[little_sparky]

Hi everyone,

Will a L/F pilot starting plasma cutter work with a CNC machine? (Is it like a blowback start?)

Background info:
I am looking at making a CNC plasma cutter and know that a HF cutter won’t work but people use blowback style plasma cutters.

However in Australia the only plasma cutter I can find that isn’t HF start is a UNIMIG razorcut 45 which uses a “Pilot L/F” as a means of plasma arc starting.

My question is if this is like the blowback method used widely in CNC plasma cutters? The razorcut 80 uses the same staring method and has CNC connectivity which to me seems like it should work?

I will attach a PDF of machine.

Regards,
Little_sparky

[asuratman]

Hi,
You can add plasma arc sensor to start arc volt.

[Arzems]

Hi,
You can add plasma arc sensor to start arc volt.

Hi,
Is there any other name for plasma arc sensor
I can't find it;
Or if you gotta a link for it ..
That's great

[asuratman]

You can contact Andrew Shad with neuron cnc.

[Beefy]

I think you are being given some very incorrect info here.

The above mentioned "plasma arc sensor" appears to be just a current sensor. You run the ground lead through it and it detects the amount of current flowing.

So a current sensor cannot initiate the plasma arc, it just senses current once it's flowing. As can be seen on the PCB it has 3 terminals: +12v, GND, and Arc OK. Once a specific current level has been sensed (most likely adjustable on the PCB), the PCB outputs the Arc OK signal to let your CNC controller know the arc has been established. The PCB can in no way "start arc volts".

To start the arc, you normally have to give a signal input to the plasma cutter. That is normally done via an output from the breakout board, which is turn is controlled via the computer (CNC controller). The computer may be connected to an external motion controller board which in turn is connected to a breakout board.

The Unimig sounds like a non-contact pilot arc start (which is what you need), but I'd confirm with Unimig themselves or check with several distributors to make sure you are getting the same info from all of them.

In my Hypertherm the pilot arc start works something like this. Inside the nozzle, the electrode can move up and down. With no air flowing, the electrode is pushed into contact with the inside of the nozzle via spring pressure. When air flow starts the electrode is pushed back via the air pressure and as the electrode breaks contact with the inside of the nozzle, the pilot arc is struck, thereby ionising the high velocity air stream, which subsequently contacts the plate you are cutting. The plasma cutter senses the pilot arc has reached the metal (current in the ground lead), and then the main arc is established when the plasma cutter raises the current to the set level.

Hopefully with the above info you can make a more informed decision.

[asuratman]

For sure, you can ask neuron cnc. He got solution for plasma cutter without pilot arc. Before, I plan to make plasma table with this thing. But at this time I have no room, electricity and I already got oxy cnc table. So that I postpone to make it. Soon, I will make plasma table with the tool above to cut thin plate around 3-5 mm.

[rodw]

I'm also in Australia.. Unless you have the budget of $3-$4k for a Hypertherm, I would recommend the Everlast
PowerPlasma 50 PowerPlasma Plasma Cutters

The Unimig you are considereing is currently on special at Hare and Forbes but for $200 more you can have an Everlast that includes a CNC port and blowback torch.

I've had one of these and sold it recently to upgrade to a 3 phase Hypertherm 45XP as my circumstances have changed.

I Purchased a machine torch from Everlast but according to Rtech in the UK who rebadge the Everlast with their tables, they now suggest getting the Tecmo PM70 torch which apparently uses Hypertherm consumables.
http://www.tecmo.it/upld/repository/File/03.PH.pdf

I'm in Brisbane. Feel free to PM me if you want to know more.