Grant Erwin wrote:

I have a 4" tube which I want to scribe lines on. The two lines will be
parallel to the tube axis and should be exactly 180 degrees apart, i.e.
on the opposite sides of the tube.

I know how to draw one line down a tube, but I am looking for a good trick
to locate the other line.

Ideas?

Grant

Got it, thanks. I was mitering a 45 degree cut, then rotating one piece
to make a 90 degree bend. All done, looks OK too (it's just for a barbecue).

Grant