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Import Drill Press Chuck Key Keeps Slipping

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Wireaddict

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#1
I have 2 Chinese 1/2 inch drill chucks, one for my LMS Mini Mill & the other for my drill press which is also Chinese. Both are marked "JT 33" which I understand is the drive taper. My problem is that the drill press chuck key slips when I try to tighten it securely (when using larger drills.) I bought a new #3 Jacobs key which seems to fit OK but it still slips. I tried the nearly new key for my import Mini Mill chuck & it's no tighter. Am I correct in assuming that my d/p chuck gear's the problem? Thanks!
 

MikeInOr

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#2
On both my HF drill presses I have replaced the Chinese chucks with quality Jacobs chucks that I bought used for pretty cheap on ebay... it is definitely worth upgrading your chucks in my opinion.

The problem is definitely your chucks. Whether it is how the teeth were cut, how long the outside body was cut or where the holes for the chuck key were drilled in the body I would recommend not wasting any more time or money on them.
 

mikey

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#3
I once looked at a friend's drill press chuck that did the same thing. We found that the round shaft in front of the geared part of the chuck key was a bit too long. After grinding it down, the gear on the key meshed with the teeth of the chuck much better and the slipping stopped. Might check yours.
 

Fabrickator

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#4
You're probably over tightening them if you have a decent chuck and the proper key. When you chuck a drill bit, start with giving side #1 (1 of 3 ) give it a soft draw down, then change the key to the next hole (#2 of 3) and do the same all. Usually this is enough. If it slips, then finish by going around again with a firmer re tightening of all three sides. A good chuck doesn't need to be "death grip" tightened to hold a fresh shank drill bit. If the drill has slipped and been chewed up, get a new one. It probably won't drill a straight/true hole anyway.
 
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