er40 collet chuck out about 20 thou

[irishwoodsman]

hey guys, warm weather today so i thought i would try out my new er40 collet chuck seems its out about 20 thou, or the collet is any ideas, the collet is a technic 20.00:thinking:

 

[British Steel]

Hi,


I assume you know the right way to install the collet? Remove the nut from the chuck, slip the "blunt" end into the nut and rock/rotate so the extractor ring in the nut engages the slot in the collet, then install both together into the chuck, add workpiece, tighten.

If you still get excess runout:

First check for me would be to take the collet and nut away, and put a DTI on the taper inside the chuck - if you see runout mark the high point and peak measurement with a felt pen or such, then move further back into the taper and see if the high point moves and/or the deviation changes. If the highpoint moves from one point to opposite or the deviation changes, the chuck's out of square with the lathe spindle, if it stays at the same location and the runout doesn't vary, it's off-centre but square - if there's no measurable runout on the tapers, the collet's to blame!

Dave H. (the other one)

 

[irishwoodsman]

ok i used a indicator on the inside of chuck with out collet same thing then i did the out side of chuck same thing, i stuck my finger in the spindle bore and it feels like someone let something spin in there not smooth at all, any ideas on how to smooth it out without destroying the taper

 

[irishwoodsman]

stupid me, i didnt have the collet snapped in to the nut all the way that took care of about 10 thou, now i'm still off about 8 though:thinking:

 

[British Steel]

Not sure quite what you mean there!

Did you find runout on the chuck's internal taper, and damage to it, or was the damaged surface the *spindle* taper you put the chuck into? I'm guessing it's an ER40-on-a-stick with a Morse taper and drawbar into the spindle?

If it's the *spindle* internal Morse taper that's damaged, you could run a Morse taper reamer in from the tailstock end to clean it up, if necessary - if there's just a small burr or three (which is enough to put the chuck off centre) you may be able to clean it up with a three-square scraper[1]. To check whether it's just a burr, put marking blue (if you have it, if not a marker pen will do a passable job) on the chuck's Morse taper, fit it and give it a slight twist in the spindle. Any burrs will leave a clear spot that'll point you to where they are

If it's the chuck taper the best would be to internal grind it - although this would mean facing the open end of the chuck to get the correct taper gauge length.

[1] take a worn-out riffler file (the pointy curved ones, triangular in cross-section) and heat to "boiled carrots", leave to cool as slowly as possible, then grind / file off the teeth, hone to get sharp edges, harden by heating to "boiled carrots" again and quenching in oil - then hone the edges again to get 'em *really* sharp. This'll leave it really brittle, so careful!, but it should be hard enough to scrape the burrs down.

Dave H. (the other one)

Dave H. (the other one)

 

[irishwoodsman]

ok i took some 200 grit sandpaper to the spindle bore and got it to within 4000ths i know i got 1000ths runout on the spindle that leaves me 3oooths to try to get to 0 thousanths:biggrin: