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Author Topic: How does m code control plasma?  (Read 5364 times)

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How does m code control plasma?
« on: January 05, 2015, 08:36:39 PM »
HI

I am trying to figure out how to connect up my mach3/smoothstepper/homann breakout/diy cnc table to my hypertherm45 plasma cutter.
At the moment I am only trying to fire the plasma cutter from g-code.

I can't figure out how it is done. It seems that people just use M3 and M5, but on my setup, that will only turn on my router which won't turn off till the job is done.

Do people edit these codes or something?

Thanks
Dazza000

Offline BR549

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Re: How does m code control plasma?
« Reply #1 on: January 05, 2015, 10:12:21 PM »
Normally you would setup 2 different profiles for Mach3 to work with each configuration Router/Plasma.

In Router setup M3/5 to run the spindle and in Plasma setup M3/5 to turn on/off the plasma unit.

(;-) TP
Re: How does m code control plasma?
« Reply #2 on: January 05, 2015, 10:47:46 PM »
eek! does this mean that I have to go through the whole table setup again just to set up a plasma config? Is there an easier way?
thanks
dazzaxyz
Re: How does m code control plasma?
« Reply #3 on: January 19, 2015, 06:02:46 PM »
Why don't you just copy your profile and rename the copy "Plasma"? All you should have to do then is change M3 and M5.
Re: How does m code control plasma?
« Reply #4 on: January 19, 2015, 10:19:03 PM »
You need to let your CAM software take care of the M3's and M5's (plasma on and plasma off).

Mach3 needs to turn the plasma on using the spindle on output, which you'll have to find on your breakout board and use the spindle relay contacts.

Your hypertherm plasma unit has a contact that closes when the arc comes on, the "arc established"  contact thatshould be connected as an input to Mach3.

To light the plasma, Mach3 should send a plasma on command to close the spindle contacts, and then the program should go into feedhold until the arc established input is true, at which point motion starts.
How do I do this in mach3?
Re: How does m code control plasma?
« Reply #5 on: January 20, 2015, 12:51:32 AM »
Hmmmm, the m3 command is definitely firing the torch, but Mach3 doesn't go into "feedhold". It just continues on regardless of a proper pierce or not.

1 torch comes down.
2 torch fires
3 a short delay i think allowing piercing
4 torch (still firing) cuts path.
5 torch stops firing at finish of path
6 torch raised

but I don't seem to have the handshaking right.
Re: How does m code control plasma?
« Reply #6 on: January 20, 2015, 07:15:36 PM »
Relying on a timer for plasma ignition is only ok if your plasma unit has a consistent preflow time and reliable ignition. (some plasma units have a short preflow time if the postflow is still on, this messes up timed starts at your cnc).
The best way is to hold machine motion until the plasma lights. Most plasma units have an arc on output (contacts).

In your case, I suspect they're not connected, you would have had to use an input pin and a macro
Sorry I can't help more, since I'm new to mach3, and don't have a plasma cutter, but I'm sure this has been done before. I would also like to implement a plasma interface, I see the thc controls, is there any documentation out there that descibes their use and implementation? I can't find any.










Offline BLM

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Re: How does m code control plasma?
« Reply #7 on: January 20, 2015, 08:21:32 PM »
If you have the arc-ok signal connected to Mach3 it should hold for that signal to activate before motion. It will only hold for arc-ok if the THC is turned on in Mach.