acme thread class C question

[aroundhere]

I posted this in the Industrial section, but didn't get any hits. My problem has deepened somewhat since yesterday. I need to machine a .50-8 acme (class C centralizing) into a part. The standard acme 8p insert can only machine a .8" min od. Has anyone machine something acme this size that would be used a lead screw/nut? Can you get a tap for something like this? Or get a tool ground or a custom tap?

I am designing a drive screw and nut for a new tool. I am familiar with standard acme threads, but after researching lead screws, they use a class C or centralizing acme. From reading the handbook, it seems that the major dia's are different than the class G acme. I cant find inserts for a class C in the few places I have searched. Has anyone machined or specified class C acme screws and nuts? If so, are there inserts or do you end up having to tweak the class G? I found the formulas where I can calculate the thread dims but I am more concerned about making it as simple as possible for my machinist which has never machined a class C. thanks for feedback

 

[mcgyvr]

Not really my area (but I see you aren't getting any help so far so..here I go).. but I'd assume those are rolled/ground not cut threads..
Also if this is just for a proto you can buy finished precision acme bar stock and associated nuts (anti-backlash,etc..) from many vendors (mcmaster carr/misumi,etc..) and just turn the ends you need.. And I'd assume for production you would just purchase from a house thats specializes in that rolled/ground precision acme stock.

 

[aroundhere]

I was going to buy the nut initially, but it was too short and the bronze temp rating was to 250F, where I need 350F. I may be forced to go with a .625-8p. Thought my biggest hurdle was going to be the class C Acme, but now it seems the small size and large pitch it a tough one. Im sure it will require custom tooling if that is even an option. thanks