@redneck: We have thought about that, but no one in our group knows anything about GPR. Also, we will most likely be in the fully autonomous class, meaning it's not going to be remote controlled.

As far as how the magnet will be positioned in the ground, we have no idea. We also don't have any ...

Pneumatic spear like thing that jabs down into the sand a certain distance, with the sensor on it. Pull it up and move somewhere else and stick it back into the sand.

Would that work or am I talking out my arse?

Well it is a fairly large area, I think 20' x 20', and it is a race against the ...

Ya that's kinda the way we are leaning right now. They're cheap, so it's worth a shot even if it doesn't work out. I have no clue how sensitive they are since I have never used them.

I don't know yet. That is one of the guidelines they haven't given us, so I think we are supposed to assume that it is a regular beach with litter and such.

I will be going to a robotics competition in the fall. There are two classes of competition, autonomous and remote controlled. My team will most likely be in the autonomous division. The goal is for the robot to drive around in the sand and detect a magnet that is buried 6-12 inches deep. Once it ...

Sounds awesome if you're dumping that much air that fast. I would say get some tougher ammo, and see what kind of incredible results you get from that. Also a wad of a shock absorbing material behind the projectile should protect it from the jar of initial acceleration a little bit.

CannonBall wrote: i shot threw a house door but i hoped for more damage.

Like busting the back door down?

Awesome gun man. I feel inspired.

Oh. Well I guess it would be your call, I've never made a piston gun. I have done some plumbing, and we never had to wait 24 hours to run pressurized water through the pipes, more like one hour. Of course, the pressure was not much over 50psi. It's good that you thought about the impact from the ...

I have used guns at lower pressures just hours after gluing them. It would also depend on whether or not you are using a combustion gun. I have actually had the glue burn in a gun that I did not let cure completely. It didn't explode or anything, it just leaked for a while after that.

If you have one laying around, then it would work. It would look nice and clean that way also, you just don't quite get that homemade feel like yeti talked about.

That's sweet. I've been wanting to make a nerf sniper. I have to little pest brothers that I would love to get from about thirty feet.

What kind of performance are you getting? And what kind of pressures are you running?

That would be extrememly hard to open at those pressures!how mnay Square Inches do you think is on that buuterfly valves sealing plate?Then times that by 300psi and your getting close to the amount of force you are going ot need to get it to move.

It looks to me like it pivots in the the middle ...

So somebody needs to buy this and let us all know how well it works/how fast it opens.
Not it