125mm HBM Chuck too heavy for Myford ML7???

I think one of the main problems is in a chuck that requires a back plate, this adds the weight of the back plate, and pushes the weight further out from the bearings, ideally the chuck (on any lathe) should be as close as possible to the bearing.

Ian S C

Definitely agree with you Ian. The Pratt chucks mentioned couldn`t get any nearer the bearings.

Alan

Ian S C:

I agree also. However, it is worth pointing out that, on my own machine, with the Myford pattern PB 4" SC chuck I cannot machine right up to the jaws without the saddle oversailing the gap or winding out the topslide.

Some years ago I bought a used 4.5" Taylor 3J with a view to making a backplate and using the chuck with my S7. These excellent chucks are very heavily-built and an instinctive feeling that it would be wagging the dog has kept me from doing so.

I assume that the Myford pattern chucks are no longer available new but, depending on the construction of any given chuck, it is sometimes possible to reduce overhang by positioning the backplate thread within the chuck body.

It's only now that I realize that the Myford does not have a filler piece for the gap, this seems a silly omission when it comes to face plate work, I suppose all Myford 7 lathes are like that.

Ian S C

From memory Ian some of the face plates make use of the gap.

Personally I am not convinced that Myford have always supplied chucks that don't need a back plate. I have the impression that it's a more recent thing even on 7's.

John

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Ian,

You are correct in thinking that no Myford 7 lathes have loose gap pieces. The reason for this is actually allow for oversize work attached to the face plate e.g. flywheels and similar. Myford also offer a 9" diameter faceplate that certainly needs the gap.

In general loose gap pieces are a mixed blessing as they are often difficult to set up properly especially when the front on the bed is a bit worn and the gap piece is still in pristine condition so creating a very shallow step. Loose gap pieces are normally only found on larger lathes such as Colchesters.

I do not think it is quite fair to criticise the original Myford gap bed design as this makes a small machine very versatile without more expense and complication.

I have Myford (Nottingham) document from 2009 which lists a few chucks on back plates for 1 1/8" spindle noses.

I am not at home until late today, will see what I can tell from it when I get time.

Loose gap pieces spend most of their time in the gap. If lathes for a job are sized correctly they are only intended for occasional jobs. In fact it can be a right pain getting them back in exactly where they need to be.

Myford's problem with the 7's if that is the correct word is that they are budget machines and that explains many things about them. They are still budget machines now.

Some one mentioned bearing wear on an ML7. That's what the shims under the bearing caps are for. Periodically when the bearings are too loose to do what's being asked of the lathe they caps should be removed, a very thin layer off the shim removed and the top 1/2 of the bearing scraped back in. At the same time this is done all of the bearings should be blued because at some point both of the lower bearing halves will need scraping to level and align the spindle and get good contact all over them. A new spindle will probably be required at some point especially with the later phos bronze bearings they supplied. Myford have always had a good stock of ML7 spindles. When I requested one of a super 7 they reckoned they had never supplied one but did make a few for spares. The same sort of problems crop up with these too but the bearings can always be made to fit the spindle.

Loose bearings on a ML7? At some point, crap finish, carbide tooling chipping more often than they should and even relatively easy materials to machine throwing bits of swarf all over the place. A fix some use that doesn't really help all that much is to set the belt to the headstock very tight. That increases the bearing wear even further.

John

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Adding to my previous post:-

The document I mentioned is titled: Accessories and Ancillary Equipment for Series 10, Series 7 and 254 Plus Screwcutting Metal Turning Lathes.

At some 35 pages it seems very comprehensive and was handed to me at a Myford Exhibition Stand, not sure exactly where though.

In the list of Chucks for Small Bore Spindles - Bored 5/8" Threaded 1.1/8" x 12 TPI Whitworth Form, there is part No 40/120. Which appears to be a 125mm (5")  3 Jaw TOS Svitavy Geared Scroll (self centring) Chuck, complete with 2 sets of jaws (inside and outside) and key. Fitted to an A3091 Backplate.

This particular listing covers Series 7 Machines.

I do not have the knowledge or experience to comment on this matter, but did think this might be of interest to those posting comments in this thread.

Edited By V8Eng on 29/11/2015 20:17:15