This is a Marchant "Silent Speed" ACR8D electromechanical calculator from the 1940s. It is currently jammed up, stuck on a division problem it never finished, and is apparently the most complicated mechanical calculator out there. Wish me luck!
Well this is disappointing. While trying to loosen up stuck mechanisms a few teeth broke off of an important gear. Guess this is now a parts machine.
@lwriemen Many 3D printers themselves use 3D-printed gears, so they at least can hold up to those stresses. In this case the teeth are small enough they might not hold up so well to constant stress against metal gears.