ER40 Adjust True Camlock Collet Chuck Build

davidpbest

H-M Supporter - Commercial Member
H-M Supporter - Commercial Member
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Dec 26, 2015
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Earlier this year I purchased an ER40 collet chuck with integral D1-4 mounting from hhip.com (their part #3901-5042). I wasn't completely satisfied with the quality and it didn't have sufficient stick-out from the spindle nose to get cutting tools to it using my solid tool post. I also had inconsistent registration to the spindle with unacceptable TIR. This is that chuck.

Stock ER40 Camlock Chuck from HHIP.jpg


I decided to replace it with a better solution - one that was adjustable to the centerline of the spindle rotation, along the lines for an Adjust True or Set Tru scroll chuck.

After some research I bought an ER40 plain back collet chuck from an eBay seller, did some checking of it when it arrived and concluded it was built to decent tolerances. Then I bought a Bison D1-4 camlock backing plate, some 1045 stock from McMaster and set about making a sleeve to join the Bison backing plate to the ER40 collet chuck.

This is the result - it has four M8 set screws around the perimeter that can be used to precisely center the chuck. I'm very happy with the result.

Completed Chuck.jpg


Here's a nose-on view - you can see the centering adjustment set screws if you look closely.

Face View.jpg


Although a bit expensive, the Bison D1-4 backing plate is exactly what I expected - outstanding quality:

Backplate.jpg


I'm attaching the drawing for this implementation in case anyone wants to do the same.

Also, there are more images and description of the build process here:

https://flic.kr/s/aHsm1PtHsq

Hopefully this will be useful to someone here. Enjoy.
 

Attachments

  • ER40 Adjust True Collet Chuck Assembly.pdf
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Nice job!

Sent from my Pixel XL using Tapatalk
 
Really impressive. Nice work!
 
An excellent design, thanks for sharing. I'm pleased with the versatility of the ER40.
 
I luv that you did this! Don't know that I'm up to it, but it's great you posted this for guys like me.

Rich
 
I still am amazed that one of the better quality tooling outfits I.E. Maritool, hasn't made a high quality D1-4 ER40 chuck. That hhip is pretty poor inconstant quality, some say that it meets their stated spec (which is constantly changing by the way, for the worst) to mine that doesn't meet it at all.

Very nice job on your design! Mind giving us the seller details and part #'s for the purchased items?

Just noticed that you did give us the info in the photo stream, thanks!
 
Very nice! I want to use this principle on some similar applications. So if I understand the sketch, you
- snug the X axis cap screws so the ER plate so its is flush but still adjustable
- adjust the 4 opposing set screws so it runs concentric
- lock the cap screws down so assembly it stays put

Brand comment FWIW. Most of my rotating tooling is Bison purchased years back. But it has become stupidly expensive in Canada. I needed some small diameter chucks for my rotary table so took a shot with Gator brand. I figured I'd get a D1-4 backplate for the lathe thrown in. Its the kind you machine the lip to suit the chuck recess & that operation went fine. I was also interested in a repeatability test between the Gator & Bison back plate (meaning how it aligns to lathe spindle nose). Maybe I got a good one because I could not measure any concentricity deviation using 0.0001" DTI. I also have a Bison 5C collet direct mount (non Set-Tru). Rather curious, but it favours a certain pin alignment over another. Not a huge amount, but its there & repeatable (using Bison brand 5C collets). In hindsight I should have got Set-Tru. When I rotated the Gator D1-4 backplate to different pin/hole positions, nothing changed, same concentric reading. I don't think the pins have much to do with it as long as they are seated properly & the cams can pull it into the nose snugly & equally. Seems like grinding accuracy of nose taper is the critical thing?

You probably now this but it was news to me. To get the runout specs quoted on ER4 collets, it takes a surprisingly hefty torque rating. I'm probably overly squeamish but do you put the lathe in low gear to tighten/untighten the ER collet cap?
 
I have found it necessary to use a pin wrench (or box wrench depending on the ER chuck) when tightening ER32 collets. David, there seems to be a pin wrench hole in the first chuck pictured?
 
I have found it necessary to use a pin wrench (or box wrench depending on the ER chuck) when tightening ER32 collets. David, there seems to be a pin wrench hole in the first chuck pictured?

Yes, there is a pin wrench hole on the perimeter of the ER40 chuck I used, but of course it's covered up because the rim of the chuck is now recessed into the adapter sleeve. And I agree that considerable torque can be required to tighten the ER40 collet sufficiently, and I have come to the practice of using my conventional chuck key in one of the Camlock square locking holes as the opposing lever force against the ER40 spanner. It would be easy enough to put a few pin wrench holes around the adapter sleeve if you wanted, but I've gotten used to using the square chuck key and actually don't care to introduce yet another tool into the inventory just for tightening the ER40 chuck. Others may feel differently.

Since I brought up the spanner, there are of course two types - the claw type and the UMW type that encircles the nut and tabs into the slots in about 4 places. Thus far I have broken two of the claw type because they were cast from pot metal, and now I have a Lyndex that appears to be a forged casting and has stood up so far, although it is light weight and probably wouldn't withstand a lot of mistreatment. The claw type I like the best is one I made myself from 3/16" steel flat stock (20 minutes on the bandsaw and grinder). I have two of the encircling type wrenches, both stamped from sheet steel, and of those, the one that I favor is the DZ wrench.

Where I have had more issues is with the ER40 chuck nut. I now have a collection of about six of them, and most of the imports do not grip the groove on the nose of the collet sufficiently to pull it out of compression when the nut is backed off - the collet simply pops loose from the nut. This one does not grip the recess on the collet nose at all, which was a big disappointment considering the cost. The USA made Maritool collet nut doesn't grip the collet nose firm enough to suck the collet out of the taper if tightened to torque spec. The nut that came with the HHIP collet chuck is total junk IMO. The nut that came on the the Shars R8 ER40 collet arbor I purchased is nicely finished, but isn't ball bearing, thus difficult to loosen, and again doesn't grip the collet well enough to retract it from moderate compression. There are two ER40 collet nuts that I am satisfied with (both ball bearing type), including the one that came on the plain back collet chuck that I adapted, and the Parlec. The Parlec is closest to the original Rego-Fix nuts I have on other equipment where you press the collet into the nut at a slight angle to engage the retract ring firmly into the groove around the nose of the collet. It can be fussy to learn the technique at first, but the collet will not come loose from the nut unless it's angled to the side.
 
Very nice! I want to use this principle on some similar applications. So if I understand the sketch, you
- snug the X axis cap screws so the ER plate so its is flush but still adjustable
- adjust the 4 opposing set screws so it runs concentric
- lock the cap screws down so assembly it stays put

Exactly. I believe that's the way most Set-Tru chucks function for adjusting runout. The Set-Tru 6-inch 3-jaw scroll chuck I purchased from Precision Matthews (which is an outstanding quality copy of the Bison), has four set screws in the chuck body, that push against a projection on the back plate that's recessed into the chuck body. When I first tried to adjust it, it wouldn't budge. There was no tolerance between the back plate projection and the recess in the chuck. So I simply skimmed off about 0.008-inch of the back plate projection, remounted the chuck and I had the the necessary adjustment capability. On that chuck, the bolts that secure the chuck to the back plate come from the back plate side. On the ER40 adapter design I did, the chuck can be secured from the front or back, but I decided to use the front to make it easier to do the TIR elimination adjustments.

You probably now this but it was news to me. To get the runout specs quoted on ER4 collets, it takes a surprisingly hefty torque rating. I'm probably overly squeamish but do you put the lathe in low gear to tighten/untighten the ER collet cap?

No, I use the regular square chuck key in one of the spindle camlock chuck cam-holes as the opposing force against the ER40 collet spanner. Low gear isn't enough to lock the spindle when tightening the ER40 collet chuck.

 
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