By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

Stuck Chuck

All Topics | Latest Posts

Search for:  in Thread Title in  
Neil Wyatt07/01/2020 11:26:28
avatar
Moderator
18232 forum posts
714 photos
77 articles

I'd file flats above the thread on the adaptor and consider using a well fitting flat bar in a pair of jaw slots, at the risk of causing distortion. Combine that with penetrating spray, warming the chuck body and using a freezer spray like 'shock unlock' or similar on the adaptor.

Or the old school approach - set it up with a bar, apply easing oil and tap it gently with a small hammer for half an hour.

Neil

Ian P07/01/2020 11:38:18
avatar
2420 forum posts
101 photos

Without wanting to take this thread off topic I am curious about the security of fastening a relatively large chuck to a rotary table by means of such a coarse small-ish diameter thread.

Quite rightly, on this and other forum there are frequent warnings about chucks becoming loose when a lathe is run in reverse. Surely the potential for a chuck held on a rotary table to come loose is (depending on the actual machining operation) is far greater.

The chuck in question looks to be ideal for attaching to a rotary table by clamps in the groove on perimeter of the chuck body, no worries then about it moving or stuck adapters.

Ian P

peak407/01/2020 11:47:42
avatar
1187 forum posts
143 photos

I might be missing something blindingly obvious here.
If the adaptor essentially replicates the nose thread of the headstock spindle, presumably is just screws in to the chuck from the back.
That being the case, if you hold the chuck in a vice, or strap wrench if you're at the kitchen table, then you need to turn the screw clockwise to release it. (looking from the chuck jaws inwards).
I only mention this, as twisting the wrong way is just the sort of thing i'd do if I was tired.
This would particularly be the case if I'd just been involved with removing a drill chuck securing screw from inside one of those.
blush

Bill

 

Edited By peak4 on 07/01/2020 11:49:51

Robert Atkinson 207/01/2020 12:40:12
avatar
768 forum posts
17 photos

Steve, how is the adaptor initially installed in the chuck? Is it screwed in from the front (jaw) side or the back side? Is the section in the chuck fully threaded? I could assume its not fully threaded and goes in from the front , but assumptions are not a good basis for sound engineering.....

Robert G8RPI.

Maurice Taylor07/01/2020 13:26:43
128 forum posts
17 photos

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 Gilligan07/01/2020 13:38:47
avatar
16358 forum posts
712 photos
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 , […]

.

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

... and the adaptor is a double male-threaded screw 

angel MichaelG.

.

See my post at 11:12:24 today.

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

Dave Halford07/01/2020 13:51:35
921 forum posts
9 photos
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 P07/01/2020 14:23:39
avatar
2420 forum posts
101 photos

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

JasonB07/01/2020 14:28:41
avatar
Moderator
18868 forum posts
2069 photos
1 articles

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 Golez07/01/2020 14:50:29
128 forum posts
125 photos

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 Taylor07/01/2020 15:10:26
128 forum posts
17 photos

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.

JasonB07/01/2020 15:22:22
avatar
Moderator
18868 forum posts
2069 photos
1 articles

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

Versaboss07/01/2020 15:57:35
458 forum posts
51 photos

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 Crow07/01/2020 18:13:42
224 forum posts
70 photos

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 P07/01/2020 18:42:49
avatar
2420 forum posts
101 photos
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

JasonB07/01/2020 18:49:51
avatar
Moderator
18868 forum posts
2069 photos
1 articles
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 P07/01/2020 18:57:24
avatar
2420 forum posts
101 photos

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 207/01/2020 19:08:25
avatar
768 forum posts
17 photos

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

Robert G8RPI

Michael Gilligan07/01/2020 19:38:44
avatar
16358 forum posts
712 photos
Posted by Ian P on 07/01/2020 18:57:24:

[…]

Or have I missed the bleedin obvious?

 

Ian P

.

Not at all, Ian

[ unless I’m there with you ]

MichaelG.

.

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

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

Steve Crow07/01/2020 19:46:35
224 forum posts
70 photos

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

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Support Our Partners
EngineDIY
Eccentric July 5 2018
cowells
emcomachinetools
ChesterUK
Warco
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest