Chuck Adapter

Perhaps this is one for Michael? you’re good at finding stuff.

I want to be able to fit my wood turning chucks on my metalwork lathe. The MW lathe uses a fairly standard 72mm register and my WT chucks are threaded M33 x 3.5mm.

Ideally something not too expensive. I seem to remember seeing something that may have done the job but a bit pricey at over £100.

Vic

if you just get a spigot with a m33x3.5 thread on one end

put the plain end in your chuck 3 or 4 jaw or collet chuck on your MW lathe then your WW chucks on the thread

Ian

I’ve tried that, too much overhang. It also reduces the length I can turn on my modest 14” lathe.

There are MT2 to M33 adaptors. I got mine from RC machines in Luxembourg but I'm not sure if they ship to UK post Brexit.

Simon Hope lists one on his website - looks like it is threaded for a drawbar, which is what you'd need. About £30.

Thanks Norman, I’ll have a look. Maybe they do a MT3 version?

I just turned one to fit my woodworking chuck onto the Emco. slice of EN3 the right diameter. Hold in metalworking chuck to machine the face that goes onto the spindle. Then mount on spindle to turn and thread a spigot to fit woodworking chuck. Far more rigid than any MT fitting will ever be,

Also check if the M33 thread is cut directly into the woodworking chuck body, many have a threaded insert that can be changed to suit various lathes so you may be able to remove that and only need a plain spigot for your adaptor.

Edited By JasonB on 01/05/2023 16:40:53

Please could you clarify the 72mm part.

Is that the spindle register?

If so, that seems quite large for a 14" lathe.

Is the lathe one that has, in effect, the chuck backplate integral with the spindle?

Reading JasonB's post above, I guess that it is so I think what you are looking for would resemble a backplate-mounted ER collet chuck, without the nut and having an M33 thread on it instead of the ER thread.

It may be that a standard backplate-mounted ER chuck could be modified (ER32 has M40 thread, but the wall might be too thin).

An alternative might be an ER20 one (M25 threads) and a bush which is M25 female to M33 male.

Edit:

One of these would work with the idea above:

https://www.ockenden-timber.co.uk/woodturning-chucks-accessories-nexus3r-woodturning-chuck-c-107_108_109_975/thread-adapter-insert-34-x-16tpi-to-m33-x-35-p-2908

just thread the inside to suit the ER thread.

The other option with that one is to surround it with what is effectively a thick washer so that its diameter matches the mounting holes in your backplate and then secure the two parts together (welding is easiest, any mechanical fixing has to resist axial and rotational forces).

Edited By DC31k on 01/05/2023 17:15:25

My 14” lathe has a fairly standard flange mount with a 72mm register. This from arcs site, dimension H is 72mm.

**LINK**

As a point of interest all my wood turning chucks are direct threaded M33 x 3.5mm. I avoid chucks with screw in adapters as I had one once with unacceptable runout.

Basically I need a flange with a 72mm recess on one side and a M33 x 3.5 ISO thread on the other.

it would look something like this. This one is German, I don’t think it fits my lathe but it’s €129 plus postage from Germany.

Would it be possible to post a link to that item please?

The difficulty is in writing the correct search terms to find what you want. If we know what that is called in German, some translation might find a UK equivalent.

link

I didn’t bother posting a link as this item is designed to fit a lathe with a somewhat unique mount in the general wood turning world.
A friend has one of these lathes so I will at some point take some measurements to see if it can be made to work for me. At what could likely cost me in excess of £150 and still need further work though I’m somewhat reluctant.

VB36 has a 60mm spigot and the hole PCD would also be too small

Can you not turn one as I suggested, would have thought a lathe that size can do 3.5mm pitch screw cutting.

Yes. It would need modifying. I’ve increased the register and redrilled the mounting holes on similar items.

Not something I fancy doing on an already expensive item. It may even have a hardened surface

My lathe only goes up to 3mm pitch. I think it would even struggle to cut that.