Quote Originally Posted by BillTodd View Post
Are you assuming the plate you're cutting will be flat enough ? - I thought the whole point of steppers on the Z was to track any warp in the material ???
I'm not so sure about that, I plan on torch height control but I'm hoping I won't need it.

I suspect THC is for people who weld up their plasma table frame, realise it simply isn't square, then go searching for a solution. I've watched lots of movies of plasma cutters in operation and have yet to see the plate lift.

I think people use steppers for the Z so they can set pierce and initial cut height, THC merely requires up and down control which a DC motor does admirably. I set cut and pierce heights using a mechanical memory for plate thickness, it's one of my favorite bits, more on that later.

I also want to separate the torch positioning assembly from the plate support and water tray. I want to be able to lift the ways and gantry off the table without removing a single bolt. I plan a 4 point contact, one locator at each end of the two 30mm rails that form the Y axis. The location points are all adjustable in X, Y and Z so I can set everything square.

While I'm rambling about machine philosophy, I think a plasma table frame is there to support the slats which the metal rests on. If you lose sight of that you may be in trouble.