It is just about as hard as I expected it would be to get the rails lined up in a custom Eurorack case
On Saturday night me and my buddy spent a full 2-3 hours scratching our heads trying to figure out the best way to get rails lined up precisely. We settled on using an existing module I have assembled into a set of spare short rails. Perfect!
No, it was not perfect. Turns out there were just enough slop contributors in that method to hose us. Mainly, I shouldn't have used a module with forgiving mounting holes (I used a Mannequins Three Sisters) because we built that forgivingness into the holes we drilled and the Three Sisters fit great but my DIY Benjolin with itty-bitty-no-tolerance mounting holes doesn't fit even a little.
Hindsight is 20/20. What I should've done is make a template based on precise measurements of the rails. Simple. But also not so simple because annoyingly, the TS169 vector rail datasheet does not spec out the precise location of its middle mounting hole, and it's very much not dead center. And so I had some Monday-morning caliper time to figure out where those holes are. See the image below; the green line is where I'm trying to align my screw holes, and as you can see, that's offset from dead center in the rail.
After doing the same math over and over, converting from mm to mils to mm to mils, and generally just being trash at mechanical stuff, I think I've finally got myself a little template, which I generated as a blank PCB file in KiCAD because I have no idea how to use any other CAD tools.
If you find yourself in need of a drilling template for TS169 vector rails for a 7U Eurorack case, please help yourself to my cute little template. Little dots are where the drill needs to go through, the smaller hole is the diameter of the screw, and the bigger circle is the diameter of the 10-32 screw I'm using so I could verify spacing. The dotted lines give you a way of aligning to the top edge of the case so you get about one module face plate of depth when a module is installed in the case, just to ensure nothing is sitting too proud of the case.
My plan is to get two pieces of plywood, drill them with this template, and assemble. That will give me a chance to check the spacing before committing on the actual case, which I now have to plug and re-drill. Keep me in your thoughts in this trying time.