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  #31   Spotlight this post!  
Unread 25-01-2017, 12:20
jvriezen jvriezen is offline
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Re: Gear Sliding down Ramp

I have no idea how it compares to the real thing, but we put on a layer of 1/8" hardboard, smooth side up, and it slides pretty well on that.
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  #32   Spotlight this post!  
Unread 25-01-2017, 15:14
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Re: Gear Sliding down Ramp

Quote:
Originally Posted by Pandaboy1293 View Post
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.
Take a piece of FRP put a gear on it... lift it up on one end and record the angle at which the gear begins to slide. The tangent of that angle is the STATIC friction coefficient. That can be compared to other static coefficients. The static coefficient of friction is always greater than the kinetic coefficient of friction. Remember that these coefficients are based on two materials....so there is no "Coefficient of Friction" for FRP.... it would have to be FRP and carpet, or FRP and wood or something...

good luck!!

If anyone actually does this for both FRP and the orange peel HDPE I would be interested in seeing what that number is.
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  #33   Spotlight this post!  
Unread 25-01-2017, 16:54
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Re: Gear Sliding down Ramp

Quote:
Originally Posted by Bob Steele View Post
If anyone actually does this for both FRP and the orange peel HDPE I would be interested in seeing what that number is.
Not those numbers, but we did measure the CoF of a gear with an actual FRC (2015) carpet yesterday (laying flat) using the well-known ramp method, finding it to be 0.43*. Static and dynamic were indistinguishable; once the gear started it moved at a slow steady rate down the ramp. As the gear weighs 18.4 oz per the game manual, expect to have a frictional force of about 8 oz.

* 39" long piece of plywood backing, hand raised, tape measure measurements, so you might want to put around a +/- 0.02 on it.
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Unread 25-01-2017, 16:58
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Re: Gear Sliding down Ramp

We have some HDPE for our feeder station, took some video of the gear going down if anyone is interested in that. I apologize now for it being in a bad orientation, didn't pay attention at all when i recorded.

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Unread 25-01-2017, 21:01
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Re: Gear Sliding down Ramp

Quote:
Originally Posted by MikLast View Post
We have some HDPE for our feeder station, took some video of the gear going down if anyone is interested in that. I apologize now for it being in a bad orientation, didn't pay attention at all when i recorded.

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Running these side-by-side, my perception is that your unupushed video is slower than field tour. Is that just because of the video angles (the field tour going out of frame soon)? I haven't tried to break it down frame by frame.
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Unread 25-01-2017, 21:04
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Re: Gear Sliding down Ramp

Field tour vids make the surface look matte. This looks shiny?

Did you have "orange peel" HDPE?
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Unread 25-01-2017, 21:10
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Re: Gear Sliding down Ramp

We just took some fine sandpaper to our polycarbonate and it slides very well. Seems that the glossy surface was sticking to the gear somehow.
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Unread 25-01-2017, 22:35
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Re: Gear Sliding down Ramp

Quote:
Originally Posted by SenorZ View Post
Field tour vids make the surface look matte. This looks shiny?

Did you have "orange peel" HDPE?
Dont know off the top of my head. Ill ask someone who knows tomorrow.
Natural HDPE.
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Last edited by MikLast : 26-01-2017 at 16:38.
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