# Er32 chuck for my 11 inch Logan



## Chris Hamel (Apr 4, 2022)

I decided I wanted to make a chuck for holding er32 collets that would fit on the spindle of my 11 inch Logan.  I found an er32  holder that attached with a flange on eBay.
	

		
			
		

		
	



	

		
			
		

		
	
  I then took a round chunk of aluminum and machined it to screw on the spindle of my lathe.  This was quite a chore since my spindle is 2  1/4" x 8 tip.  In addition to that the last half inch of the spindle is not threaded and is actually a bit oversized.  2.310".  I kept at it and ended up with a nice fit.  I mounted the piece on the spindle and trued  up the face and the OD.  I then bored about a .200"  recess that fit the OD of the er32 adapter.  Since i machined it with it mounted on the spindle,  I knew it had to run true.  The er32 adapter came with three holes tapped with metric threads, so I planned to drill them out to fit 1/4" bolts.  I found out the steel was hardened, so I used 10 -32 bolts instead.  (They fit inside the threaded holes.)  I'm not worried about whether 10-32 is strong enough since the recess is doing all the work.
	

		
			
		

		
	



	

		
			
		

		
	
I chucked a piece of 1/2 " rod in it and checked the runout.  Somewhere around .001.


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## benmychree (Apr 4, 2022)

I think it would be worthwhile to invest in some metric bolts, 10-32 is pretty wimpy for this application.


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## woodchucker (Apr 4, 2022)

thats a lot of material. I would think you want to reduce the amount of space between the front of your spindle to your er32..
but that's me..


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## benmychree (Apr 4, 2022)

woodchucker said:


> thats a lot of material. I would think you want to reduce the amount of space between the front of your spindle to your er32..
> but that's me..


I thought that also, but did not choose to say so, but yes; it may not effect function, but it does not look right.


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## wrat (Apr 4, 2022)

Looks fine to me!
10-32 steel bolts (metric is certainly no stronger) will hold hundreds of pound in shear per each.
The rim is captured, so just like you said, it's gonna hold things in place.  You're just holding it inside the hole - that takes all the radial pressures.
How much does it need to hold?  Simple:  however tight the collet can get.  
Chances are, your workpiece will spin in the collet LONG before you shear off those bolts.


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## benmychree (Apr 4, 2022)

wrat said:


> Looks fine to me!
> 10-32 steel bolts (metric is certainly no stronger) will hold hundreds of pound in shear per each.
> The rim is captured, so just like you said, it's gonna hold things in place.  You're just holding it inside the hole - that takes all the radial pressures.
> How much does it need to hold?  Simple:  however tight the collet can get.
> Chances are, your workpiece will spin in the collet LONG before you shear off those bolts.


And if that is not true, you could be wearing it, I suspect the manufacturer sized it to the stated size for some reason.


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## Chris Hamel (Apr 4, 2022)

The space between the front of the actual spindle and the flange is only about 1/4"


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## woodchucker (Apr 4, 2022)

Chris Hamel said:


> The space between the front of the actual spindle and the flange is only about 1/4"
> 
> 
> 
> ...


ok, cool, it's such a big honking piece of AL that it looked like a long stickout. that's good..


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## mickri (Apr 5, 2022)

How did you drill the holes in the aluminum adapter for the screws to ensure that the holes were concentric?


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## Chris Hamel (Apr 5, 2022)

I tapped on the adapter to make sure it was seated and then I used a transfer punch.


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## wrat (Apr 5, 2022)

benmychree said:


> And if that is not true, you could be wearing it,


Perfectly true!
STILL looks fine to me!
Heck, I'll look again and see.  Yup.  Still looks fine to me.
Your opinion may differ.  And why not?  I'm simply an Engineer.  I wouldn't trust me, either.  Okay.  But it's no more *true*.


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## rdean (Apr 5, 2022)

A clean, neat machining job done well.

Will be useful and safe within the limits of the ER32 collets.
No one can for see what might happen but it is no more dangerous than many other lathe operations we do regularly. 
Safety ultimately lays with the operator.

Ray


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## Chris Hamel (Apr 5, 2022)

I figure I can't chuck more than 3/4" and I rarely take more than .025" per pass, so I think I'll  be ok.   Then again, if I can determine the size and pitch of the existing threads and locate some bolts, changing how it is attached is no big deal.


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## benmychree (Apr 5, 2022)

What I was talking about was the material at the back of the backplate, not the front; make it look more like a normal backplate.


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