Our team is building an elevator this year like most teams are. I was wondering what is everyone’s experience with spacers used at roller bearings for elevators, would this be better then traditional ball bearings?
It depends, mainly on what material you actually use.
For starters: Nothing beats a ball bearing at being low-friction. I mean, it’s rolling, there’s very little friction there.
However, if for some reason (like $$) you can’t use a ball bearing, then using other materials is fine, just be sure you can handle a bit more friction. Here’s my preferred list:
UHMW
Teflon
Delrin
Other plastics like HDPE come to mind but I’d go with those three if possible. You’re looking for a slippery or slick plastic in a round form, essentially–that would allow you to drill a hole, cut to width, and install on a bolt.
In addition to the material of the spacer as Eric pointed out, concentrically is a important factor.
We converted last year’s practice robot to continuous from cascading for an off season seminar and used McMaster 1/2" OD #10 ID nylon spacers in a pinch. They were noticeably eccentric and definitely were not as good as the bearings. It obviously depends on the specific spacer you choose but I would put it between a roller bearing and just plastic on metal.
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What are you trying to gain by not using bearings?
The only thing I can really think of would be the price. You can get 1/2" OD bearings for about $5/piece from McMaster. If that’s too expensive, you can use sleeve bearings (aka bushings) for less than $1/piece from McMaster. You’re not going to find spacers much cheaper than that, and sleeve bearings are actually designed for this application. That means they’ll have better concentricity, better wear properties, etc.
It also depends on how your elevator is designed and where the loads are. In a traditional 2"x1" elevator, almost all your mechanisms are cantilevered off the front, and so your elevator experiences much higher loads front-to-back then side-to-side. It’s more critical to have bearings supporting the higher load.