Polycarbonate....

[Dr Fritz]

does the Polycarbonate have a lot of friction? my team and i are wanting to make a frictionless pad for the magnets on the mini-bot. does anyone have an idea as if this works or not?

[SushiKitten]

In my experience polycarbonate usually does not have to much friction. One idea our team is playing with is using polycarbonate cylinders to make rollers that would reduce friction. I don't know if you could incorporate something like that into your design but I hope it helps.

[Dr Fritz]

yeah cool we are also making rollers for our magnets. we has decided on aluminum with delrin on the rollers and i am finding out if delrin could be used

[Tristan Lall]

Polycarbonate has more friction than many other common engineering plastics. It wouldn't be anywhere close to my first choice for a roller, and I would be similarly wary of it for a sliding pad.

However, given that you don't really have to much choice (<R92> implicitly bans raw Delrin on the minibot, for example), and durability in the long term is not a concern, it's probably going to be fine.

Now, if you want, there's a way to exploit a loophole in the rule to enable you to use certain other plastics. Buy plastic fasteners, and modify them to your specifications.* (Keep the bill, to facilitate your explanation to the inspector that you started with a fastener.) You can probably figure something out to convert a Nylon bolt into an appropriate roller.

*I should note that FIRST's Q&A hasn't ruled on this strategy; while ordinarily they say things like aluminum sheet metal is allowed, implying that it doesn't matter if the final form on the minibot renders the part no longer a sheet, it's entirely possible they could decide to be inconsistent, and define a fastener as something that still works as a fastener, rather than something originally sold as a fastener.

[Dr Fritz]

this is true I have another thread about ball bearings made out of raw materials so what about PVC does it as well have a lot of friction?

[Tristan Lall]

PVC won't be very good as a bearing—it's weak and soft. Besides, only specific types of PVC are allowed, so you'd be stuck machining your bearings from PVC pipe and fittings (and fasteners, if you can find any, and the above theory holds). (That would be unbelievably annoying to make.)

If you're referring to using PVC as a roller or sliding plate without a bearing, then I think it ought to be a bit better than polycarbonate.

[Dr Fritz]

i mean we are thing roller or bearings you know ok so as a roller better then ploy?