VN Acme size

Manderioli

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I am considering replacing my Y axis lead screw. I briefly measured the lead screw before leaving my shop and came up with 5/8-6. When researching the cost, I noticed there is also a 5/8-5 style. Does anyone know what Van Norman used?

The X axis lead screw measured 3/4-5.
 
Way to green to make a comment here, but I think the "dials" are 200 thou per revolution. I would assume it's 5 tpi. My knee is only 100 thou so I am assuming 10 tpi on that. I bet Cal knows the correct answer. Good luck and it would be awesome if you shared what you learn and some pictures.

John V


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You make a very going point about the dials for thousands per revolution. I will need to inspect mine as I’m sure that will relate to the tpi as you mentioned.
 
I'd be surprised if it's not either 5 or 10 tpi- anything else would be very unusual
 
Arrived at the shop tonight and found both X and Y axis have 0.200” per revolution.

My Y axis lead screw is 5/8-5” x 10” length and has a deviation of roughly 0.020” of tooth thickness. The middle is worn the most.

In the photos, you can see the acme nut holder for table with an adjuster for slop. When the adjuster is fine tuned for middle of lead screw, it will bind at the ends.

If I wanted to replace the acme lead, I do not want to machine an entire shaft with the various features ranging from fine thread jam nut, thrust plate, and keyway.

I think simplest way is to:
1) cut old lead screw off
2) bore hole in remaining shaft
3) order a 5/8-5 lead screw
4) turned one end to fit in bored hole
5) fix in place (tig weld would be easiest)
Any foreseeable problems with the above process?

BA66779C-889A-4F81-A88E-974AC47A4EE8.jpeg
 
Be sure to check for yourself but that looks like a left hand screw.
 
Yes you are correct, which makes the acme most costly.

McMaster only carries 3 and 6 foot lengths. MSCDirect costs more than McMaster. Any one know of a place that might carry 12”?
 
I can only add that in addition to the Tig Welding, begin with pinning the parts together. Looking forward to your updates!
 
I took your advice and pinned the assembly together. I did not weld the assembly as the 3/16" is sufficient.

I am now considering replacing the 3/4-5 X axis lead screw due to excessive play in the middle
 
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