Second Cannon Ever

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
igotoneforya
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Wed Feb 07, 2007 1:52 pm

This is my second cannon I ever built. Its all SCH 40 Propane metered with dual spark ignition. I will be upgraded to Stun gun ignition. Its hard to get one shipped to NJ. Well what do you think Good?
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Last edited by igotoneforya on Wed Feb 07, 2007 3:18 pm, edited 7 times in total.
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MrCrowley
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Wed Feb 07, 2007 2:02 pm

Ok.






Can I see It?



Please :P
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StealthSpud
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Wed Feb 07, 2007 2:06 pm

Yeah it would be nice if there was a picture or something!
igotoneforya
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Wed Feb 07, 2007 2:24 pm

Sorry my pics are to large and i dont know how to link my photobucket pics to the forum.
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MrCrowley
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Wed Feb 07, 2007 2:42 pm

Photobucket gives you the URL and the IMG tag of each image you upload. Just copy and paste it. If you want the picture to show up you put....

[img]UrlOfPictureHere[/img]
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rl93
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Wed Feb 07, 2007 5:01 pm

ITs sch-40. I hope it dosent explode.
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MrCrowley
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Wed Feb 07, 2007 5:13 pm

Is that a wye? Wye's are DWV. Unless that's some special wye you got there.
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Pete Zaria
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Wed Feb 07, 2007 5:31 pm

Your construction is very clean, it looks well designed, planned, and built. Very nice second gun.

However, I'd bet money that wye is DWV.
Sch40 is just a measurement of wall thickness - it is NOT a pressure rating. It would need to say NSF-PW to be pressure rated. I think your chamber is NSF-DWV (Drain Waste Vent) which is NOT safe to use for hybrid mixtures. Fine for a regular combustion gun though.

How is this cannon a hybrid? I don't see a union or any other pressure-triggered valve, or a compressed air hookup... A hybrid gun uses a PRESSURIZED fuel/air mixture, where a combustion gun uses a fuel/air mixture at atmospheric pressure. Are you pressurizing your chamber before ignition? If not, it's not a hybrid. I would NOT risk firing a mixture above 1.5x in DWV pipe, at least not if I was anywhere near it.\
Also, your chamber fan would work better and last longer if you moved it to the back end of the combustion chamber. Fans at the front tend to get fried after a while.

Again, very nice design and construction. Let me know about the hybrid part though please.

Peace,
Pete Zaria.
Last edited by Pete Zaria on Wed Feb 07, 2007 5:51 pm, edited 1 time in total.
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zeigs spud
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Wed Feb 07, 2007 5:37 pm

it's your second cannon ever and it looks great!!!!!

prob is that it isn't a great cannon...sorry :?

you have the vent fan right where the barrel connects to the chamber...not good idea...

that and how is it a hybrid? got any busk diskis for it?
igotoneforya
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Wed Feb 07, 2007 6:13 pm

Well first off the wye is dwv and if you look the fan is in the rear not by the barrel. All i keep reading is how dwv fittings are no good. I have been to every plumbing supplier online and i have yet to see a SCH 40 fitting over 2 inches. I would like to know where these SCH 40 or Sch 80 parts in four inch can be found. Money is no object to me when building a cannon i would love to find fittings in SCH 80 in four inches i just don't see them. When i would ask for SCH 40 fittings everyone of them come out with dwv ones. I have been so frustrated looking for these parts. I have read every forum i could find looking for info and yet to have found a place that sells SCH 40 fittings over 2 inches. I am trying to build something i can shoot and not worry about explosions. I wish i could find 4 in cleanouts caps hubs in SCH 80 any information ua guys give me would be great.
Last edited by igotoneforya on Wed Feb 07, 2007 6:20 pm, edited 1 time in total.
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MrCrowley
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Wed Feb 07, 2007 6:19 pm

http://www.mcmaster.com

Most people wouldn't use sch40 in a hybrid let alone DWV. Oh and can you explain how this is a hybrid? Where is the burst disk?
igotoneforya
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Wed Feb 07, 2007 6:26 pm

I guess its not a Hybrid i thought a propane meter made a Hybrid. Would this be safe for regular combustion say Right Gaurd? What about my last post about SCH 40 or SCH 80 parts over 2 inches?
Killjoy
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Wed Feb 07, 2007 6:28 pm

one word...mcmaster.com
also, how is that a hybrid? I can't see any place for air input and im suspicios of that dwv, but then again ive put oxygen and acetylene in a pvc cannon and almost died so im not one to talk about safety.
Still the cannon looks awsome.
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BC Pneumatics
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Wed Feb 07, 2007 6:32 pm

Killjoy, your post is very repetitive. Read the posts before you, and don't mimic what others say.
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Pete Zaria
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Wed Feb 07, 2007 6:33 pm

igotoneforya wrote:I guess its not a Hybrid i thought a propane meter made a Hybrid. Would this be safe for regular combustion say Right Gaurd? What about my last post about SCH 40 or SCH 80 parts over 2 inches?
Read up on hybrids here: http://www.spudfiles.com/spud_wiki/inde ... rid_cannon

Yes, your current gun is safe to burn Right Guard or even propane in. Just no hybrid mixtures of propane/compressed air.

I get pressure rated stuff from local plumbing supply stores - never hardware stores. All hardware stores have is DWV and common brass parts. If you don't have a local plumbing supply store near you, you'll have to order online.

Even if it's not a hybrid, your design and construction are very clean for only your second gun. Nice job. When you do attempt a real hybrid, I'd suggest using SCH80 NSF-PW parts ONLY. Or metal, if you can afford it.

Peace,
Pete Zaria.
Last edited by Pete Zaria on Wed Feb 07, 2007 6:37 pm, edited 1 time in total.
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