Day: November 13, 2012

The alert reader will have noticed two slip faults in the jellyfish cookie cutter:

Look closely…

• Above the wide lip, to the right (+X)
• Below the top edge, to the front (-Y)

Those failures came from two separate cable snags that stalled the X and Y stepper motors for about 1 mm of travel. Fortunately, I wasn’t paying attention and, by the time I figured this out, the thing was nearly built, so I let it run to completion. The thick base plate accounts for most of the plastic, anyway.

First, the cable bundle on the right snagged on the socket-head cap screw just in front of the X axis limit switch (hidden behind the bundle here). This picture, taken after the +12 V pin in the HBP connector burned through, shows the typical snarl of wires inside a Thing-O-Matic:

The rewired thermistor cable snagged on the bulldog clip holding the top aluminum plate. This picture, taken after the thermistor pads fell off the HBP, shows the filler plate I put in place to prevent the cable (entering from the top and passing below the white cable on the HBP) from jamming in the gap between the Y axis stage and the case, but you can see how the bulldog clip handle could snag it when the platform moves rearward from the front left corner (+X +Y):

The fat gray cable flat against the case in that picture carries the X axis stepper drive signals up-and-over the Y axis. The thinner gray thermistor cable emerges from the electronics bay inside the case corner, then arches in from thetop.

My buddy Aitch recently gave me a few meters of corrugated wire loom, so I moved the bulldog clip rearward and bundled all those loose HBP wires in one tidy snood:

I’m sure something else will go wrong, but the machinery looks marginally less haphazard and the cables don’t snag while I’m watching…