[jurban]

Hello,
I photographed the process of tapping into the trigger circuit for a Harbor Freight plasma cutter so that I could control it through my CNC router. The goal was to make the trigger non-permanent so that I could remove it from the CNC router and use it by hand. I then connected it to a relay board to isolate it from the controller. It works very well.

http://picasaweb.google.com/joseph.a...RouterControl#

Here is a video of the first test: [nomedia="http://www.youtube.com/watch?v=BueblmPQCOg"]YouTube- Torchmate + Harbor Freight Plasma Cutter Test[/nomedia]

Comments for improvements are appreciated.

--Joe

[engineeron]

thanks to all my friends on cnc

[Made of Metal]

I have a quick question about using a Harbor Freight plasma with a Torchmate 2x4 system. Does the air cooling on the torch interfere with the cutting sequence. If so, does anyone know how to disable the air cooling feature on a Harbor Freight plasma unit.
Any help or past experiences would be appreciated.

[winegar]

No need... I use my Harbor Freight plasma cutter on my cnc table and it works fine!.... http://www.cnczone.com/forums/plasma...4x4_table.html

[jeff johnson]

I am thinking of doing this and am grate full that you took the time to take photos. I see it was done back in 2010. Did everything work out ok and is it still?

[jurban]

Hi Jeff,
It has been working pretty well since I built it. I've continued to adapt the 2x2 Torchmate platform with a spindle, cutter and even a low powered laser for etching.

The plasma cutter has been decent, although not as consistent as I would like. For instance, I'm working on a piece right now and decided to make the holes slightly smaller so that I could ream them out with a drill because I can't be assured that the flame will consistently be directed directly down, thereby causing a bevel undercut. Even though I've cleaned out the nozzle parts and replaced all consumables, it still randomly changes direction on me. Also, I've still not mastered minimizing the dross. But, I have built a water table that does make it easier to adjust for it as it is continually cooling the metal.

I've also designed and built a holder for the plasma gun to mount it to the gantry. I could post the drawings if interested. It is all cut using the plasma cutter, and then welded. It's about a 2 hour project.

--Joe

[jeff johnson]

Thanks for the reply. I noticed in your Youtube video that your Z goes down and touches the metal then comes back up to a certain height before it turns on the torch. Is that programmable in Mach? I have a 4X8 router table and I am pretty familiar with Mach. Does Mach know when to start and stop the torch? Sorry for asking a lot but I am really interested in what you did.

[jurban]

Jeff,
I don't think you are viewing my machine. What you are (potentially) seeing is an AHVC, or Adjustable Height Voltage Controller. My system is static and does limit the capabilities and quality of the cuts. An AHVC will continually adjust the height of the nozzle as it goes through the cut. It also starts the cut by contacting the surface and rising to a set height. None of these are included in my machine as I manually set the height and do my best to keep the material level. I don't always succeed and sometimes have to quickly stop a job, re-position the material, and re-start it at the same point. If I don't it will start to drag the nozzle across the surface and pull the material with it.

I plan to start working on an open source AHVC project. But I'm at least a year away from starting given the inventory of projects ahead of me at the moment.

Mach 3 will have to know when to start and stop a torch. Typically it is an M-code (e.g. M53 turns it on and M54 turns it off). I use the Torchmate control software, so I'm only familiar with that. Your CAM software will typically have the ability to be configured to insert the correct M-code where required. The control software is typically where the delay is managed (e.g. Turn on torch for 1 second, then start cut). I hacked into the Torchmate controller box to output the trigger leads to a separate relay box. I was able to purchase the relay board and I use that to control the trigger of the HF plasma torch. This was all mounted in a metal box with terminals, plugs and fuses. This interface board allows me to keep the controller electronics far from the torch's high voltage and its interference. I am able to run 4 relays on this board, one of which I use to turn on an LED strip light under the gantry. I'm also planning to run a solenoid that turns on air for a high speed grinder. Any number of items could be controlled this way.
--Joe