acourtjester wrote:3.5" EMT tube 0.080" thick
i noticed your using emt tube which is galvanized and gives off nasty poisonous fumes
if you have a good exhaust fan it may not be an issue
or you could go with exhaust tube, it's available up to 6''
if the slag on the inside is a problem for you...
we do mostly exhaust copes and holes in 2.5'' and 3'' stainless tube
the slag build up on the inside of the tube was unacceptable and made for bad slip joints
i setup an aquarium pump on one of the 120 volt outputs to run water from the table inside the tube
slag on the inside of the tube has been virtually eliminated
i add a m08 command in the g-code to turn the ''coolant'' pump on
you can see the water flowing before the torch starts in this video
https://www.youtube.com/watch?v=Ilc_ldF7eLE