short lengths of the U-channel with our favorite chop
saw, and cut them in half along the minor dimension
to make L-shaped brackets. We aligned the brackets
with the side of the gearbox and used a sharp drill bit
to scratch some markings for the mounting holes. We
christened a new center drill with the brackets (our
last one broke on some 0.062” spring steel that we
affectionately referred to as “Bruce Springsteel” —
more on that in a future article).
Optimistically, we drilled mounting holes
corresponding to all the holes on the side of the
channel. Repeat three more times, and we have our
However, we needed something to mount them
to. For our base plate, we envisioned something that
would add some structural integrity to the VEX robot
base, give the gearboxes a surface to mount to, and
provide the bottom jaw of our crusher. We found a
scrap piece of 5053 that was thick enough to provide
the structural integrity we demanded, but bendy
enough to give us the shape we required.
The base plate needed to be a sort of stretched
out Z shape, with a flat surface to attach to the VEX
base, an angle down to the ground at about 45°,
and a flat surface to attach the bottom jaw to. We
put the necessary bends into the 5053 using a vice,
some blocks of aluminum as a makeshift brake, and
brute force. Of course, it worked, because if brute
force isn’t working that just means you aren’t using
enough (just ask Team Toad).
We wanted to mount the gearboxes directly
onto the base plate for maximum stability, but there
was a problem — the profile of the large gears
eclipsed the profile of the gearbox, so the large gears
collided with the bottom of the base plate. That was
nothing a few placed slots couldn’t fix, so we marked
out the position for the slots with our faithful calipers.
We cut out the slots by drilling out the ends with our
Unibit and then using a hacksaw to cut along the
The bends in the baseplate made it easy to get a
good bite with the hacksaw, and after a little finessing
with some files, we had some fine looking slots ready
to welcome the large gears. With the slots in place,
we marked out the various holes on the base plate for
attaching the gearboxes to, then the plate to the
robot, and knocked those out with the drill press.
The crusher was almost ready, except that it was
as toothless as the Abominable Snowman after the elf
dentist got hold of him in Rudolph the Red-Nosed
The chief criteria for our teeth is that they needed
to be robust and sharp. We selected a length of right
angle 6061 aluminum that we cut to length with the chop
saw. We did our initial dental work on the teeth using a
58 SERVO 03.2018
INSTALLING THE GEARBOXES.
BEWARE OF ROBOT!