Today I got around to stripping the robot down to look at the damage done.


First up, the previously-seen weapon arm flapping issue:


Pulling this apart, I found a smashed up gear (already spoiled above). The broken half had embedded itself in a lump of grease at the top of the 'box, which I suppose was lucky:

Not much I can do about this right now, but it's actually quite a nice little piece of kit so might try and replace that bit some day, if I can.
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I'm not sure if this was caused by Mattock or my cack-handed overtightening of the bolts securing the weapon to the shaft:
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Also within the weapon subsystem, for curiosity here is the BEAUTIFUL rework I did on the relay switch:
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I know what you're thinking, what rework right? There's no visible bodging on there AT ALL.


Next, drive. Both sides were pretty messed up. My bodged-together wheels just about survived the day, but I think some refinement is needed. First, there's not enough contact between the reverse-threaded screw that holds them in place and the inside of the hub, so one of them just came undone by the frankly rather unsubtle means of stripping the thread. I mean, rude or what.
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The other problem is, press-fit components can obviously be un-press-fit, with sufficient application of force:
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Sufficient forces were evidently applied. This wheel was also hard to get off, since obviously the motor can turn when you try and unscrew it. In the end I jammed something against the motor fan to hold it still and then it came off.

Both motors were a bit wobbly. They sit in a hole drilled in the side of the chassis and a U shape in an internal bulkhead, then there's some complicated clamping gubbins to grab hold of the various protuberances on the gearbox and motor to hold them both steady.
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The big flangey screws (1) sit in the slots in the motor mounting face (A) to stop the whole thing slipping axially, while the two countersunk screws (2) sit in the slot in the top of the motor (B) to stop it rotating.

Two blocks on the base stop the gearbox from rotating:
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Again, this worked pretty well but a few things need refining. First, Argos are not so kind as to make all their motors the same:
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Don't think a 4mm screw head will fit in that slot...

Second, the axial restraint puts a lot of force on the flangey screws, which has damaged the slot in the motor, and on the bayonet-style fitting from between the motor and 'box, resulting in breakage, and consequent wobblage:
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All in all though, this would probably keep trucking for a few more fights (maybe with some extra duct tape to be sure).


Finally, a couple of shots I never took while building, the wiring, including battery mounted for combat, and location of the F2 ESC:
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A few lessons learned:
  • Mount the wheels and drive motors better - those things take some whacks.
  • Cheap eBay gearmotors cannot take direct impacts (who'd have thunk it). If we want to go clampy, we may need to go big cogs or preferably linear actuator.
  • Do a proper mass budget. Although in some ways I was happier not knowing the first time around.
  • Sort out the mixing on the Tx so the robot doesn't rotate faster the Magnetar's drum when you try and go around a corner (thanks again to Eoin for the hint there - I'll have to look through the Tx manual)
  • Give the robot a shorter name - understandably, it rapidly became known as just "Wedgeley".



We've definitely got the bug for this so expect to see us again at Robodojo (probably in May) with something bigger and better (or failing that, heavier and repaired).

Cheers for reading!