Hi,
I just cut the first pieces with my new DIY CNC plasma today!!
It uses 3 steppers with chain drive for all axis. Z is a floating design with limit switch
for detecting zero at plate surface with G28.1 Z. Movement is 70cm x 70cm.
Torch is a PT-31 machine torch. Steppers are controlled with chinese 3-axis
TB6560 card - replaced 12V fan with 24V one and removed the "current
reduction when not moving" feature.
I initially had problems with RF interference from the Chinese CUT-40 HF-start
plasma, but I managed to solve the problem cheaply. I added a ground wire to
the copper electrode sticking out from the plasma torch - this way it creates always
a "pilot arc" (at full current) and initiates the cutting reliably without HF interference.
Without this it would not ignite reliably and would emit HF interference, causing
limit switches to trip, USB mouse at PC to stop working etc.. None of that now,
the immediate arc to groundwire will shunt the RFI, I'd say.. Based on some test
cuts, it works very nicely. I figured out that the electrode is touching ground through
the workpiece anyway, so it won't hurt connecting ground to the electrode always - and
this way it ignites reliably. It will also send a nice plasma flame to air if it is far away from plate!
I'll send some photos later. Now the main point is that this way one can use the
cheapest of the cheap Chinese CUT-XX plasmas for CNC, to save amateur costs!!
I haven't seen this anywhere else so I might have invented a new thing here!