Retractable top slide or cross slide?

[Ian Owen NZParticipant @ianowennz]

I am considering adding a retractable top slide or cross slide to a Taiwanese belt drive lathe I purchased.

Along with a couple of other additions.

The Taiwanese lathe were a bit “course” on the feed so I am considering changing the carriage feed to an electric motor feed instead of the geared feed, I’ve seen a couple of examples of that but neither had a “clutch” mechanism in the case of trouble.

A while ago I came across a write up about a reversing clutch for the leadscrew that was designed for the Warco BH600 lathe, from memory it was designed by Graham Meek. This would be a great addition for threading along with either the retracting top slide or a retracting cross slide.

The Hardinge HLV used the reversing leadscrew and a retracting top slide, while the Schaublin 125 used a retracting cross slide, and they both used electric motor feed for the carriage and cross slide feeds. I like the way the Shaublin drive was executed but need to determine how the “clutch” worked to see if I can duplicate it.

I know there are a set of plans for the Myford 7 retractable top slide, are there any plans for a retracting cross slide?

Where would one locate the drawings for the Warco BH600 reversing leadscrew?

Thanks

Ian

[Clive FosterParticipant @clivefoster55965]

I prefer the retracting cross slide as I use the “zero-2-zero” angular infeed method of screw cutting which is inherently suited to a retracting cross slide. Always felt teh retracting top slide idea was a bit cumbersome and somewhat limited.

Many ways of doing a retracting cross slide. Probably the simplest is the screw set threading stop clamped to the cross slide ways as per SouthBend and Boxford. Stop body sets how far back the slide comes on retraction, screw sets for far forward it goes for the cut. Obviously limited to jobs that can be done by putting the cut on via the top slide, hence “threading stop”, but its way simple.

I like the system fitted to my P&W Model B 12 x 30. Basically the cross slide dial and feed screw thrust bearings carrier connects to the slide proper via a short, very coarse, male thread. Turning the whole boss through 90° gives plenty of movement to clear any normal thread depth. Form memory approaching 1/4″. Bound to be two start thread. But it’s big lathe. Probably rather less movement would do on a smaller machine so a single start thread could work. In principle easily made. Needs some form of lock to hold the moving boss in the forward position for normal work.

The P&W also has provision for a threaded rod on the cross-slide to act as a forward travel stop using a pair of setting nuts. Essentially same idea as the SouthBend threading stop but operate over the full cross slide travel range. handy if you have number of components to do.

I’ll take some pictures tomorrow.

Clive

[BazyleParticipant @bazyle]

The drawings for the Meek design for the BH600 were on a website that looked like a plain text newsletter. A quick google found this pdf from 2012.
https://modelengineeringwebsite.com/Screw-cutting_clutch_3_files/Metric%20BH600%20.pdf

There is also a cross slide retraction design for a 12×24 style lathe somewhere on the web. As far as I remember it was similar to other designs with the saddle ‘fixed’ bearings put into a tube that could then be moved back by a lever.. Some Holbrooke lathes had this built in with, I think, a way of rotating the feedscrew back one turn and returning without losing its place.

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