Faceplate was the cause

OK so your on about a chuck backplate - NOT a faceplate.
but my original answer still stands, put your faceplate or backplate on to your spindle and turn it until it is running true with your spindle. Then you will have concentricity with your machine. reattach your chuck to the BACKplate using new repositioned fixing holes if needed and using a DTI or some other miniscule distance measuring doodah and adjust until totally or as near as damit its totally central with no discernable runout..

Z

Edited By Ziggar on 03/02/2014 14:04:14

"Okay, so remove the chuck from the backplate (leave the backplate in position on the spindle) and slightly reduce the diameter of the register that holds the chuck 'central'. When you refit the chuck you will find it is not concentric, but can be made so by using a DTI either on the circumference of the chuck body or on a good piece of bar held in the chuck jaws. Just leave the backplate bolts loose(ish) whilst you nudge the body to its best location. It's a similar process to that used when using a four jaw chuck."

I guess this approach will depend on just how non-concentric the centre hole is, there may not be enough adjustment in the bolts. And doing it this way, ie machining a bit off the register, can the chuck afterwards be trusted to remain concentric?

I think I'd do as above (Ziggar's post) and machine the circumference of the backplate to make it concentric. Then use a rotary table or similar means to drill new mounting holes for the chuck. 

Edited By Carl Wilson 4 on 03/02/2014 15:24:54

Edited By Carl Wilson 4 on 03/02/2014 15:28:24

Edited By Carl Wilson 4 on 03/02/2014 15:29:24

Edited By Carl Wilson 4 on 03/02/2014 15:29:50

Yes it can. I do it this way because it's possible to get a decent three-jaw chuck to have less runout than by relying on the backplate to chuck register. As long as the bolts are reasonably well tightened, I've never had one move.

Point taken about the mounting holes, but if they're quite close then they could be eased with a file.

Martin.

Looks a very nice machine Becky; in fact pristine, has it ever been used before you got it? I can't see any contact /wear marks on the pulleys, gears etc. How are your headstock bearings lubricated as I don't see any oil cups / grease fittings.. modified with sealed angular contact bearings perhaps? Pity about the probs with your chuck run out, I can only concur with above comments, in particular with Bogstandard2 remedy, if that doesn't get you within .0005" - .001" then nowt will, good luck.

George.

Well I have read all the replies and whilst most advise is good I would attack this from a different angle.

First of this machine regardless of it's paint job, is, at the least 67 years old and no one has no way of knowing what it's been through.

Without getting into an argument on the register to thread debate what is critical is the register FACE on the spindle.

If that isn't true then nothing that screws on it will be. Now you can sit there with a clock all day long checking but the only true way is to take the smallest lick off the face whilst it's running under power in it's own bearings.

Do I hear sound of heretic, sacrilege etc ? Long , short is it was true 67 years ago but we don't know about today and we are not talking about taking 1/2" off.

Now it's no good getting the spindle true only for the backplate to sit on wonky so the chuck needs taking off the backplate and the backplate screwing on the wrong way round to the end, not tight though.

Then back off one full turn approx, not critical. the distance between the register face and the face of the backplate at this point is the length you need for a spacer, spacer can be anything doesn't have to be a good fit on the spindle thread, in fact it want to be loose, could be a bit of steam pipe.

What does matter is the faces need to be parallel. Becky cannot make this because of the wobble, needs making on a decent lathe or even surface grinding, but once made and fitted between the spindle register and the front of the backplate the register face on the backplate can be machined and a chamfer put in the bore on  the edge.

Now and only now can it be turned round and the facing operation previously described be carried out.

It's pure logic when you think about it

Edited By John Stevenson on 03/02/2014 21:38:48

If Becky can find (Borrow? But keep swarf out of it!) a Ball Race (or even the inner track of a Taper Roller Bearing), of the right size, in good, or preferably new, condition, this would probably be a splendid spacer?

Howard

4th paragraph, that is the first operation.

There it is!

thank you every one.

there is plenty to go one here.

once I have bought a new back plate I will apply all the suggestions that are applicable.

I have posted another question but this time on milling machines on another thread.

cheers

becky

Hello Rebekah

I have commented before on your nice looking lathe. Before my present machinery I inherited my father's ML4 which he bought new in 1945

That had a 1 1/8" diameter plain spindle section and 12 tpi 1 1/8" Whit form thread on the nose for fitting on chucks etc. Knowing the rear vertical face to which chuck backplates etc could be screwed to a stop was true, as John Stephenson has described a perfectly valid correction if it is needed in detail, I modified the nose with a close fitting collar that I loctited to the plain section behind the nose thread.

With some careful reaching with long tools, it was then possible to turn a new diameter of 1 1/4" as a location diameter for the more up to date ML7 chucks, faceplates etc.

I seem to remember telling you about this dodge in our previous exchanges, it is well worth the little effort involved.

Brian

hiya all,

success, I destroyed two plates in the process but I now have a chuck mounted on my lathe.

now just need the tumbler gears (tufnol)