MPCNC: GCMC Spirograph Shakedown

The MPCNC instructions recommend running it for a while, taking it apart, then putting it back together, so all the parts have a chance to relax and get used to working together. To that end, I figured doing some full platform plots would run the rollers over the entire length of the rails:

MPCNC - Full-platform Spirograph - first pass
MPCNC – Full-platform Spirograph – first pass

I taped three B-size sheets together, with an A-size sheet in the far right corner, into a 29×19 inch sheet to put borders around the MPCNC’s 28×18 inch work area. The tape is on the top surface to prevent embarrassing accidents where the pen snags on an edge, at the cost of blurry lines where the ink doesn’t stick quite right.

The far left corner of the paper washes up on the tool length probe’s base, but the pen position turns out to be so repeatable (it should be!) you can swap them with gleeful abandon and get good results:

MPCNC - Full-platform Spirograph - multicolor
MPCNC – Full-platform Spirograph – multicolor

The pen rumbles along at 12000 mm/min = 200 mm/s = 7.8 inch/s with no hint of wobblulation. Most likely, those big loops aren’t particularly challenging, although watching the big central assembly whip around a tight curve can be startling.

I modified the pen holder for 3-point support, as the recess for the pen flange isn’t quite deep enough:

MPCNC - Pen holder - 3 point grip
MPCNC – Pen holder – 3 point grip

Good old masking tape holds the pens securely enough for now.

The glass plate I’d been using for B-size plots doesn’t cover the full area, but I’d set the Z axis limit switch to trip just before the bottom of the rails whacked into the glass. Extending the travel by 5 mm required a snippet of black tape:

MPCNC - Z axis switch - table limit
MPCNC – Z axis switch – table limit

The patterns come from a scratch-built Spirograph generator, because I wanted to review what’s new in GCMC. More on the software tomorrow …

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