drill bit to drill a new set of clearance
holes in the sprocket. The other task
for Monday was countersinking all
of the holes in the inner side rails
and mounting the Nutstrip that I
got from Kitbots.com.
The modified shaft is next to a
stock shaft showing the
difference in the keyways.
There was not a lot of progress
on Tuesday, because I was waiting
for a parts order with the 0.201”
drill bit I needed to modify the
weapon sprocket, and proceeding
with assembly would require a good
portion of the work to be undone
to get it drilled out. I did get two
small but important parts done: I
cut and glued a rubber shock pad to
the area on the front of the chassis
that would be hit by the attachments,
and I modified the keyway on one of
my De Walt shafts to allow the sprocket
to sit in the location it needed to.
I tossed a 1/8” end mill on my
mill, clamped the shaft as best I
could, and dropped the bit into the
existing keyway groove. With a slow
spindle speed and ample cutting
fluid, the new keyway was easily
added to the shaft. In addition to
this, the bearings for the weapon
were glued into the bearing blocks
and round weapon hubs.
The first task of the evening
was to drill out the sprocket and get
the weapon rack assembled. Once
again, a slow cut with ample cutting
fluid resulted in a quick and easy
modification to the steel part.
The next step in the build was
assembling the weapon rack. Stage
1 was assembling the weapon hub
which consists of the main 4130
steel universal attachment block; the
two outer aluminum rounds are
aligned with it; and three long 10-
24 bolts are run through the length
of the parts. I next added the
sprocket and used the existing
tapped holes to pull the assembly
together. The other three bolts were
added with locknuts on the end,
The 19 tooth sprocket after modifications.
The weapon rack is assembled
and ready for integration with
the side rails.
SERVO 04.2012 33