My first 2" cannon (just something little) :)

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.
High-PSI
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Wed Nov 03, 2010 9:45 pm

MrCrowley wrote:
Anyway, yes, I think this thing will out perform any plastic cannon
Any plastic cannon 2" and under anyway, there are some huge piston valved PVC cannons on the site lurking around :shock:

I love the cannon though, I think this design is much better than the original layout in your first post. It looks amazing and should be lots of fun. $400 is quite expensive for a cannon like this but I guess you pay for it in safety, performance, ergonomics and reliability. Damage videos are a must :)

Looking forward to seeing other cannons from you in the future.
Agreed. Yes, I know a 3 inch PVC cannon with a piston valve will do more damage at 100 psi than this cannon will at 200 psi. That being said, I just like overbuilt stuff.

Also, yes, it is alot of money for one cannon. But, I figure, this thing will be around for a long time. I am not worried about any problems with it. Besides, as I menitioned, the heavy weight reduces recoild quite a bit.

I have a nearly finished 1-1/4 inch cannon with a very similar layout. I am also building an all metal 300 psi 1/2 inch gun. I will post pictures of those guns as I have something of substance to share.

Matt
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Moonbogg
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Thu Nov 04, 2010 12:13 am

$400.00 for that cannon is not a lot in my opinion. To me, it seems well worth it to have a 200psi spud gun and not have to worry as much about it breaking or failing. By the way, and I hope I didn't miss this, but how much does it weigh?
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MrCrowley
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Thu Nov 04, 2010 12:22 am

Moonbogg wrote:$400.00 for that cannon is not a lot in my opinion. To me, it seems well worth it to have a 200psi spud gun and not have to worry as much about it breaking or failing. By the way, and I hope I didn't miss this, but how much does it weigh?
29 pounds :wink:

And yeah, for the reasons I stated, I think $400 can be acceptable for a cannon like that too.
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Thu Nov 04, 2010 12:27 am

MrCrowley wrote:
Moonbogg wrote:$400.00 for that cannon is not a lot in my opinion. To me, it seems well worth it to have a 200psi spud gun and not have to worry as much about it breaking or failing. By the way, and I hope I didn't miss this, but how much does it weigh?
29 pounds :wink:

And yeah, for the reasons I stated, I think $400 can be acceptable for a cannon like that too.
29...Yep, thats heavy!
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Thu Nov 04, 2010 1:17 am

Extremely impressed, and I think now that you've actually fired it you appreciate the recoil too, it will be worse with heavier "proper" projectiles so I really think some sort of muzzle brake is in order.

Also, your kids are very lucky to be involved in such father-son bonding experiences, I think I'm more jealous of that than the laucnher ;)

And yes, damage pics/videos and chrony results please!
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Thu Nov 04, 2010 1:29 am

Would a muzzle brake even be necesary? Though it would make it look badass :P

I imagine this cannon will see about 2500 joules max with heavy projectiles (~500g) and considering the weight of the cannon, recoil shouldn't be too bad. I actually fired a shot this afternoon which was at about 2200 joules (with a 25g projectile I think it was) and my cannon is only slightly heavier. Recoil was fairly insignificant. Then again, his launcher is shoulder fired and mine fired from the hip.

I guess if it isn't much of a problem to machine one, you may as well.
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Thu Nov 04, 2010 1:43 am

MrCrowley wrote:Would a muzzle brake even be necesary? Though it would make it look badass
Works for a 12 bore, will work for this :)

It would be amusing if this happened though :D

Image
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Thu Nov 04, 2010 6:00 am

Looks awesome with the new chamber arrangement. Is that compressor a Viair? I have one of them on each of my vehicles for the train horn setup and they're worth every penny!! Did you TIG weld that chamber? You can P.M. me if you need a place to shoot around here as we spoke about before! Keep up the good work man.
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Thu Nov 04, 2010 7:14 am

That is a Helix compressor. I looked at the Viair, but was told the Helix was higher volume? Who knows....... All I know is, these compressors are PERFECT for this type of thing. :)

The barrel on this cannon is 4 foot. I also have a 6 foot barrel threaded up and ready to go. But, that would make the cannon 8 feet long. Still, maybe I will machine a muzzle brake and have a 7+ foot barrel with a decent brake on the end and just install the longer barrel at the field (wherever that field is).

I still haven't even built the shoulder rest/stop. I may not, however. The gun seems fine without it. But, then again, I was only firing a 30 gram slug. I would imagine a 300+ gram slug would have crazy kick!

We shall see.

Fixer,

Yes, I will PM you. I have a family, so it can be tough to get away. But, what the heck, I need to really test this beast!

I am at the shop today. I will try to setup the twin compressor arrangement while there (or at least start on it).

Matt
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Thu Nov 04, 2010 8:20 am

There's some interesting discussion about recoil here, you could conceivably make a shoulder rest on which the launcher can slide on rails, and these could include a suitable spring/gas ram/hydraulic buffer. I wouldn't recommend you actual fire it from the shoulder for initial testing with heavy projectiles.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Thu Nov 04, 2010 11:25 am

One of the first things I noticed on looking at some of the models of the compressors is the 200 PSI Helix is 100% duty cycle, unlike any of the other 12 volt ones.
http://www.s10forum.com/forum/f233/chro ... rs-440763/

One of the reasons I bought the compressor I did was because I can run it with 100% duty cycle and not overload my car's electrical system. I can fill and shoot all afternoon. 200 PSI instead of my 100 PSI is sure tempting.

Filling a tire with a 12 volt compressor is not a problem for most compressors. Most won't handle an afternoon of shooting.

The Viair I looked up is listed for only 35% duty cycle. That in real terms is pumping for only 20 minutes out of an hour. Waiting 40 minutes out of each hour is not the way to spend the afternoon shooting.
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Thu Nov 04, 2010 12:02 pm

One thing to remember is the fact that claims for these compressors are normally WAY over-estimated. For instance, Helix claims 60 seconds to take a 5 gallon tank from 0 to 200 psi on 12 volts with only one compressor. That is a freakin CROCK! My Helix takes 2 minutes to fill my two gallon tank to 200 psi. Also, the compressor gets hot in that time. If I stayed with one compressor, I would definately install a fan on the head. Two compressors have twice the thermal mass (obviously) and will fill in half the time. So, heat should not be an issue. We shall see.

Beyond that, I want to try electric actuation for my pilot valve. I think my pilot volume (the trigger pilot tube) is too high. I can tell by the sound of firing the cannon that it is not opening as fast as it could. I know it is opening all the way, though, because the diaphram slug has marks from bottoming against the cap.

I will post more pictures and info as I have it.

Oh, the 29 pounds it weighs is not too much to handle. I do not think I would want any more, however. I am also nearly 6 foot tall, 185 pounds and really strong. So, maybe it is just not a big deal for me to handle. I do not know. I can say that I do like a little heft in my cannons. My PVC cannons feel like toys that are going to break at any moment. Of course, that is just my perspective. I do like the fact that I can build a PVC cannon in an afternoon. This one took me 20 hours to build.

Oh, bear in mind, I am using a lithium polymer battery pack, not my car's sytem. This is a truely stand-alone total system.

Matt
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Thu Nov 04, 2010 12:17 pm

I have a feeling the LiPo battery is not good for a full afternoon of shooting. Due to the noise, I presume you launch one shot and get before you attract too much attention. The sound in your video is fantastic. I could see that attracting all the neighbors to see what was going on.

After having shot a few hacky sacks at higher pressure, I presume it did not survive the shot. They tend to come apart at much lower pressure. I have found parts of them after I did some distance tests.
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Thu Nov 04, 2010 12:28 pm

That pack is only one of many I have. I build electric bikes as a side business. So, I have many of those. I also have a battery management system I will run the pack through so I can keep tabs on my power useage.

That one small pack you see on the video is good for about 15 to 20 shots (tank refills) before I would need to recharge it. Not too bad. I also have field chargers. So, that is no problem. I will, most likely, run two of those packs in the compressor.

Oh, and, yes, I fire it once, then go inside. I have to drive a few minutes to get to a large vacant area to do any decent amount of shooting. And, yes, the hacky-sack came apart partially in that shot.

What are your thoughts about my pilot volume and valve opening time? The reason I ask is, my 1-1/4 inch cannon has more of a "Rap" sound to it and this cannon has a bit of hiss as it fires.

Matt
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Thu Nov 04, 2010 1:19 pm

High-PSI wrote:What are your thoughts about my pilot volume and valve opening time? The reason I ask is, my 1-1/4 inch cannon has more of a "Rap" sound to it and this cannon has a bit of hiss as it fires.
Must be something wrong with my speakers then, if that muzzle report is what you call a "hiss" then I shudder to think what you would consider an impressive noise :shock:
hectmarr wrote:You have to make many weapons, because this field is long and short life
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