Somebody help an ambitious noob...
Posted: Tue Jun 26, 2007 10:36 pm
Removed
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Somebody help an ambitious noob...
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Posted: Tue Jun 26, 2007 10:42 pm
Are you sure you want to make a combustion because you could make a pneumatic which would be bettter for smaller projectiles
Posted: Tue Jun 26, 2007 10:43 pm
C:B refers to the chamber to barrel ratio, meaning an 0.8:1 ratio gives you a chamber volume that is 80% that of your barrel.Something that I would really appreciate help with is the combustion to barrel ratio, what does this really mean? I planned on using a 6" sch 40 chamber (only because this is what I have used before) breech loaded, with either a 1-1/2" or 2" barrel.
If you're using the pipe sizes describes, assuming you have an inline configuration (barrel attached inline with chamber as opposed to inside it) this means you want around 9-10 inches of barrel for every inch of chamber.
Re: Somebody help an ambitious noob...
Posted: Tue Jun 26, 2007 10:44 pm
It is actually chamber to barrel ratio. It is simply a ratio comparing the volumes of your chamber and barrel. An optimal chamber to barrel ratio, or "C:B", is around .7:1.Goody454 wrote:OK, so I work at a hardware store (Willey's, Greensboro, VT in case anyone's from the area) and I have decided to make a Cannon that will make all of my buddies guns pale in comparison. I have built two or three basic cannons (combustion) in my time that have had absolutely no prior planning that went into them.
When I decided to embark on my new build (also combustion) I figured I would see if there was any support out on the web and I found this site (which by the way is absolutely amazing), and I realized that there was a whole world of potato shooting that I didnt know existed. I soon realized that I was over my head after browsing the site for a short while, but I am eager to learn. I couldnt find an area aimed towards noobs, so if anyone could give me some pointers for building a good gun I would greatly appreciate it.
Something that I would really appreciate help with is the combustion to barrel ratio, what does this really mean? I planned on using a 6" sch 40 chamber (only because this is what I have used before) breech loaded, with either a 1-1/2" or 2" barrel. I have always used aerosol sprays in the past, but I am very intrigued by the propane delivery system and would love to give that a shot (no pun intended). As far as ignition I plan to use a basic BBQ ignitor as the cost is more my style than that of the stun guns and other such things I have seen on this site, and I am very interested in the possibility of using a rifled barrel if it is actually worth-while.
I dont want to build a replica of another gun, so please dont think I'm trying to copy your design. I just need some good information on how to make a good, accurate cannon.
Thanks in advance,
Goody
BTW: I have already made sketches for a .50 cal style tripod made from galv pipe that has provisions for windage and elevation adjustments.
Edit: I am planng on spending no more than $100 on this cannon and that includes my 15% discount.
To go with metered propane, check out this and this.
Also, are you set on building a combustion? I started out building a pneumatic cannon, but it all depends on if you have an air compressor, or a bike pump.
Edit: Damn, Jack beat me to it.
Posted: Tue Jun 26, 2007 10:50 pm
hmm, where to start.
i would recommend a compression union for breech laoding. if you intend to only launch potatoes the go with the 1.5'' barrel, i find that few spuds fit tightly in 2''.
yo make a grip, take a 1'' tee, cut it in half and attach a 90 degree elbow and about 6 inches of pipe and put the bbq ignitor in there and just use hose clamps to attach it to the chamber, dont even try to glue it.
do you really need a 6'' chamber? that is really expencive and over all uneffective. use 4'' pipe instead.
look into a chamber fan, it will make you cannon unbeliavably more powerful.
a C:B, or chamber to barrel, ratio is the amount of volume in the pipes. most people say that 7:1 is "ideal". this is true if you want it to be fairly quit. i personally like about a 9:1 because it is louder and much more impressive when you are showing it off mainly because you can hear a much louder bang.
to figure out the C:B of your cannon, just find the volume of the barrel and the volume of the chamber and compare the two.
if you need help you can PM me.
edit- damn, jack and modderX beat me.
i would recommend a compression union for breech laoding. if you intend to only launch potatoes the go with the 1.5'' barrel, i find that few spuds fit tightly in 2''.
yo make a grip, take a 1'' tee, cut it in half and attach a 90 degree elbow and about 6 inches of pipe and put the bbq ignitor in there and just use hose clamps to attach it to the chamber, dont even try to glue it.
do you really need a 6'' chamber? that is really expencive and over all uneffective. use 4'' pipe instead.
look into a chamber fan, it will make you cannon unbeliavably more powerful.
a C:B, or chamber to barrel, ratio is the amount of volume in the pipes. most people say that 7:1 is "ideal". this is true if you want it to be fairly quit. i personally like about a 9:1 because it is louder and much more impressive when you are showing it off mainly because you can hear a much louder bang.
to figure out the C:B of your cannon, just find the volume of the barrel and the volume of the chamber and compare the two.
if you need help you can PM me.
edit- damn, jack and modderX beat me.
Posted: Tue Jun 26, 2007 10:50 pm
er, first, your link dosen't work.
The Chamber to barel ratio is the ratio of volume in you chamber to your barrels volume. like a 2:1 ratio cannon (this is just an example, don't use this ratio) would have a chamber 2x the volume of its barrel. A good ratio for most cannons is 1.5 to one. Use the search button on how to measure this and calculate it.
Be shure that your bbq sparker is a good brand, some brands need to be replaced every 25 "clicks" or so, But I recommend a Lantern lighter, the flint kind. You can get them from Ace hardware stores and the website.
I've only just drawn up my plans for a spudgun and most of this info can be found throughout the forum.
Again, use the search feature. It's helped me alot.
The Chamber to barel ratio is the ratio of volume in you chamber to your barrels volume. like a 2:1 ratio cannon (this is just an example, don't use this ratio) would have a chamber 2x the volume of its barrel. A good ratio for most cannons is 1.5 to one. Use the search button on how to measure this and calculate it.
Be shure that your bbq sparker is a good brand, some brands need to be replaced every 25 "clicks" or so, But I recommend a Lantern lighter, the flint kind. You can get them from Ace hardware stores and the website.
I've only just drawn up my plans for a spudgun and most of this info can be found throughout the forum.
Again, use the search feature. It's helped me alot.
Posted: Tue Jun 26, 2007 10:53 pm
My links work fine for me..Spedy wrote:er, first, your link dosen't work.
The Chamber to barel ratio is the ratio of volume in you chamber to your barrels volume. like a 2:1 ratio cannon (this is just an example, don't use this ratio) would have a chamber 2x the volume of its barrel. A good ratio for most cannons is 1.5 to one. Use the search button on how to measure this and calculate it.
Be shure that your bbq sparker is a good brand, some brands need to be replaced every 25 "clicks" or so, But I recommend a Lantern lighter, the flint kind. You can get them from Ace hardware stores and the website.
I've only just drawn up my plans for a spudgun and most of this info can be found throughout the forum.
Again, use the search feature. It's helped me alot.
Also, an optimal C:B ratio would be <1:1 such as Jack's suggestion of .8:1 or mine of .7:1
Posted: Tue Jun 26, 2007 10:59 pm
Removed
Posted: Tue Jun 26, 2007 11:04 pm
Mate theres only a few simple things you really need on a decent combustion; a fan, a decent sparker and some proper fueling and measurements. And possibly pvc cementing and all that too but anyway 
Take it in stages and calculate a decent c:b ratio, buy some decent pipes and a mini-gun styled handles rock
Take it in stages and calculate a decent c:b ratio, buy some decent pipes and a mini-gun styled handles rock Posted: Tue Jun 26, 2007 11:12 pm
Welcome to the forums, combustion is mostly out of my territory, i live in suburbia and the nieghbors complain about loud noises. not that i car but my parents seem to. but id like to pass on some knowledge.
I agree with Modder and jack <1:1 C:B ratio would be considered ideal. also if your gonna do breech loading lookup the pass through or through barre design. instead of a BBQ ignitor consider maing an ignitor out of a used disposable camera flash circuit, there is a thread around here somewhere. search for 'flash circuit igntion'. your local walmart photo center usuall gives them out if you say your looking for one for a science project. and the rest of the parts are usually cheap/free depending on what you already have. Also like Hi said look into a chamber fan.
And you should go with a propane metering system, propane will give you much better results than aerosols.
If you need anymor help you can also feel free to PM me.
~rednecktatertosser~
I agree with Modder and jack <1:1 C:B ratio would be considered ideal. also if your gonna do breech loading lookup the pass through or through barre design. instead of a BBQ ignitor consider maing an ignitor out of a used disposable camera flash circuit, there is a thread around here somewhere. search for 'flash circuit igntion'. your local walmart photo center usuall gives them out if you say your looking for one for a science project. and the rest of the parts are usually cheap/free depending on what you already have. Also like Hi said look into a chamber fan.
And you should go with a propane metering system, propane will give you much better results than aerosols.
If you need anymor help you can also feel free to PM me.
~rednecktatertosser~
Posted: Wed Jun 27, 2007 2:28 am
FAN FAN FAN FAN FAN!!!!!!!
The better those gases are mixed the more bang for your buck you get- probly like an extra 33% No B.S.
Peace
Scotty
The better those gases are mixed the more bang for your buck you get- probly like an extra 33% No B.S.
Peace
Scotty
Posted: Mon Jul 02, 2007 7:04 pm
http://www.angelfire.com/80s/sixmhz/camera.html camera ignition plans
Posted: Mon Jul 02, 2007 7:15 pm
I will second, or, maybe eighth the motion that you include a fan, flash circuit, and propane meter, and the volume of your chamber should be approximately .8 that of your barrel.
Posted: Mon Jul 02, 2007 7:16 pm
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Posted: Mon Jul 02, 2007 7:17 pm
Goody welcome to the forum...
Research pneumatic well. It cost a bit more in parts then a basic combustion.
Kenny thanks for the link...i havent tried \a camera flash yet..
Research pneumatic well. It cost a bit more in parts then a basic combustion.
Kenny thanks for the link...i havent tried \a camera flash yet..