Mounting a new lathe chuck

I have an 1940’s lathe and the chuck is worn on it. I’m unable to find a direct replacement for the chuck and I’m looking for a precision engineering company to marry up a new chuck (that I would provide) to the original chuck back plate. Precision is the key here as the two need to be married so that the centre is within a thousand’s of an inch.

Just put on a chuck with soft jaws or use an independent 4 or 3 jaw chuck. Self centring chucks are not accurate enough to guarantee what you want at all diameters.

Martin C

Spencer the best way to mount a new chuck is to turn a new register on your existing backplate on YOUR lathe mounted on the spindle thus ensuring the chuck is better than 0.001" -- it must be providing the backplate fits your spindle correctly and assuming the new chuck is of good quality. The ultimate TIR of work mounted in the chuck has many variables not least the chuck itself.

This is assuming your backplate has enough thickness to accommodate a new register, if not make a new one, I just made one a couple of days ago for a pal and we fitted a new chuck to it on his machine. He's well pleased !

John

Filling in your profile might help, if a recommendation is forthcoming. Shipping could be one problem.

Is this a three jaw chuck? You would be lucky to achieve better than a thou. runout for any three jaw unless the lathe is good, the chuck is a very expensive one and you are very lucky.

If your lathe is one of the common 1940s makes, Myford, Drummond etc, you can buy a new back plate with the spindle thread and register already machined. Mount it on your own lathe's spindle and turn the back plate to fit your new chuck. This will result in a more accurate job than sending it out to a machine shop. OR as suggested already if the old back plate has enough "meat" left on it, machine that to fit your new chuck.

Of course, best result will follow if you make sure the headstock bearings are well adjusted, ditto carriage and cross slide gib strips etc before machining the new back plate.

Definitely turn the backplate in place, that's best practice. With a little care the result will be as accurate as your lathe.

Neil

Definitely turn the backplate in place, that's best practice. With a little care the result will be as accurate as your lathe.

Neil

Definitely turn the backplate in place, that's best practice. With a little care the result will be as accurate as your lathe.

Neil

As far as the ready machined backplates are concerned I have tried several different ones for "modern" Myford and they are invariably oversize on the register bore therefore do not run true.

At least that's been my experience, I have measured several of them and they all seem to be plus 2 to 4 thou when they should be a max of plus a few tenths. The same seems to be the case with Myford fitting male adaptors for say rotary tables and they are the opposite being minus 2 to 3 thou on the register diameter.

I now make my own unless they come from a source that produces them within the correct tolerance.

John

Hi Spencer welcome to the forum but what lathe do you have that needs a new chuck. I have just replaced the 3 jaw chuck on my M Type Drummond and bought a new plate from Lathes.co.uk I just had to machine the location and face for the chuck in situ.

David

Brilliant Dave , Thank you for sharing as its been a devil to get one on mine for my 100mm drive dont just assume your spindle size as unless it fits perfectly it will not work and break the threads in back plate . Yes i did this

i wanted a 100x 1" x 10 tpi backplate for my spindle on my Drummond too. I havent found one yet, I found a 5" one and am looking for a front bolt bernard at present.

M