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Unread 02-02-2017, 10:56
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Re: Fuel leaves behind a thin film

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Originally Posted by Kevin Sevcik View Post
I suspect this starts cropping up when you move from gravity feeding into a shooter wheel to controlled conveyor feeding. If you don't get the spacing right, the conveyor is still holding the fuel when it contacts the shooter wheel, and the shooter wheel slips until it gets enough grip to rip the fuel out of the conveyor. At least, that's my experience from multiwheel frisbee shooters.

Basically, anything where physics is going to force the wheel to slip at high speed on the fuel for a prolonged time is probably going to melt some of it off.
I will definitely be looking for this now. Though i do have our infeed running the same speed as our shooter feeder rollers, so maybe we won't see the extended contact...
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Unread 02-02-2017, 10:58
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Re: Fuel leaves behind a thin film

Is there any prolonged effect of the polyethylene buildup on the shooter wheels even after scraping it all off every match? How often are we all going to have to replace our shooter wheels?

From testing shooter prototypes in the snow, even a little bit of ice or water buildup reduces shooter speed far more significantly than I ever would have thought.
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Unread 02-02-2017, 11:01
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Re: Fuel leaves behind a thin film

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Originally Posted by EricLeifermann View Post
We have not seen this in any of our testing.
We have not seen this in our testing either. Our compression is fairly low so that could be part of it.
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Unread 02-02-2017, 11:10
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Re: Fuel leaves behind a thin film

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Originally Posted by Chris is me View Post
5. Pick kids for pit crew who love sanding things.
QFT. If you can get a student who's excited about maintenance in your pit, the'll make sure it gets looked after between each match.
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Unread 02-02-2017, 11:26
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Re: Fuel leaves behind a thin film

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Originally Posted by jamesmcip View Post
Is there any prolonged effect of the polyethylene buildup on the shooter wheels even after scraping it all off every match? How often are we all going to have to replace our shooter wheels?

From testing shooter prototypes in the snow, even a little bit of ice or water buildup reduces shooter speed far more significantly than I ever would have thought.
This entirely depends on your kind of wheel, your shooter dimensions, your motor power, etc. and is the kind of thing every team has to figure out themselves, unfortunately.
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Unread 02-02-2017, 12:36
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Re: Fuel leaves behind a thin film

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Originally Posted by Alex Chamberlin View Post
Try acetone or benzene.
Acetone doesn't dissolve polyethylene. Benzene may dissolve the wheel as well.
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Unread 02-02-2017, 12:41
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Re: Fuel leaves behind a thin film

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Originally Posted by flemdogmillion View Post
Acetone doesn't dissolve polyethylene. Benzene may dissolve the wheel as well.
Really there aren't a lot of solvents that dissolve polyethylene but not polyurethane rubber or silicone rubber or polycarbonate or anything that might be around a shooter.

Isopropyl alcohol as a cleaning method rather than a solvent may help with removal a little, but really Elbow Grease and Friction are the way to go here.
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Unread 02-02-2017, 13:17
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Re: Fuel leaves behind a thin film

Our shooter is a gravity fed double wide 4 inch stealth wheel "fly wheel". The ball compression created by the fly wheel is less than 1/4 of an inch. WE have found that the build up is due to the quick ball acceleration. The issue we ran into is once the residue build up hit a certain thickness it began to peel off some ball would hit that bare spot on the fly wheel and be sent much farther than ones that hit a residue covered section. We attempted to calibrate our shooter with the build up, but we ran into that issue. So, we will just dedicate a team member to sand our flywheel after every match to clear up our issue.
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Unread 02-02-2017, 13:21
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Re: Fuel leaves behind a thin film

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Originally Posted by Chris is me View Post
Really there aren't a lot of solvents that dissolve polyethylene but not polyurethane rubber or silicone rubber or polycarbonate or anything that might be around a shooter.

Isopropyl alcohol as a cleaning method rather than a solvent may help with removal a little, but really Elbow Grease and Friction are the way to go here.
Our wheels clean off just being rubbed by hand (isopropyl and tower work better), sanding isn't necessary for all wheel types.
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Unread 02-02-2017, 14:37
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Re: Fuel leaves behind a thin film

To remove the film off a smooth wheel, first cut across the film with a sharp knife or razor. Then you can probably peel it all off easily.
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Unread 02-02-2017, 15:05
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Re: Fuel leaves behind a thin film

You might try varying the compression of the ball in your shooter.
The material you see is probably a result of the wheel spinning on the surface of the ball. It is also evidence of a certain amount of inefficiency in applying energy to the ball due to this slippage.

We found that by increasing the compression slightly, not only was the residue reduced, but we shot further and with more reproducibility.

Compression is really key in getting your shooter to work consistently. It is worth experimenting with small changes to see what happens.
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Unread 02-02-2017, 15:33
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Re: Fuel leaves behind a thin film

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Originally Posted by Bennett548 View Post
I have noticed that the fuel leaves a film [that] seems to reduce the effectiveness of shooter wheels by reducing their coefficient of fiction, and reduces the grip of rollers and polyurethane belts.
You're using a petroleum-based (mostly) aliphatic FUEL and you're surprised that it leaves a lubricating film? Today MUST be Groundhog Day.
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Unread 02-02-2017, 15:40
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Re: Fuel leaves behind a thin film

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Originally Posted by EricLeifermann View Post
We have not seen this in any of our testing.
Same here, though we'll be looking out for it now...
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Unread 02-02-2017, 15:45
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Re: Fuel leaves behind a thin film

For everyone mentioning compression, is this a pretty constant compression throughout the contact arc? And if so, are there any teams trying out a gradual increase or decrease of the amount of compression? That might help with all sorts of things.
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Unread 02-02-2017, 17:03
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Re: Fuel leaves behind a thin film

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Originally Posted by Bob Steele View Post
You might try varying the compression of the ball in your shooter.
The material you see is probably a result of the wheel spinning on the surface of the ball. It is also evidence of a certain amount of inefficiency in applying energy to the ball due to this slippage.

We found that by increasing the compression slightly, not only was the residue reduced, but we shot further and with more reproducibility.

Compression is really key in getting your shooter to work consistently. It is worth experimenting with small changes to see what happens.
What Bob says!

I recall that in '06 we were consistently shredding the surface of the Nerf balls with our shooter wheel. We thought that decreasing the compression would help, but it made the problem worse... increasing compression was the answer.

Note that if you have a buildup of plastic from the fuel that means that you are removing the PE from the fuel... thus damaging a field element. If you are removing so much plastic that you need to clean your shooter wheel every match, then you are likely violating the "don't damage the field" rule.

Jason
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