Monday, August 1, 2011

Stepper Heat Sinks

I've been using some Pololu A4983 Stepper Motor Driver Carrier boards to run the stepper motors on my mill, but I noticed the other day that they are overheating and cutting out briefly, even with a small fan blowing on them. This isn't surprising, since I'm not running them with any sort of heat sink. As a test I held a bit of brass rod against the top of one of the chips and the glitching went away immediately.

To make some heat sinks I decided I would cut down a heat sink I pulled out of some salvage equipment. Probably a computer monitor. I stopped by the Makery to use the sawzall and scroll saw to chop it up into suitably sized bits, then returned home to finish them off.

I spent some time with the dremel to make a 5x5mm pad on the bottom of the heatsink. I just eyeballed it, but the micrometer says they are all within 0.15mm of the target size, except one, which was off by 0.5mm. Not bad for eyeballing.

I didn't have any thermal tape, which would be perfect for this, so I just put some thermal compound on it to be a weak adhesive. I'll just have to be careful with them for now. Once I have the machine running with this cobbled-together electronics setup I'll use it to make something to mount the parts more robustly.

Now they just have to sit around so the heatsink compound can set up a bit.
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