Stuck Chuck

[Maurice TaylorParticipant @mauricetaylor82093]

After reading the instructions ,it is obvious how the chuck is mounted. The thread in adapter plate is the same as thread in the chuck ,the threaded adapter is screwed into adapter plate leaving enough thread to spin the chuck on , like it spins onto lathe mandrel. To get it off put adapter plate in vice and knock chuck round as if it was stuck on lathe mandrel.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Maurice Taylor on 07/01/2020 13:26:43:

After reading the instructions ,it is obvious how the chuck is mounted. The thread in adapter plate is the same as thread in the chuck , […]

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Except of course that one is 3/8 and t’other is 3/4

… and the adaptor is a double male-threaded screw 

MichaelG.

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See my post at 11:12:24 today.

Edited By Michael Gilligan on 07/01/2020 13:52:57

[Dave HalfordParticipant @davehalford22513]

Posted by Ian P on 07/01/2020 11:25:08:

I would still like to know why a headless screw can jam in the parallel (through?) thread of the chuck.

Ian P

Indeed, Loctite? Or a tapering thread which would make the direction of insertion rather important.

As the OP has done this before without issue it can only be some swarf has got in the threads during tightening and locked them up.

I would try high strength Loctite in a nut assuming it went in from the rear of the chuck then blowlamp the nut off after it comes out.

[Ian PParticipant @ianp]

I did consider that the chuck thread might not run all the way through the chuck (it would be unusual though) but why the adapter would jam so tightly is a mystery. How tight it actually is something is depends on the person judging it and the method of applying the force. To anyone with a reasonable size vice on a strong bench, removing the adapter looks to be fairly easy, in Steve's case though he says he has a kitchen table workshop so just holding the vice and screwdriver in alignment whilst applying the turning force could be challenging.

Its not easy to see the state of the slot or the end of the screwdriver but neither look good. Not much can be done to improve the slot now that it is at the bottom of a recess, but the screwdriver looks quite rounded.

Unless the adapter to chuck thread has galled a good fitting screwdriver and some means of holding everything aligned should be all that is needed. I would think that the slot is potentially capable of imparting higher torque than anything gripping the short 3/8" thread.

Ian P

[JasonBModerator @jasonb]

Is there any chance you fitted the adaptor to the chuck first and screwed it in too far and then tightening the chuck jaws against it has damaged the thread at some time. Should be put into the R/T first and tightened than the chuck screwed in place.

Similar damage could be done with the Unimat3 threaded adaptor but you really have to fix that to the table first so unlikely to happen

Also leaving a pool of cutting fluid in the chuck recess to dry if the R/T has been used horizontally may corrode the threads

[Raphael GolezParticipant @raphaelgolez]

Steve, is it like a mandrel type of attachment to the chuck? I can only think (from the picture) that the chuck is secured by this single screw? I think you need more leverage to unlock the screw itself. Get proper fitting flat head driver bit and attach to a long socket drive connected to a long handle ratchet wrench. You can apply enough leverage this way. You must secure the chuck on your vice with a vee block to increase the gripping force. Hope this helps.

[Maurice TaylorParticipant @mauricetaylor82093]

If you look at the photo of the back of Steve’s chuck the 3/4 part of adapter comes through the adapter plate,so the chuck and the adapter plate are acting like a giant lock nut on a 3/4 threaded bar .Hold adapter plate solid and turn chuck,it won’t come out with screwdriver ,the slot is there to hold adapter while fitting chuck.

[JasonBModerator @jasonb]

There is not a separate adaptor plate that chucks have that "groove around them

These are the adaprors that fit the 3/8" thread in their rotary tables

Edited By JasonB on 07/01/2020 15:22:32

[VersabossParticipant @versaboss]

Two pages discussions about removing a stubborn screw? The OP didn't show his kitchen vise, but if it is anything usable I would:
– remove two jaws
– clamp the remaining two (180° naturally) in the vice
– file two flats on the protruding part of the screw (don't think these adaptors on a Sherline are hardened)
– use a wrench, mole-grip or what-have-you and apply torque! (in the correct direction…)

I don't think the financial loss would bring someone to tears.

Kind regards
Hans

[Steve CrowParticipant @stevecrow46066]

Many thanks for all your suggestions and questions.

Just to answer a few of them- When I mount the chuck, I screw the adaptor into the rotary table until is seated. Then I screw down the chuck until that is seated on the table. On removal, I unscrew the chuck and the adaptor is left in the table to be easily removed via the slot.

This time, the adaptor came out with the chuck and remained jammed. I always try to remove swarf when mounting a chuck so maybe I damaged a thread? I have no idea.

I've ordered some nuts and I'm going to try a split nut/vice first to see if I can save the adaptor. It's not the cost as much as inconvenience.

If that doesn't work Ill be fiilng some flats.

[Ian PParticipant @ianp]

Posted by Steve Crow on 07/01/2020 18:13:42:

Many thanks for all your suggestions and questions.

If that doesn't work Ill be fiilng some flats.

What wrong with using a well fitting screwdriver?

Ian P

[JasonBModerator @jasonb]

Posted by Ian P on 07/01/2020 18:42:49:

Posted by Steve Crow on 07/01/2020 18:13:42:

Many thanks for all your suggestions and questions.

If that doesn't work Ill be fiilng some flats.

What wrong with using a well fitting screwdriver?

Ian P

Did you read the first post?

"Next I got the biggest, baddest screwdriver and ground the end to fit the slot exactly, put the chuck in the vice – didn't budge."

[Ian PParticipant @ianp]

I have another thought on this stuck adapter.

Looking at the picture of the chuck that Jason posted, it appears that the hole in the face of the chuck is larger than the 3/4" thread, therefore I would assume that the adapter (if the threads were not binding) would pass right through.

If that is the case then there is no need to waste time unscrewing the adapter, what it really needs is 'tightening' from the back.

I'm not sure which way Steve has been turning the slotted end but if a 3/8" nut and a small diameter washer or two were put on the adapter it could then be rotated clockwise (looking at the back of the chuck) with virtually unlimited torque using a spanner on the nut and the chuck jaws held by any method.

Or have I missed the bleedin obvious?

Ian P

[Robert Atkinson 2Participant @robertatkinson2]

I know is obvious, but you have tied turning it both ways?

Robert G8RPI

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ian P on 07/01/2020 18:57:24:

[…]

Or have I missed the bleedin obvious?

 

Ian P

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Not at all, Ian

[ unless I’m there with you ]

MichaelG.

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Edit: … and I think Dave Halford was there first.

Edited By Michael Gilligan on 07/01/2020 19:41:20

[Steve CrowParticipant @stevecrow46066]

To the two latest suggestions.

I have tried turning it both ways.

If I fit a nut to the back, it won't clear the threaded hole in the chuck and will foul about halfway through.

Also, when using it the last time, when screwing the chuck down I felt a small amount of extra resistance than usual in the last few turns. Not enough to worry me at the time (so I thought). All the threads on adaptors, chuck, table and spindle are quite snug to start with.

This leads me to believe that the jam is happening on the last couple of threads. Screwing it in would compound this.

Steve

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Steve Crow on 07/01/2020 19:46:35:

[…]

If I fit a nut to the back, it won't clear the threaded hole in the chuck and will foul about halfway through.

[…]

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Sorry, Steve … You have completely lost me: I’m bewildered

… and I cannot find a sectional drawing of the wretched chuck.

When you finally get it apart; do please share some photos

MichaelG.

[EmgeeParticipant @emgee]

If the chuck mounting is the same as the adaptor/reducer then surely the adapter can be fitted from the front or back of the chuck as it is threaded same diameter for the 3/4" threaded length.

Emgee

[Steve CrowParticipant @stevecrow46066]

I'll try to explain. The adaptor can be fitted from the front or back but a nut on the 3/8 thread will jam against the back of the chuck long before the adaptor is removed. I hope this is clear.

Steve

[Frances IoMParticipant @francesiom58905]

have you tried one of the freezer sprays directed at the adapter (via the protruding screw_ – possibly using a thin cardboard to isolate the chuck from the spray – might give just enough movement to free a stuck thread – have the screwdriver ready but not inserted until you reckon the adapter is cold enough

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Steve Crow on 07/01/2020 22:32:19:

I'll try to explain. The adaptor can be fitted from the front or back but a nut on the 3/8 thread will jam against the back of the chuck long before the adaptor is removed. I hope this is clear.

Steve

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Surely that depends on the size of the ‘nut’ Steve !!

You are not obliged to use standard commercial nuts

I would drill and tap a length of suitable diameter rod, and use that as a long ‘nut’

MichaelG.

[Grindstone CowboyParticipant @grindstonecowboy]

Idea – but probably a lot of bother, and may cause further issues if, as you say, the thread gets tighter the further the adaptor screws into the chuck: a bit of round bar that will pass through the chuck, bored and threaded to fit the adaptor with a couple of flats for a big spanner?

Having said that, I prefer the idea of a split nut to hold the threaded end firmly in a vise and wind the chuck off – you could tighten the jaws onto the square of a 3/8" or 1/2" drive ratchet or breaker bar. Pop the whole thing in the oven for half an hour or so first and apply the freezer spray as Steve suggests.

 

Edit – Michael types faster than me.

Edited By Grindstone Cowboy on 07/01/2020 22:47:37

[JasonBModerator @jasonb]

Posted by Steve Crow on 07/01/2020 22:32:19:

I'll try to explain. The adaptor can be fitted from the front or back but a nut on the 3/8 thread will jam against the back of the chuck long before the adaptor is removed. I hope this is clear.

Steve

That is why several washers were suggested, if they are say 14-15mm OD then they will clear the thread and allow the adaptor to turn at least enough to hopefully free it. You can also hack the nut down in size which is preferable to putting flats on the adaptor.

Main reason for using the method suggested is that the nut won't unwind from the 3.8" stub so you don't need to worry about trying to lock two together or Loctite.

Edited By JasonB on 08/01/2020 06:58:28

[Maurice TaylorParticipant @mauricetaylor82093]

I would have sacrificed the adapter by now.Clamp chuck in a vice and turn adapter clockwise using 18 inch Stillsons,this will turn adapter out same way as it went in.

Maurice

[not done it yetParticipant @notdoneityet]

I’m like Maurice, except that by now I would have made a ‘screwdriver’ the full width of that slot.

However much force could be applied with the screwdriver shown in the pic on the first page, at least four times the torque would be applied using the full width of the slot with that same force! Simple physics.

With two spanners. One operating on each side would likely increase that torqe available at the scew slot by another factor of two.

If unable to unscrew it with that increased torque, I would likely try as per Maurice (but possibly with a slightly smaller stilson), then machine most of it away if that failed.

[Author]

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