Re: stuck chuck


eddie.draper@btinternet.com
 

Dear Niel et al,

I just took a couple of shims out, 0.002" or 0.003" each side (the spindle clearance is normally very precisely set with the bolts hard tight), put the cap back on, tightened hard down and it was immobile.  Afterwards, I just reassembled normally.

This is a 14.5" lathe without bushes.  The spindle just runs in the Cast iron of the headstock & bearing cap.  I would have thought the same would work on one with bearing shells, so long as the shims are normally located between the shells rather than just at the caps with the shells abutting hard against each other.  never seen a SB with shells taken apart.  My Myford is certainly shimmed between the shells.

Don't whatever you do take out a big pile of shims, or you could distort or fracture the bearing cap while tightening it down.  Is that what you were referring to when you mention "expand the bearing" below?

Eddie

On Thursday, 23 January 2020, 14:10:54 GMT, N Jen <niels.jensen@...> wrote:


To Eddie Draper,
I like your idea of removing a few shims at the front bearing of the spindle to immobilize the spindle. Just for clarification, did you expand the bearing after reinstalling the bearing cap in order to clamp down on the spindle?  I have a stuck chuck that I need to remove and want to use your method. 

Sent from Niels' iPhone

On Jan 22, 2020, at 2:21 PM, eddie.draper@... via Groups.Io <eddie.draper@...> wrote:


Managed to get the stuck chuck off today.

Gripped an offcut of 1 1/4" Whitworth hexagon in the chuck.  Engaged the belt on the slowest non backgear speed, just to use the inertia to reduce shaft rotation.  Applied a 3/4" drive electric impact wrench via a socket.

30 secs later, nothing.

Removed a thin shim from both sides of the chuck end headstock bearing and clamped it up tight.  Applied both the impact wrench plus a long open ended spanner to the hexagon, and applied a 14lb hammer to the spanner.  It took a few blows, but it came off.  If the headstock spindle had still rotated, I was intending to similarly lock the other end bearing.

Note:  I had used ISO 1000 viscosity steam oil on the threads when assembling it.

Chuck run back on gently, headstock bearing shims refitted, and lathe used normally.

PHEW!

Eddie

On Monday, 13 January 2020, 09:04:35 GMT, eddie.draper@... via Groups.Io <eddie.draper@...> wrote:


Me too!  Also, I note that the illustrated machine has V belt drive and there appeares to be a gap between the pulley and the gear.  Our 14.5" has flat belt and no gap.  Ideas anyone?  I have a rather seriously stuck chuck at present, as it started to unscrew when I switched off, so to prevent it going flying, I switched back on again rather hurriedly and it seated in place with a significant bang.

I would caution against using the front diaphragm of the headstock casing as a reaction point, as it is a rather thin casting.  Whatever you do, keep the forces acting dead in line through it and do not drive a wedge between it and the bull gear, or you may fracture it out.  The dog for the bull gear to mandrel connection on the 14.5" is on the outer end, and the only exposed part is a rather slender handle that I would hesitate to use for this.

Hoping to upgrade to a similar size machine with Camlock!

Eddie


On Sunday, 12 January 2020, 19:14:49 GMT, Steven Schlegel <sc.schlegel@...> wrote:


Is the shaft square in that area, or do you get leverage off the pin? I am trying to figure out how it works.

Steven


From: SouthBendLathe@groups.io <SouthBendLathe@groups.io> on behalf of Chips <sakr4360@...>
Sent: Sunday, January 12, 2020 9:21:36 AM
To: SouthBendLathe@groups.io <SouthBendLathe@groups.io>
Subject: Re: [SouthBendLathe] stuck chuck
 
Newb here, first post.
Mine was stuck when I got it due to sitting for 20+ years and yes I broke a tooth on the back gear.
Make one of these from 1/4 thick plate then put it on the bull gear opposite side of the little push pin that engages the pulley. Then you can crank on the chuck.
You can thank me later.

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