I disassembled, cleaned and debured one of my keyless chucks. After
reassembling I checked it with my edge finder. Still showing 0.006"
runout. Took it apart again and carefully hand lapped the jaw that
was forcing the edge finder farthest in. Checked again and found some
change. After several tries I got it down to 0.0015". Seemed pretty
good so I checked several more times after re-chucking it. Fairly
consistent with a max of 0.002" and min of 0.001". OK, so now try
some bits for comparison. Took a 7/64" bit, 0.005", not so good. A
1/2" bit, 0.012", Arrggggg. A 7/16" bit, 0.008", that's it, I'm done.
The test prior to the final lapping of the jaw gave me about 0.003" so
I took the outer shell off and put a little light oil on the jaws then
reassembled it. Checked again and it was at 0.013"????
I'm concluding that this Chinese drill chuck is JUNK!
It's time to order a good one and stop wasting my time trying to make
these things accurate. I'll probably try an SPI unless I happen to
get lucky and win an Albrecht on eBay.
Thanks for all the advise.
--- In GrizHFMinimill@yahoogroups.com, "dak_1953" <dkolean@...> wrote:
> OK, here's the deal. I've got four chucks on four different R8 arbors
> and they all exhibit between .004" and .009" runout as measured with a
> DTI at the nose of the chuck with an edgefinder or end mile chucked.
> I've chucked the same end mill into a collet and get .0005" runout.
> Three of the chucks are keyless and one is keyed. They are all 1/2"
> capacity. All are Chinese models, two of the keyless are the same
> from the same vender. The other keyless is a different model.
> I know I should just get a name brand chuck however, I find it hard to
> believe that the last four chucks I've gotten could all be bad.
> Frankly, the cheap chuck that came with my X2 mini mill was better
> than any of these. I really don't want to get an expensive chuck
> right now just to find out it was something else.
> Any suggestions on what I may be missing?
> Thanks for your help,