indicating on threads?

[Cavalry]

Sometimes I have to cut a already threaded piece in the lathe(stepped threads usually) If its too big for a collet it makes it difficult to indicate in the chuck being there is no smooth surface. I have always just clamped a piece of sheet metal so its perpendicular to the ways and rubbing against the piece, then placed the indicator on top of the sheetmetal. Not perfect by any means but it gets it pretty close.
I am sure there is a better way?

[Setup boy]

I am not so sure I know what you trying to do but if I take your thread lead "indicating on threads" and go with it I am assuming that you are trying to find the center of a threaded hole. If that is the case I would find a shoulder bolt screw with the same size thread and run that down flush and indicate the body of that. If you don't have them find a dowel pin, drill rod or turn down some round stock and put that in the threaded hole and indicate that depending upon the depth of thread concerning rigidity. But from the description you gave of what you wanted to do I think I might have wasted five minutes of my life that I will never get back because I assumed. Uhhh....did this help?

[moe1942]

From your description I don't have a clue. Just describe what you want to do and I might be able to explain several ways to do it.

[Cavalry]

sorry boys...that was vague, even for me. 17hrs is too long a day for anyone. Hopefully its more coherent now

[moe1942]

For starters if you are chucking on the threads you are pissing into the wind. You will never accurately indicate the rod. I have to assume you are doing this in a four law. If so, a three jaw will provide accurate enough results on threaded rod.

A little trick I use so I don't clamp down on the threads: get two nuts of that size and make one narrow kerf cut across one flat on each. Thread on the rod so one nut is in the back and one in the front of the jaws. This will allow you to get a more accurate set up of threaded rod.

If you still are bent on indicating I will add more.

[Roundrocktom]

Cav -- photos help.

Moe -- you wouldn't have have an automatic screw mache for threading? I need about a 100 plugs. 14mm x 1.5m thread with two stepped ends.

Make 'em one at time out of 6061T6. Not bad when you get a rhythm going, but gets old after the first 10. Rough, finish, two steps, thread, part.... repeat. 3 jaw chuck, need to build a feedbar someday.

Tom

[Cuda]

Originally Posted by Cavalry

I am sure there is a better way?

If your trying to indicate on the O.D. of a thread then yes their is a better way, if the O.D. of the thread is running true to the thread, and it should be then you just use a wide flat indicator tip, it has to be exactly square to the work so the edge of the tip won't fall into the V of the thread, but it can get you within .001 easy. You can buy a tip set for AGD indicators for $10 or less that have many different type tips.