CNC plasma cutter

#1

Thanks to @chrismhs I have been seriously considering making myself a CNC plasma cutter like this one

http://www.instructables.com/id/CNC-Plasma-Table/

I’m very happy with the electro-mechanical bits, less sure about the control bits. The Instructable calls for a PC with a parallel port, which I don’t have and which seems a bit old-fashioned.

I’m aware of lots of possibilities for controlling CNC machines, but has anyone any direct experience of this kind of thing?

Mostly looking to cost the project at the moment, so recommendations for controller boards much appreciated.

1 Like
#2

I got as far as the electronics on a desktop sized CNC using and Arduino + stepper motor hat although it could only power the smallest stepper motors IIRC and it didn’t run Mach3 (although any G-Code handler should work in theory?). The serial port is that the whole thing needs some kind of clock to ensure synchronicity between the drivers and software. The Arduino route basically means that the drivers and connected directly to the Arduino’s clock but if you go another way, you need to use a serial port to connect your PC’s clock to the drivers.

#3

Very old software used direct drive from the parallel port, there’s open source software for a pi to do it now

#4

For embedded systems, I normally use DN2800MT motherboards, which are extremely widely used and although Intel doesn’t make them any more, other manufacturers do (Mitac, Asrock). As they are designed for industrial systems, they have parallel port on a header (though I’ve never used it), and many other advantages: designed for fanless, Mini-ITX half-height (170 x 170 mm) with simple power etc, and I fit them with mSata solid-state storage. I have found them to be extremely reliable in industrial installations, without screens, and where it costs (sometimes a lot of) money to “press return to continue”. As yet, I’ve been unsuccessful in getting reliability out of Raspberry Pi in my industrial environments.

If it was me, I’d certainly consider something like this, however unfashionable. There’s a lot of latency-inducing stuff between the CPU and the pins in any USB-type solution, and of course multi-dimensional NC likes to keep a good lock-step. Worth asking Frank too, he’s done lots of NC.

Intel DN2800MTs on ebay are showing at about £60.

Just tuppence for your consideration.

All best,
J.

#5

My experience is: you don’t want to de-bug motion control on expensive and/or heavy mechanics!

#6

A YouTube channel I watch built their own (actually a conversion of a timber sheet machine). They have a special controller for the z-axis, which monitors the plasma voltage and keeps the head at the right height to maintain a consistent cut.

I’ll see if I can dig out the details

First test


Special z axis thing

#7

Still doing the rounds - the CNC demoed in the space a couple of weekends back used it on the manual control.

#8

It remains the lowest latency, most comprehensible way of outputing real logic

#9

what about buying one of these and strapping a plasma cutter to it:

#10

I think plasma needs the 3rd z axis too so it can control the arc and voltage

Courty

#11

#OffTopic

…just reminded me of…