Stepper Motor Driver #1

The first part I constructed was a stepper motor driver. This is a board that controls one stepper motor (there are three stepper motors in the printer). It converts the power to the appropriate voltage and current, and translates the signal from the motherboard into a signal that a stepper motor can understand. As you will see in the pictures, it contains two ethernet (RJ45) jacks. This doesn’t mean the board understands ethernet signal; it is utilizing the ethernet cable because it is more convenient and organized than soldering a bunch of wires individually. The makerbot electronic components all communicate with each other using ethernet cables.

I soldered the first stepper motor driver together. It came like this:

stepper driver unassembled

tiny components

There are a whole bunch of tiny components, which are too small to be soldered using a regular soldering iron. Instead, I used a method called hot plate reflow. A solder paste is first applied to the bare pcb board; it is a thick gray paste which, when heated sufficiently, turns into hard metal. After the paste is applied, tweezers are used to place all the components in the right places.

The board, components in place, goes on a hot plate. Since the solder melts at a lower temperature than the board itself, the hot plate doesn’t damage the board. When the melting point of the solder is reached, it all pops and becomes hard metal, effectively soldering all of the components into place.

hot plate in action

The larger components required a typical soldering iron. Finished:

stepper motor driver #1, complete

Unfortunately the solder paste I used wasn’t the greatest, so I am waiting on some higher quality stuff in the mail. I ran some power through the stepper driver and the appropriate LED lit up, but it remains to be seen whether it is fully functional or not. Fingers crossed…


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