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STORY:
After
acquiring drive motors and gearboxes for Dr.
Inferno Jr., I needed to find the best wheels to put the
power to the ground. In past robots, I generally used crazy custom
wheels tailored to the application. I didn't have much experience
picking out appropriate wheels from a catalog, so I ordered a
whole bunch from McMaster-Carr
and Tower
Hobbies and did a qualitative, subjective
comparison (that is, I didn't actually mount & test most of
these wheels on bots--many of my comments are based on impressions
I got from handling & studying them).
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THINGS
TO LOOK FOR IN A WHEEL FOR A COMBAT ROBOT
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Light
weight: makes it easier for your drive motor to quickly
speed up, slow down, and reverse direction; heavy wheels also
use up valuable weight that could be better used in other
components
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Sturdiness:
needs to take a beating and not break up
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Tread:
the stickier the better for pushing and high acceleration/deceleration
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Diameter:
for a given drivetrain setup, smaller wheels give more pushing
force and lower top speed, larger wheels give less pushing
force but higher top speed; using smaller wheels should also
tend to draw less current, letting your robot run longer on
a battery charge and taxing your speed controller less
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Tread
Shape: flat gives more contact area (better), rounded
gives less contact area
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Core/Hub:
want it to be sturdy yet easy to machine, with enough area
to attach to driveshaft or hub
- Stiffness:
cushy wheels will have a larger contact patch, give your robot
a smoother ride, absorb shocks, and accommodate mounting flaws
(tweaked chassis, bent axles, etc.) but may wear faster than
hard wheels
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Cost:
try not to let cost influence your decision too much; then
again, you always want to be able to afford to have spares
on hand; all prices quoted below are from March 2000
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Application:
wheels designed to support push-carts or to catch landing
model airplanes are not designed to be driven by motors--reworking
of the hubs is necessary. Any text below in "quotes"
is taken from the catalog descrption, explaining its features
or application.
If
you want to learn about other drivetrain issues or want to see
a rough rule of thumb for preferred wheel/tire size, visit Coolrobots'
builder's
corner.
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Wheels
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Description
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Pros
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Cons
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Verdict
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McMaster-Carr
2322T31
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ALUMINUM
HUB
Rubber
tread on aluminum core (solid or spoked), smooth tread (thin or
standard thickness), 150+lb capacity, size: 5"-14" dia
x 1.5"-5" wid
Example:
3" dia x 1.25" wid, 0.5lb, $22.24
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light,
quite grippy tread, tough hub, small hub bore on larger sizes, easy
to machine aluminum |
smaller
sizes have large hub bore, pricey, raised central ridge on tread,
rounded tread |
Recommended
Easy-to-remove
bearings, easy to machine, light & grippy. Suitable for all
sizes of bots.
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left:
McMaster-Carr 2829T11
right:
McMaster-Carr 2829T54
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COLSON
THERMO-CUSHION RUBBER PERFORMA
Polyurethane
tread interlocked on smooth or ribbed polyolefin core, gray tread
or black tread available (gray appears softer), 75+lb capacity,
size: 2"-12" dia x 0.125"-3" wid
Examples:
left 3" dia x 1.5" wid, 0.3lb, $9.89; right
3.5" dia x 1.25" wid, 0.3lb, $7.13
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light
weight, quite grippy tread, small hub bore on larger sizes, tread
compresses, reasonable price, easy to machine, flat tread |
smaller
sizes have large hub bore, plastic may not be durable enough |
Recommended
Easy-to-remove
bushings, easy to machine, light & grippy. May not be suitable
for huge bots. "Tread will not break up when rolling over
debris." Dr. Inferno Jr. was upgraded to Colson wheels
after the CB ones shredded.
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left:
McMaster-Carr 22865T11
right:
McMaster-Carr 4996T11
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ALUMINUM
HUB
left:
Rubber tread on aluminum core (solid or spoked), smooth tread
(thin or standard thickness), 150+lb capacity, size: 5"-14"
dia x 1.5"-5" wid
right:
Neoprene
molded on solid aluminum core, smooth tread, 200+lb capacity,
size: 4"-10" dia x 1.5"-2.5" wid
Examples:
left 5" dia x 1.5" wid, 1.5lb, $22.24; right
3" dia x 0.9375" wid, 1.3lb, $18.69
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average
weight, small hub bore, fairly grippy tread, very durable |
average
weight, average tread grip, raised central ridge on tread should
be removed first, not cheap |
Pretty
decent for a heavy duty bot. Overkill for a small one. Tread needs
a little work to remove ridge.
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orange:
McMaster-Carr 2351T97
red:
McMaster-Carr 2351T98
black:
McMaster-Carr 2319T11
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IRON
orange
& red: Polyurethane molded on cast iron core, smooth thin
tread, 290+lb capacity, size: 3"-12" dia x 1.25"-4"
wid
black:
Rubber molded on solid or spoked iron core, smooth tread (hard
high capacity or less hard lower capacity), 170+lb capacity, size:
3"-16" dia x 1.375"-5" wid
Examples:
orange 3" dia x 1.25" wid, 1.5lb, $12.45; red
3.5" dia x 1.25" wid, 1.3lb, $13.21; black 4"
dia x 1.5" wid, 2.6lb, $7.52
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cool
colors, bulletproof, small hub bore |
not-so-grippy
tread, heavy! |
Too
heavy & not grippy enough. Not well-suited for robot drivetrain.
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blue:
McMaster-Carr 2472T21
gray:
McMaster-Carr 2497T121
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PLASTIC
blue:
Solid polyurethane, smooth tread, 300lb capacity, size: 3"-8"
dia x 1.25"-2.5" wid.
gray:
Polyurethane tread mechanically locked on polyolefin core, smooth
tread, 125lb capacity, size: 3"-12" dia x 0.9375"-3"
wid
Examples:
blue 3" dia x 1.25" wid, 0.3lb, $12.89; gray
3" dia x 0.9375" wid, 0.2lb, $3.56
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light,
small core bore, 1-piece models are simple |
skinny,
not grippy, all plastic (durability?) |
Ok
for a very light bot, perhaps not for larger ones. Easy to work
with. 2497 series is low cost!
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black:
McMaster-Carr 2670T14
maroon:
McMaster-Carr 2670T83
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WIIIIIDE
Polyurethane
tread on steel core pallet and lift truck wheels, smooth tread,
size: 3"-8.5" dia x 2"-6" wid
Examples:
black 3.375" dia x 3.9375" wid, 3.0lb, $19.56;
maroon 3.25" dia x 5.9375" wid, 3.5lb, $24.24
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extra
wide, very durable |
large
core bore, not very grippy, heavy, not cheap |
Crazy!
Maybe good for a giant bot, especially if a stickier tread could
be applied. Silly for a smaller bot.
"Abrasion resistant."
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top:
Tower Hobbies CBAQ3020
bottom:
Tower Hobbies CBAQ3010
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CB/TATONE
FOAM-FILLED R/C AIRPLANE WHEEL
C.B./Tatone
foam-filled wheels, "support airplanes weighing up to 100lb",
treaded wheel size: 3.5"-4.5" dia, smooth wheel size:
4"-5" dia
Examples:
top smooth, 4" dia x 1.5" wid, ~0.2lb, $21.39/pair;
bottom Bow-Tie, shallow tread, 3.5" dia x 1.5"
wid, ~0.1lb, $21.39/pair
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light,
grippy, cushy, fairly hearty hub disassembles easily, durable foam-filled
tire can take some abuse |
price,
rounded profile (on both smooth and treaded models), a little skinny,
tires wear noticeably during heavy use |
Recommended
Good all-around model. Reinforce the hubs or make beefier
ones. Not cheap but worth it. Good for small bots, not big
ones. I used 3.5" ones on Dr. Inferno Jr. with custom aluminum
hubs. The wheels ended up wearing somewhat on Overpowered Box &
totally shredding themselves on Dr. I Jr. |
top
left: Tower Hobbies DAVQ5540
top
right: Tower Hobbies DAVQ5730
bottom
left: Tower Hobbies DAVQ5740
bottom
right : Tower Hobbies DAVQ5035
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DAVE
BROWN LITE FLITE FOAM-FILLED R/C AIRPLANE WHEEL
Dave
Brown Lite Flite foam-filled wheels, "for large scale airplanes",
smooth & flat or treaded & rounded, size: 4"-6"
dia
Examples:
top left 4" dia x 1.125" wid, ~0.1lb, $8.59/pair;
top right 3" dia x 0.75" wid, ~0.1lb, $4.99/pair,
bottom left 4" dia x 1.25" wid, ~0.1lb, $8.59/pair;
bottom right 3.5" dia x 0.875" wid, ~0.1lb, $5.49/pair
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light,
seem grippy, smaller models squishy, smooth wheels have flat tread,
cheap price
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larger
models stiffer, treaded wheels have rounded tread, plastic hub
durability questionable
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Recommended
A good all-around model. Reinforce the hubs or make beefier ones.
Very high profile tires. Very inexpensive. Good for smallish bots,
not for big ones. |
Left:
Tower Hobbies DUBQ0775
top:
Tower Hobbies DUBQ0895
bottom:
Tower Hobbies DUBQ0843
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DU-BRO
AIR/FOAM-FILLED R/C AIRPLANE WHEEL
left:
Low Bounce, captive air rubber tire on nylon hub, smooth tread,
size: 1.75"-3.5" dia
top:
Low Bounce captive air rubber tire on nylon hub, shallow lined
tread, size: 1.75"-3.5" dia
bottom:
Lightweight foam-filled rubber tire on nylon hub, shallow lined
tread, size: 1.75"-6" dia
Examples:
left Low Bounce smooth, 3" dia x 1" wid, ~0.1lb,
$5.49/pair; top Low Bounce treaded, 3.5" dia x 1.25"
wid, ~0.1lb, $5.99/pair; bottom Lightweight treaded, 3.25"
dia x 1.25" wid, ~0.2lb, $8.59/pair
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seem
grippy, captured air model cushy, very inexpensive, teeny
hub bore, light weight, foam-filled model more durable |
captive
air versions may puncture, spoked plastic hub offers little support,
foam-filled model very stiff, overall durability a concern |
Some
potential if they can be mounted well and do not get damaged. Small
bots only. Captive air models have good tires but potential puncture
problems, foam-filled is more durable but stiffer. Hubs are minimal
& skimpy. |
Tower
Hobbies DUBQ0790
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DU-BRO
INFLATABLE R/C AIRPLANE WHEEL
Du-Bro
Big Wheels Smooth Tire with positive seal valve, size: 4"-6"
dia
Example:
4" dia x 1.5" wid, 0.3lb w/ hub, $11.59/pair
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mega-grippy,
very cushy, low cost, teeny hub bore, light weight |
air-filled
tire can pop or leak, rounded tread, air valve near tread could
get damaged, weak plastic hub |
Much
potential if they can be mounted well and do not get damaged. Small
bots only. |
Left:
Tower Hobbies PROC9002
right:
Tower Hobbies PROC9004
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PRO-LINE
1/8 SCALE R/C CAR TIRE
Pro-Line
Road Rage & Bow-Tie, tire only--no hub, diameter, "fits
any 3.2"-3.4" front or rear 1/8 wheel"
Examples:
left Road Rage off-road knobby, 4" dia x 2" wid,
~0.1lb, $18.39/pair; right Bow-Tie, street tread, 4"
dia x 2" wid, ~0.1lb, $18.39/pair
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light,
wide, flat tread, sticky, Bow-Tie well-suited for flat surfaces |
need
to purchase or make hubs, questionable durability, Road Rage tread
suited for off-road use |
Not
good for a beginner (need to buy or make wheel/hub), nice piece
of tread if mounted properly. |
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Missing
Link with screwed-down vacuum cleaner belts
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VACUUM
CLEANER BELTS
Available
at any vacuum shop, hardware store, or department store.
Examples:
Precision "traction" belts, $1 each
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cheap,
super grippy, customizable (number and arrangement of belts) |
not
durable, assembly required, need to be attached to a correct-sized
wheel hub |
Good
solution for a smaller robot if custom wheels are desired, not good
for a big bot. |
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