# Need help with stuck 3-jaw chuck Unimat sl



## Deloid (Nov 8, 2019)

I spend almost all my time with my watchmakers lathes but occasionally I need to use the Unimat SL. Today I was making a replacement part for a clock and the brass rod I drilled is now stuck in the chuck. I cannot open it with the two steel rods. This has never happened to me before but I have to admit, I haven't cheaned the machine in 30 years.
Any advice as to how to proceed?
Thanks,
Dean


----------



## markba633csi (Nov 8, 2019)

Have you tried prying the two steel rods with a screwdriver or similar tool? Always works for me
Might want to spray a little liquid wrench in there too
Mark


----------



## Deloid (Nov 8, 2019)

I'll try that today and update later.
Dean


----------



## Deloid (Nov 8, 2019)

Mark,
I tried that and it didn't budge. I also tried long drill bits that had a tighter fit...one surprisingly bent instead of snapping off.


----------



## chips&more (Nov 8, 2019)

The chuck has (3) tommy bar positions. Make sure you are using the (2) outer positions. Not the position to undo the chuck from the spindle. And also make sure you are going in the correct direction.


----------



## darkzero (Nov 8, 2019)

Maybe try sticking it the freezer & try when it's cold. As a last resort can try mounting the chuck in a bench vise & use a pair of Channel Locks, but of course use pads so you don't mar the chuck.


----------



## francist (Nov 8, 2019)

Deloid said:


> also tried long drill bits that had a tighter fit...one surprisingly bent instead of snapping off.



Save that one for the next time you need to drill around a corner.....


----------



## Deloid (Nov 8, 2019)

francist said:


> Save that one for the next time you need to drill around a corner.....


Hahaha!  Thanks...I needed that. It really did make me laugh.


----------



## Deloid (Nov 8, 2019)

chips&more said:


> The chuck has (3) tommy bar positions. Make sure you are using the (2) outer positions. Not the position to undo the chuck from the spindle. And also make sure you are going in the correct direction.


Thanks. I know the process very well but I do have to admit that when it wouldn't budge I doubted myself and did actually check my now very old manual.


----------



## Deloid (Nov 8, 2019)

darkzero said:


> Maybe try sticking it the freezer & try when it's cold. As a last resort can try mounting he chuck in a bench vise & use a pair of Channel Locks, but of course use pads so you don't mar the chuck.


I like the freezer idea. Maybe a touch of heat then freezer? I don't understand the channel lock idea. It's off the spindle of course but I think I'm missing something here


----------



## darkzero (Nov 8, 2019)

Deloid said:


> I like the freezer idea. Maybe a touch of heat then freezer? I don't understand the channel lock idea. It's off the spindle of course but I think I'm missing something here



Can try either or but don't think both is necessary consecutively. Wouldn't hurt to try I guess. Just throwing an idea out there.

I don't have a Unimat chuck but I do have some import micro chucks that all work the same. On a couple of mine the body extends out the rear. Clamp that in the vise, then turn the ring with pliers.

Or if yours doesn't extend out the rear like my other 2, clamp the ring in the vise & turn the body with pliers.

Again this would be an absolute last resort for me. If there's something that is causing it to bind rather than just actually being very tight, this 200 lb gorilla method may do more harm than good.

(Just took quick pics as examples, again I'd use padding to proect the chuck surfaces if I'd actually resorted to this, avoid if possible)


----------



## Deloid (Nov 8, 2019)

Thanks everyone. I got it with the use of kroil since this morning followed by a freeze. I think I have a duty to overhaul the entire lathe now.
Dean


----------



## francist (Nov 8, 2019)

I’m glad you got it Dean. 

I was wondering though, would hook spanners give any better mechanical advantage over Tommy bars? I’m asking the question in general to anyone following this thread (I just didnt want to hijack before the OP got his problem figured), maybe some mechanical engineer types?

It seems like with Tommy bars you end up expending most of energy against the side of the holes themselves, especially as they get a little galled around the edges. But with hook spanners the force feels a lot more positive. Or is it just my imagination? Anyone know?

-frank


----------



## darkzero (Nov 8, 2019)

I think hook spanners may be good to keep around, in cases like this, more leverage for loosening a tight stuck chuck. I believe these types of chucks are used with tommy bars to avoid often risk of over tightening. They shouldn't need to be tightened down really hard. Tommy bars are easier/quicker to use too. Kind of like keyless drill chucks that have holes for spanners, used only for loosening. I have spanners for all my keyless chucks (just in case) but I have ever only needed to use one once.

But good thinking Frank, I never thought to use a spanner wrench for these types of chucks. But I don't use them often & have never had one get stuck. Hmm, thanks for the excuse to buy more tools!  

On second thought, maybe I have a spanner that may fit what I have, maybe I'd just need to make a new pin for it to fit my chucks.


----------

