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| I'd flip my normals for you. |
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#16
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Re: Gear Sliding down Ramp
Yes, section 3.13 of the rules, details in figure 3-36.
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#17
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Re: Gear Sliding down Ramp
It is in the rules under Arena 3.13
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#18
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Re: Gear Sliding down Ramp
Sorry, but those actually are completely different plastics for the application.
The coefficients "look similar", but going from 0.28 to 0.38 [as quoted earlier in thread] is a 30% increase in friction! Textured FRP or textured ABS are both much better choices than smooth polycarb, if you can't get HDPE in either smooth or "orange peel". Consider bringing the gear to the store to test your substitute-of-choice before buying? (Our smooth HDPE works great, I haven't tested our textured ABS) |
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#19
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Re: Gear Sliding down Ramp
We used some fiberglass and it worked pretty well but you have to be careful when cutting it.
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#20
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Re: Gear Sliding down Ramp
Code Orange cut off a piece of FRP that they used so we (SMbly Required) didn't have to order it. We both used it for the ramp and it works very well.
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#21
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Re: Gear Sliding down Ramp
Practice with something as close to the real thing as possible. If your robot is relying on the gear slowly plopping out of the chute because you designed around a wooden chute you'll be really upset at comp... unless you do floor pickup. Then whatever
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#22
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Re: Gear Sliding down Ramp
Upon searching some reference material, we found that Formica has a similar coefficient of friction to HDPE. If someone on the team has recently renovated an old kitchen, perhaps you can find a piece large enough. We find it works well for us - no problem with sliding.
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#23
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Re: Gear Sliding down Ramp
In a similar-to-but-not-exactly-related vein:
Adding a bit of duct tape to the bottom of a gear and then sliding it across the school's tiled (linoleum?) floor was approximately the same friction as a plain gear sliding across carpet. Just keep adding tape until they 'feel' the same. |
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#24
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Re: Gear Sliding down Ramp
I just used b/c plywood with one coat of water based polyurethane then I sanded and put furniture wax on it. Works great
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#25
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Re: Gear Sliding down Ramp
Or just spend $13.25 plus shipping and get HDPE to line your chute.
https://www.mcmaster.com/#8619k426/=1625apw This is working great for us. |
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#26
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Re: Gear Sliding down Ramp
Imho everyone should just acquire some HDPE from Mcmaster. Its not that expensive(~20$ for a 2'x3' sheet) and it allows you to get a very similar experience you will get on the real field. If you find something at your local shop that has lower friction than the HDPE it is equally as bad as using plywood or polycarb. At the end of the day you want something that acts like the real field will act.
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#27
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Re: Gear Sliding down Ramp
Grainger also has HDPE for slightly less and no shipping cost if you can pick it up at a local branch:
https://m.grainger.com/mobile/produc...searchBar=true Once we found out our school district had an account with Grainger for the facilities group we have started leveraging it, better vendor for plastics on both cost and shipping if you usually rely on McMaster. |
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#28
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Re: Gear Sliding down Ramp
We found that a material that is called "Starboard" which is used in marine applications among others is actually HDPE with the orange peel surface. We found it at TAP plastics.... it is SIGNIFICANTLY easier to slide the gears....on our practice version.... the gears actually slid all the way down without any push on the part of the human participant.
Regular HDPE is significantly different in that it has a noticeably higher coefficient of friction. We are covering our retrieval stations with it... 1/4" pieces cost about $35 or so. (We picked it up at the store) All told for 4 pieces it cost us $160 or so.... that was 4 pieces... STARBOARD.... hmm I wonder if they also have PORT? |
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#29
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Re: Gear Sliding down Ramp
That's for after ship day.
(I'm sorry I don't normally go off topic like this but I had to) |
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#30
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Re: Gear Sliding down Ramp
Does anybody know what the CoF of FRP? My team is using and I'm concerned that it might not work for what we need it to.
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