CBHV: Masterclass entry

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
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Brian the brain
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Tue Aug 30, 2011 3:52 pm

Well...what the heck..

Let's turn this into a build log:

Need to fix a damaged O-ring on the checkvalve ( due to a bur on the hole for the fixating bolt.. :cry: ) I'll fix that tomorrow.

The pump piston is solid brass ( 25mm round bar) with a floating O-ring and airpassage cut into the head.

It connects to the Leverarm via a 9 mm steel rod, one end lathed to fit the mechanism and heat-crimped onto the piston head.

I also need to clean up the cut out on the seamless pipe. :roll:

I have gone with a massively large reservoir ( for this design at least) so the pressure will stay high up to the point where the ammo leaves the muzzle.This will be tuned in by adjusting the hammer spring. :wink:

So...The first time I'll pump it up it will need a LOT of pumps...after that the reservoir will retain some pressure so I won't have to start at 1 Atm.
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It's got a leaky O-ring on the outside of the checkvalve due to a burr...I'll fix it tomorrow.It does build up pressure though!
It's got a leaky O-ring on the outside of the checkvalve due to a burr...I'll fix it tomorrow.It does build up pressure though!
Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Labtecpower
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Tue Aug 30, 2011 3:57 pm

Ziet er mooi uit!

Je bent ook wat onderdelen van hang- en sluitwerk aan het gebruiken zie ik :D

Nog steeds de buis van de brommer?
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Brian the brain
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Tue Aug 30, 2011 4:26 pm

Nu niet meer...' t is nu een pompbuks :wink:


Oh...it's working now. :D

It just needed some cleaning and some oil.Now everything seals and it builds up pressure pretty well!
Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Gun Freak
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Tue Aug 30, 2011 4:42 pm

Holy god...
Screw the contest... You won :D
OG Anti-Hybrid
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Golf Ball Cannon "Superna" ■ M16 BBMG ■ Pengun ■ Hammer Valve Airsoft Sniper ■ High Pressure .22 Coax
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MrCrowley
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Tue Aug 30, 2011 5:36 pm

Image

Just kidding, please don't hurt me! :D


This looks really amazing Brian, you seem to have outdone yourself again with the new valve and the design looks great so far.
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POLAND_SPUD
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Tue Aug 30, 2011 5:47 pm

cool

now if I might provide some constructive criticism...

have you considered putting the pump the other way round... uhmm I guess that isn't clear enouh

I mean that the lever gives you most force when it isn't needed (at the very few cm of stroke) and least when it is most needed (the last few cm of stroke)


Also... what's the point of this type of pump... wouldn't it be better to build a smaller pump (piston OD of let say 6mm) without a lever?

Note that I understand that how these pumps work... my question is wouldn't it be better to do 10-12 strokes instead of let say 3 strokes that require more strenght ?
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Technician1002
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Tue Aug 30, 2011 5:54 pm

That pump style is noted for a good mechanical advantage on the last 10% of the stroke. This is why it is popular on air rifles. Air rifles don't come with a straight stroke like a bicycle pump for a good reason. The mechanical advantage permits higher pressure.

Air compresses. Pump resistance is high on just the last part of the stroke.
A water pump works better with a linear motion. Resistance is the same the entire stroke length.
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POLAND_SPUD
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Tue Aug 30, 2011 6:05 pm

ohh yeah sorry I must have had a brain fart... I own a PCA airgun that has exactly the same pump design
I mean that the lever gives you most force when it isn't needed (at the very few cm of stroke) and least when it is most needed (the last few cm of stroke)
It's exactly the other way round, sorry :D

Still the piston seems rather large.. are you planning to develop a PCA or a PCP with an onboard pump.. mind you I am not asking about this particualr gun but what you are aiming at?
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warhead052
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Tue Aug 30, 2011 9:25 pm

Holy crap that looks good. I thought it was going to be a pneumatic mp5 though?
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jackssmirkingrevenge
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Tue Aug 30, 2011 11:35 pm

Labtecpower wrote:Ziet er mooi uit!
Agreed :shock:

About time we saw a decent self-contained HPA launcher :D
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Brian the brain
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Tue Aug 30, 2011 11:54 pm

Still the piston seems rather large..
A large diameter means that dead space is smaller in comparison to the length of the stroke.

I tried a 16mm version earlier and that topped out at 20 bar while pumping remained easy
The stroke simply wasn't long enough to compress it any further.

The O-ring groove and checkvalve moevement mean there is a small amount of dead space.This determines the limit of the pressure the pump can reach.
Holy crap that looks good. I thought it was going to be a pneumatic mp5 though
?
Not really.I said the valve could be used as such when you use a T-bolt system and run the reservoir on top of the barrel.

I'll try a CO2 version later.

I've always wanted this sort of -" all I need is dirt"- type of cannon.
I have some more pipe So I can experiment with different designs.Just Have to switch the valve over.
Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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wyz2285
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Wed Aug 31, 2011 4:58 am

Looks really good, But I thought you were going for a PCP :roll:
CpTn_lAw wrote: :D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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jackssmirkingrevenge
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Wed Aug 31, 2011 5:11 am

wyz2285 wrote:Looks really good, But I thought you were going for a PCP :roll:
He is going to have a self contained launcher with the performance benefits of a pneumatic but which will not need compressors or external pumps, I think it's a pretty good project.

Check out the FX Independence - 30 ft/lbs and no need for a SCUBA tank to fill it (though you still have the option), heck if I wasn't reserving spare cash for machinery and tooling I'd definitely buy one!
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Brian the brain
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Wed Aug 31, 2011 6:16 am

Get the machinery and build your own!
Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Labtecpower
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Wed Aug 31, 2011 6:19 am

Get the machinery and build your own!
I don't think you have excuses, do you? :D
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