9"hercus lathe ( southbend copy ) half nuts

hello everyone the half nuts on my 9"hercus lathe are worn out. I about to try and repair them. They look like a 3/4 acme thread.
Would that be right? A hercus is a direct copy of a 9" southbend lathe, did they use an amce or square thread on their leadscrew? Any information would be greatly appriciated kind Regards Twistdrill
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    While I don't have a South Bend to check, it is almost certainly an Acme thread, as half nuts will not close easily with square threads, and square threads are harder to cut.
    You might be able to find a supplier with NOS half nuts from a South Bend, an Hercus, or a Boxford (the UK maker which at one time made a clone of the South Bend (under license, I believe, during WWI.

    You have what I know, and what I can guess.
    Good Luck,         DoN.
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Hello Twistdrill,
If you want to take the easy way, the half nuts are probably still available from Hercus, at a price.
Another source is Mick Moyle's Engineering Supplies at 40 Edward St Summer Hill 2130, phone (02) 9799 8444. You can email them: snipped-for-privacy@moyles.com.au. Last time I was there they had a set of half nuts in stock.
I have no connection with the company except as an occasional customer.
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Regards, Chas.


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Twistdrill,
I have an electronic copy of Hercus's "Text Book of Turning" that I could send you, if you like. It's similar (but different enough to be very interesting) to South Bend's "How to Run A Lathe". It's a rather large file (56 pages) in .pdf format, so you'll have to make sure that your ISP will accept a file that large. If you want the book, send your e-mail address to davey(at)maine.rr.com and I'll send it right out (I'll also send a separate e-mail telling you it was sent so that if your ISP rejects the book that you know that I did make the attempt).
Dave Young
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thanks guys for the help, I had a real close look at the leadscrew and yes its an acme. I set about cutting bronze replacements using believe it or not the worn out half nuts. The lathe was not running, I made a handle to screw into the drive pulley and left the half nuts engaged and commenced screwcutting by hand.
Went a bit deeper and wider on the thread than I thought and when I finished it I fitted it to leadscrew, not to bad, still tight, I'll put a bit of lapping paste on it and lap it in on the far right hand side of leadscrew. this area won't be used.
I also priced a new set of half nuts from hercus and they are $A168.00 plus delivery. So Ii thought I would give it a go to make my own.
I'll keep you informed on how I progress kind regards Twistdrill
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