Hello,

I am rehousing a webcam for use in astronomy and I turned down on my
minilathe a simple adapter tube out of aluminum to fit the standard
1.25" diam eyepiece holder.
I now have to turn an inside thread to hold
a standard filter. The filter requires a 1.125" x 40tpi thread. I am
trying to grind my own highspeed steel tool and having some difficulty
getting the threads to look right. They are there but look flattened.
Does someone have a dimension or procedure for grinding such a
tool to work with aluminum? Would the same tool work for delrin? I
have searched the web many times and I can turn up very little on this
subject.

Please advise,

Vince Coppola