Converting an old pen plotter into a PCB milling and pyrography device

Build Logs
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So, we have this old A3 pen plotter, a Roland DG DXY-800A. Old as the hills, pre-HPGL. Years ago (mid-90s), I remember driving the thing using QBasic. It did come with a “driver” of sorts, an old DOS program that could read early Autocad. The handbook was full of example code for various versions of BASIC (including Apple II BASIC).

I still have the unit, and some of the pens (new in packet). I’ve lost the manual for it, but a few years back I did find enough information about it to write this Perl script, which takes some rudimentary HPGL as input and spits out the equivalent draw and move commands. I had it working with Inkscape, parsing its HPGL.

I’ve since found a scanned copy of the DXY-880A manual, so there’s the other instructions covered, and detail on the DIP switches needed to use RS-232. Thus I don’t need a parallel port to drive this, I can use serial (even USB serial). An Arduino could probably bit-bang the parallel port anyway, it’s basically the IBM PC/XT printer interface which is 5V TTL.

The plotter has positioning accuracy to 0.1mm in theory, a shade under 4mil.

My thinking is this. There was a holder for a standard pen available years ago. This could probably be 3D-printed, and maybe make it take a Dalo pen for drawing PCB designs onto copper-clad fibreglass for conventional chemical etching.

If a suitably small high-speed motor could be found and cutting bit, then alternatively, this could directly mill out PCBs.

Furthermore, it may be viable to make a holder for some nichrome wire (maybe mould some bakelite?) to allow computer-controlled pyrography, basically automating the making of the signs that I’ve been doing by hand around the space lately. While the laser cutter is obviously going to do finer detail, the plotter should be faster and less idiosyncratic.

The brains are fine, and still work, so while I could make new drivers for the stepper motors and replace the brains driving them, there’s no need for that since I know how to drive it. It’ll be the mechanical side of things that’ll need working out.

This could be a useful electronics prototyping and artwork tool for the space if I can get it going, since the plotter fundamentally doesn’t care what’s underneath the pen (or even that it’s holding a pen).

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I’m still sore after someone decided to pull apart the multi-pen plotter I went to some effort to resurrect a few years back. Subtract one working plotter and replace it with a pile of junk parts :frowning:

In any case, I’d be really surprised if the mechanism in this would be strong enough to mill sideways without deflecting badly. It’s only designed to hold really light pens and move them about quickly. We’ve got enough stuff here we could build another XYZ table that could do a better job - especially since we pulled apart the Pandora.

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I agree with @pelrun. Leave the plotter as it is, as a plotter. Make it go with modern stuff so it can plot from all sorts of sources maybe?

In regards to the PCB CNC, the one in craftpunk should be able to do that nicely. It does need some TLC, though. If you want to I won’t object to having it rejiggered.

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The Pandora was that enormous 3D printer with a tiny (w.r.t build volume) print head, right?

There’s a good point regarding force, I seem to remember the unit travelling about 3cm/sec when plotting so it’s not what I’d call “swift”, however the stepper motors directly drive the mechanism. Undoubtedly a purpose-built machine would do a better job. My thinking was, okay, it might have to take multiple passes, but still should be possible to engrave/etch something. The Dalo pen technique sounds like the better option.

Interesting to hear of the fate of the previous plotter… wonder what the motive was.

Plotters for general CAD work aren’t all that attractive these days due to the fact inkjet and laser printers can usually outperform them for most tasks. This might be useful in craft punk though for plotting designs onto fabric or other things that can’t go through a printer.

Thinking early this morning, might be possible to interface this to a single board computer with the help of some shift registers (unless there are enough GPIOs already to bit-bang the parallel port) and voltage level translation.

Expanding that Perl script to do the rest of HPGL or perhaps implementing a Postscript to DXY translator might enable its use with CUPS, add networking and we could send plot jobs to it. There’s room on the underside where a Raspberry Pi or BeagleBone could fit to do this. That, along with some pen holders for various size pens would pretty well future-proof it.

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I suppose we can give it a look… what sort of TLC is required?