Leo Lichtman wrote:
"Don Foreman" wrote: Clamp tube to bench. Set height gage for 1/2 tube
dia. Scribe both

sides of tube.

^^^^^^^^^^^^^^^^^^^^^^
Or: Measure tube circumference accurately. Set mark half-way around. To
check accuracy, do it again the other way 'round. If the two marks do not
agree, go half way between them.

You could check accuracy on Don's method by turning the tube over, just in
case your height gauge setting isn't spot on.




Place two tubes side by side and secure together - duct tape works ok.

Use a big magic marker to color in a fat line down the length of the tube.

Slide a hard straight edge down the length to scrape off a narrow
straight line.

Rool 'em over.

Do it again.