Building a spud gun: Tips / Tricks?

[Racerboy]

3 inch will most certainly not offer very long ranges, 2.5" PCV should work as long as the tennis ball can freely move up and down in it, try it at a hardware store. You want the maximum compression possible to get the farthest range and power.

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[AdinX]

3 inch will most certainly not offer very long ranges, 2.5" PCV should work as long as the tennis ball can freely move up and down in it, try it at a hardware store. You want the maximum compression possible to get the farthest range and power.

Sadly I don't think 2.5" PVC exhists
it's either 2" or 3"
2" is way too small
3" is gonna be large

wat do

[xSetrox]

use a grill lighter to fire
use acetone as a fuel. works great.
my dad has an excellent spud gun that is literally a PVC pipe with a bolt on one end and a grill lighter attached, with its terminals inside the pipe. then he takes the bolt off and sprays acetone in it. then he puts the bolt back on and puts a potato or whatever inside and presses that lighter and bang. it goes pretty far.

[Ninja Decoy]

My dad and I made a potato cannon once. We used the ignition from an old long lighter (ones with the triggers) and attached it to 2 nails that go inside the chamber. It was rather simple. We used hairspray, which WAS good, but it stopped working after a little bit of time because the hairspray coated the nails and they eventually were too covered up to light the fuel.

It was fun though. Treated it more like a mortar. It went very far and it shot full potatoes.

[AdinX]

use a grill lighter to fire
use acetone as a fuel. works great.
my dad has an excellent spud gun that is literally a PVC pipe with a bolt on one end and a grill lighter attached, with its terminals inside the pipe. then he takes the bolt off and sprays acetone in it. then he puts the bolt back on and puts a potato or whatever inside and presses that lighter and bang. it goes pretty far.

To my understanding of my local laws, that's illegal. However I think compressed air is okay where I live (still checking)

That and using a gas just seems way more dangerous than I'm willing to go for, considering it's only launching tennis balls, however someone else could take this to heart for their own project.

[xSetrox]

I broke the law then
hey mom

[Axo-Tak]

Put that into simple terms
I'm assuming you mean figure out the pressure that would build up after firing?

Yes. Calculate the pressure, and design based on that.