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Chuck Dismantle

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Alan Worland18/08/2011 17:10:11
247 forum posts
21 photos
I have an old (probably very old!) 3 jaw 4 in chuck which I am trying to dismantle for cleaning.
After removing the backplate it can be seen that the rear centre section will come out but appears to be prevented by the scroll operating gears, and I cant see how they come out!
The manufacturer is - The DE Witch Machine Co of New London, Conneticut USA (needless to say I cannot find them) and is unusual in that the chuck key requires a female square to fit
Other chucks I have retain the gears by a pin or screw.
 
Alan
Alan Worland18/08/2011 19:56:21
247 forum posts
21 photos

Thanks for your reply, when the schroll is tapped it moves the centre section (with a join line around the bolt holes) - oily line in second photo

However it will only move about 25 thou before it stops against the gears (they go tight)
and I cant see any method of retaining them! third photo

I believe I somehow need to pull the rear section out to gain access to the gears and their retaining method
 
Alan
Alan Worland18/08/2011 21:23:55
247 forum posts
21 photos
Whoops! Thats what happens when you take photos in the half light!
The name is 'DE Whiton', (not Whitch) who appear to be well heard of in the chuck world!
Having another look it seems I might have to make a puller to extract the rear section.
 
Alan
Richard Parsons19/08/2011 11:02:10
avatar
645 forum posts
33 photos

Hi Alan.


If you look at the back of the chuck you will see in the screw holes a discontinuity. This indicates that the centre of the chuck back is separate and splits on a line at about 1/3 of the screw’s diameter. The screw threads actually hold the whole thing together. The front view confirms this. You will see a fine band showing where the inner part joins the outer from the back.


When assembled the whole thing would have been machined. The 'DE Whiton' company did not mean it to come apart.


If you have a small woodruff cutter, cut two shallow grooves just on or below the joint as seen in the photograph. Use a brass punch and drive the back out. If that does not work. If SWMBO is agreeable (or is out) stick it in the oven at about 120° C for an hour and try the brass drift again.


Good luck. If you have to be really rude to it well at the moment it will not work so you cannot make it much worse.


Dick

mgnbuk19/08/2011 13:41:52
1394 forum posts
103 photos

The 'DE Whiton' company did not mean it to come apart.

I rather doubt that - depending on what it is used for, cleaning of any chuck can be a regular occurence. I would not expect to have to dispose of a chuck just because it wanted cleaning !
I would try the following -
 
Place a stout piece of reasonably flat timber on a solid surface.
Firmly "rap" the chuck (rear face down) squarely onto the timber.
 
I would expect the inner section to move until the clearance from the rebate was taken up - this may provide a split line accessible though the centre that a drift will fit in. If not, set a couple of pieces of wood to effectively increase the depth of the rear rebate & "rap" again until the centre section drops clear.
 
This method has worked for me in the past with 3 jaw chucks.
 
In a previous employment, this was the method employed to remove the interference fit front bearing from large lathe spindles (large as in 16"- 24" + bore bearings). These fitted up to a shoulder & few manufacturers provided holes for drifts to remove the bearings. A long bar was bolted across the front of the spindle nose, the spindle stood on the opposite end on an old sleeper - loosely suspended from the crane in case it slipped or toppled - and was "bumped" by 2 people on the bar onto the sleeper. The bearing would (slowly !) work it's way off with no damage to the spindle. The replacement bearing would be heated to expand it & just slipped into place.
 
1st post here after lurking for a while !
 
Regards,
 
Nigel B.
Alan Worland19/08/2011 20:47:41
247 forum posts
21 photos
Thankyou for all your advice! As I said if the scroll was tapped back into the body it would push the rear centre out but would then stop because of the pinions and yes the join line goes through the bolt holes (photo must be better than I thought!)
Today I had a surge of inspiration! I found an old suspension rubber bush which was a very tight fit in the chuck bore, I then found some thick close fitting washers and with a length of 10mm studding compressed the bush in the bore - really tight
I could then tap out the rear of the chuck, voila!
It was a really tight fit but very well machined with the pinions coming out from inside
Dont think it has seen much use but will have to make a key for it so once its cleaned and oiled I can check its accuracy
Thankyou all!
 
Alan
Richard Parsons20/08/2011 15:16:43
avatar
645 forum posts
33 photos

Nigel Thanks I forgot that trick. It rather like bopping a carden shaft to draw the cup out of Hardy-Spicer joints. The cup comes out on the side where you hit.

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