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Total noob needs advice on the next step.

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: bullrees » Mon Jan 18, 2010 12:56 am

I drilled out the center like you said.........but also have some solenoid parts to cut off the air for that. The bleed already has a screw so why do I need to epoxy it? Crap....guess i brok my promise now.
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Unread postAuthor: MrCrowley » Mon Jan 18, 2010 12:58 am

I thought the bleed valve might get in the way and be a pain, but if you're happy with where it is you can simply leave it there.

Glad to see this is coming along nicely, you're picking up everything pretty fast.
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Unread postAuthor: bullrees » Mon Jan 18, 2010 1:18 am

Thanks Mr.C

I don't know if I'm getting it fast but I'm sure documenting my ignorance well. Hope it helps someone else.

Put in the fitting(outside view)
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inside



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EDIT:swear word
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Unread postAuthor: jackssmirkingrevenge » Mon Jan 18, 2010 1:34 am

bullrees wrote:I don't know if I'm getting it fast but I'm sure documenting my ignorance well. Hope it helps someone else.


That's fine, I post almost all my projects here, successful or otherwise, it leads to some level of ridicule but all in all is part of the learning experience.

One tiny editorial note, perhaps you could resize your photos slightly before posting them?
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Unread postAuthor: bullrees » Mon Jan 18, 2010 1:48 am

ok....... for real.....last thing in my noob post....just finished it with the advice of the great folks here. Thanks guys.

Finished( I think)
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Unread postAuthor: MrCrowley » Mon Jan 18, 2010 1:51 am

For starters I would get rid of the hose, limits performance. If you want to keep it, at least mod the blowgun (I believe I made a how-to on modding blowguns in the how-to section). Also get rid of the nozzle on the end of the blowgun, that will definitely hinder performance greatly!

After that, go try it out :)
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Unread postAuthor: bullrees » Mon Jan 18, 2010 2:08 am

jackssmirkingrevenge wrote:hahaha! Mom must be so proud :D

Definitely mod the blowgun, you'll be impressed by the difference. Also, 60 psi is a tad low, if you're using pressure rated fittings there should be no safety issues with cranking it up to 150 ;) except your your target of course, the c-cell should go straight through the monitor :D


You would be surprised at the size of the steel in the back of that monitor. But no worries...I also have an old 19 inch tv and so other bits and parts that will get the spudgun treatment.

As this was the first test after a good cure time on the parts I wanted to keep a low psi (60) in case i screwed anything up.

My compressor only goes to 125 psi but I'm sure I'll do that soon enough.
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Unread postAuthor: bullrees » Mon Jan 18, 2010 2:19 am

Sorry for the double post ....again. The sun was in my eyes, my shoe was untied, I had a flat tire, it sliped.....sry :P
MrCrowley wrote:For starters I would get rid of the hose, limits performance. If you want to keep it, at least mod the blowgun (I believe I made a how-to on modding blowguns in the how-to section). Also get rid of the nozzle on the end of the blowgun, that will definitely hinder performance greatly!

After that, go try it out :)


Getting rid of the hose is easy.....the fittings are the same.

I went with 3/8 hose because I thought it would do better than 1/4 but didn't think of no hose at all because of trigger placement.

Crap....didn't know there is a blowgun mod at all. Now I have to fire my whole blowgun staff..they were lazy anyway. I'll have to look into it myself.
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Unread postAuthor: MrCrowley » Mon Jan 18, 2010 2:23 am

A 3/8" hose would be worse because it has more volume. Which means the blowgun takes longer to 'evacuate' the pilot volume of all the air, which means the valve opens slower which in turn means lower performance.

A blowgun mod is not essential at all if you don't have a hose on there anymore, but it does help. Not sure how much performance increase you would get on a cannon this size though.

Maybe for now it is best you leave it, you'll only be missing out on something like 30fps at most I would think. You can really start seeking performance with your next cannon, there will be a next cannon right? :P
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Unread postAuthor: bullrees » Mon Jan 18, 2010 2:41 am

MrCrowley wrote:A 3/8" hose would be worse because it has more volume. Which means the blowgun takes longer to 'evacuate' the pilot volume of all the air, which means the valve opens slower which in turn means lower performance.


I'm a bit lost there...as long as it gets out of the valve who cares where it goes then.Seems bigger is better/leaves faster and allows the main to open faster.

EDIT: I see now...the bg would need to be 3/8 also.


Yes there will be a next gun...I bought two sets for this but even so. You fools have set me on a course to the poor house.
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Unread postAuthor: jackssmirkingrevenge » Mon Jan 18, 2010 2:47 am

bullrees wrote:You fools have set me on a course to the poor house.


Unless the little guy's aim improves, it will be the poor-but-well-ventilated house :D

I concur with MrC, lose the hose and the nozzle on the blowgun and crank up the pressure.
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Unread postAuthor: MrCrowley » Mon Jan 18, 2010 2:51 am

I'm a bit lost there...as long as it gets out of the valve who cares where it goes then.Seems bigger is better/leaves faster and allows the main to open faster.


Everything between the diaphragm in the valve to the blowgun is under pressure (this is called the pilot volume). If the pilot volume was say 5cm^3, which is bloody tiny, when you trigger the blowgun the pressure in the pilot volume would pretty much immediately escape out the blowgun in to the atmosphere. This would mean the diaphragm in the valve can open straight away with no flow restrictions (from any pressure still being in the pilot volume).

If you increase this area to 50cm^3, naturally the blowgun will take longer to remove all the pressure from the pilot volume. Which means the diaphragm can't open as fast and with as much flow in the same period oftime. It's quicker to empty a bath with only 500ml of water in it compared to 5000ml of water.

I see your theory is that if the hose has more flow, the air can escape faster. That's true if your blowgun was also 3/8", but there is a point where having a hose with more flow, which increases volume, will be worse than having a hose with less flow but smaller volume (assuming you keep the same sized pilot valve).

There'll be a fine line between the two somewhere, but it doesn't really matter since you don't need a hose in the first place. But you are correct in thinking that bigger is better when it comes to pilot valves. You could pilot that sprinkler valve with another 1" sprinkler valve and you would see better performance.

Sorry for the long post, bit unnecessary as I can see you already get the logic behind it. :P
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Unread postAuthor: bullrees » Mon Jan 18, 2010 2:57 am

jackssmirkingrevenge wrote:I concur with MrC, lose the hose and the nozzle on the blowgun and crank up the pressure.


Done............ hose is gone....camera battery is dead so I'll update this in the am.
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Unread postAuthor: bullrees » Tue Jan 19, 2010 9:16 pm

Sry double post...again but Mr. C made me with his bg mod.

Thanks for the explanation. I see what you mean now Mr. C. Basically the tube would need to pressurized also and that volume of air would need to exit ..slowing everything down.

I'll be increasing the pressures also.I just wanted to start with something lower to see how ricochets would act and to be sure all the joints were good.

Thanks also for the blowgun mod. I haven't fired the gun yet with a blowgun at all but I have a modded blow gun and a normal one. I am curious how I could test any increase in velocity. There seems to be too many factors involved to make a definitive conclusion without controlling many of the factors.

Anyways..point out any screw ups I made with the BG mod.

BG no hose
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Input from pressure side(original)
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Input from pressure side (mod)
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Output side(original)
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Output side(mod)
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Valve(original)
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Valve (mod)
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Unread postAuthor: MrCrowley » Tue Jan 19, 2010 11:07 pm

Much better pictures than the one I took :wink:
But it looks just like how I did mine. Personally i've never had it leak, but it has been known to happen. The only time mine leaked was when some dust and crap left over from the mod interrupted the seal so make sure you give it a good clean.

This should also get rid of that honking noise you can hear in your video. Let us know how your testing goes.
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