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.

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.

lexan is a name brand of polycarbonate

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.

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… :smiley:

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

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.

I have found the surface of a white board offers little friction. We tried the polycarbonate route and found it less slippery than plywood.

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.

Is there reflective tape on the peg/ platform for the gear placement?

We had observed the same non-slide of the gear. A little spray of some dry lube and no stick.

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.

This product worked well for us in 2015 to serve as the feed chute surface for totes.

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.

Yes, section 3.13 of the rules, details in figure 3-36.

It is in the rules under Arena 3.13

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)

We used some fiberglass and it worked pretty well but you have to be careful when cutting it.

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.