Shooter Question

We are working on our shooter design, but are unsure about a few things. We haven’t built many shooters in the past, at least not successfully. The manual says the balls are 9.5" diameter. We assume there should be some compression on the balls to help feed them into the shooter and then ultimately shoot them out, but we are not sure where to start with the compression. Should we go for a 9.25" gap, 9.375". 9.125"? What have you used (and with what wheels) and found successful thus far?

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There are plenty of topics on this already.

https://www.chiefdelphi.com/search?q=shooter%20after:2022-01-08

And there’s a lot of it specifically here:

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You can check this link.

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Build something, play around with it! I would expect the answer to be in the 7" to 8" range, though. So make your prototype highly adjustable.

(no, I didn’t read through the fine links suggested by others)

Thanks for your input. I understand your point about building something and playing with it, unfortunately we don’t have a lot of spare material laying around to build with. I’ve looked through the links above and it seems, like you said, that most teams are going for between 1.5-2" of compression, so we are going to start there and see how it goes. Thank you

When we’ve made shooters in the past, the usual method is to build a prototype box out of plywood and 2x4s, and then add a spinning wheel or roller, and then move the 2x4s which support the “track” around until it shoots well. Then design and build something based on this setup.

I looked through some old pictures, this is our finished shooter, and the prototype, from 2012. Just to give you an idea of how crude the prototype can be, and still tell you useful information.

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The key is accurately capturing all of the geometry from that prototype and getting that into the comp shooter. Don’t be surprised if your comp shooter is significantly worse than the plywood prototype…

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This video by 971 will walk you through designing a prototype shooter for Infinite Recharge 2020.

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Im not sure if this helps very much. But the team i was a part of always used a 1 inch compression rule… for foam balls we always used a dual motor shooter. A set of wheels on top and bottom set at different speeds to give spin as needed. If we used a 1 wheel set design it always had .3 to .5 in compression. It always gave us a good smount of force and power comming our of our shooter. Even with rubber balls it was usually very effective.

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On Saturday we did our first shots, and we were able to get away with 2.25 inch compression (7.25" gap). Even with our more inflated ball it seemed to work perfectly, and looked like it could handle more compression.

We likely don’t have exactly 3.5 PSI, but our more inflated ball was probably close enough. I imagine that 2.5" compression might actually be possible, if any teams want to test this.

Has anyone built a shooter with that 2 inch compression mentioned above? We would be pinging the ceiling with 1/2" compression at 80% power with our Falcons and ratio. I think you all need to clarify in your examples what flywheels you are using because we are using four colsons on a single rod and getting that result. Solid rubber wheels will behave entirely different than the soft rubber flywheels with that much compression. You can see our build blog with our setup along with many of the other open alliance prototypes. Check any build thread and I think you will find your results are varied quite a bit.