THC (Torch Hight Controllers)

I’ve asked this question but never really get an answer.

What THCs are there in the market? I only really hear of Price THC, the Mesa THCAd-10 I believe it’s called, and the Promas.

I keep hearing that Proma 150 compact THC (which is what I have) is a cheap option. But all the ones I’ve heard of are about the same price. So there must be others. What are they and what are their advantages?

Using the THCAD-x allows use of THC native to the Plasmac interface. The Price and Promas are standalone if I'm not mistaken. In terms of cost, using the Mesa THCAD card and Plasmac for THC is quite less expensive than, say, the Price. I would argue it works much better as well.

Yes I haven’t heard many complaints about it. And I figured it’s quality was good, but when I was buying my hardware I wasn’t knowledgeable enough to realize that. I was too worried it was worse bc of its price. I don’t care for the price thc for some reason. I’ve never used it but I don’t like it.

What other THCs are there though? You also mentioned only the several I talked about

Aldenflorio wrote:

Yes I haven’t heard many complaints about it. And I figured it’s quality was good, but when I was buying my hardware I wasn’t knowledgeable enough to realize that. I was too worried it was worse bc of its price. I don’t care for the price thc for some reason. I’ve never used it but I don’t like it.

What other THCs are there though? You also mentioned only the several I talked about

You can make your own replacement for THCAD
if you can make or buy a good voltage divider.

@taloot Used esp32 for his Laser and made an open source THC
forum.linuxcnc.org/plasmac/39204-opensou...-laser-and-co2-laser

You can ask him for assistance, it will help you and others too.

Hypertherm do THC;'s but they are not for amateurs. I got a quote for a system and it started at $40,000AUD.

CandCNC do THC's as well but in my experience they are junk compared to the THCAD. I spent over $10,000 AUD on a CandCNC system and I scraped it for a Mesa 7i76e and a THCAD10.

Really nothing even comes close to the features and reliability that the THCAD offers.

Sometimes the most simple solutions are the best and most cost effective.

dvn4life1972 wrote:

]. I would argue it works much better as well.

I have over a years worth of heavy duty cutting experience with a Mesa 7i76e and and THCAD10 and they have never let me down. Day in day out they just work!

After my horror experience with CandCNC I would not trade my current setup for anything else!

I think its important to understand a few things here:
1. The traditional THC's like Proma exist becasue few CNC controllers can manage torch height control internally so must depend on external hardware. But its not possible to get full control over the process as its hard for the two systems to communicate in real time (1000 times a second).

2. The very best plasma controllers (like the AUD $40k Hypertherm system thefabricator03 mentioned ) manage torch height control internally so they can get superior results and full integration between voltage sensing and all seeing all knowing CNC motion controller. They don't need external THC's becasue they can do it all themselves.

3. If the Linuxcnc motion controller knows the torch voltage, it can control the torch height like the very best high end controllers costing AUD $40k. Its just that companies like Hypertherm have a bit of a head start in this area. We are learning what they already know and applying it to Linuxcnc.

4. Neither Linuxcnc or the THCAD are THC's. The THCAD provides a nice, neat, accurate and robust method of telling the linuxcnc motion controller what the torch voltage is. This allows the motion controller to manage the plasma cutting process.

5. With a THCAD in conjunction with Linuxcnc, the concept of a THC becomes obsolete. LinuxCNC becomes a full plasma aware motion controller.

So in answer to your question, the best upgrade you can do is to toss out your Proma THC and buy a THCAD. If you can afford to, also throw out any parallel port BOBS in use and replace with Mesa hardware. That way you are upgrading to a tightly integrated plasma controller.

Rods correct, the THCAD is not a Torch Height Controller. I had Tom from CandCNC mention that to me and I pointed out that its actually a non proprietary way to measure arc voltage in real time, which is a whole lot more useful than a THC.

As far as I am aware Tommylight wrote the original code to integrate the THCAD into LinuxCNC to be used to for plasma cutting and Phillc54 combined it into his PlasmaC configuration for LinuxCNC. Its their hard work that has made LinuxCNC a power house for CNC Plasma control.

thefabricator03 wrote:

As far as I am aware Tommylight wrote the original code to integrate the THCAD into LinuxCNC to be used to for plasma cutting and Phillc54 combined it into his PlasmaC configuration for LinuxCNC. Its their hard work that has made LinuxCNC a power house for CNC Plasma control.

I think the original THCAD integration was done by BigJohnT Thornton with THCAD.comp who also had a axis config. Early integrations replicated a THC within Linuxcnc with up/down signals like a Proma. RickG was another user back then.

Tommylight had an advanced config using parallel ports and the Proma 150 which was only available here on the forum.

With the introduction of External offsets that he developed, Dewey Garrett tried to develop a PID based component (hpid.comp). I spent a lot of time with Dewey trying to get this to work but it failed for reasons I don't understand. Then Skunkworks (Samco on Youtube) published a video of cutting corrugated iron using external offsets in another way. Grivajlp also did some good work and developed some python code to control the Hypertherm RS485. This was picked up by theIslander261 who got a working config. Then Phill announced "another plasma component". I think he based it on Tommylight's config and what he read in some technical documents from major players. He was like a sponge and quickly incorporated suggested features. I had been sharing the journey with theIslander. He adopted Plasmac and contributed a probing circuit and Phill incorporated features to suit his needs. I followed theIslander to Plasmac about 2 years ago. Somewhere along the way, theFabricator came on board and grivaljp contributed his RS485 code. Phill developed an Arduino RS485 emulator and worked with the Fabricator to perfect communications to Hypertherm machines.

Tommylight gave up on his beloved Proma config and joined the Plasmac movement using both the THCAD and Promas. I think the THCAD has won the battle there!

A few people contributed some work with post processors. PCW had an idea about ohmic sensing using his new THCAD-5 and offered a free THCAD if somebody could experiment with it. With a lot of handholding and numerous emails between PCW and myself, I wrote ohmic.comp as part of that project which Phill published to Master and V2.8 for me. This evolved into ohmic3.comp which is here on the forum for download which was developed to get more reliable probing on water tables as people had reported some problems with Hypertherm machines. Then along came the chief testpilot Snowgoer who pushed every button and ran every possible piece of gcode to see what he could break (starting with ohmic3.comp).

So in summary, there have been a lot of contributors to Phill's baby Plasmac. I think all of us should be thankful Phill's boss gave him a Hypertherm 30 amp plasma cutter as a retirement present a few years ago!