6" X 10tpi Lh Acme Id Thread

[Newby2]

I have to machine a nut to fit a 6" machine shaft with a 10TPI left hand Acme thread.
Any thoughts? Thanks in advance.
Steve

[skmetal7]

i have a though: that's fricken huge!!


good luck!!

[dan dimock]

Man, I have try to come up with a way to help, but sorry, no help here.
Good luck.
Dan

[lerman]

It really depends on what type of equipment you have.

The usual way to cut threads is on a lathe. http://internaltool.com has appropriate tooling.

As an alternative, you should be able to cut them on a CNC milling machine with either a single point tool or a thread mill.

Ken

[Newby2]

For everyones information, this nut is used to retain the speed regulating wheel of a centerless grinder. The wheel diameter is about 12" diameter and is about 15" long.
I will be cutting this on a Jet 13" X 40" gear head lathe. I do have an ID thread kit that includes acme inserts.
Would one want to advance (or retract, depending on how you look at it) the tool at an angle, as with conventional threads, or advance the tool straight in?
Again, thanks!
Steve

[Geof]

With that size of lathe you may be better off advancing the tool at the thread half angle. Ten TPI acme at 6 inches diameter will give a good cutting load. What is the material? If it is something like 4140 you have a good challenge ahead of you.

[Newby2]

Geof, the material is 1045. Wouldn't advancing the tool at the half angle using a form insert result in a root diameter that is to wide?
Thanks
Steve

[Geof]

Originally Posted by Newby2 Geof, the material is 1045. Wouldn't advancing the tool at the half angle using a form insert result in a root diameter that is to wide? Thanks Steve

C1045 ugh, not much better than 4140.

Advancing at the half angle means the tool is cutting on the front and on one flank; the other flank of the tool is travelling parallel to the flank of the thread. Some people suggest going slightly less than half angle so this side takes a very slight skim cut producing a smoother surface.

[Newby2]

Geof...Just got off the phone with my Dad, (80 years old) and he said the same thing, slightly less than half the angle.
I'll give it a try Monday on a scrap piece. Thanks for your advice and will let you know how it turns out. (or in in this case!)
Steve

[Newby2]

The nut is done and installed with a fit and feel better than I expected. There were a couple of buggers on the threads of the shaft but a little lapping compound took care of that.
Thanks to Geof and my Dad. Boss is happy, I am happy, and all is well.
Steve