Documentation: order of operations for gear box assembly

[GarthSnyder]

I've had a really good experience with the docs so far. What a huge amount of work must have gone into this!

However, one thing has tripped me up not once but twice, in both cases costing 20 minutes or more of backtracking. It's probably an issue inherited from Sturdy Bunny or V1 of the ERCF manual, but the fact that a lot of people will be upgrading from V1 likely makes it more significant.

Page 45 helpfully advises, "Make sure the wires are routed in the channel between the 2020 extrusion and the Gear_Box_Back. If you route the wires through the other opening, you won’t be able to connect the wires later!"

The problem is that by the time you reach this instruction, the pass-through area has already been fully locked down. Unfortunately, it isn't large enough to accommodate any sort of connector, even a JST. If your cables have connectors on them, you have to de-construct all the way back to page 34. In particular, you have to release the set screws on the 20T pulley and remove the gear wheel from the D shaft, because there are screws that hold earlier parts together that can't be accessed through the gaps in the wheel.

As I said, I blundered into this problem twice. The second time, I was actively thinking "make sure to keep the cables routed properly so you don't run into that same problem again!" I had forgotten the details, though. The fact that several parts have cutouts for cables lulled me into a false sense of security. The actual pass-through is small, asymmetrical, and half lined with sharp-edged 2020 extrusion, so it doesn't really announce itself as the designated route.

It would be helpful to have a note at the top of page 34 that says something like, "Installing the Gear_Box_Back will finalize the path out of the gear box for ALL wiring in this half of the ERCF, including the wiring for the endstop switch, the gear motor, and any wiring that emerges from MicroFit connectors (if you use them). You can thread wires through the gap later, but there isn't enough room for crimped-on connectors. If your wiring is pre-crimped (e.g., you are upgrading from ERCF V1), make sure that ALL wiring goes through the cable channel NOW. If you do end up with a straggler cable, it's likely more time-efficient to cut off one end and recrimp than to disassemble the gear box."

[Miriax]

I merged in Ark's fixes that add more wiring clearance to the gearbox to help address this. This is as fixed as this issue will get until we redesign the gearbox.