So it's almost time to put together the drivetrain for Goose2, including the ~3 meter roller chain running from the drive wheel at the bottom up to the intermediate axle at the very top. And one thing I learned from Goose1 is that chain length calculators can't be trusted at that length. It will seem very snug if you assemble it horizontally, due to sag, but then be WAY too loose once tipped up vertically. The ceiling is too low to do that in the shop, so we only found out during final installation. Embarrassing.
I really wanted to do better this time around, and tonight I put together a system for doing just that. I needed a way to mount two sprockets ~3 meters apart, vertically. I also wanted that distance to be finely adjustable, so I can be empirical about the final axle spacing. Luckily, I already had something exactly like that -- the legs of the gantry crane! With these clamped at the top and bottom, and the crane extended to its max, I've got about 150 mm to spare.