reprap

The week isn't complete without a lab fire

I made the last few connections on the 2nd printer last night, fired it up and did some test prints.

First discovery, those really tiny surface mount resistors can't handle a quarter watt. I didn't bother to calculate the power dissipation, after all it was just running a single LED. After it popped, smoked and caught fire (how exciting!) I ran the numbers:
18v, 2v drop on the LED, 1000 ohms resistor, that's 16ma. Perfect. 16ma @ 16v = 0.288 watts. OK, that's not so good on a resistor the size of a pinhead.

Anyway, I peeked underneath after becoming confident that the fire was out, determined it was just the LED resistor, and powered back up. I don't really need the LED, it's just pretty.

I did a test print, the nickel calibration piece. The first one was too small, I investigated and found that those are 10 tooth cogs I printed for the X and Y axis, not 12 tooth. Recalculated, fixed the firmware, printed again, it's fine.

Now my problem is that the filament is misfeeding. I think the problem is that my extruder is biting the filament far too hard and it's deforming the filament and dropping ABS shavings down into the hole and jamming things up. I'm going to get slightly longer screws to reduce the pressure on the extruder and see how that goes.
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