Plasma Attempt #2

[BillTodd]

A little Maxon rare earth motor with an epicyclic box raises and lowers the head (God bless ebay) with optical stops to set the cut and pierce heights.

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 ???

[Robin Hewitt]

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.