Friday, August 19, 2005


3-Axis motorisation complete

We've wired up all 3 axes of the carriage and got them under control of PIC microcontrollers. The turntable is not yet callibrated, but the linear axis (X) and vertical axis (Z) do self-calibrate on power-up.

Weedy little stepper motors from floppy drives did not have enough power to directly drive the vertical screw. Nor did a larger motor liberated from an old Brother printer. But 3:1 reduction gearing did the trick, as you can see in this photo. The vertical drive stepper is at the bottom of the carriage assembly:

The existing control circuitry is starting to look a little complex, though all we have to add is the driver for the extruder and the thermal control for the nozzle heater:

The illuminated LED lower left indicates that the vertical motion has hit the upper limit sensor. There is a manual override for vertical adjustment, unclogging nozzles etc. The 4 LED cluster is for checking stepper drivers. The drivers are the ones with axis-labelled cables next to them.

The RS232 still needs connecting. But we also need a nozzle and NZ has run out of cheap glue guns. Our attempts to use a thermistor as a current limiter failed, with the heater taking 4A and burning the PTFE insulation - bad thing. Evacuate lab immediately and ventilate.

We're getting close; I can smell it. Or is that more burning insulation...

Vik :v)

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