Hello, this is my first post in this forum:)

I've just started in my new job which is setting up a new shop with a couple of lathes.
My question is how do I blunt my threads? We make mostly ACME threads.

I've read a thread about it in this forum earlier, but I could not really make out how to do it anyway:(

Any help would be appreciated.

Something about the Higby method rings a bell, but I can't remember it either.

I think in a production environment, a person would want a lathe with C axis and live tooling to mill the lead in thread.

In a job shop (to do a few parts), you could set up a die grinder in the toolpost with a carbide burr to do this task. The axis of the die grinder would be parallel with the lathe spindle axis, but the grinder would also be set with its centerline above center of the lathe.

The method I picture is to lock the spindle of the lathe, with the completed Acme thread in such an orientation that the skinny part of the thread is "up", and so that a tangential pass with the cross slide will move the carbide burr across the sharp part of the thread, and flatten it out.

If necessary to take repeated passes, I think one should be able to leave the die grinder at a set height (with the outside of the burr tangent to the minor diameter of the thread), and simply re-index the spindle a little bit to bring fresh material into the cut line.

Depending on the helix angle and possible interference of the burr with the good thread, you might need to swivel the compound rest to the helix angle of the thread to obtain clearance.

Does anyone know the Higby Method? Only 1 of our lathes has a C-axis.

Does anyone know the Higby Method? Only 1 of our lathes has a C-axis.

See: http://www.practicalmachinist.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=13;t=000074;p=0

Ken

what exactly is blunting a thread - removing a burr at the crest? ideas: turn lathe on and let a file with a safety edge ground on held at an appropriate burr removing angle work its way along the length, set a too up to take the smallest chamfer possible on an acme thread edge, if a V thread start with a small OD so it doesn't come out a sharp V, if you want to get fancy, grind a profile onto the thread cutter that puts a small radius on - no haven't bothered to try the last one :D. higby is handy but won't help with this one