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Archive for June 1st, 2011

Thing-O-Matic: Heart Gears FAIL

This one didn’t work out at all and, after a few attempts, I gave up:

Failed Heart Gears objects

Failed Heart Gears objects

It turns out that the myriad gear teeth curl up slightly as they cool. At some point, one of them will snag the nozzle and, even with good steppers in full effect, yank the XY stage to a dead stop. The missed steps cause that ledge a few millimeters up from the plate and, of course, the gears don’t mesh at all.

I watched it happen and stopped the print as soon as I could, but I didn’t catch exactly which tooth did the damage. Then I extracted just the bottom few layers by importing the STL into OpenSCAD, subtracting a block from the top, exporting what’s left as another STL, then built just that chunk.

Of course, that worked perfectly:

Heart Gears - curling gear teeth

Heart Gears - curling gear teeth

Printing each object separately should eliminate the problem: the nozzle would remain within the outline at all times and, with a smaller part, the plastic would stay bendy.

Maybe next year…

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