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Stuck Chuck

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Michael Gilligan07/01/2020 21:16:02
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16358 forum posts
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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.

[…]

.

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.

Emgee07/01/2020 21:27:30
1709 forum posts
225 photos

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 Crow07/01/2020 22:32:19
224 forum posts
70 photos

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 IoM07/01/2020 22:36:12
831 forum posts
26 photos
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 Gilligan07/01/2020 22:44:05
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16358 forum posts
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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

.

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 Cowboy07/01/2020 22:46:54
343 forum posts
27 photos

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

JasonB08/01/2020 06:56:58
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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 Taylor08/01/2020 09:01:58
128 forum posts
17 photos

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 yet08/01/2020 10:53:34
5007 forum posts
20 photos

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.

Martin W08/01/2020 10:57:19
854 forum posts
29 photos

Even if you get the adapter out its not worth the risk of using it again so just accept that it is scrap. If it were mine I would find someone with a suitably sized lathe and get them to bore the adapter out and then remove what remains. Should be able to bore close to the root diameter of the thread so there is minimum material remaining to get out.

No brute force or special tools required and much gentler on the chuck

Martin

PS If this has already been suggested then ignore this post

Edited By Martin W on 08/01/2020 10:59:06

Hopper08/01/2020 12:52:49
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4804 forum posts
105 photos

It has a screwdriver slot for a reason.

You need the proper tool for the job: a simple impact screwdriver with wide, straight bit. The basic old type you rap with a hammer while twisting. Available on eBay for 15 quid. Search for Impact Driver Motorcycle.

Or take it to a local motorcycle shop and have them use theirs on it. Probably only cost you 30 quid there!

Impact driver will jar screws loose that you can never shift with a screwdriver and pliers etc. It;s the impact wot does it.

Michael Gilligan08/01/2020 13:20:54
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16358 forum posts
712 photos
Posted by not done it yet on 08/01/2020 10:53:34:

[…]

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.

.

dont know ...

(a) Really ?

(b) Contradicting your assertion on another recent thread

MichaelG.

Michael Gilligan08/01/2020 14:00:39
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16358 forum posts
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Posted by Hopper on 08/01/2020 12:52:49:

It has a screwdriver slot for a reason.

You need the proper tool for the job: a simple impact screwdriver with wide, straight bit. The basic old type you rap with a hammer while twisting. Available on eBay for 15 quid. Search for Impact Driver Motorcycle.

Or take it to a local motorcycle shop and have them use theirs on it. Probably only cost you 30 quid there!

Impact driver will jar screws loose that you can never shift with a screwdriver and pliers etc. It;s the impact wot does it.

.

With the greatest respect to your experience and expertise, Hopper ... I must beg to differ

The screw [in its present setting] should be free-running in the chuck thread: it is therefore not 'over-tightened' but 'stuck' ; so I am not entirely convinced that impact [unless, perhaps, applied repeatedly] will have the desired effect.

MichaelG.

Howard Lewis08/01/2020 20:07:53
3605 forum posts
2 photos

A suddenly applied load will have twice the effect of a gradually applied one. (Draw the force vs time graph. A rectangle as opposed to a triangle )

Hence my suggestion of an air impact gun, applying multiple sudden loads, to hammer it loose!

Keep hammering, it will eventually slacken.

Removing the crank shaft dog bolt from a Rover/Honda engine, that had been tightened to 285 lb ft took time, even with a 3/4 drive gun, but it came loose in the end!

Howard

old mart08/01/2020 20:32:27
1980 forum posts
151 photos

The good thing about the humble impact driver that you hit with a hammer is more than just the instant high torque, as you hit it the axial pressure is also instantly high, which stops the bit slipping out of engagement.

I would tend towards screwing the adaptor out in the opposite direction from the original assembly. That is clockwise viewing from the head with the screwdriver slot. There must have been a bit of swarf trapped as it was screwed together.

I would start by giving the 3/8" end a sharp rap with a copper hammer, and the slotted end likewise with a soft drift.

Mike Poole08/01/2020 20:35:18
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2738 forum posts
64 photos

A square drive screwdriver in a carpenter’s brace can shift a lot of tight screws. An impact driver seems a big expense for one job but it will be useful on other jobs sooner or later.

Mike

Martin W09/01/2020 01:05:22
854 forum posts
29 photos

If the adapter has become that difficult to remove and this is due to the threads galling or having jammed because of swarf/detritus etc. then using force to unscrew the adapter could leave both the chuck and the adapter with damaged threads.

It's your choice at the end of the day but I know how I would proceed and it would be with a minimum of force.

Hope you can free it up without damaging the chuck.

Martin

Hopper09/01/2020 12:35:54
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4804 forum posts
105 photos
Posted by Michael Gilligan on 08/01/2020 14:00:39:
Posted by Hopper on 08/01/2020 12:52:49:

It has a screwdriver slot for a reason.

You need the proper tool for the job: a simple impact screwdriver with wide, straight bit. The basic old type you rap with a hammer while twisting. Available on eBay for 15 quid. Search for Impact Driver Motorcycle.

Or take it to a local motorcycle shop and have them use theirs on it. Probably only cost you 30 quid there!

Impact driver will jar screws loose that you can never shift with a screwdriver and pliers etc. It;s the impact wot does it.

.

With the greatest respect to your experience and expertise, Hopper ... I must beg to differ

The screw [in its present setting] should be free-running in the chuck thread: it is therefore not 'over-tightened' but 'stuck' ; so I am not entirely convinced that impact [unless, perhaps, applied repeatedly] will have the desired effect.

MichaelG.

I am. That's what impact drivers are for: freeing stuck threaded fasteners. Works on screws ranging from 1/4" to 1" and more on 80 year old motorbikes that have sat out in the weather in some farmer's paddock half their life and on every other piece of machinery I've ever worked on. Well corroded threaded aluminium inspection plugs etc etc etc included. Yes you will often need to hammer on it multiple times.

For bigger stuff such as fork top nuts with say a 1-1/8" very fine thread, torqued to 140 foot pounds when it left the factory in 1975, I'll use a half-inch drive air impact gun hooked up to appropriate socket. Not much in the typical home workshop will stand up to that.

I'm just suggesting the hammer blow type here because of cost. And if that and/or a propane torch won't shift it, you might as well machine the thing out and buy a new one. Or maybe try filing two flats on the protruding threaded bit and turn it with a wide-jawed shifting spanner.

Edited By Hopper on 09/01/2020 12:40:42

Edited By Hopper on 09/01/2020 12:42:25

Michael Gilligan09/01/2020 13:41:42
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16358 forum posts
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Fine, Hopper ... I will keep out of the discussion, and await Steve’s failure analysis.

MichaelG.

Edited By Michael Gilligan on 09/01/2020 14:10:55

Steve Crow09/01/2020 17:40:51
224 forum posts
70 photos

I've managed to remove the adaptor.

I used a split nut held in a large vice (at work) and a bar held in the jaws. It was very stiff for the first turn and after that ran free.

There appears to be no damage to the adaptor, I've tried it in my 3-jaw and rotary table and it screws in by hand.

It looked like there was a small amount of damage to the thread in the chuck about 3/4 of the way in but it was hardly visible. I'd ordered a 3/4 ANF tap which arrived today which I ran through the threads and now that is fine.

So, a happy ending with everything left servicable. I'm going to clean up and deepen the slot in the adaptor next.

I'm so glad I didn't do anything destructive and tried a gentle approach.

A big thanks for all the suggestions. I didn't expect this thread to run to 3 pages!

Steve

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