Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Cartierusm on March 12, 2018, 09:57:00 PM
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Ok so I've got a CNC router I built decades ago, recently rebuilt it with a Pokerys57CNC and Mach 4 to bring it up to modern times. I need to plasma cut some parts and figured I'd slide a water table onto it and cut away!!!
I know nothing about CNC plasma cutting or very little. So questions...
1. Any advise about using a nice cnc router with a plasma cutter so I don't screw anything up? I plan on using a slide on water table to capture all the bad stuff.
2. Do I need to modify anything or can I use it as is? I assume I'd only need a THC if I were cutting all the time on it and/or warped or multi level parts.
3. I assume Mach 4 Plasma works like Mach Mill and just runs the machine with coordinates and all the other stuff like torch cut width compensation and so forth is all adjusted in the CAM program.
4. Normally I use RhinoCAD and RhinoCAM to generate my GCode. What do I use for plasma, cause I assume it has special settings for width of the plasma stream (don't cross the streams), etc... I know people use sheetcam, but is there anything I can do in my current CAD/CAM?
5. If I'm not using A THC is there a specific height I use for all materials that the torch should be from the workpiece?
6. I assume I can just turn on my plasma torch with it's existing CNC port and a relay hooked up to my Pokeys57CNC? Do I need to do anything to protect the electronics from the plasma system?
7. Last question! I hope. Feeds and Speeds for plasma, is there a chart then just tweak from there?
Thanks in advance. I can guess and research most of this, but I like the opinions of you people as you know best.
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Hi,
I assume I'd only need a THC if I were cutting all the time on it and/or warped or multi level parts.
No, thats not correct, THC is the single most important thing that you can do to make a plasma table work
properly. Does the 57CNC board support THC? Note that THC is rightly enacted by the motion controller not Mach,
the communication lag means Mach would be hopelessly behind the eight ball.
If I'm not using A THC is there a specific height I use for all materials that the torch should be from the workpiece?
A couple of mm is common UNTIL THC takes over and thereafter it will maintain whatever height to attain the cutting
voltage you set, 120-130V as a rule.
If you dont have THC then you set a height and hope.
Craig
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Ok, that's not hard. I've seen wiring diagrams I can just make a quick disconnect for the Z motor and the THC. Any inexpensive THCs you know of?
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Hi,
I repair welding equipment for a living including plasma tables, one of the big ones well over $100,000 second hand. I've seen a few cheap ones,
say $1000US but I've had to become pretty adept at fixing them too.
The cheapest and best THC solution I'm aware of is a motion controller which supports it. Vital Systems Hicon is the one that comes to mind. PoKeys are
very flexible and it may well be that they have THC support also.
The Hicon controller is $600 for the basic unit and probably add another $200 to get THC activated. $800 might sound expensive but in the realm of pro
THC controllers its as cheap as chips.
Craig
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thanks. I sent a message to Pokeys to see if THC is supported.
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1. Any advise about using a nice cnc router with a plasma cutter so I don't screw anything up? I plan on using a slide on water table to capture all the bad stuff.
One thing for sure - it will not be a nice router for long once you start plasma cutting :)
Don't forget fume extract - downdraught or water table will be needed, its not optional really.
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Thanks. I won't be doing much on it and as I said in the first post I'll be using a water table that I slide on.
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Pokeys support, which is great BTW, says that Mach 4 currently doesn't support THC, but NFS is working on it and Pokeys is working on implementing the plugin for that Mach update.
So if Mach 4 doesn't support THC, does Mach 3? Cause I have a mach 3 license from when I switched everything over to Mach 4 and I have a C10 BOB that I could use.
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Mach3 supports THC movements of the Z axis, you need a THC controller like a Proma or higher.
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Hi,
thats not quite correct, THC is a controller function not a Mach function. Mach may not have screens etc set up
but that does not prevent a controller from enacting THC.
Look at Vital Systems Hicon, it has THC with the appropriate screens for pierce height, anti dive parameters etc.
Almost all controllers support Mach3 THC functionality. That wide support is still developing with manufacturers
of Mach4 boards. Sounds like PoKeys is not there yet.
Craig
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A friend uses his router table to do plasma work in his house basement / workshop. He
replaces a spoil board section with a water pan, which has a drain, uses decking boards with
evenly spaced nails sticking up to support the work. He uses an axial fan which attaches to a make
shift hood above the table and table and simple pull down clear shades to keep debri and fumes
inside the curtain area ( the router table is not ruined form plasma use) and draw out
exhaust fumes to outside.
He uses a macro to touch and fire the torch which is done using a macro.
So the macro provides probing, removes floating head travel and sets the Z height, and
acivates a output from Mach3 to fire the torch.
Controller is located close / under the table, the plasma machine about 4 feet away from the
table with the computer about 8 feet away from both the table and plasma machine. Has no
problems with fumes, sparks, electronics interference, etc.
You can use LazyCam to generate good gcode but to use the Plasma module you will need
a pro license. In use you import dxf and use the mill module as normal but prior to posting use
the plasma module as that has imputs for torch specifics. I didn't put a plasma module use section in the manual.
So he has both worlds and frankly for min investment realy dose nice work with both machines.
It is a stepper system. You don't need to spend a fortune to do things sometimes. I must note that he
was a professional welder and knows how to set up a plasma machine to work correctly and
that in itself is half the battle to do good cutting with it.
Personaly don't use a plasma machine but thought this info would be of value.
RICH
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Rich, thanks, that's helpful. It made me ask some questions.
What does a CAM software or Post Processor do for plasma? I figure it creates a lead in and lead out and offsets the cut for the width of the plasma stream as well. Anything else?
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Another question, all the designs i'm looking at have a 'touch n' go' system where the torch is hooked up to a floating slide attached to the Z axis. I understand how to build this and how it works, but I don't understand the execution.
I understand it lowers the torch until it hits something and the floating Z keeps it from damaging anything then it backs off until it hits a limit switch. So electronically what's happening? I mean does it use the tip of the plasma torch as it would an electronic touch sensor? And it always backs up to the limit switch, the switch doesn't change based on thickness of material. Kind of confused on how the electronics know all the distances, distance of the torch to the material and why it's hitting a limit switch?
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if you Google for: plasma floating head
you will get a lot of Information, how a Floating head works.