Saturday, June 12, 2010


Something I had trouble getting to grips with, was how small all the electronics are.

Even though the webspace is full of pictures similar to the one below, it's hard to realise just how small things are until you have it in your hand.

As you can see, I decided to go with the (as yet experimental) Arduino Mega, with Pololu stepper drivers. Some RepRap info on this setup can be found here and here.

I ordered the Arduinos and stepper motors from reprapsource in two batches.. both orders came without delay or hassle.

I put one of my Nema 23 motors in the picture for comparison. I honestly didn't realise that the Mega would be this small either... In fact I ordered an Arduino Nano (pictured below), so that I would have a small Arduino micro around for play and a special need... Had I realised just how small everything is, I'd not have bothered...

One of the things about the Pololu boards, is apparently they run hot.. I decided that I would make some heatsinks, as my steppers are rated for 1.5A. I am still at a loss as to how you can design a 5mm chip die that will do 2A.

Pictured below is my heatsink design. I simply sliced a strip of copper, and bent it over a 3mm thick bit of scrap metal. Pinched the sides with some ViceGrips, and tapped a flat on the bottom with a hammer. It looks big on the Arduino, but positively giant on the Pololu.

Not realizing that I could get the Pololu driver boards here in Europe (though I notice no one seems to be in stock), I ordered them directly from Pololu in The States. It took 13 days for the order to get to my door in The Netherlands, and I got dinged an extra 37 euros in customs/handling fees. (The order had other stuff in it, totaling $137 US.)

I also bought a Mega Shield from reprapsource to mount everything on as per johnnyr, but will buy a custom designed one if it becomes available before I'm ready to start mounting everything.

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