drill press chuck run out

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Forum topic by steveman posted 02-26-2013 09:45 PM 1049 views 0 times favorited 1 reply Add to Favorites Watch
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6 posts in 2315 days

02-26-2013 09:45 PM

I’ve got an old cummins drill press. It is pretty big for a bench-top model.

I’m getting too much run out at the bit. When I check the run out with a dial indicator, I get very little run out at:

- The exposed morse taper above the chuck: I only get about 1 to 2 thousands of run out.
- The top of the chuck: same
- The bottom of the chuck: same

But when I check the run out at the bit, I’m getting 20 to 25 thous of run out.

I assume this means the problem is with the chuck jaws? They are not clamping equally or something?

I’ve done my best to clean everything. I’ve removed and thoroughly cleaned the chuck and arbor, including removing the chuck from the arbor to clean both tapers. The arbor has a MT#2 into the spindle, and a (jacobs?) taper into the chuck.

I ordered a new (but cheap) taper and chuck, and have the same problem. Perhaps cheap ebay chucks are just as bad as my old chuck?

Could this be something other than the chuck?

I’m not exactly sure my bits are straight either. Any suggestions on an affordable but reliably straight bar/pipe to use to check runnout at the bit?

If it is the chuck, and recommendations on 5/8 #2 morse taper/jacobs taper chucks that clamp straight?


1 reply so far

View RogerInColorado's profile


321 posts in 2130 days

#1 posted 02-26-2013 10:32 PM

I’d try several different bits before I bought a new chuck, and I’d check runout right at the point the bit and the chuck meet. I’d measure with both round bits and bits that have flats milled on three sides.

It should also be possible to take the chuck apart, after you dismount it from the spindle, and clean it up really, really good. Be sure to mark the jaws and the chuck to make sure you put the jaws back into the same location in the chuck.

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