Who could have possibly imagined that using a datasheet and a CAD tool would be more accurate than eyeballing it?
Quick and encouraging update on last week's complaints about how hard Eurorack rails are to get right: using a template seems to have solved all my problems.
I created this template , grabbed some scrap wood to act as test rails, and marked and drilled the whole thing in fifteen minutes on the high dollar drill press at work and everything worked out great.
Learning from my mistakes, I used blanks with little tiny, minimal tolerance mounting holes to test instead of something more forgiving, and I tightened the plates into the rails before tightening the rails themselves to make sure they were properly perpendicular. And it all worked great. Next step is plugging the messed up holes in the case and re-doing it all. I'm cooking.
Also, just a brief note about my Gauche Electrosound blank. If you're not up on Gauche I suggest you check him out, there's 5U and 3U options in the catalog, and every bit of hardware he's got that I've touched has been unbelievably cool, flexible, and extremely well engineered. I've got the 3U static wavefolder in my case and use it on every single patch as a wavefolder sometimes and as a fun CV processor other times. I got to take Horse for a spin a few months back and it ruled. Saving up to scoop one of my very own.