Wedge set for MT3 arbor removal

petertha

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Before I commence making something, does anyone know if there is such a thing as a wedge set for MT3 arbor removal? Specifically I have a drill chuck arbor that really likes to stick in the tail stock. Its not the end of the world to remove, but its a PITA. I have to remove the crank handle, cross pin, slide out the quill barrel from the TS casting & then tap it out with rod & hammer. (I could do it in the lathe too but I don't want alter alignment or put undo stress on the quill clamping assembly).

I use to think this occurred because the screw ejector was bottoming out before it could eject, but I measured & tested, this is not the case. In fact this arbor has a tang extension so has added length. I can see the arbor physically displaced out of the quill if its only gently inserted in the socket. So the issue is the leadscrew cant overcome the friction once its stuck. Both the arbor OD and socket ID are in very nice condition, maybe too nice they stick together. I remember blueing it once upon & it had a really good mating pattern. First I thought maybe some swarf particle was stuck in there. Then it happened again so I've been using a light oil film. That helped but it stuck again. Maybe I should be using a light smear of anti-seize? I'm not doing anything heavy duty, just normal use.

Anyways onto wedges. The MT3 big end is about 0.940, but that doesn't match any of the typical drill chuck wedges in the numbered series 1,2,3 or 6 that I can tell. I figure I could get a wedge set between the back side of the chuck body & front lip of the quill barrel. Because I don't see anything commercially available, I'm guessing this just isn't a common issue? How would one remove a big MT3 ended drill fro example if the lead screw didn't eject it? is it common to lubricate the mating parts?
 

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MontanaLon

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Drill chuck wedges are to remove the JT adapter from the chuck. If you were to use it on a chuck stuck in the tailstock it would likely just pop the Jacob's taper out of the chuck and leave the MT end stuck in the tailstock.

The quill screw gives you a ton of mechanical advantage to pop the MT loose. I mean they jack up railroad cars with screw jacks.

Another option would be to make a bushing that fits around the quill and butts against the rear of the chuck before the quill bottoms out when withdrawing it and bears against the back of the chuck. But it really seems to me there is an issue with one or the other tapers, male or female causing it to stick. Might be easier to ream the female taper as it is harder to see if there are issues inside than issues on the male taper.

Antisieze would likely work too well and cause the chuck to spin when you need it to stick.
 

Tozguy

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An MT taper that sticks is a good thing, I would use only the lightest oil (way lube) on a trial basis to see if it is easier to eject but still hold strong when necessary.
On my TS the MT ejects when the quill is fully retracted but sometimes it takes a few taps on the handle to break it loose. That is how it is designed to work so I don't expect that it will harm anything to tap the handle to eject the MT tool from the quill.
 

petertha

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MontanaLon, that is an excellent point you made about wedges having the unwanted result of popping the chuck off the arbor & still leaving the arbor in the quill to deal with. Didn't consider that. I think this particular chuck is an integrated shank, but I really don't know what that means. Is the shank integrally turned with the chuck body or 'permanently mated' at the factory before taper grinding... but could also be separated with enough force?

And yes, I would have thought the leadscrew would give lots of mechanical advantage. The leadscrew nut appears to be brass so I didn't want to mangle it.
 

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RobertB

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The handwheel doesn't have a lot of leverage (it's not like you are using a 24" breaker bar on it) so you can crank pretty hard on it without damaging the nut. Put some pre-load on it with the handwheel and a light tap on the end of the leadscrew with a brass hammer should pop it right out.
 
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