Gun Pump designs

General water gun discussion.
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zeda.beta
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Gun Pump designs

Post by zeda.beta » Thu Apr 08, 2010 10:22 pm

Hello,
I was wondering what the difference is between homemade and commercially made pumps? Some people try to build them because they will be more reliable, but others say that the scrounged ones from old guns work best. Why the difference?
-Zeda
Edit: Martinshark pointed out that this is the 1000th thread!
Last edited by zeda.beta on Wed Apr 14, 2010 9:05 pm, edited 1 time in total.
I reject your reality and substitute my own.
Quack damn you.

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martianshark
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Re: Gun Pump designs

Post by martianshark » Thu Apr 08, 2010 10:40 pm

Homemade pumps are harder to make, and hard to make reliable. However, you don't have to go rip it off an old gun and it's made out of wood, which is a lot stronger than plastic. This is especially good if you're selling homemades because the materials are ready to go at the hardware store.

Salvaged pumps are much easier to get because you can just take it off an old gun, so you don't have to go through the trouble of building one from scratch. They tend to be flimsier, but you can put a wooden dowel down the rod to make it stronger. Many people prefer to get salvaged pumps rather than buying a correctly sized wooden dowel, buying correctly sized O rings, attaching them, figuring out where to get a handle/how to put a handle on, etc... For personal homemades, salvaged pumps are usually the best choice.

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cantab
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Re: Gun Pump designs

Post by cantab » Thu Apr 08, 2010 10:59 pm

A third option would be commercially-available pumps. The only things that I know of that would do the job are syringes, but getting large enough ones might be tricky. Perhaps contact a lab supplies company for a 'gas syringe', they're quite big I think.
I work on Windows. My toolbox is Linux.
Arsenal:
Super Soaker: XP215, 2xXP220, Liquidator, Aquashock Secret Strike M(odded), Arctic Blast M, CPS1200, CPS2100, SC Power Pak, 3l aquapack, 1.5l aquapack
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soakernerd
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Re: Gun Pump designs

Post by soakernerd » Thu Apr 08, 2010 11:09 pm

The other day at home depot, they had a big syringe with check valves. it was for pumping water out of a basement or something. I would have gotten it, but for $30 it didn't seem worthwhile.

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martianshark
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Re: Gun Pump designs

Post by martianshark » Fri Apr 09, 2010 2:39 am

I saw something like that there too, but it was more like $10.

Wouldn't syringe guns be cheaper? They have a ton of them at my dollar store. Of course, it would probably only be good for some CPS homemades because the thin plastic would break on an APH once pumping gets hard.

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soakernerd
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Re: Gun Pump designs

Post by soakernerd » Fri Apr 09, 2010 12:45 pm

I usually use dollar store syringes as plungers for homemade nerf guns. For some reason, I never thought of using the as pumps. The big difficulty to overcome there would be mounting check valves.

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C-A_99
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Re: Gun Pump designs

Post by C-A_99 » Fri Apr 09, 2010 6:00 pm

The diameter of those syringes may be too high which will make pumping more difficult. Getting them attached to a check valve system is easy though; simply seal it to where the homemade pump would usually go. These syringes have at least as good of a chance to become properly working pump as any homemade does since the conventional methods of creating homemade pumps have so many problems it's not even funny.

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zeda.beta
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Re: Gun Pump designs

Post by zeda.beta » Sat Apr 10, 2010 3:17 pm

Then I might consider using this huge syringe I have laying around, it is around 1 1/2 inches in diameter.
-Zeda
I reject your reality and substitute my own.
Quack damn you.

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martianshark
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Re: Gun Pump designs

Post by martianshark » Sat Apr 10, 2010 6:05 pm

That would probably be way too big.

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cantab
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Re: Gun Pump designs

Post by cantab » Sat Apr 10, 2010 8:35 pm

Depends on the use. For an APH, it will reduce the maximum pressure you can reach. But for a CPH, the pressure is determined by the bladder. I believe most commercial CPSes actually use relatively low pressures. Indeed, a lower pressure for a CPH has an advantage - it allows a larger-diameter pump given the same pumping force, increasing pumping flow rate, which in turn makes larger pressure chambers and higher outputs more practical. The Water Warriors Hydra Pak exploits this to some extent I believe.

Also most stock guns are meant for kids. Adults are usually stronger.
I work on Windows. My toolbox is Linux.
Arsenal:
Super Soaker: XP215, 2xXP220, Liquidator, Aquashock Secret Strike M(odded), Arctic Blast M, CPS1200, CPS2100, SC Power Pak, 3l aquapack, 1.5l aquapack
Water Warriors: Jet, Sting Ray M, Shark, Argon M, Tiger Shark, PulseMaster
Others: Waterbolt, The Blaster, Storm 500, Shield Blaster 2000, generic PR gun, generic backpack piston pumper (broken), 3l garden sprayer M, 10l water carrier:

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C-A_99
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Re: Gun Pump designs

Post by C-A_99 » Sun Apr 11, 2010 3:41 am

The problem with lower pressure CPS is that the stream velocities are fairly low. Slower streams are far more easy to dodge regardless of how much range the nozzle may actually have. Any pump above 3/4" is far too large and will require a very weak PC or it will be considerably difficult to pump. Pumps that are too stiff also tend to be more exhausting to operate.

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