[nowwhat]

I am cutting a 2 3/4"-6 acme thread on a hyundai hit 30s lathe and need to know how to blunt the first and last thread at 45 deg. from root to crest.

[tim-tbl]

I don't think you can, but someone may know better.

[JPMach]

It's called a Higby cut I believe. Somewhere on this forum was described how to do it with a grooving tool. Use the search and try Higby thread or something like that.
It's commonly used on fire hydrant fittings.

JP

[nowwhat]

Thanks, I'll do the search.

[JPMach]

I was wrong it is spelled Higbee cut and it wasn't this forum it was another, here is the link.

http://www.practicalmachinist.com/cg...3;t=000074;p=0

JP

[nowwhat]

Thanks a bunch, I will need that!