Lathe chuck removal

having now acquired a independent 4 jaw chuck, Im somewhat perplexed on how to remove the current 3 jaw chuck from my Myford ML7. There's lots of hints on removing a stuck 3 jaw chuck but nowhere can I find the "official" way to remove it under normal circumstances, i.e. Where it's not stuck on and the manual hasn't shed any light.

Lock the headstock (maybe by engaging the backgear if the ML7 doesn't have a locking bolt). Put a piece of timber (hardwood for preference) in the chuck crossways. Use a piece a bit over 1" square and a couple of feet long, holding it near the end. Apply pressure to the timber to undo the chuck. If this doesn't work try hitting the timber with your hand. if still no joy then clout the timber with a hefty hammer!

Myford ML7 lathe Notes on Installation and Maintenance (Publication No 701) states:-

"When removing a chuck (or face plate), do not "yank" the chuck off with the headstock locked with back-gear, but set the headstock for normal back-gear drive, and after placing a piece of hard wood on the lathe bed, pull the spindle round by means of the belt so that one jaw of the chuck or slot in the face plate strikes the wood sharply. The most obstinate chuck is released in this way, and a great deal of load is taken from the back-gear teeth".

It worked for me, good luck and take care not to pinch your fingers between the belt and pulley.

Gordon.

Mine was a bitch not a cats in hells chance by Myfords recommended method, belt slips.

Only way out lock the spindle but wont say how on here, spanner on a jaw and sharp tap left hand thread.

Perhaps it is worth again mentioning Lawrence Sparey's Myford spindle locking spanner (my brief article about my own version of this is behind the clock on the editor's mantlepiece).

Using the back gear to lock the spindle is fraught with danger, any torque or shock applied to the chuck is carried by little more than one tooth of the back gear. If the chuck is not jammed on the nose it may well release easily but if it is stuck hard then think about the load on the poor tooth. Resist the temptation to use the chuck key as a lever as the sockets will break. Try a very large Allen key tightened in the chuck jaws or a bar locked in the jaws to give a lever. At the end of the day a backplate is cheap compared to the damage that can be done to the spindle and gears so unbolting the chuck and machining the backplate away can make economic sense. If the chuck is of the threaded body type then maybe the risk of damage is a bit more worthwhile. It is worth stopping to think where the force you are applying is going, there is usually a key or pin that is going to transmit the drive so shocks and high leverage is going to be applied to some parts that were not designed to take these forces. Locking or jamming pulleys or gears is the only strategy available but just remember that most of these parts can be bent or broken if too much power is applied.

Mike

Edited By Mike Poole on 11/04/2017 22:47:56

Have sent you a message

Thanks for all the tips, also looking at a spindle locking handle, would come in handy for tapping and threading

Curtis Rutter:

I have replied to your rmessage.

Edited By ega on 12/04/2017 17:01:22

I remove my chucks by fiitting a piece of occtagonal bar in the jaws and use a spanner after locking the headstock.This has also worked on a jammed chuck.

\Frank

Bricky How do you lock the headstock on an ML7 ?

Roy ( And please don't say put it in backgear )

?

I have a Super 7 and I don't know if the ML7 has a spindle lock.

Frank

Neil Wyatt:

PM sent re your ?

No it doesn't

I'll add a useful thread address here simply because I abhor the use of PMs for useful information which should be posted on the open forum where it will be helpful to people searching later rather than providing them with a dead end and some PM references.

http://www.model-engineer.co.uk/forums/postings.asp?th=112932

Nick

Edited By Nick Hulme on 13/04/2017 08:45:06

Nick Hulme:

Thanks for reminding me of this thread. The reason for my resorting to PM now was that I envisaged sharing with the OP an article submitted for publication in the magazine and wanted to avoid any question of conflict with MTM's house rules.

As the owner of an ML7 with a busted tooth on the back gear, I'd second all comments regarding not using back gear to lock the spindle. The 20DP teeth are not very sturdy and the gear is cast iron so prone to snapping rather than yielding.

If the belt slips while using the Myford recommended method it might be worth looking at new belts - if they are over 10 years old they will have gone hard and slippery. It is not usually possible to slip a properly tensioned new V belt by hand.

When I fit the new back gear i will be drilling the extra hole needed to use the Sparey locking tool, though.

Edited By Hopper on 13/04/2017 12:24:57

The chucks on my lathe screw on (but have dogs to prevent then unscrewing when used in reverse).

I have drilled a hole into the chuck, or backplate. Into this Is inserted a piece of round silver steel, which is gripped (not welded) into a boss on a piece of rectangular bar. With the belt tightened, and the retaining dogs removed, the rectangular bar is held with the longer side vertical, and the end hit with a copper/hide mallet. Works every time!

Applying the same technique to a piece of fairly large diameter hexagon, (or square if a 4 jaw) gripped in the jaws should work equally well.

Another possibility would be to cut a piece of wood so that, when resting on the rear of the bed, a chuck jaw makes widespread contact. Spinning the chuck, BY HAND , not power, so that one of the jaws hits the wood, may slacken it. Preferably, the contact between wood and jaw should be as close to the chuck body, as possible.

Howard

If Chuck is really stuck this helps

**LINK**

There are to many broken back gears out there.

It should be taken as read NOT to engage back gear as a means of locking the Mandrel to remove the Chuck.

A friend regularly used to ask me to cut new gears for him until he realised the error of doing this.

With a tight belt, the motor and mandrel ought to provide enough inertia for the "sharp tap" technique to free the Chuck. Once it has slackened a few degrees, it should be possible to unscrew it by hand. If it doesn't. there is something really wrong!

A suddenly app;lied force has twice the effect of a gradually applied one. If you don't believe what my Physics master told us, just draw the graphs!

Is it necessary to advocate a wooden chuck board to safeguard the bed when the chuck does unscrew?

Howard