The Voron 2.4 has a “CoreXY” drive system, meaning instead of having one axis’s stepper on a gantry moved by another axis’s stepper, it has two steppers in the back corners connecting across the Y rails and the X gantry to the printhead with a complicated routing of two belts, to reduce mass of the gantry and facilitate higher acceleration. Turning a single stepper would move the gantry diagonally; so the two steppers work together to perform Cartesian moves and are called A and B instead of X and Y.
The instructions have you insert these two M5 machine screws as well as three M3 machine screws before building the A and B blocks’ idler pulley stacks; but there is no earthly reason to insert the M3 screws until after you’ve built and secured the idler stacks and you’re ready to attach the steppers, so just don’t.
The instructions omit that the steppers need to be installed with their cable connectors in this orientation 20220601 edit — with their cable connectors facing toward the center of the back plane of the printer.
The instructions again tell you to put the pulleys on the motors with threadlocker as the first step of assembling this stage, before assembling the blocks and installing the motors onto them. No. Again, no. It’s only a wee bit inconvenient to wait until the motors are affixed to the blocks before installing the pulleys, and it allows you to align the drive pulleys to be planar with their idlers, which seems important.
One timing pulley is installed teeth up, the other teeth down, corresponding with the position of the single idler pulley on each block.
If you want to criticize the print quality and fit of my Voron parts, you could rightly do that … or you could reflect on the fact that what I’m doing here is assembling a new, better 3D printer.