Hi,
what is it that you need the post to do?

Craig

Craig,
Basically it needs to turn the plasma torch on and off. Because there is a time delay with the plasma torch coming on,  there needs to be a G4 dwell of a couple seconds before any G1 moves.

In Mach3, the Plasma post processor initially  moves the torch up .5” before the first cut is made.  After a cut is made the torch Is again moved up a half inch as the torch  moves to the next cut position.

For what I’m doing currently, I don’t need THC, but I would think that needs to be built into the pose processor because most machines use THC 

The Mach4 post processor, liberty machine made for laser cutting does not work for plasma cutting because of the time it takes for the Torch to start up.

It might be easiest to develop a plasma pose processor, starting with the post processor that’s already there for Mach4 laser cutting and build a time delay G4 into it

Tweekie said Andy was working on this but I haven’t heard anything.

Thank you,
Chuck

Hi,
Ok you've made some points.

but I would think that needs to be built into the pose processor because most machines use THC

That's what I'm have said before THC is not, nor can it be anything to do with the post. Remember the post produces Gcode....but THC is not driven by Gcode, it's a realtime
voltage control loop, that is a realtime hardware control that if you like 'overrides' the Gcode file.

As for some of the rest:

Basically it needs to turn the plasma torch on and off. Because there is a time delay with the plasma torch coming on,  there needs to be a G4 dwell of a couple seconds before any G1 moves.

This is best handled by a macro. Call m101() for instance. Anytime m101() is encountered in the Gcode file the torch will turn on, with the required delay and NOT proceed with any
subsequent Gcode UNTIL the macro is complete.

In Mach3, the Plasma post processor initially  moves the torch up .5” before the first cut is made.  After a cut is made the torch Is again moved up a half inch as the torch  moves to the next cut position.

These too would be perfect candidates for macros, say m102() and m103().

Now you have three macros to control the behaviour of the torch now all you have to do is induce the post to insert in the Gcode file the macro calls at the required time.

There are a number of possibilities. One that I have used for defining a 'Safe location' in four axis toolpaths is called Pass Through. In Fusion/Manufacture/setup/ManualNC you'll find some
useful methods to insert code into a Gcode file, including Pass Through. All of these option can be automated.

I would suggest that you start by defining exactly the steps that you want the machine to take, for example the Torch Start sequence above. Code that sequence as a macro....then insert that macro
into the Gcode either manually or in automated fashion. There is no Gcode instruction to Start the Torch, so a post can't really do that, what it could do is insert a macro, which is just one line,
in this case m101, and you code what you want to happen in that macro.

Craig

Hi Craig, thanks for the detailed response.

I understand now what you were saying about the THC.

I have never messed around with macros, but It sounds like I need to learn how to do macros and along with the 288 page post processing guide you sent, create a post processor for Plasma.

I am really surprised that no one out there using Mach4 has not developed a  post processor for plasma cutting.

Thanks again for all your suggestions.
Chuck.

Hi,
if you look on page 6 of the Mach4PlasmaConfiguration PDF in Mach4Hobby/Docs you'll see that m3, conventionally means StratTheSpindle, but in the Plasma ScreenSet
it means StartTheTorch with the settings applied as stored in the registers, things like PierceDelay and TargetCutHeight.

It would appear that the m3 macro is already there and available.

Now all you have to do is have the post insert m3 to start the torch, and an m5 to stop it. Posts do that normally anyway, given that m3 means StartTheSpindle and m5 means StopTheSpindle.

I am really surprised that no one out there using Mach4 has not developed a  post processor for plasma cutting.

The Fusion Mach4 Post Processor is written by and maintained by Autodesk. Its covered by intellectual property law....it belongs to Autodesk. Autodesk encourage you to use it
and modify it to match your needs but at all times it remains Autodesk property. The post itself takes the underlying movement code, an Autodesk proprietary protocol, and then generates
the Gcode according to the post. Note that while the post is published the underlying protocol is not. If you wanted to write your own post then you would have to reverse engineer the Autodesk
protocol...and I would NOT expect Autodesk to help you, although I don't think reverse engineering it would be considered an infringement.

Have you seen the Plasma Tool Select screen of Fusion.
When you go to choose the tool for Manufacture, select Cutting rather than Milling and you'll see Waterjet, Laser and Plasma as options. May I suggest you experiment with those and see what sort of
code Fusion generates as is before you worry too much about modifying the post.

Craig

Hi,
digging around a bit more and I found this already in Fusion. You can modify it to suit your needs, but its already there, you have to take advantage
of what Autodesk has already loaded into Fusion.

Craig

Hi,
ask yourself whether its likely that Fusion cannot produce code for Plasma, Waterjet etc. This is a company worth hundreds, maybe billions of dollars
and sells hundreds of millions of dollars worth of software annually....do you suppose they would ignore things like Plasma, Waterjet and Laser? I rather think not.
That suggests that there is capacity to do things that you and I are unaware of but exist nonetheless.

It's probably worth a posting a request for information about Plasma (Cutting) specific features on the Fusion Forum. If there are features you can use, and I've already seen a couple
of them, and feel bound that there is more then someone will gladly tell you what they are and where you can find them.

Craig

Craig,
Yes, I have been using the different cutting manufacturing process in fusion.

I am able to define the Cutter paths for the Plasma Cutter and then when I go to post process those cutter paths, if I choose the Mach3 plasma post processor, everything works perfectly when running that G code on Mach3.

There is no Mach4 Plasma post processor, that I can find aware of and if I use the post processor for laser cutting, it does not have the time delay required for Plasma since Laser turn on time is instantaneous, so if I use the  laser post  processor for Plasma,  the cut doesn’t start for about two seconds after the command is given to the Plasma Cutter.

So the post processor for Plasma Cutting  for Mach4 would be very similar to the Mach4 Laser post processor except it needs a G4 dwell time of about two seconds before a G1, G2, or G3 command is requested.

Chuck
 

Hi,
I had no trouble generating a Plasma Toolpath but it fails when going to post. This usually means that some feature in the post is turned off.

This happened to me when I was trying to post four axis toolpaths. I had to go into the post and define the fourth axis, it was already there, I just had to turn it on
with the appropriate data. I suspect that this issue will be the same thing. That is to say you need to go into the Mach4 post and define certain things, in effect turn
the Plasma feature on.

This is a slam dunk for the Post Discussion board on the Fusion Forum. Ask there and you will get the info you need to turn on the required features.

Craig

Craig,
Relative to, “ I had no trouble generating a Plasma Toolpath but it fails when going to post. This usually means that some feature in the post is turned off.”

You say it failed when you went to post, what post processor did you choose?

If I post process to Mach3 plasma, it works fine.  So I am not dead in the water plasma cutting, but I would like to be able to do Plasma Cutter under Mach4.

I will take your advice and post this question to the other group you mentioned.

Thanks again for your help,
Chuck