Myford Mod

I'm sorry it's sideways (my phone is insisting that it be so!)

What does the hive mind think about my Super compound slide?

The indexing handle works as normal, albeit with horrendous backlash & not as smoothly as I'd like. When pushed forwards the small lever at the back advances the slide by precisely 1/8th of an inch & vice versa.

Knowing something of the history of my mistress I think that I know it's precise use but I'd like to hear your unpredudiced ideas before offering my own.

Edited By JasonB on 07/08/2020 06:54:27

Quick retract for screw-cutting as in GHT's Model Engineers Workshop Manual

It mirrors the lever on the Hardinge HLV-H so I tend to agree with Keith.

I agree with Keith

GHT describes this also in the the ME in the mid 1970's. I have to say I have considered this upgrade on my Myford S7 (a kit of material and gears is available).

However it is a bit concerning to hear you mention this backlash. I guess it is the gearing modification inside the housing of the topslide....introducing this backlash due to the modification is not something I would consider a good thing.

However GHT in my view designed some very good kit and I would think that the backlash seen, may be due to inaccurate build by the maker not a design fault, but I stand to be corrected...

Regards to all

Derek

I made one of those. My topslide backlash is no more than expected from the leadscrew and nut and not problematic.

As has been said it's George Thomas' screw cutting retractable topslide and normal operation is with the slide fully forwards. My main reason for the mod is it gives me a larger free movement micrometer dial which is lockable and the handle is shifted away from the tailstock giving more clearance. You will also not the little lever on the gib strip which locks the topslide.

To be pedantic, any play in the gearing merely shows on the micrometer but does not move the leadscrew so cannot be regarded as backlash in the usual sense of the term. Micrometer or gearing backlash is adjustable, as one of the gears is on an eccentric spindle. I suggest getting in touch with Kirk at Hemmingway Kits for a set of drawings and full description of operation. Alternatively it's in Georges book The Model Engineer Workshop Manual along with lots of other usefull items.

This modification also moves the topslide dial away from the tailstock body, I would consider it a very useful modification to a Myford and one is on my to do list, which despite lockdown and a lot more workshop time doesn’t seem to be getting any shorter. Don’t know if this a good or bad thing.

That's food for thought, a very useful insight.

TVM.

Andy

I too have made one, but in my case the drive is via a modified timing belt and not gearing, more complex to make but means it uses a standard leadscrew, thus keeping the rotation "normal".

Agree it moves the topslide away from the tailstock but the far more important use for me is in screwcutting, where it enable quick retraction of the cutter.

Quick retract for screwcutting and general use is more useful on the cross-slide and fitted as standard to some lathes like the Holbrook.

This is a good example except today their server is down so hopefully will be available again soon. Don't be put off by the type of lathe, as well as directly compatible with many of the larger import lathes the key thing is the principle which can be adapted for other machines.

Internal photograph for those who might be interested.

Edited By KWIL on 07/08/2020 11:51:05

GHT's rotation is normal too, but nice mod KWIL.

regards Martin

GHT's is normal rotation, but you have to make a LH Leadscrew!

It is clear from GHT's description that turning the LH leadscrew and nut was challenging; I think the Hemingway kit included these items.

The timing belt seems ideal - thanks for the photo - but was presumably not available in his day.

It does indeed.

regards Martin

I like the idea of the timing belt as it uses the standard leadscrew. Bought a Hemmingway kit years ago, but never built it due to other life issues and I had converted the lathe to metric, which meant making a 2mm pitch LH screw. This method removes that issue. Have both imperial and metric screws, the lathe is currrently set to imperial.

What size timing belt and pulleys did you use?

Thanks

Peter