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-   -   Gear Sliding down Ramp (http://www.chiefdelphi.com/forums/showthread.php?t=154125)

rlance 23-01-2017 11:04

Gear Sliding down Ramp
 
I built a player station this past weekend and was trying to get the gear to slide down on its own. I realize I was using polycarbonate and not HDPE like is actually used, but I could not get the gear close to sliding on its own. I wouldn't think the HDPE is that much slicker than the polycarbonate and the specs I found appear to show that HDPE is a little slicker, but not much. Has anyone else run into this problem with their player station?

The angle in the rules says it is 72 degrees from vertical, which is what I am pretty sure I am using.

Ginger Bread 23-01-2017 11:14

Re: Gear Sliding down Ramp
 
My team made this out of wood and the gear has a great deal of friction even when we put lexan on top of the wood to simulate the field.

anthonyttu 23-01-2017 11:18

Re: Gear Sliding down Ramp
 
lexan is a name brand of polycarbonate

EmileH 23-01-2017 11:19

Re: Gear Sliding down Ramp
 
Polycarbonate and HDPE are NOT the same. HDPE has a coefficient of friction of 0.28 according to this chart, whereas standard polycarbonate (lexan) has a CoF of 0.38.

rlance 23-01-2017 11:23

Re: Gear Sliding down Ramp
 
Quote:

Originally Posted by EmileH (Post 1635089)
Polycarbonate and HDPE are NOT the same. HDPE has a coefficient of friction of 0.28 according to this chart, whereas standard polycarbonate (lexan) has a CoF of 0.38.

Yes, I realized we were not using the exact material, but the chart you referenced is showing a bigger difference in co-efficient of friction than what I was finding last night. We will obtain some HDPE and see what happens.

Billfred 23-01-2017 11:26

Re: Gear Sliding down Ramp
 
Quote:

Originally Posted by rlance (Post 1635090)
Yes, I realized we were not using the exact material, but the chart you referenced is showing a bigger difference in co-efficient of friction than what I was finding last night. We will obtain some HDPE and see what happens.

It may be easier/cheaper/faster to get some FRP (the white pebbly stuff you see in public bathrooms) from your local home improvement store. That's what's specced for the team versions of the field, and things slide very well down the one we have here at AndyMark.

Jon Stratis 23-01-2017 11:29

Re: Gear Sliding down Ramp
 
Quote:

Originally Posted by Billfred (Post 1635093)
It may be easier/cheaper/faster to get some FRP (the white pebbly stuff you see in public bathrooms) from your local home improvement store. That's what's specced for the team versions of the field, and things slide very well down the one we have here at AndyMark.

Man, the one time I wish we still had some Regolith sitting around... :D

rlance 23-01-2017 11:38

Re: Gear Sliding down Ramp
 
Quote:

Originally Posted by Billfred (Post 1635093)
It may be easier/cheaper/faster to get some FRP (the white pebbly stuff you see in public bathrooms) from your local home improvement store. That's what's specced for the team versions of the field, and things slide very well down the one we have here at AndyMark.

That is great to hear. I'll run and get FRP. Thanks.

rlance 23-01-2017 11:55

Re: Gear Sliding down Ramp
 
Quote:

Originally Posted by Billfred (Post 1635093)
It may be easier/cheaper/faster to get some FRP (the white pebbly stuff you see in public bathrooms) from your local home improvement store. That's what's specced for the team versions of the field, and things slide very well down the one we have here at AndyMark.

The team version also has the angle 1.7 degrees steeper, which I assume is to account for the difference in co-efficient of friction between the HDPE and FRP.

dradel 23-01-2017 12:36

Re: Gear Sliding down Ramp
 
I have found the surface of a white board offers little friction. We tried the polycarbonate route and found it less slippery than plywood.

nuclearnerd 23-01-2017 13:46

Re: Gear Sliding down Ramp
 
We have HDPE sheets on our wooden chutes. It's not the same texture as the field versions (they use something called "orange peel", which is not commonly available here), but the gears still slide much better than on wood alone. That said, the "static" friction is still high enough that the gears will stick to the chute until you give them a (very) little push. I wonder if the real field has the same behaviour.

Robosparks2926 23-01-2017 13:56

Re: Gear Sliding down Ramp
 
Is there reflective tape on the peg/ platform for the gear placement?

cpapplefamily 23-01-2017 14:04

Re: Gear Sliding down Ramp
 
We had observed the same non-slide of the gear. A little spray of some dry lube and no stick.

Drivencrazy 23-01-2017 14:07

Re: Gear Sliding down Ramp
 
We had some orange peel HDPE from the scoring platforms in RR. Significantly faster slide than the plywood and polycarb. If your designs are sensitive to the exit trajectory of the gear, I'd get some.

Have not compared to FRP.

mwmac 23-01-2017 14:08

Re: Gear Sliding down Ramp
 
This product worked well for us in 2015 to serve as the feed chute surface for totes.

https://www.woodcraft.com/products/slick-strips-3-width

This year, given the width of the loading station and the size of the gear, it made more sense to us to use the frp alternative.


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