Pen Plotting With Third Iteration Z-Axis

After third iteration of CNC Z-axis was installed, we wanted to perform a simple test. This particular assembly already had brackets to hold a spindle of some kind. We don’t know what it used to be, but measuring the hole we infer it was approximately 65mm in diameter. We didn’t have a suitable cutting tool on hand, so we reverted back to the old standby: testing it as a pen plotter.

We didn’t have any 65mm diameter pen, either, but we do have plenty of plastic bits in the form of failed and abandoned 3D prints. A few blocks were fished out of the bin and took up space so we could clamp a pen in the spindle holder. A pen could not reach the surface of the XY table, so a cardboard box and a few sheets of foam were used to raise the working surface. It’s not precise by any stretch of the imagination, but it’ll suffice for a pen plotting test.

The test plot was the ~25 minute variant of a Sawppy portrait. This file previously helped us determined UGS was not going to work in this particular configuration, and that bCNC worked better. Now we’ll feed this G-code throub bCNC to plot with the new Z-axis holding a pen.

Since the pen was clamped rigidly in the holder, and the work surface was crude with boxes and foam, the paper was not level. For one side of the sheet, the pen barely made enough contact to draw. On the opposite side, it dug deeply enough to start damaging the paper. But it did not tear, so we’re calling it unintentional embossing.

The results looked pretty good! It’s a good confidence booster before I return to more housekeeping tasks of building this machine.

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