The joy of jigs

SPIDriver's pledge rewards will ship soon, and the premium package includes two interface boards that make hookups a bit neater. When I launched the SPIDriver campaign, I expected to be making a couple of dozen of these boards, tops. I was wrong. We need about 350 of them, and all will be hand assembled here. This is quite feasible -- it's just scaling up the time and materials. But the volume makes it worthwhile to make a little more effort upfront on tooling.


This is a through-hole board with connectors only. There are no components. The soldering is relatively straightforward. The hard part is holding all the parts in place during soldering. In particular the pin headers all need to be held straight.

This calls for a jig, which is a stand to hold all the parts in place while they're being soldered into position. I'm using acrylic sheet for this. It's cheap and rigid, and laser cuts really nicely. Here's the jig, made from a glued stack of laser-cut acrylic pieces.


While it doesn't look very impressive, it makes assembly fast and consistent. The acrylic is custom-cut to hold each part exactly. There is very little play in any of the cutout slots.

I'm particularly pleased with the top layer, which holds the 3- and 6-pin headers in place. Here's the SVG design for it, and the laser cut sheet:


This is it attached to the jig - ready to accept the 3-pin and 6-pin headers.
The brass pins lie in the shallow grooves, holding them straight during soldering.


Here is the complete assembly process. This is sped up - in real life it takes me about 30 seconds. The younger fingers of the assembly people will likely be much faster.