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Simple mass-producable gun

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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What do you think of this gun?

Poll ended at Sun Feb 22, 2009 9:42 am

Good gun!
4
17%
Could be better
6
25%
Neutral
5
21%
Lousy.....don't bother with mass producable guns!
9
38%
 
Total votes : 24
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Simple mass-producable gun

Unread postAuthor: limbeh » Sun Feb 08, 2009 9:42 am

This is a simple chamber - ball valve - barrel gun.

It's purpose is not so much for shooting, but more as a training tool in my science club (which I run).

It is extremely cheap & easy to make. Unit cost is about S$8 per gun (using new build components & after factoring epoxy and PVC primer & cement), while assembly time is around 15 minutes if guns are individually built, and around 10 minutes if they are mass produced by a group of people assembly line style. However, the 3 day epoxy drying time cannot be ignored.

It's purpose is as a fun way to train juniors in construction skills like drilling (which they can later use in research), and research skills like safety & observation. For this, many aspects of these are advantages:

- Simple - easy to teach the skills
- Cheap - can be done on a large scale
- Basic generic design - opportunities for juniors to be creative and modify the design, so long as it is constructed properly (I am supervising)
- Inefficient - opportunities for juniors to think of how to improve
- Dirty - make them get used to it
- Not so ghetto - I can control parts to prevent unauthorised production.

Unauthorised production is dangerous because there is always the risk that someone tries to build one on their own, WITHOUT SUPERVISION, does something stupid and gets spudding banned in the process (this is Singapore........even Australia can't compare in strictness).

Pictures are below. No damage pics as we do not destroy things with them and we have not made enough ballistic gel yet. Videos will be uploaded soon when my firing range (some open ground in school) has nobody around.

Any suggestions or comments about this?

Thanks.
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Unread postAuthor: john bunsenburner » Sun Feb 08, 2009 9:55 am

Personally i think there are a few better ways to get kids close to science. Also the kids might get the idea of making their own guns and seeing how simple this one is i doubt they will be very experienced and will get hurt. If you want to teach physics build a tesla coil with them or an induction heater or a coil gun, lost of fun and its a little more difficult to replicate at home. Another thing they might enjyo is a vortex chamber, which is very simple teachers quite alot of phisics and cn even be used( have a brain stroming session in which they can exchange ideas about the real world use of these machines). Over all it is a very nice idea but i am afraid its not very doable. What would be intresting is wether or not your little club is volantary and what age the kids have and what exactly you want to teach or demonstrate.

P.S. I have a friend that is in Singapore and says its great.
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Unread postAuthor: Biopyro » Sun Feb 08, 2009 10:21 am

Realistically it would probably cost only a small amount more to use a PVC chamber - just to make sure they are clear on only using parts which are definately safe. Imagine a few years down the line, the kid attempts a replica and forgets you need a fizzy drinks bottle - ouch!
Otherwise it's good, but I'm not sure all those fittings are necessary - Perhaps by using a PVC chamber you could keep the same price because you'd cut out the fittings.
I had a look at putting something similar together, and the most expensive bit is the valve Which is £50 for 5, the pipe for 5 is £20!
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Unread postAuthor: john bunsenburner » Sun Feb 08, 2009 10:23 am

Make a hammer valve its the cheepest way and i can make about 50 in a hour i bet you can to.
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Unread postAuthor: limbeh » Sun Feb 08, 2009 10:47 am

The kids are about 14-15 years old.

Yes, this is only one of the activities that my club does, but this is a spudgunning forum, so we only post the relevant stuff up there.

At a club level, spudgunning is a means to an end, not an end in itself. We probably spend like a day or two building and shooting the thing, plus another few days on safety, then we move on.

As it is, we do have a few sessions to show them the dangers: A defect cannon, plus a few youtube videos where things go wrong when it isn't feasible to show the thing for real, as well as our older ones telling stories about their own accidents. That works for us.

All guns and tools are locked up in school in very secure areas (metal cabinets with multiple locks in a locked room). I run this like a military armoury, so nearly impossible for the kids to steal guns.

As for controlling parts, it's quite easy in Singapore. PVC primer for one is almost impossible to find.

As for cost, this is the breakdown of costs:

- Ball valve $4.50
- schrader valve - 20 cents
- 1/2" pipe - 3ft min - 30 cents per foot
- 1/2" fittings x 2 = 30 cents each
- 3/4" fittings - 50 cents each
- epoxy glue, pvc primer & cement - about $1
- Bottle - free, go get a dumped one

About S$8 per person. In perspective, with S$8 you can eat 3 meals here (or 1 at McDonalds), so it's not that cheap for them to make one everyday.

I don't see much use in having a PVC chamber....adds unnecessary costs and trouble transporting them when discarded soft drink bottles are free and on site.
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Unread postAuthor: Biopyro » Sun Feb 08, 2009 10:58 am

Fair enough - don't get me wrong, I love the idea, there really are few better was to get kids into science and it really pleases me to see someone taking it into their own hands.
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Unread postAuthor: john bunsenburner » Sun Feb 08, 2009 11:15 am

14-15...i also think spudguns are good fun but shouldn^t they be on a slightly higher levle...I just dont quite see the point, sorry...
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Unread postAuthor: Biopyro » Sun Feb 08, 2009 11:20 am

Woah no! Many of the people here are much older and still enjoy spudguns.
It's not so much that they are learning the basics of these things, but just seeing how it's fun. Spudguns can be challenging for someone with any amount of engineering knowledge.
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Unread postAuthor: sputnick » Sun Feb 08, 2009 11:20 am

I do not understand, so you want to mass produce these guns, and not allow them to make them their selves, but you think it will be able to teach them about skills like "drilling"? I assume you must mean military drilling, also, teaching kids that pop bottles are a safe air container really does not sit well with me, you will have a whole group, specifically the ones you taught and the friends of those you taught, going around trying this at home, and ending up with exploding pop bottles. I'm sorry, but this whole idea seems rather daft. I would try to design something like this, simple still, but maybe more safe, say just 3/4 pipe/ball valve/ then 2 45 elbows to make it more stock like, then a 1/2 inch copper stock, a small one. That way, there is absolutely no danger of them over pressurizing, and the very limited C:B ratio means it will be near impossible to do any real damage, if this is just a tool to teach about science, then you don't need a large amount of damage, you wouldn't put volatile chemicals into the hands of novice chemistry students, so why would you give them a gun capable of doing real damage...

In my opinion, I would say if anything, give the students very small, underpowered guns, with very strict safety equipment (again, another skill they really need in a science career) and then if you really must demonstrate a powerful gun, keep one very large one for the teacher to demonstrate with. I'm sorry, but I do not like your original idea, it does seem to much like you are urging kids into building potato guns, instead of actually introducing them to science.

EDIT: and also, kids not being able to find the materials is a very bad thing in my opinion, if there's one thing you don't want is to have kids finding all the materials they need, then upon finding no proper glue, using white glue to attach pipe. I personally would make building the gun a special part of the experience, give them each a little film canister of glue, all the pieces for the gun and the PVC CHAMBER since pop bottles are not a safe air containment method, and maybe see if they would be more interested in going into a career in the skilled trades or some other construction job, because remember, you are not trying to force kids into going into science, so this could be a multi-job experience.

EDIT EDIT: I really need to stop writing an essay about everything...
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Last edited by sputnick on Sun Feb 08, 2009 11:31 am, edited 2 times in total.
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Unread postAuthor: CpTn_lAw » Sun Feb 08, 2009 11:22 am

this is a good first for a 12 yr old. as long as pressure is limited to...say 60 psi. after that, they should learn how to do it themselves. Plus, making this a mass production implies there is a mass demand...and i doubt that.
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Unread postAuthor: trigun » Sun Feb 08, 2009 11:24 am

Well i think 14- 15 year olds are very well capable of handling the responsability. The problem is the 1 or 2 kids that aren't and do go and blow something up. One thing leads to another and your to blame be careful.

P.S. I'm only 16 so i got to support my age group
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Unread postAuthor: sputnick » Sun Feb 08, 2009 11:31 am

TRIGUN, yes you are 16 and very likely capable of handling it, but remember he is talking about children who have never dealt with these before, and so could have zero knowledge of firearm safety, of pressure ratings, of just common sense for that matter. I suppose this idea could be acceptable if he spent the first 2 or 3 days with smaller projects that built up to that one, and taught everyone about safety, but again, that transforms it into not a science club project, so much as a gun club project, and I am reasonably sure that many people would not take so well to that.
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Unread postAuthor: limbeh » Sun Feb 08, 2009 11:54 am

I'm a student, not a teacher. A few years older than trigun.

The whole idea is to give the kids an overview of what they can do, and they can continue further on the things that they like in their own expense and time. As for how this has to do with research, it's is another long story.

Well, seeing the kids, I'm quite sure that most of them can be trusted after some time, but as trigun has said, its the 1 or 2 hardcore destructive ones that are the most dangerous ones that I have to prevent. Even here, despite children being more guai than what I hear of going on in the West, there are still such cases around. Thus, all the controls.

Not that I don't let my people make guns, but I don't let them make guns without my knowing (they can make them all they like when I'm around). Giving them the components would result in them proliferating - you can't control what they do with them.

Even if they build a safely functioning gun, spudguns are dangerous by nature - they shoot. I don't know about the West, but kids here aren't familiar with gun safety (as guns and quite a lot of weapons here are illegal), so the chances that someone does something stupid with them is high. Better not to tempt them.

We counter the inferior parts substitutions by having the exploding cannon demonstration. And btw combustions and hybrids are illegal here so that makes our job easier by eliminating the 2 more dangerous spudding methods.

I thought pop bottles were safer in that they don't explode like PVC but rather rip like ABS? Which is exactly what I need to limit pressure.

Our practical pressure limit is 90 psi - we limit to standard bicycle pumps (I don't allow anything else) and they have hardly gotten anything more than 95.
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Unread postAuthor: SEAKING9006 » Sun Feb 08, 2009 6:09 pm

I am all for this.

Reason; You gotta remember, these are high school students. When you bring up one thing about them, you can't forget all the others. Such as attention span, and how much you can press something to them.

If you spend a week discussing the construction of these things and safety, they aren't going to forget what happens when you don't make them right, because every time they were taught about making them they had endless safety regulations slammed down their thoughts. And as they are taught, for good reason. It's the same as teaching one's son to shoot. You really never end up discussing or using a firearm without the whole safety deal. Remember, if they end up thinking about making one later down the road and you taught them well, they will think; "How did this go again? Oh yeah, bottle... Wait!! It has to be a soda bottle or it could explode! I've seen what badly made cannons can do, and I don't want to loose an arm."


It's not WHAT you teach them to do, it's how safely you teach them to do it. Like how my Dad taught me with guns, which began at age 5 with a pellet rifle, and my first lever-action .22 at 7 (and I think I remember throwing knives at a tree around age 4). To this day, I feel awful weird holding a gun anywhere but a range or in a burglar's face (which he also taught me to take care of. God help any man who dares break into my home).
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Last edited by SEAKING9006 on Sun Feb 08, 2009 8:47 pm, edited 1 time in total.
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Unread postAuthor: Killjoy » Sun Feb 08, 2009 7:58 pm

I did something similar to this this summer. I taught a camp of twenty six 11 to 15 year olds how to make piston valve cannons. Took a little over a week but was well worth it.

It was really a great experience to teach kids how to use dremel tools, saws, and drill presses and show them that 15 bucks and some manual labor on their part can result in a cool thing they can be proud in. And also to teach the kids how to use tools safely and to also teach them firearm and cannon safety, something their parents had never done or just had no idea about.

I'm really glad to see someone else following a similar route to teach kids about this kind of stuff. I feel like in this age of technology the concept of working with ones hands and the concept of personal safety has been lost.
I also like the simplicity of this one, good to get the kids started, though a more advance design could be suggested for the near future,

Two thumbs up on this one. I'd give it three thumbs up if I had another thumb.
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