What is this lathe fixture?

Hi all.

Any idea what this is? It was included with my Churchill Cub Mk3 lathe.

It almost looks like a modified motorbike flywheel.

I'm not sure if the back plate has been welded to it, and it's a DIY job, or if this is some standard-issue part.

It is almost perfect for a job I want to do where I need to swing a large (400mm) brake disc and have it as close to the headstock as possible so that it stays within the removed / gap part of the bed. I would true-up the face of this and press the brake disc up against it with the large MT3 live centre.

I'm hesitant to alter/damage any original parts for this old lathe, but also I'm just curious, and I would like to find sources for more similar parts. I suspect the RDG tools Boxford 4" 100mm 4-hole backplate has the same PCD, and with the correct taper and register could be used as a starting point for similar things.

Thanks

Carl

Edited By Carl Farrington on 21/01/2023 23:39:34

I think it's a safer version of a drive/catch plate for turning between centres.
Use this with a drive dog, rather than a small faceplate with a post sticking out of it.
They seem to have been supplied with several lathes.

See the photo(s) part way down this page on Willson lathes.
http://www.lathes.co.uk/willson/index.html

Bill

Edited By peak4 on 22/01/2023 00:05:19

And the pic a couple above it makes suddenly apparent the big advantage of a slant bed lathe. That faceplate is massive! Huge swing for that size of lathe with no gap needed. Nice.

Is that going to be secure enough for something as large and heavy as a brake disc? Can you not bolt the disc to the faceplate?

For a faceplate of a given diameter, it makes no difference where the bed is. It could be below the spindle centreline (most conventional lathes), vertically at the back (e.g. Mazak Integrex, if it could even be called a bed in that case), above or any of 358 other places on a circle. The radial distance from spindle centreline does not change.

For the 'huge swing' over the bed, consider the impoverished swing over the cross slide that results from that design.

Look at the picture. If the bed went straight across, the faceplate would have to be smaller diameter.

The swing over the cross slide is exactly the same as for any lathe with the same vertical distance from the front bed way to the centreline of the spindle.

Edited By Hopper on 22/01/2023 09:08:43

Edited By Hopper on 22/01/2023 09:12:59

Edited By Hopper on 22/01/2023 09:13:15

Peak 4 has the identification right. There was one with the Cub Mk3 lathe I found in a junk yard 3 years ago. Mine came with two sizes of drive dogs that can be contained within the drum shape but it doesn't have the cut away, a user modification in my view

Regards Brian

.

That would make a lot of sense

… The cut away does seem to rather defeat the ‘safety’ aspect of the device.

MichaelG.

.

Perhaps better expressed by the [non-confrontational and, I would say, accurate] statement on this post from another forum:

**LINK**

https://www.mig-welding.co.uk/forum/threads/remember-that-strange-lathe-on-ebay-willson-slantbed.67022/

[quote] One of the big advantages of the slant bed design is it's ability to accommodate large diameters. well, bigger than most other lathes of a similar overall size. [/quote]

Impressive little video too.

MichaelG.

Who asked you? Wind your neck in. Enough of the snide comments already.

Edited By Hopper on 22/01/2023 11:07:22

Nobody asked me, Hopper

… This is a forum

and if you consider “perhaps better expressed” as snide, then I think you should look to yourself.

Meanwhile … you may, or may not be interested to know that the earliest patent application I have seen for a slant bed is from MURATA

MichaelG.

.

Ref. https://worldwide.espacenet.com/patent/search?q=pn%3DJPH0788703A

Edited By Michael Gilligan on 22/01/2023 11:15:37

As a Willson user I am delighted to see this lathe receive some attention and interest on the forum.

My slant bed came with the safety catch plate mentioned and it was successively converted to a small faceplate and then to serve as a chuck backplate.

The standard faceplate came into its own when I wanted to shorten a pair of cycle cranks from the common 175mm length to 165mm:

The new eye is on centre for screwcutting and the far arm of the spider just clears the bed by dint of removing the sheet metal cover. This would have been impossible on the "straight bed" version of the lathe.

Edited By ega on 22/01/2023 11:50:49

Awesome. All the advantages of a large gap bed lathe, without the gap weakening the bed. An idea brilliant in its simplicity, yet it never took off because it's different from the norm. Bit like any alternative to telescopic forks that has been offered to motorcyclists since the year dot. Any number of set ups are better, but tradition rules and buyers avoid anything that does not look "normal".

What I really meant to say is that I am holding from behind with a large *bull nose* live centre, pressed up into the factory taper inside the brake disc.

The idea is that I true up the face of this safety catch-plate (Thanks Bill, and everyone else!). I was originally intending to use some thick wall tubing and true up the end of that, but some of the discs I want to work on have a large offset / height, and the taper is on the inside / less-ideal side, meaning everything comes too far over from the gap in the bed.

The disc will stay in place until both sides are skimmed, rather than being flipped around half way through.

Edited By Carl Farrington on 22/01/2023 12:17:23

I very nearly bought one a few years ago.
There were two lathes to view on consecutive days, but in different directions from my house.
Looked at the Willson first, and then the Harrison, which I rejected; unfortunately I then missed the Willson by about ½ hour.
I eventually ended up with a Warco GH1330, which is a rather different sort of beast.

Bill

Sounds like quite a job. Pics would be of great interest I am sure, if you have time while in the thick of things!

Hopper:

Someone commented that the "gap" is as long as the bed! I think quite a few were sold, partly on the strength of their safety features attracting educational users (I think mine came originally from a local college).

Another unusual feature was the roller-type cover to the feed and leadscrews as seen in the image you posted.

Not sure about the gap theory. It still looks pretty solid. Missed those covers though. Rather unique aren't they. Would keep the swarf off the leadscrew as well as schoolboys' shirt-tails out of the working bits.

Carl,

As another Churchill Cub Mk 3 owner I've sent you a PM.

Regards Brian

Thanks Brian, I shall go and have a look !