Myford collet chuck – how to fit it?

[WaldorfParticipant @waldorf]

Hello to all

I've recently purchased my first (new to me) Myford S7 lathe together with a very comprehensive kit of accessories. Setting up the vertical milling slide was straighforward, but when it came to fitting the collet chuck, I ran into a snag. There's an articulated stay on the side opposite the handle which has a threaded section and a locking nut. I can't see where this should attach to the lathe itself.

It's no doubt obvious to anyone who's ever used one, but not to me! Can anyone point me at a copy of the instructions for this chuck?

[WaldorfParticipant @waldorf]

[paul rushmerParticipant @paulrushmer83015]

Hi

I have one of these but hot fitted it yet, I assume the thread on the clevis (Anker) should screw in where there is a cap head be side the spindle in the top picture. Some one will post a picture soon!

Paul

[Clive FosterParticipant @clivefoster55965]

Paul has it right I think. See **LINK** see about 1/3 rd down page for drawing on slightly different headstock. Also see **LINK** for a clear picture.

Clive

[Andrew TinsleyParticipant @andrewtinsley63637]

There should be a hole in a cast in lug at the back of the headstock. The threaded portion of the collet chuck extension should simply go into the hole and then use the nut to secure it.

Earlier ML7 headstocks did not have this cast in lug at the rear. It looks as though yours doesn't, so you will have to make up something to do the job.

Andrew.

[KWILParticipant @kwil]

Yes that is how you fit it. The Cap screw is not normally there other than to keep the swarf out!

[Andrew TinsleyParticipant @andrewtinsley63637]

Looks like I might need some new glasses!

Andrew.

[Malcolm Jones 1Participant @malcolmjones1]

My collet chuck has a different fixing to yours, just a threaded rod with locking screw that screws into the hole in the head stock that has the cap head screw in it, the other end of the rod has an eye to bolt it in to the closing ring.

[WaldorfParticipant @waldorf]

Thank you all for the very helpul responses. As suggested, I removed the capscrew (it was only finger tight) and fitted the stay in its place:

However…

The chuck doesn't hold the cutter very firmly. Tightening the chuck by hand as much as I can (gripping the ring with an old towel) the cutter pushes back into the collet even whentaking a light cut on some aluminium. I tried various cutter and collet combinations. I assumed that the purpose of the handle is to release the cutter, but when I tighten the chuck up as far as it will go, there's very little movement in the handle.

What am I doing wrong?

[Clive Brown 1Participant @clivebrown1]

It's important that the collet and cutter shank are the same nominal size, this type of collet has very little size tolerance.

I wouldn't trust my Boxford collets to grip cutters really firmly anyway, I suspect Myford collets are little different. The ER collet system is much better for this sort of task I find.

Even so, the collet nut has to be really tight.

Edited By Clive Brown 1 on 30/07/2017 22:00:04

[Neil WyattModerator @neilwyatt]

I think you should be using the lever to close the chuck, after spinning the nosepiece on by hand.

It is meant for rapid production, so you can put work in and out really quickly without having to do any screwing up or unscrewing between parts.

Neil

[RobboParticipant @robbo]

Neil is correct. You insert the collet with the lever in the open position, tighten up the collar by hand and then close with the lever to tightly grip the collet. Then to change the collet it is only necessary to open with the lever, insert new collet and close the lever.

[WaldorfParticipant @waldorf]

Posted by Neil Wyatt on 30/07/2017 22:36:47:

I think you should be using the lever to close the chuck, after spinning the nosepiece on by hand.

Thank you Neil, that advice is spot on. I discovered that the technique is to gently tighten the ring until it is "just" possible to move the lever fully to the left (it feels just like an over-centre cam action). The cutter is released by moving the lever to the right.

I was tightening the ring too much by hand which ironically meant that the collet was never gripping the cutter fully. Most of the collets have no markings at all, a few are marked Hardinge. Some are clearly well used, so a new set may be in my future!

[Neil WyattModerator @neilwyatt]

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