When you’re coping a piece of round tubing to make a strong welded joint, you usually need a pretty expensive, dedicated tube-notching rig — or the willingness to eyeball it and hope for the best. Hal at MetalGeek.com offers the world a nice compromise: the Tube Coping Calculator. Just plug in a few details about the tubing that needs to be fitted, and the program generates a handy pdf template that shows you where to cut.
Print out the template and wrap it around the tubing, then cut along the line with a grinder or even a hacksaw to make a nice-fitting joint. The Tube Coping Calculator can make free templates for simple two-piece joints, for tubing from 10″ down to .1″. (If your joints are more complicated, they’ll ask you to pay for the software.)
The templates can be output in several different file formats including pdf, png, postscript, HPGL, and G code. Hal also links to a standalone DOS program that does a similar job, for when you don’t have access to the interwebs.
The Tube Coping Calculator [MetalGeek.com]