How to remove this lathe chuck?

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How to remove this lathe chuck?

This topic has 21 replies, 13 voices, and was last updated 2 May 2023 at 06:45 by DiogenesII.

Viewing 22 posts - 1 through 22 (of 22 total)

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29 April 2023 at 20:17 #643134
Sonic Escape
Participant
@sonicescape38234
I want to remove the chuck from my lathe. I want to see if it is possible to add a collet holder or a 4 jaw chuck. I think I have to remove 3 screws with an Allen key. But they are stuck. Also somebody forced them before, they don't look good. I'm afraid that if I try harder I might destroy the screw top and then I don't see how I could remove it. Is is barely enough space for the Allen key. What would be the best method?

Also why this thing looks like a giant screw? Is it really threaded in the head stock?
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29 April 2023 at 20:17 #11464
Sonic Escape
Participant
@sonicescape38234
29 April 2023 at 20:24 #643135
JasonB
Moderator
@jasonb
Look at the "L" type spindle taper at the bottom of this pdf. The ring you have arrowed unscrews fron the thread on the chuck backplate

Edited By JasonB on 29/04/2023 20:26:12
29 April 2023 at 20:31 #643137
Sonic Escape
Participant
@sonicescape38234
Thank you! So I have a back plate like this.

Now I found also a video where I could see it better
29 April 2023 at 20:36 #643138
JasonB
Moderator
@jasonb
That's it. There are various sizes the pdf should have the information to tell which you have.

It would be better to keep your existing backplate fixed to your existing chuck. Then get a new backplate for any new chucks as they are best fitted to the spindle nose and finish turned on the lathe to fit the chuck exactly.
29 April 2023 at 20:49 #643142
peak4
Participant
@peak4
No idea what's available in your part of the world, but if you look up "L00 chuck" on eBay, (that's L zero zero) you will see several options which illustrate what's easily obtainable.
Usefully, some sellers list fittings as Loo (all letters) which might lead you to cheaper options, always assuming yours does measure up as that size. e.g. HERE
https://www.ebay.co.uk/itm/353930991295

5C collet chucks seem a viable way to go, but obviously you could use an L00 backplate with a 4 jaw or ER collet system.

Over here in the UK some Boxford, Colchester, Harrison lathes, amongst others, shipped with the l00 taper spindle fittings.

Bill

Edited By peak4 on 29/04/2023 20:53:53
29 April 2023 at 22:41 #643152
Clive Foster
Participant
@clivefoster55965
Consider sticking an arrow or similar marker on the lathe to indicate which direction to turn the locking ring for undoing the chuck.

I've known several people who really ought to have known better try to turn it the wrong way. Even in one case to the extent of applying a hammer to the spanner!!! Fortunately the spanner was a casting and broke before the lathe did.

I the days when I occasionally drove a lathe with an L series mount I made sure to think carefully before attempting to change chucks. Never personally actually heaved the wrong way but came close more than once before brain kicked in.

I guess its the inside out thread arrangement that catches folk out.

Clive
29 April 2023 at 23:13 #643154
Chris Crew
Participant
@chriscrew66644
As far as I can see in the photograph the Allen screw looks to be more like a Torx head to me.
30 April 2023 at 10:08 #643178
Baz
Participant
@baz89810
Chris looks to me like a cap head that someone has rounded the hexagons off.
30 April 2023 at 11:49 #643199
not done it yet
Participant
@notdoneityet
Posted by Baz on 30/04/2023 10:08:02:

Chris looks to me like a cap head that someone has rounded the hexagons off.

Agreed, likely a wrongly sized allen key. Easily sorted with the chuck removed from the lathe (unless the others are chewed even worse!).
30 April 2023 at 12:39 #643210
Martin Johnson 1
Participant
@martinjohnson1
I have a lathe with L00 fitting. Easy way to change chucks is to hook the C spanner to screw into the headstock. Get a suitable bar to sit between chuck jaws then heave one against t'other.

I like the fitting as it is very quick to change chucks which is useful to a model engineer.

Martin
30 April 2023 at 15:32 #643237
Nigel Bennett
Participant
@nigelbennett69913
More than once when faced with a radged-up hexagon socket in a cap head screw, I've been able to hammer in a next-size-up Torx bit and unscrew the offending item. The battering-in of the socket seems to help the offending screw release. I hope it doesn't come to that for you!
1 May 2023 at 08:29 #643334
larry phelan 1
Participant
@larryphelan1
Does anyone remember the locking ring on the bottom bracket of old style bikes [1940/1970.] ?

Seem to recall that one of them was left hand thread.

I suspect the your locking ring is likewise. Make yourself a "C" spanner to suit .

Regarding those other screws, like a dog with a bone, leave them alone !
1 May 2023 at 08:32 #643335
JasonB
Moderator
@jasonb
Its a right hand thread
1 May 2023 at 08:47 #643337
Michael Gilligan
Participant
@michaelgilligan61133
Posted by JasonB on 01/05/2023 08:32:38:

Its a right hand thread

.

… As is quite evident from the second photo in the opening post

MichaelG.
1 May 2023 at 10:17 #643350
Clive Foster
Participant
@clivefoster55965
Even though it is obviously right hand thread many folk find the "inside out" layout makes it feel that you have to turn it the wrong way to undo a chuck.

In many cases there is no significant visible thread, the Harrison I used showed about half a turn, which doesn't help.

I always had to think first.

Clive.
1 May 2023 at 14:22 #643389
David Davies 8
Participant
@daviddavies8
Larry Phelan wrote:-

Does anyone remember the locking ring on the bottom bracket of old style bikes [1940/1970.] ?

Seem to recall that one of them was left hand thread.

Classic British bicycles have their bottom brackets tapped 1.370" x 24tpi. The fixed cup which is fitted on the chainwheel side is left hand thread.

The adjustable cup and its lock ring are right hand thread.

Pedals differ as well. The chainwheel side one is RH thread and the other side is LH thread.

Time to go out for a ride I think!

Dave
1 May 2023 at 18:42 #643445
larry phelan 1
Participant
@larryphelan1
I stand corrected, yet again !!!
1 May 2023 at 19:03 #643450
Sonic Escape
Participant
@sonicescape38234
Thank you for all suggestions. I'll leave those screws alone. Now I'm looking for a C spanner. In the end I want to be able to remove the working piece and put it back without loosing the concentricity. I find this to be very annoying with the current 3 jaw chuck.

I would like to use an ER40 collet rather than a C5 type. I read that ER is more tolerant to the diameter of the workpiece. A 4 jaw chuck would be the second option. It is more time consuming to adjust.
1 May 2023 at 20:42 #643464
DiogenesII
Participant
@diogenesii
Why do you have to take it out and replace it?

Best practice is to work out how to do the operations that need to be concentric without disturbing the part – often it can be as simple as making the the part with extra material to hold in the jaws, and then parting it off once all the critical operations are done.

If you need to make the parted end look tidy then it's okay to put it back in the jaws as a last operation because errors of concentricity in a facing cut aren't always so visible.
1 May 2023 at 20:50 #643465
Sonic Escape
Participant
@sonicescape38234
Posted by DiogenesII on 01/05/2023 20:42:00:

Why do you have to take it out and replace it?

Best practice is to work out how to do the operations that need to be concentric without disturbing the part – often it can be as simple as making the the part with extra material to hold in the jaws, and then parting it off once all the critical operations are done.

If you need to make the parted end look tidy then it's okay to put it back in the jaws as a last operation because errors of concentricity in a facing cut aren't always so visible.

Yes, this is true. But these days I have a stainless steel bar and a mild steel bar that I keep swapping. I'm trying different tools. Or sharpen them to see the difference on both materials. Yesterday for example I did a 32 to 12mm plastic adapter for a diamond grinding wheel. And again I had to remove the bar from the chuck. And tomorrow I will put it back because I want to see how is the finish after I hone the tool with the diamond wheel. And so on …
2 May 2023 at 06:45 #643496
DiogenesII
Participant
@diogenesii
I understand, my apologies.

When you remove a piece, use a fine marker to put a line on a chuck jaw and the work, so that you can put back in exactly the same position as it was last time you worked on it.
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