Restoring a mill - Advice on Acme-threaded rod?

Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.

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Dave_S
Posts: 22
Joined: Mon Jan 06, 2003 3:44 pm
Location: Orange, CA

Restoring a mill - Advice on Acme-threaded rod?

Post by Dave_S »

I've got a 1961 Clausing 8520 mill I'm restoring. I bought new leadscrew table nuts from Clausing ($$$$$!!), but now I see my Y-axis leadscrew is worn badly. Knowing I'd have to mortgage my home for a new leadscrew from Clausing, I started looking for Acme-threaded rod on the Internet. Basically, I can make my own leadscrew pretty easy from a threaded rod, but I'm having trouble locating the following:

11/16" x 10 tpi Acme thread, L.H. in a 3-4 ft. length. Actually, I only need 12.5 ", but I figure I need enough material to screw up (pun intended) my first attempt. Most Acme threaded rods increment in 16ths up to 5/8", then jump to 3/4". I figure someone has to have 11/16" as a standard size.

Also, can someone explain about 'general purpose' rod versus 'precision' rod? Something about a 2G (g.p.) versus 2C (precision) thread fit. Also, are ground or rolled threads the way to go here (versus turned or die-cut?)

I'd sure appreciate any help you might offer.

Dave S.
GeorgeGaskill

If you're using the feed screw for measurement ...

Post by GeorgeGaskill »

(using the dials), you need the most accurate screw you can get. If you have a DRO for measurements, then anything close should work.
D_R
Posts: 297
Joined: Mon Feb 03, 2003 6:44 pm

Re: Restoring a mill - Advice on Acme-threaded rod?

Post by D_R »

Try Superior Thread Rolling in LA. My past experience with them has been good. Haven't talked with them for a few years though. 1-213-875-1200 is the last number I have for them.
Dave_S
Posts: 22
Joined: Mon Jan 06, 2003 3:44 pm
Location: Orange, CA

Re: Restoring a mill - Advice on Acme-threaded rod?

Post by Dave_S »

Thanks D_H.

Superior no longer sells Acme. I’ve been calling around everywhere (Ray Industries in WI, Dependable Acme in NY), but nobody sells 11/16”. I haven’t given up yet, but I may need to convert over to 3/4". In my estimation, this wouldn’t be too big a deal. I think there’s enough meat on my brand new brass table nut to tap with a ¾ x 10 acme. I’ll keep the remainder of the shaft identical, so it should accept existing bearings. I only need to ensure there’s sufficient headroom inside the knee and cross-slide for the larger diameter leadscrew. Anything else I should look out for? Opinions welcome
Mike_Henry
Posts: 373
Joined: Sat Jan 04, 2003 1:05 pm

Re: Restoring a mill - Advice on Acme-threaded rod?

Post by Mike_Henry »

You might try calling McMaster-Carr. They have nothing in 11/16" but might be able to source it for you.
Mike, near Chicago
Al_Messer
Posts: 2664
Joined: Sat Jan 04, 2003 7:12 pm
Location: Mid Tenn.

Re: Restoring a mill - Advice on Acme-threaded rod?

Post by Al_Messer »

Dave, if you have access to a lathe, why not make your own? When I was taking Machine Shop, I watched an older machinist that was restoring an old lathe that had an 8 foot bed and he spent nearly a month working two nights each week making a new Acme feed/lead screw as the original one had disappeared. Take it slow and easy and you should be able to do it O.K. Good luck on your restoration project!!
Al Messer

"One nation, under God"
Dave_S
Posts: 22
Joined: Mon Jan 06, 2003 3:44 pm
Location: Orange, CA

Re: Restoring a mill - Advice on Acme-threaded rod?

Post by Dave_S »

Thanks everyone for the input. I found 11/16" is just NOT available unless made custom. This leads me to my next post, called "Leadscrews - Rolled, Cut, or Ground?"
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