Re: THC Torch Height Control any thoughts??

--- In CAD_CAM_EDM_DRO@y..., "forreal_77" <forreal@a...> wrote:

> I have looked at the rutex.com site...does anyone know if this

works?

>

There are, in theory, two main issues with a THC design. The first
is that while most Plasma units maintain a somewhat constant current
for a cut, the voltage will vary based on the "gap" and the thickness
of material being cut. If you take a portion of the output voltage,
compare that against a reference voltage and use that to power a
motor you have a closed loop servo. By setting the reference voltage
to a level that compensates for the material and the desired gap then
you should be able to maintain a constant spacing.

The second issue is the beginning arc or "piercing cut". You have to
move the head closer start the arc then wait (pause ) for punch
through. I had planned on building my own THC until I saw the Rutex
unit (kit). For less than $500 you can build up their electronics
and use a simple DC motor for the position motor. I plan on buyint
their unit. Based on the quality of their Servo Motor boards that I
bought to control two 1/2hp 130DC PWM DC Motors, I fell confident
they know what they are doing. Their unit solves both of the issues.

This does not constitute a "crash control" sensor that will preceed
the torch head and stop the machine in the event of severe material
curl or warping. One could be added to the mix as a separate device.