After September’s motor mounting issues and with Crab pushing the weight limit I decided it was finally time to switch to brushless drive.
I designed and machined some heavily pocketed replacements for the solid 20mm HDPE side panels. To save machining both sides and faffing around with registration all the pockets are on the outside. This also means the mounting plates are on the outside so I can remove the motors without taking the whole bot apart, which was getting tiring!
A well timed lasered order allowed me to get some laser cut aluminium brackets to mount the motor/gearbox assembly to the side panels, some aluminium blanks for mounting the motor to the gearbox, some steel drive gears with a D shaped cutout I couldn’t easily machine, and finally some hardox bits to discourage the pesky saw bots.
The aluminium discs got a boss and some counterbores machined into them to replace the mounting plates that come with the AliExpress gearboxes I’m using and adapt them to the hole pattern on the motors.
After pressing a pinion onto the 42mm brushless motors these mount to the gearbox with the new adapter plates, then the gearbox is screwed to the mounting plate which fits nicely into the pocket in the side panels. The gears are just pressed and loctited onto the gearbox outer shaft, and the slot in the mounting plate allows the gearbox to be removed from the plate without taking the gear off.
All up this saved 350 grams per side and made maintaining the motors much less of a hassle.
The claw armour pieces were welded together, with a scalloped piece across the front. This replaces a plastic block on the claws which was my previous solution to keeping the tips away from gaps at the edge of the arena, which they like to get stuck in.
If I was doing this again I’d have added a bit more meat to these parts. They’re largely held together with TIG filler rod and hope.
Finally the scallops got screwed on in strategic places to make sawbots sad.
Final product: A tougher brushless Crab!