I really don't trust an electronic tachometer like this, that at least all seems reasonable to me. I might try it on the fan shroud too. I sure wish my kids didn't lose my mechanical tach. That thing was bulletproof. And, being non-digital, it never lied. But.... It could be a pain to use sometimes......


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## Susquatch (Apr 22, 2022)

Oh yes, here are all the left over pieces from the block. I was reasonably careful to keep them as big and as useful as I could. Hopefully, they are all hiding a future part inside them that I will find someday. For now, they go into my piles of scrap and stock.


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## thestelster (Apr 22, 2022)

Susquatch said:


> I reversed the power wires on the spindle motor. That does indeed reverse its direction.
> 
> I should have been a little more confident of that given that the wires are polarized - a red wire and a black one.
> 
> ...


If you go onto the Dumore website, there is quite a bit of information regarding tool post grinding, https://www.dumoretools.com/resources


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