ABOUT THC

Do i need external thc hardware with linux cnc ???
or inbuilt thc config can work ???

the external THC
is a part that handles the 5000V that the torch produces at firer up
and controls the 100-200V that is on the torch during cut

so YES for THC300 or Proma THC >>>>NOT THE SD Version

the internal thc handles the pin and the behaver

Before I order a mesa THC which version (0-10v or 0-300V) will I need for an old simple cut 40 machine


And is it possible to use this machine? With a new torch

300V version

pl7i92 wrote:

300V version

Thanks: I am sure you once mentioned how to get the source of the signal out of the machine could you please point me to that.

I can't see why you want to waste money on a new torch!

Just mount the THCAD300 inside the case, power it from 5 volts from your control box.
Alternatively, use the THCAD-10 and mount it in a metal case on the outside and put the necessary resistors 50:50 in wires from the electrodes. There was quote a discussion on this on the plasmac thread recently as both Phill and JTKnives have Hypertherm 30 amp machines with no CNC port.

Pretty sure thats a HF start machine so you will really need to pay attention to grounding. Separate wires back from every motor to a central star ground point on the machine and attach it to a ground stake. Also use an IEC mains power connector with built in EMI filter for your control box power.

yes this is a plasma hf and I would use 10, it seems to me that the mesa on hf machines recommends external resistors.

my plasma does not have hf, I have the thcad10 in this box where before I had an analogue thc made by me, never had disturbances, the output of the external divider is very similar I should have no problems, what do you say Rod?

I can't see why you want to waste money on a new torch!

I thought about repairing it but decide to get a new one £15 from China. I acquired the cut 40 for free.
.

Just mount the THCAD300 inside the case, power it from 5 volts from your control box.
Alternatively, use the THCAD-10 and mount it in a metal case on the outside and put the necessary resistors 50:50 in wires from the electrodes. There was quote a discussion on this on the plasmac thread recently as both Phill and JTKnives have Hypertherm 30 amp machines with no CNC port.

I am now confused re the 300 or 10 . Also why the 300 inside the case and the 10 on the outside !! I will try and find the post you are referring to.

Re the grounds: Yes although this is my first Plasma I have built several routers and conversions all with Mesa stuff .

Clive, the arc voltages are not very healthy (and probably lethal). If you have the 300 inside the case everything is contained and just a 5 volt power in and a 5 volt frequency out is all that is required.

But if you bring the wires outside it is a good idea to use a THCAD-10 and add the scaling resistors on the inside of the case so the voltage is no longer lethal in the outside world.

The other thing going for the THCAD-10 is that you can control the full scale reading so you might find with your machine you can get away with a 150 volt or 200 volt range so you have greater resolution in the decoded torch voltage.

There is a good document about grounding at Hypertherm if you can find it and another one done by Torchmate (a Lincoln brand). Both are required reading. The Hypertherm is a how to and the Lincoln one explains what EMI is all about and how to manage it.

@Billy, my THCAD-10 is in my control box and that has never been an issue with a blow back torch.

From what I can understand is that in a HF environment, keeping the THCAD close to the plasma reduces the chance of EMI as the frequency output is more immune than a simple divided (low) voltage signal.

At one stage, I purchased a cheap USB Oscilloscope which gave some interesting insights into noise. Most of it seemed to be coming in via the mains power. This was the single most effective noise reduction measure I implemented.
www.jaycar.com.au/iec-emi-power-line-filter-6-amp/p/MS4003

It took me a while to work up to following Hypertherm's earthing recommendations but it would be easy to do while building a machine... There would be details in my Spaceship thread.

insted of a handtorch use the P80 ist the most comen one chhep and very good spare parts good to handle
www.ebay.de/itm/P80-CNC-Brenner-Schneidb...er-Kopf/202340731120

about 50USD

There are 2 Connector versions be shure it fits your cable

THC300 cabeling and Config tread
forum.linuxcnc.org/49-basic-configuratio...fig-that-works#47531