View Full Version : thc300 help

08-24-2010, 09:59 PM
Hi all,

I have a thc300 torch height controller that i cant get to work properly.

Everything appears to work correctly but the THC will not make z-movement corrections with the THC enabled (thc Lite flashing). All the mach3 leds (up, down, ark ok) appear to lite up when required, except the torch active led. The "torch active" led does not lite up under any condition. Also the thc correction dro never changes from 0.000 While the torch is cutting material, the led display shows a dc voltage that seems appropriate to the torch to material distance. This value changes as the torch to material distance changes.

I am using a smooth stepper and a pmdx-131 break out board for interface , Sheetcam with the THC-300 post processor to generate my code. The torch offest portion of the code appears to work, but not the correction.

Does anyone know why my z-axis correct Huh?

Any help is greatly appreciated


08-28-2010, 05:19 PM
Part of the problem is the Smooth Stepper and THC300 (or any MACH THC for that matter) will not work right together. Too much delay on the inputs to form the closed loop that the THC needs with the Z axis.

If the UP and DOWN LED's in MACH are working and you have ARC OK then the only thing left is you don't have a licensed copy of MACH and/or the THC logic is not turned on. THC logic is disabled in the demo version. I don't know if it will work without the parallel port driver active, even IF you have a licensed copy..

You probably needed to discuss with your THC300 vendor how you intended to use it. It would have saved you a lot of frustration and about $150.00. I get several e-mails a month asking about using our THC's with the SS and I always respond with "it won't work".

TOM caudle

09-01-2010, 10:45 AM
As I understand it the parallel port driver is needed (for reasons presumably best known to Art) to actually control the Z axis for both THC and Probe. I came accross this when experimenting with Mach's emulating feature on a machine without the PP driver. Although (as you've found) the LEDs light up nothing else happens as it should. Add in the PP driver and all is well.

As Hood explained on the Mach forum - there are no plans to "fix" the smoothstepper in this regard and to be honest I'm not sure how it could be fixed unless the smoothstepper was given direct control of Z because as Tom has implied - there is no "tight" synchronization between the smoothstepper and Mach - there can't be by the very nature of USB. You asked on the Mach forum if you could run the PP driver AND the smoothstepper - no-one answered but FWIW personally I doubt it. One way to find out though.