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Improving Runout on keyless chuck?

Eyecon

Active Member
I have an import albrecht type keyless 5/8 chuck that had less than .001” runout when I first bought it. Used it a couple of times and it has been sitting in a drawer for over a year. Took it out a few days ago as I needed to switch between 1/8” tools and 13mm+ larger drill bits and the runout is now over .003”…usually not a problem for drilling it’s just annoying since I’m using small center drills to locate holes from transfer punches and I can see the runout as I rotate the chuck by hand. Again, not a huge deal, just wondering why the runout would increase so much and if there’s anything I can do to improve it. I’m fairly certain there is no corrosion since the chuck was properly stored…would it be worth it to try and take the chuck apart to inspect? Any other tips with these chucks to get a decent runout?
 
Could be tolerance stack up - what is the chuck mounted to? An MT3 or similar arbor? There is the fit of the chuck to the arbor, and the arbor to the lathe/drill press/ etc. Could even be the machine that has developed runout (we hope not but possible). If that is the case then clocking it differently can help a bit. Even the act of removing it and re-installing it could solve it if there is debris in the interface that is the cause.
Runout can also vary depending on the diameter chucked up, so if you only checked it previously with one size of tool, it could have been out but you didn't notice.
Are you sure of the quality of the center drills? I had some Aliexpress that were badly sharpened off-center...
Lastly - if using small tools (small centre drills) do you have a smaller chuck that could be used instead that has better runout (I know not a solution for runout but a work around for the problem). EDIT - I reread and saw that your are switching between a large tool and a small one.... the question to ask is changing chucks easier than changing bits, and can you do all the small stuff at once, then switch to the larger size).
 
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Maybe you already know but its important to measure runout on a very accurate & reliable 'standard'. Some guys use end mills in a pinch, gripping & indicating on the shank. But for sanity check, first measure across the EM across multiple axis. You really need to read tenths however you do it. Don't use 'drill rod' even though they say its ground, it can be eccentric 0.002". And drills shanks can also be unreliable depending on the quality. I've had some with raised stamped sizing on the shanks that affect TIR which needed to be stoned off just to run proper. I have an accurate ground/hardened dowel pin & it stays in a bag I only use for this kind of stuff, kind of helps eliminate chasing your tail. Its important to lock the quill & table & any other source of variation. Usually on the keyless, tightening torque is pretty consistent.

You may also find that TIR changes as a function of diameter; a small rod may have one runout, a large diameter another. Or it changes as a function of jaw engagement (holding on 10mm vs holding on 20mm). So just play around with this, try different radial orientations. Eliminate all other variables on the same standard as a first step. Assuming you have clean surfaces, no swarf between arbor & quill seat & nothing changed since the last setup where you got low TIR, you might be seeing repeatability issues on the jaws themselves. It could be grunge in the mechanism. i would soak it & blow it out with compressed air before embarking on disassembly. Hopefully you may find the chuck is actually OK & the issue is banana cutting tool which is not uncommon.
 
Thanks for all the replies so far. A few things I should have mentioned:
-the chuck is mounted through a J6 to R8 arbor
-the J6 taper on the arbor has less than .01mm runout
-I’m using a .01mm dial test indicator mounted on a Noga magnetic base
-I am using a gauge pin (10mm) to test the TIR on the chuck…same one I used before

I think I’ll try the soaking and blowing out first as suggested before attempting reassembly.
 
All great comments above.

I don't think anyone mentioned axial runout. Runout can vary by distance out from the chuck. A long test rod will have more runout at its end than a short one.

Rather than use endmills, it is nice to have a few precision ground rods that you know are good.
 
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