Attempting to Cut BaneBot 56mm Shaft

Does anybody know the material of the shaft in the BaneBots 56 mm gearbox? And has anybody tried cutting/truncating it and have any tips. We have a small Smithy mill that we can use, but don’t know if this is the best way to cut it.

The shaft is steel. BaneBots has been monitoring these boards lately so maybe someone there will offer more detail on the type of steel and what hardening (if any) is used.

It is generally not a good idea to side load a planetary gear set like this, so the set up for your cutting operation should include supporting and clamping the shaft on both sides of the cut to minimize side load.

There may be a safe, reversible method of disassembling the unit so that you can securely clamp the shaft and final spider assembly for cutting, but since I haven’t attempted that I can’t offer advice – maybe Dr. Joe or (again) someone from BaneBots can, or maybe you’ll need to experiment.

Purely out of curiosity, why do you want to cut the shaft?

We want to cut the shaft for several reasons. One, the shaft sticks out way past the walls of the chassis and the 28x38 box. Two, if we leave it long, it interferes with the motion of the chain and the position of the drive sprockets.

our team would be cutting them off (assuming 4 transmissions and the sprocket is mounted up against the transmissions) to shave 2/3 of a pound off the robot…and it still would not be enough…

Get a pneumatic cutoff grinder. It will make quick work of the shaft. You can also use a regular 4" electric grinder with a cutoff wheel in it. Just keep a eye on the shaft temperature.

We opened our 42mm up today. Once you’ve got the four screws out, everything’s pretty easy to take apart.
That was the little gearbox, not the 56mm. I can’t vouch for the assembly of the 56, but there are good odds that it’s the same, so if you just go slow and make sure you don’t lose or break anything, you should be fine.
Before you close it up, make sure you clean and lube it up if you got any dirt in the gears or lost a lot of the grease.

It’s quite easy to remove the output shaft from the gearbox.

Remove the 4 2.5mm hex head screws around the periphery of the geabox on the output side, and pull the output side endcap off. You can then undo an external retaining clip on the inside end of the shaft, and pull the shaft off.