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The basic design
theme of the rebuild: replace the drum rollers with
real bearings. The drum bearings go around pieces of
modified aluminum pipe, which will be attached to the
frame. The endcaps of the drums will rest on the
outer races of these bearings. And the drive
motors will be mounted inside the pipes! |
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The components of
one side of the drive train. The screwdriver motors
are much smaller than the old drills. I think they
will be powerful enough for Daffodil's
not-very-demanding drive needs, and weight had to be
saved to make the bearing scheme and the two battery
pack scheme workable.
The motor/gearbox slides into the inside of the pipe,
and the 3/4 aluminum drive shaft couples loosely with
the output from the gearbox. The rings are to hold
everything in place, including two stages of bronze
bushings to support the drive shaft, and a shaft
collar between them to stop the shaft from moving back
and forth. This setup will hopefully be quite strong.
The old setup was fine but some of the 12 lbers
Daffodil could see at HSRC -- Dizzy Dragon, Ixion,
Mini-Mauler (and of course 911) -- can pack quite a
punch.
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New wheel. Just
like the old wheels, cut from 1/2 inch lexan. This
time instead of vacuum cleaner belts the tread is made
from some conveyor belt material that isn't quite so
smooth. We'll see if it works, or if it stays
attached any better! |
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The new "arms".
The purpose of the arms is to get leverage against the
ground, or else it wouldn't move very well. But the
old design required the entire bot to flip over
whenever Daffy changed directions. This new scheme,
because the arms touch the ground on both sides of the
bot, should make it much more drivable. |
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The motor that
drives the drum. It is a small airplane motor with
built-in gearbox. In place of the propellor, a little
2" castor wheel, which presses on the inside of the
drum to make it turn. |
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Battery packs.
One of Daffy's problems is that the batteries run out
of juice because the weapon motor has to work so hard.
So, besides making the drum hopefully more efficient,
the drive motors will now get their own smaller
battery pack to take some of the load off.
The packs are shaped so oddly because they wrap around
the pipe segments shown in the earlier pictures. The
entire guts of the bot -- frame, drive
motors/gearboxes, weapon motor assembly, batteries,
electronics, radio gear, wiring, power switches --
have to fit in a cylinder about 3.5 inches across and
about 12 inches long. That's not much space, and every
little nook and cranny counts!
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The pieces of the
drive showing how they will work. |
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Here is one of
the axles, after adding a tapped plug at the end to
help hold the wheel on, and a keyway. |
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The wheel with
the hub and axle attached. |
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The assembled
unit. I wonder if the people who make these
screwdrivers know what we do with them? |
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Here's the unit
from the "back", showing how the screwdriver gearbox
fits inside. |
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Next step:
attach the drive train units to the frame. This
picture shows the basic layout of the frame pieces. |
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Here is a shot of
the fully-assembled frame |
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After assembling
the insides, large amounts of electrical tape were
used to keep wiring and so forth from getting caught
in the spinning drum. |
