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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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Unread postAuthor: POLAND_SPUD » Tue Feb 10, 2009 1:30 pm

@john bunsenburner
don't take it personally but I think you should spend some time on improving your english...
not that I think that mine is good but this should help you to express your ideas in a way that would be easier to understand by other members...

first of all, do not translate word by word from your language... instead find equivalents of expressions from your language in english...

secondly, spend some time organising your ideas into several paragraphs.. this really makes the text a bit easier to read...
if you can't explain something using words then add some pics


again.. no offence but I stop reading your post after 4th or 5th line becasue it's just one neverending paragraph and I takes me several seconds to understand what you tried to say in each sentence...

if you want people to read your posts make them readable and understandable...
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Children are the future

unless we stop them now
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Unread postAuthor: john bunsenburner » Tue Feb 10, 2009 1:38 pm

Sorry about the block text, it should be more easyly readable now.
I am not sure if i am really using words form my language atleast i couldnt spot any.
I will try and not write in these big long block texts any more as i see how difficult they are to read. Thanks for pointing it out to me poland.
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"Did you ever stop to think that out of the seven deadly sins envy is the only one which doesn't give the sinner even momentary pleasure"-George Will
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Unread postAuthor: limbeh » Tue Feb 10, 2009 8:34 pm

True.....no hard feelings indeed. It's just that my science club spudders who were helping me out were with me then and we were all laughing like nobody's business. Many of them take part in Chemistry & Physics Olympiads.....

Now in all the ruckus I forgot to answer the question. Yes, the club is totally voluntary (in terms of joining), it's not like we operate a science club conscription . We go by a crawl-walk run style - we start them off with basic level stuff like the crappy spudgun which you see, then we progress on to more advanced stuff. Along the way, if they choose to advance to further levels like spudding, we help them out also.

I understand well your feelings about teachers / senior students who don't let you develop your plans, since I had that in some other group (some cadet corps) back and my plans to run hard PT sessions got constantly rejected. That's exactly what I'm trying not to be! That's why I'm here looking for better ideas......

And of course, yes, we want all the intelligent kids we can get, but the problem is managing it. They cannot be managed in the same way, we have to manage each one differently. And the risk is high: any of them does something dumb and we get into trouble, having the police show up isn't a sneezing matter here.

Plus, spudguns are very attractive. Already we have requests from people who are willing to pay us to make spudguns for them (and we tell them either to join us or forget it). Therefore the temptation to smuggle a spudgun out is very high. Thus all the safeguards to make sure that spudguns don't get into the wrong hands and that the complete knowledge of where to get what doesn't get into the wrong hands.

We would probably have to emphasise danger by having an exploding cannon (note: deliberately built improperly so it explodes) every now and then to scare people that spudding is dangerous, don't try it on your own, come to us.......
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Last edited by limbeh on Fri Feb 20, 2009 10:40 pm, edited 1 time in total.
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Unread postAuthor: maverik94 » Tue Feb 10, 2009 10:13 pm

Ok, sounds like you really are into leading this club! Cool! Anyway, Be carefull, and good luck to you! (Hope no-one gets hurt and cops dont get involved)
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Unread postAuthor: Ragnarok » Wed Feb 11, 2009 12:22 am

limbeh wrote:Ah.... finally Ragnarok comes. Was waiting for him to comment on the gun.

It seems like everyone expects my input on things these days...

john bunsenburner wrote:I am not boasting, i wouldn't of posted any of this if not to prove a simple point: That preventing the hardcore kids is simply the wrong way about it!

It was an attempt to demonstrate that the kids that sometimes behave like "hardcore" children are actually the brightest ones. All I want to say is that each and every one of these children might or might not become something great academically speaking and that you have to give each of them a fair chance.

You're assuming all hardcore is good hardcore. Most people on this forum are hardcore, and most of those a good hardcore.
However, there are people who's interest is just making a mess for all the wrong reasons. I know of people who would be very interested to get their hands on my launchers, but for all those wrong reasons.

Just like most people use firearms responsibly, but there's a number of people who get over obsessed and determined to misuse them. It depends on WHY they're hardcore about it.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: limbeh » Wed Feb 11, 2009 1:58 am

Ragnarok wrote:You're assuming all hardcore is good hardcore. Most people on this forum are hardcore, and most of those a good hardcore.
However, there are people who's interest is just making a mess for all the wrong reasons. I know of people who would be very interested to get their hands on my launchers, but for all those wrong reasons.

Just like most people use firearms responsibly, but there's a number of people who get over obsessed and determined to misuse them. It depends on WHY they're hardcore about it.


That's just what I was trying to say. My Ingeris needs to improve.....

Ragnarok wrote:It seems like everyone expects my input on things these days...


That's the end result of having a well earned reputation as an "expert" in spudding......people like you and JSR are the main sources of help that people turn to in constructing spudguns.

maverik94 wrote:
(Hope no-one gets hurt and cops dont get involved)


The cops already are. My own brother is a cop.....that's why my cannons are hardly if ever at home.......
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Unread postAuthor: john bunsenburner » Wed Feb 11, 2009 11:59 am

Ok another litte question or two:
1.How many people do you have there?
2.You talk of higher levle things, what would that be?
3.What main aspects of science are you focusing on? Spudguns are mostply physics(thoug in a combustion and hybrid chemistry gets involved) while most other "cool" things(atleast at this age) involve chemistry(anything from sodium to thermite and true explosives is regarded as cool)
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Unread postAuthor: maverik94 » Wed Feb 11, 2009 3:12 pm

ahhhh, does your brother know about the spud-guns? Also, what is the consequence of being caught shooting one of these things or even making one in singapore, a fine? confiscation? both? even jail? Just curious.
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Unread postAuthor: john bunsenburner » Wed Feb 11, 2009 3:25 pm

A coutnry where oyu get a fine for spitting gum on the street...or even arrested...i wonder what you ge tfor a spud gun
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Unread postAuthor: maverik94 » Wed Feb 11, 2009 3:37 pm

lol yeah, thats why I love it here in the us, Few restrictions! and it's awesome here in ky, No laws!!!! No cops!!!! Because we just don have the money, the state's broke :lol:
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Unread postAuthor: limbeh » Thu Feb 12, 2009 8:52 am

Yes, chemistry would be fun, but bear in mind that this is Singapore, you need licenses for lots of things, chemicals in particular. That's a good reason why we don't play with chemicals much. Besides, there are other fun things not involving like chemistry - like high voltage and the lot.

Of course, many of these are dangerous, hence the extremely tight control on people trying to build things on their own, lest we end up winning a few Darwin awards (I just heard of it lol).

Thank God my brother is not a science person. I can store the components but not shoot the finished guns at home. He sees the pipe, he sees the valves, but he has no idea what in the world it is. And, Killjoy, don't spoil it......

But then, there's a very good reason why I don't include much information that can possibly identify my school.
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Unread postAuthor: limbeh » Fri Feb 20, 2009 10:58 pm

Update:

Gun design has been changed. One has already been built by my juniors under my watch. As usual, <15 minutes work, <S$10.

We do not do damage videos, we are not so destructive unlike you guys in the West. At most we fire at ballistic gel.

Below are the pictures of the gun:

These are the following changes that we have made:

- 1/2" (nominal size) AW/VP JIS PVC pipe chamber instead of soda bottle. Cost only increases by about 30 cents. Chamber volume is now 30-40% of the original, C:B ratio improves from >1 to about 1:2.5 (est).

- Decreased barrel pipe size from 16 to 13mm. 13mm AW/VP (i.e. pressure rated) JIS PVC pipe is ideal size for firing AA batteries, while 16mm is too big.

The performance does speak for itself. Despite the much reduced chamber volume & the dead space caused by having to add a 16-13mm reducer fitting there, the downsizing of the barrel causes the performance to still about 75% of the original, on half the pumping.
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Attachments
1.jpg
The gun. This was built by my juniors under my watch, hence the sloppiness (PVC primer running all over).
1.jpg (12.83 KiB) Viewed 332 times
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Unread postAuthor: sputnick » Fri Feb 20, 2009 11:15 pm

Hell that actually looks like fun, put a simple stock on that you have a nice modest little plinker.

I'm not even sure why, but I have an enormous craving to build one...
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Unread postAuthor: limbeh » Sat Feb 21, 2009 12:18 am

Yes, I also thought of adding a stock and aiming sights too. However, this is a basic design.

I forgot to include, the ball valve is quite hard to turn. Lubricated it with a bit of cooking oil, substantially solves the problem.

I should have had a longer barrel in both and a elbow to connect the chamber........both are inherently inefficient, I conclude from firing tests that a lot of air is being wasted.

When it concerns simple mass producable stuff like this, we operate like Soviet Russia here: Simple, cheap & mass producable, and then users then go modify their guns to best fit their situation.

Hey, if you have an enormous craving to build one........it's only 10-15 minutes and $10 (I assume)........
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Unread postAuthor: starman » Sat Feb 21, 2009 12:46 am

I like this much better than your original. However, you could actually use a little more chamber. Going up to a 1" chamber and the same length as the one above would show noticable performance improvement. It wouldn't cost too much more. You would need a 1" endcap and 1" socket to 1/2" threaded adapter to connect to the same ball valve...really a minimal change.

Yes perhaps a somewhat longer barrel, maybe 6-12" but don't go too long. These should be practical and cool, not monstrosities that draw too much attention to themselves.
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