CNC Controller V.2

The bag of parts and the assembly instructions as received from HobbyCNC. I have been building electronic projects for over 50 years so this is no challenge except for the aging eyes. There are tools to overcome that problem (magnifiers) so that is not a real concern.

There are not a lot of components and the circuit board is absolutely great. The parts are small so some skill is required. Soldering boards may not be for everyone. The board is RoHS compliant. If that is important to you then you will need to use lead free solder to remain compliant. However, lead free solder is not required to assemble the board.

The assembled board without heat sinks. The driver chips have the heat sink surface facing the opposite direction from the original style board. I had to check this several times to make sure I was correct. The drivers chips can only be inserted one way, so no error possible here.

This is the bar of 0.500 x 1.250 aluminum. The "random length" is about 10.750 inches. The marks I made are every 2.250 inches. I placed them there only for reference when cutting, so the fat lines and accumulative error for the kerf waste are not a problem.

I set the stop on the saw at 2.250 inches and use that for the cutoff for each block. The lines just provide security that I haven't set up anything incorrectly. Cutting too short is worse than cutting too long... unless you run out of stock.

Here are the four base aluminum "billets". I love the sound of that word. It sounds so... so... massive and sturdy. "Yeah joe, I made those four heat sinks from aluminum billet. " Impressive, huh?

First action is to remove about 0.187" of aluminum with a 5/8" (0.625") end mill to create the offset for the heat sink to set over the driver chip.

The light reflection makes these tabs look ugly here, but they turned out very nice. A few light strokes with a file (see other pictures) and I had a perfectly smooth flat surface that will contact the sink area on the driver chips. The yellow pad is necessary to figure all the moves for cutting the fins.

This is a 3/16" (0.1875") end mill cutting the fin slots. This is straight forward machine work and there are a lot of slots to cut on both sides of the heat sink "billet". I touch zero on one side, then crank in the pre figured offset (from yellow pad) for each slot.

Now I can show the shape I was after. Each fin and the center bar is 0.125" thick.

Another view of the finished milling. Anyone with a manual milling machine can do this. If I was going into production I would write a CNC program to make all the moves for me.

I have drilled and tapped for 4-40 SS screws. I like stainless as there will be no corrosive interaction. At least that is my plan.

Capacitor C11 gave me a little problem. It is the only component that intrudes into the heat sink area. That was quickly fixed with a bit of machining on the second fin (in from right) to clear the capacitor.