Mellor Cross Slide Feed

Sorry, I feel I'm pestering you guys lately!

The cross slide on the Mellor lathe I am restoring has what seems to me, to be a strange drive system.

There is an internal taper on the drive gear

The rest of it is missing. If I remove the gear it looks like this.

So, I made a taper to fit the gear and screw onto to the cross slide shaft

This works a treat. However, when it is engaged, the drive gear tightens it onto the feed shaft so much that I need some serious leverage to undo it. There is certainly no chance of disengaging the feed while it's running.

I wondered if maybe some friction material between the internal and external tapers would help?

Many Thanks, David

It looks a bit similar to the cross feed clutch on a South Bend 9" or one of its clones, Boxford, Hercus etc. so you may be able to copy their set up. AFAIK the Hercus clone just uses a cast iron knob with taper like you have made in brass. Perhaps cast iron or even steel is a bit less "grippy" than brass? Other South Bends seem to have a pair of split tapered "shoes" that the knob and its threaded shaft expand into the surrounding taper. They appear to be cast iron or maybe steel. And I think they have some kind if spring pushing the tapers apart when the knob is unscrewed.

One of our Boxford owners should be able to tell us what their cross slide clutch cone is made of.

I think they are sensitive to what oil is used in the apron too. Something like ISO32 hydraulic oil would be the norm.

Also, it looks like the female taper in your gear could use a bit of a clean up, although pics often make such things look worse than they really are.

Edited By Hopper on 23/01/2023 05:21:37

Edited By Hopper on 23/01/2023 05:31:56

Edited By Hopper on 23/01/2023 05:37:13

Edited By Hopper on 23/01/2023 05:38:34

David, the original clutch is cast iron and 2-pieces. YOu might be better off emulating that, I suspect that brass will be a bit grabby and poor to release. Here's a pic of the original:

Mellor gear.

Don't lose that gear BTW they are the devil to make.

Thank you both

Split taper! That is the piece of the jigsaw that was missing.

David

I think having the tightening knob and the taper as two separate pieces would held too. The knob would screw onto the shaft and push upon the taper piece which would be held captive in the female taper by the knob. You might get away without having to split the taper that way. This would allow you to undo the knob without it being jammed up by the stuck taper and once the knob is loosened off, pressure is off the taper and so it should then let go. Should!

Yes, that is what I mean, the taper and the star wheel are separate. I don't think that the taper itself is split.

Definitely the taper and the star wheel need to be two separate pieces, perhaps with a PTFE or similar washer between them.

Ah, ok. I was thinking that if the taper was split, it would grip the spindle as well as the gear wheel. Otherwise the gear has to drive through the thread.

David