Myford S7 Half Nut

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Mike Ginn

Well-Known Member
HMEM Supporting Member
Mar 5, 2020
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After 40 years of owning several Myfords I have just managed to jam the cross slide (via the lead screw cover) against the gearbox. Fortunately I keep the V belt a little loose and the result was that the lathe stopped but the motor didn't stall. I can't see any obvious damage and the gears are all ok. I seem to have a little backlash in the half nut when engaged with the leadscrew but that might have been there for a long time.

It occurred to me that the weakest component is probably the die cast half nut and I thought I would check to see its availability. I couldn't find anyone on-line selling the half nut! I could find all manner of parts including name plates but no half nuts.

Does anyone know who sells these? My model is a S7B with power cross feed painted grey.

Alternatively has anyone made one from say bronze and used a tap to cut the thread? I am aware of epoxy/polyx type solutions but if I ever needed to replace the nut I would either buy one (if available) or make one from metal.

So does anyone know of a supply? What solutions have restorers used?


Can't you get them from Myford ? I think they were bought out by RGD Tools Ltd.
If not it should be an ideal project for 3D printing and investment casting which would be easier than machining from solid.
Hi Dan
I have tried all the on-line outfits including RG Tools with no luck. Unfortunately I have no experience of 3D printing or casting so machining would be my default. I have cut ACME lead screw threads and made my own taps in the past but in this case I would purchase a tap - if I can't locate a half nut supplier when I find the nut is needed.
I agree and was amazed that I couldn't locate it - as you say its the most likely item to wear. I do intend to make more phone calls and will keep you posted.

I have the same problem with my Enco. I wreckt the half nut a couple years ago while I was making 8tpi -- something that was actually a little too tough for the little Enco kiddy toy. I haven't bothered to even look for a new half nut as I now have the Grizz G4003G which doesn't have the problem of having a cheap half nut for kiddie sized threads. The Enco did NOT have LH thread ability. What crap.
Thanks Charles - thats excellent news. I have never been to the Midland show but with the cancellation of the London show (again) I might make the journey up the M1 to the show.
UPDATE - UPDATE Myford S7 Half Nut
I can confirm that normally stock lead screw half nuts but they are out of stonk until sometime (unspecified) next year due to supply issues (!). The cost is around £60 including tax for the pair. Please note that you are likely to need to persevere with the initial agent who will point you in the direction of Half Nuts as in Lock Nuts!. Melvin is the guy who knows what a half nut is. Since Myford still sells lathes (refurbished) half nuts are needed and I established the they will have the range - in my case 3/4 inch power cross feed half nut for a S7.

So I can wait and wont strip down the apron until I have the half nuts in my hand! Expensive - maybe, but the work involved in making one is immense and I wouldn't have access to the lathe in the process. A 3/4inch tap is around the same cost and there is no way I would be prepared to cut with a single point tool.

Hope this info is of use to someone.



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