Hi Mike

Another place worth a Try is the tap and die company

http://www.tapdie.com 0208 888 1865

He is a helpful chap

Best Wishes Martin

You certainly can clean up with a suitably profiled boring tool. Don't worry about trying to get the width at the bottom dead right. Concetrate on the flank angles and make the tool come out bit narrow. Set up for 10 tpi with your topslide parallel to the lathe bed so you can adjust the tool to trim one side at a time.

Standard machine tool makers practice back in the day to get minimal backlash nuts. Friend John used to do such for CVA.

Clive

Clive, youre going back a bit – CVA? what, in Portland Road, Hove? My Father worked there during part of the last war until he was head-hunted by the Army to be a civil servant at Preston Barracks, Brighton! CVA site flattened since I was a kid and SEEBOARD had offices built there. EDF now occupy site.

Mike, I did a silly trick once, my chucks wouldnt go on mandrel smoothly so I pushed a bit harder and got one jammed on. Got it off and decided to give mandrel thread minute inspection and found a tiny rough, scabby appearance in one place – squashed swarf. Cure was an old – fashioned thread chaser, 12TPI for Myford, set lathe going in lowest backgear speed and very carefully ran chaser along thread, scraping off the swarf. Worked a treat! Moral; if it dont go, dont force it! Anyway, reason for relating this is so you can see there is another method of thread cleaning. Good luck with your prob.

John

Loosenut, all "normal" thread forms are triangular but vary by included angle. Acme threads take the form of, for the sake of argument, a square thread with sloping sides, the included angle being a mere 29 degrees. Hope this explains it for the uninitiated.

Rick