[KwartzLab] Making a spoked, wooden wheel
punkin at mag3.14159.ca
Tue Nov 15 13:34:38 EST 2011
This is very helpful! Thank you for taking the time to write it out.
I'm making a double-treadle wheel, and your explanation helps explain part of why I hated the single-treadle (I think there was not sufficient inertia in the wheel I was using: if I didn't have just the right rhythm to begin with, it tended to stall before the treadle was re-engaged).
If the added weight doesn't improve function of the wheel, then I'd just as soon have something lighter. The frame I'm making is collapsible, and portability is important.
Excellent; I'm now learning enough about wheels that I actually look forward to making it!
On 2011-11-15, at 1:06 PM, Kevin Martin wrote:
> That is one of the main points of the wheel, to provide inertia. It has to be able to carry through the 2/3 – ¾ of a turn where the pedal cannot provide useful motive force, without too much loss in speed. If you put a crank on it you can have two pedals 180 degrees apart which shortens the undriven portions of the rotation so less inertia is required.
> The drawback of a solid wheel is that it has a lot of mass that does not add to rotational inertia, namely all the mass near the hub. All this does it make the whole thing heavier to pick up and move.
> You could use a disk of thin plywood, and build up a rim on either face by gluing on segments of wood, but this would be harder to balance since there would not be good control of the radius of the inner edge of the rim pieces.
> Ideally, the wheel should be balanced, but “being balanced” is not an absolute, so the real question would be whether a wheel would be balanced enough as built without requiring some adjustments.
> From: discuss-bounces at kwartzlab.ca [mailto:discuss-bounces at kwartzlab.ca] On Behalf Of Chris Bruner
> A couple of things that come to mind.
> 1. The spinning wheel has inertia, so a solid plywood spinning wheel will have more. Could this be a problem?
> 2. Does the spinning wheel need to be balanced?
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