Has anyone attached pulleys to "scooter wheels" such as these from McMaster Carr
Any problems ? Methods used ( mechanical/screws; glue; etc. )
8823T35 or 8946T67 (on page 1236 of McMaster-Carr online catalog)
I'd also be interested in anyone's successes with attaching pulleys directly to
other types of wheels.
It seems the pulleys on the old Evolution ER1 is glued to the wheel. While I
never had any trouble with it when I had one, it just
seems ... non-robust. Comments are welcome.
From looking at the catalog, you could cut aluminum spacers that would
go between the ribs on the wheels and allow you to bolt a pulley to the
side of the wheel. Depending on the thickness and shape of the webbing
in the middle of the wheel that I can't see in the picture, it might be
a fair chunk of work to get a flat surfae to bolt the pulley to and if
the webbing is thin, the end result might not be too good.
Some of the wheels with metal hubs have holes already drilled for
bolting pulleys or sprockets to them with simple round spacers.
A more conventional way to do this is to get wheels that bolt or pin to
a shaft, mount the pulley to the shaft and support the shaft with
bearings called pillow block bearings.
Surplus Center http://www.surpluscenter.com has a bunch of different
wheel types, pulleys, sprockets and bearings. All for a lot less than
McMaster Carr or MSC.
The original Budget Robotics Scooterbot used scooter wheels (hence the
name "Scooter Bot"). They were actually 64mm polyurethane wheels for
inline skates. That size more closely matches the typical 2 1/2"
diameter wheel in use on small desktop bots.
I bought the wheels without the bearings, as the bearings weren't
needed. In almost all the scooter wheels I've seen everything is sized
in metric. That doesn't seem to be the case with the McMaster-Carr
wheels, but those dimensions may be approximate anyway. In any case,
these kinds of wheels are LOTS cheaper elsewhere. You'll often find the
100mm wheels at various surplus outfits. The 99 Cents Only dollar store
was once selling them for $1/pair. I have one (unused) pair left you can
have, if you pay the shipping. (Send me e-mail off the list, if you're
The biggest problem is truing the wheels. This means aligning the wheels
to whatever hub you're using so that the wheel doesn't wobble (runout)
when it rotates. I machined hub pieces that attached to a standard servo
disc, but if you're good with basic shop tools, you can do the same with
a fender washer and a drill press. When mounting the wheels I'd suggest
a three-screw arrangement -- spaced 120 degrees apart. This will allow
you to adjust the tightness of each screw, which will affect the truing
of the wheel. You want to minimize wobble. Pretend you're working at
While I attached a servo disc to mount to an R/C servo motor, the
concept is the same whether you are attaching a sprocket. I'd avoid a
gear, as that requires a precision most folks can't easily achieve with
Depending on the diamter of your driver (disc, sprocket, whatever), you
might also be able to mount directly to the body of the wheel. You can
drill through the polyurethane if you need to. Don't worry: the air
won't get out, leaving with with a flat tire. Modern science!
I have a couple of scooter wheels leftover from the ER1 expansion kit, so I will
hold off on your offer for now, but I sincerely do
This is the real reason I have started on a "wheel quest". The lawnmower wheels
I have been using tend to wobble - it seems like the
two halves of the rubber part were slapped together not quite evenly - as it
rotates one side rises above the other one and then
back. It's not a big deal for now, but I do want to get it so it looks like a
quality product one of these days. I ordered a pair of
the solid rubber wheels from MSC that I plan to experiment with. I'm just trying
to educate myself so I don't end up spending tons
of $$ on parts that don't quite cut it for my purposes.
That's exactly the kind of feedback I need on attaching the pulleys! I figured
either 3 or 5 screws seemed right.
Thanks again !
If you want decent large-diameter wheels with little runout I suggest
the kind they use for steering or support wheels in the newer-style
wheelchairs. Try outfits like National Power Chair. Expensive yes, but
high quality. You can save a bit if you can find the local wheelchair
repair shop in your area. Even a used wheel is better than the cheapo
injection molded lawn mower wheels.
Small wheels for electric scooters are also a good choice. You can find
some on eBay for reasonably cheap, or mail order outfits sell them new
for $25-35. These are airless mag or spoke type, and very well made.
Diameters from about 6" to about 12".
Try looking for electric bikes or scooters in disposal stores
sell or were selling motors and parts from electric bikes and scooters.
complete rear wheel assembly approx Aus$32 = US$24
Shipping to US would be the cost probably around Aus$50 - 75
for sea mail
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