# Rotary Table Chuck Adapter Plate



## YYCHM (Mar 13, 2019)

I'm attempting to make a chuck adapter for my rotary table.






I have roughed out a piece of 1/2" hot rolled to approx. 4" dia.

Should I turn it to 4" on the lathe or mount it on the rotary table and mill it to final dimension?

What would you do?


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## Dabbler (Mar 13, 2019)

I'd turn it.  easier on the machine and low chance for breaking a $$$ end mill.

TIP:  use HSS for the interrupted cut,  Interrupted cuts are very hard on most carbide tooling.

(you can also turn it a little large, and finish it if necessary on the RT).


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## PeterT (Mar 14, 2019)

I agree with Dabbler. The trick is how to securely mount it especially for the interrupted cut. On this (aluminum) chuck mount plate I used threaded holes with bolts in from behind because they didn't detract from this particular end result. I've also seen setups with edge clamps which mitigates the holes which are on my make-it list. Either way, finish one face, flip, re-mount & repeat 2nd face. Standoffs as shown is one way to finish the OD edge in the last step. But it needs to be rigid setup & light cuts. You don't want that disc coming loose.

Even though its HRS you may see some distortion. Try & get well through the skin & aim for relatively equal removal both sides.


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## historicalarms (Mar 14, 2019)

Craig, I had to turn a lot of square plating into round slabs for that big canon you've seen and if I may offer a suggestion it would be to grind (just a shop grinder) those points down to almost finished dia. before trying to make it "round" with your lathe. I found that the increase in dia of the work-piece much diminished the cut I could take even with my 1340 sized lathe and the "interrupted cut" just magnified the effort needed (dabbler is very right about interrupted cuts being murder on carbide inserts). I just think your small lath will be taxed to the limit trying to remove much more than a minimum from the plate.


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## YYCHM (Mar 14, 2019)

Looks like it's going to have be done on the mill.  The face plate for my lathe won't accommodate bolting the disk I'm attempting to make to it.  The mounting slots aren't long enough.


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## Janger (Mar 14, 2019)

I put my face plate on the mill and milled the slots longer and wider. You have to do projects to do a project for a project yes?! The slots seemed to be metric and I needed them a little wider to accommodate imperial bolts.


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## PeterT (Mar 14, 2019)

You can probably use a similar hold-down concept on your RT. Your screw heads need to be beneath the surface depth of course, but maybe you position them where they can eventually become features like slots if it bothers you, or maybe align to a chuck back plate bolt pattern. I'm going to make something like that with a grid array of threaded holes for fixturing on the RT.


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## YYCHM (Mar 15, 2019)

Janger said:


> I put my face plate on the mill and milled the slots longer and wider. You have to do projects to do a project for a project yes?! The slots seemed to be metric and I needed them a little wider to accommodate imperial bolts.



Modifying the face plate was the first thing that crossed my mine.  Alas, the piece is just too small to mount without making a mounting adapter.  The slots on the face plate already extend to flange where it attaches to the spindle.

I'm going to try using the RT.  Probably less drama going that way anyways.  I would image turning off the corners would be a pretty bumpy ride on a mini lathe.


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## YYCHM (Mar 15, 2019)

Hmmmm.  This thing may end up on the lathe for final finishing yet.






The finish is not turning out all that good.  The RT appears to have more back lash than I expected causing a lot of chatter.

Maybe these things aren't really made for this kind of operation?


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## Janger (Mar 15, 2019)

Which way are you turning it? Turn the part clockwise for conventional milling. What RPM are you at? Is that cutter sharp? thereis a lot of stickout. Clamp it higher and lock all the the axis, x, y, z.


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## YYCHM (Mar 15, 2019)

Janger said:


> Which way are you turning it? Turn the part clockwise for climb milling.what RPM are you at? Is that cutter sharp? thereis a lot of stickout. Clamp it higher and lock all the the axis, x, y, z.



I tried turning the piece in both directions.  CCW appeared to cause the least drama.

RPM?  1/4-1/3 of low gear RPM what ever that amounts to.  I've got to get one of those hand held RPM things someday.

Brand spanking new end mill(s).

Stickout?  The only stickout is material I'm trying to remove.

Been locking X, Y, and Z every pass.  Well..... I forgot to lock X once, but that was immediately obvious.

"Clamp it higher"?  What do you mean by that?


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## Bofobo (Mar 15, 2019)

Looks like the clamping bolts are crooked, and the tool has a lot of stickout, Are you creating a shoulder? lose drive train in the RT dial?


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## Janger (Mar 15, 2019)

Mike has a point the bolts do look crooked - is the table held down tight? And yes by stick out we mean your end mill is sticking way out of the tool holder or collet. It should stick out as little as possible and move the head down closer to the part. for RPM your speed should be SFM for steel * 4 / tool diameter which = (100 * 4 )/ 0.5 = 200  <edit>  800 RPM.

Read up on speeds and feeds and also conventional vs climb milling. Your machine is probably not suitable for climb milling. nor is mine.


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## YYCHM (Mar 15, 2019)

Bofobo said:


> Looks like the clamping bolts are crooked, and the tool has a lot of stickout, Are you creating a shoulder? lose drive train in the RT dial?



Clamping bolts are straight.  Image illusion.

Tool stickout….ya I can reduce that.  Is that what janger is referring to as stickout?

Not creating a shoulder, turning a square into a disk.  I roughed out a octagon on the saw first.  I need to mill off all that extra material.

There is some slop in this RT that I haven't figure out how to eliminate.  It's supposed to be backlash adjustable but the only screw on it doesn't have any effect?  Of course instructions weren't supplied with it.


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## Bofobo (Mar 16, 2019)

YYCHobbyMachinist said:


> Clamping bolts are straight.  Image illusion.
> 
> Tool stickout….ya I can reduce that.  Is that what janger is referring to as stickout?
> 
> ...


You and I have pretty much the same stuff, that being said, the tool is undoubtedly deflecting and i would have used only the side of the end mill for a full depth of cut rather than a 2 step process. Sometimes the formula for cutter speed is out the door, in the hass i used we would have the base program brought in all according to the math and as the first parts were made we would adjust feeds and tool speeds to find the best results, perhaps you need faster ...... with my current upgraded motor my speed reader tops out at 500rpm i only made one belt groove thus far. you are running oem and i never used low gear in oem configuration because its a small mill and smaller tooling spins faster than large tooling.


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## RobinHood (Mar 16, 2019)

Looks like you want to finish the part to final OD first.

You state that your face plate has slots all the way to the edge but is not large enough to clamp the part - no problem!

Use double sided tape and some thin shim stock (maybe 0.020” or so) between the part, shim stock and the face plate. Make sure the part is centered on the faceplate using your center hole to dial it in (actually, since you already have a partially machine OD, use it). Use your tailstock with a live center to push the part against your face plate. It is called friction driving / turning. Works great.





 . The fellow uses single sided masking tape only - that works, but double sided tape is better.

Once you have a good OD, use your 4-jaw to hold it and machine a face. Flip it and do the other face. Done.


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## PeterT (Mar 16, 2019)

The tail stock in the video is an integral part of the setup, so don't neglect that. It helps support the in feed force & more importantly helps prevent the blank from coming off the face plate. I notice he said 'light cuts' & notice his blank was very close to circular to begin with with the laser cut blank. Interrupted cutting can impart a lot of torque & that has to be met by the strength of the adhesive. I'd say if you are going to do this in the lathe, try & complete your RT/milling job to get the excess off & at least you are circular. Unfortunately with the TS center in place, it makes surfacing the disc a bit more challenging because you can only go so far, but there are ways around that too.

Rudy, he didn't mention his face plate dimensions but said it was too small, so I doubt his lathe will accommodate a 4J to grip the edge.

But YYC, just looking at your bolt-up on the RT,  you are saying those studs wont fit the slots of your faceplate? Or is the issue your lathe cant accommodate the overall diameter of the plate in your swing?

Back to milling, one day you should try a roughing end mill. People get the idea they are only for production & hogging. But they are actually well suited to light duty hobby machines too. They make a different chip that removes material more efficiently than conventional & is actually easier on your machine. Save your good EMs for finishing.


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## RobinHood (Mar 16, 2019)

True about not knowing the size of the FP.... and the extra caution on interrupted cuts.


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## YYCHM (Mar 16, 2019)

RobinHood said:


> True about not knowing the size of the FP.... and the extra caution on interrupted cuts.








4" plate on a 6 1/4" FP.  The min distance between the FP slots is 3 1/2".  I probably could have made it fit, but I was concerned that there wouldn't be enough slop left to center the plate on the FP.

The RT approach to this project went from bad to worse.






Too much slop in that RT.  LOTS of chatter and vibration.  I tried low gear low speed, low gear high speed, high gear low speed and warp drive.  Nothing seemed to help.  Note the 1/2" shank cutter set close to the quill.

I'm kind of disappointed with this RT.  Is it junk or are RT's not made for this kind of operation?

In any event, I gave up and moved it to the lathe where things went much better.






Here I'm facing off after repairing the damage done to the outside circumference by the RT.  Looks much better now.

I hear every one on the interrupted cuts and carbide tipped tools now.  Didn't have a HSS to use.  First pass chipped one.  Not bad enough to abandon it though.

So the questions now is.....






How do I transfer the bolt pattern on this chuck onto the adapter plate?

The image is deceiving.  The plate is 4" dia and the chuck is 3" dia.


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## RobinHood (Mar 16, 2019)

You could take the mounting studs out. Lay a piece of paper on top of the chuck and rub it with a blunt object or a pencil (tape the paper to the side of the chuck so it does not move, if required). You will get an imprint of the features (including hole location) on the paper. Transfer the paper onto your mounting plate and center it. Use a center punch to mark out the holes. Drill a little oversize so you can fine adjust the chuck to the plate. Mark one hole on the chuck as reference and the same one on the adapter as well.

You could also use the rotary table on your mill, assuming you had the bolt circle radius of the mounting studs and they were symmetrically 120* apart.

You could also use Tranfer Pins (aka blind hole spotters) if you had them or made them.






Just out of curiosity: how are you planning to mount the chuck onto the adapter plate?


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## YYCHM (Mar 16, 2019)

RobinHood said:


> You could also use Tranfer Pins (aka blind hole spotters) if you had them or made them.
> 
> View attachment 4746
> 
> Just out of curiosity: how are you planning to mount the chuck onto the adapter plate?



"blind hole spotters"?  Your image is just a tad too small to make out what they are. A very short transfer punchs?

I used 1/2" plate with the idea in mind that I would use counter sunk hex head cap screws.  In hind sight now I should have used 1/4" or 1/8" plate and V-Head (? not the correct name) screws.

The plate will also need to accommodate a 4-bolt 3" chuck some time later.

I like the idea of employing the RT to locate the holes.  Prove it's useful for something.


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## RobinHood (Mar 17, 2019)

I’m sorry that the image of the tranfer pins did not show clearly. Here is another try:





Socket Head Cap srews or Flat Head Cap screws (FHCS, the countersunk version of a SHCS) should work fine for you. The difference is that a SHCS allows for lateral movement of the fastener in an oversized hole whereas the FHCS does not because of the countersink cone it is drawn into. This meas that hole location with FHCS needs to be more accurate.

Sure the ROTAB will do the trick just fine. Gives you a chance to practice a bit as well. Might want to do a prototype in a piece of plywood (plastic or even stiff cardboard) to see how things go. The reason i say that is: you have spent a lot of time on your adapter plate already and also have discovered some nasty backlash issue with your rotary table that you have not been able to solve yet. I hate to see you scrapping the good work you have done thus far.

Once you have proven the concept and know the hole location is good, both for your 3J and the 4J and, while you’re at it, the adapter to ROTAB fastener placement, you can then with confidence go make some metal chips....


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## YYCHM (Mar 17, 2019)

RobinHood said:


> Sure the ROTAB will do the trick just fine. Gives you a chance to practice a bit as well. Might want to do a prototype in a piece of plywood (plastic or even stiff cardboard) to see how things go. The reason i say that is: you have spent a lot of time on your adapter plate already and also have discovered some nasty backlash issue with your rotary table that you have not been able to solve yet. I hate to see you scrapping the good work you have done thus far.
> 
> Once you have proven the concept and know the hole location is good, both for your 3J and the 4J and, while you’re at it, the adapter to ROTAB fastener placement, you can then with confidence go make some metal chips....



That's a very good suggestion.  I'll do just that with a piece of wood.

I figured out the RT backlash adjustment.  The backlash can be reduced but at the cost of making the table hard to rotate.

The bolt pattern on my lathe FP is the same as the 3J chuck.  If I could figure out how to center the FP on the adapter plate I could transfer punch the hole locations.  Still scratching my head on that idea.


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## Bofobo (Mar 17, 2019)

YYCHobbyMachinist said:


> That's a very good suggestion.  I'll do just that with a piece of wood.
> 
> I figured out the RT backlash adjustment.  The backlash can be reduced but at the cost of making the table hard to rotate.
> 
> The bolt pattern on my lathe FP is the same as the 3J chuck.  If I could figure out how to center the FP on the adapter plate I could transfer punch the hole locations.  Still scratching my head on that idea.


Could use a mill with a dro, i can help! Its just like your mill afterall


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## PeterT (Mar 17, 2019)

Every situation is a bit different, but generally if you can establish a reference that will be common to subsequent machining setups, that will maintain the best accuracy & make your setups more reliable, For example
- mount the rough stock to the mill table
- drill a center hole using 60-deg center drill even if its just temporary. Now you have 0,0 established on the dials
- utilize this reference & drill other holes at their respective X,Y coordinates. Now you have your pattern of holes accurately spaced.
- scribe a circle from center like you did & rough it out
- now you can register the stock on the lathe face plate using a 60-deg center perfectly mated to the center hole like the video

Similarly, you could center on an RT to make a series of radial holes or slots by dropping a 60-deg center down. This isn't considered quite as accurate as dialing in an ID or OD surface using an indicator, but for just clearance bolt holes, probably fine. Remember FIRST dial in the center of the RT before mounting stock, THEN dial in the stock during mount up.

Sometimes I've drilled/reamed a hole & inserted a dowel pin to center off that (protrusion as opposed to hole) or offset distance from the pin. Lots of ways to skin the cat depending on the task.


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## YYCHM (Mar 19, 2019)

Well, I nailed the chuck bolt pattern using the RT.






After centering the RT and test piece to the quill, I setup a reference bar attached to the bench so that I could use my digital caliper to move the table 1.3" right.

Here I'm drilling a test pattern into a piece of hardwood flooring.






Took two test patterns to get things right.  First attempt I miss measured the table offset and indexed the RT to the wrong setting for the third hole Daaaa.  Second test pattern looked good so I proceeded to drill the adapter plate and mill the mounting slots.   I'm pretty pleased with the results.











I'm kind of in awe that the disk I made started from this.






Here is the final arrangement.  The run out on a piece chucked to the RT is very minor according to my center finder.  I suppose I could check the run out with my TDI to.

You guys warned me about this.  With the RT, adapter plate, and chuck there is very little room left to do anything. In the setup pictured, I can't remove the drill chuck from the quill.  The commercial chuck offerings for RTs are a lot shorter depth wise.  The chuck pictured here is for my lathe.

All in all a very rewarding learning experience.

Hmmmm…. do I need a tail stock for that RT?


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## RobinHood (Mar 19, 2019)

Well done!

Figuring out the sequence of operations and asking yourself “what if....” a lot just in case something does not go according to plan is the secret to success. Its almost like playing chess: its not the next move that’ll get you, its the tenth one down the line...

You will find the more complex the parts, the more of this you’ll use and the more little “prototypes” you’ll make because you just don’t want to scrap the part you have so much time invested in.


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## Janger (Mar 20, 2019)

Yes - Well done man! Yes you’ll need a tailstock. Help me finish mine!


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