ML Super7

[DMBParticipant @dmb]

Can anyone please help with the following-

Removing a chuck, push in mandrel locking pin at LH side, key in chuck and thump key with fist. Works everytime for my lathe as I dont wrench up the screw on chuck unnecessarily tight.

My club's S7 is " locked" mandrel just turns with the chuck. My guess is that the pin actually locks the pulley cluster which in turn is somehow locked to the mandrel, probably by grubscrew in the pulley cluster, which has loosened or slipping.

Any ideas, please?

John

[DMBParticipant @dmb]

Mandrel problem

[Ex contributorParticipant @mgnbuk]

The spindle mounted pulley set is free running on the spindle on an S7, not keyed – it runs on bronze bushes & there is an oil nipple in the pulley. Drive to the spindle comes from a Woodruff key in the bull gear, the bull gear being connected to the pulley cluster with the retractable half round dog that is mounted on the bull gear.

The Woodruff key is small IIRC – the parts list says it is a "No. 404" key – so there is a possibility that the key has been sheared trying to remove the chuck.

A 'pdf of the Super 7 manual is easily found with a quick Google. This includes the exploded parts diagrams at the back. Worthwhile downloading a copy for reference purposes.

I don't think it is recommended to remove chucks using the chuck key inserted in a pinion, as this can split the square end of the pinion or dmamage the pinion bore.

Nigel B.

[bernard towersParticipant @bernardtowers37738]

DMB, It could be that the direct drive pin is disconnected and the backer lever has not been selected leaving the front and rear half of the mainshaft in neutral, so if pin is locked chuck will still turn. Just been down the workshop to prove it so that could be the problem.

[Howard LewisParticipant @howardlewis46836]

Do NOT use Back Gear to lock the spindle while you unscrew a chuck, (Unless your other hobbhy is replacing gears with one or more teeth missing )

My memory of the ML7 is that there ws a small " key" on the bull wheel that locked the bull wheel to the spindle, retained by a small capscrew.

If the chuck mis stuck, there are a varirty of threads on here, telling how to slacken the chuck without damagingb the machine..

Howard

[DMBParticipant @dmb]

Hi All,

Thank you all very much for your advice. I bought my MLS7 brand new weeks b4 the dreaded vat started as up to then they were then free of any form of taxation. A manual came with it but mislaid in the house somewhere, so I am unable to study its diagrams at present. Of course, it's one of the grim n grey type but the club's one with the problem is younger and Green in colour, otherwise apparently identical. I will investigate further, next time that I'm at the club and try to work out what to do about it. Will inform you all how/when its 'sorted'.

John

[John HaineParticipant @johnhaine32865]

Clamp a piece of hex bar, say 19mm a/f or bigger – of a long joiner nut – and apply a spanner of socket rather than using the chuck key.  I think you are saying that the S7 (ML7?) at your club doesn't have the mandrel lock pin that later S7s seem to have?  Mine certainly does.

Edited By John Haine on 07/02/2023 17:16:09

[ChrisLHParticipant @chrislh]

Mine's a rather early S7, SK2142, and it has the lock pin.

[DMBParticipant @dmb]

Hi All,

Thanks again for everyone's advice. Hang head in shame – should have realised and checked club Super7 after owning mine for 50 years. I found that someone had released the swivelling half round locking pin in the bull gear. Locking that and the rear mandrel pin enabled easy removal of chuck. I only nip chucks to a sensible tightness on my lathe so no great force on chuck key. Been unlocking chucks for as long as I can remember, by gentle thump with fist on key. No apparent harm yet.

John

[Howard LewisParticipant @howardlewis46836]

Don't liker to hear of folk "thumping the key" to remove a chuck.

That sort of activity tends to broken chuck keys and damage the socket in th chuck.

FAR better to clamp a hexagon bar (if a 3 jaw, square if 4 jaw )) in the chuck and use a socket with a long bar, or a long spanner.

Alternatively, clamp a stuyrdy piece of timber across the chuck jaws and hammer the outer end of that.

Howard

[Michael HorleyParticipant @michaelhorley72278]

I have repaired two 4-jaw chucks where people have removed them by hitting the chuck key and snapping a piece off the square socket.

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