SpudFiles Wiki - User contributions [en]

Paintball

2007-02-25T02:05:15Z

Saladtossser: benstern requested this clarification

A '''paintball''' is a small hollow sphere filled with a non-toxic, washable 'paint'. They are designed to splatter upon impact and typically have a .68 caliber size. 
They are commonly available for the game of paintball, and they are round and have a fairly uniform mass - generally good for accuracy in smoothbore barrels.

== Aerodynamics ==

Paintballs are assumed to have a Cd of about .5, as they are smooth spheres. 
They may be launched out of a curved barrel to increase range via the Magnus effect (the same at work in [[hop-up]] devices).

== Use and target performance ==

Paintballs are typically launched out of 3/4" CPVC, as that is the most commonly available that pipe that is a close match for their diameter. Some prefer 3/4" sch 80, and the ultimate is recognized as being 3/4" sch 120, although this pipe is extremely hard to find and not commonly used.
Sch 120 barrels are thicker and are a tighter fit, [http://forums.spudtech.com/topic.asp?ARCHIVE=true&TOPIC_ID=2772 decreasing sag and increasing velocity].

Paintballs are typically [[breech loading|breech loaded]], and their shape allows them to be stored in magazines/clips.

Upon impact with:

* A twig, a paintball typically ruptures.
* A water-filled milk jug, a paintball typically ruptures and may pierce the jug.
* A tree, a paintball ruptures.
* A rock, a paintball ruptures.
* A person, a paintball typically ruptures, resulting in laughter (or serious injury - see below!).

Due to their low sectional density, most launchers will fire a paintball too fast to be considered safe, which is generally considered to be 300 fps. Furthermore, actually making a reliable, accurate, and rapidly firing weapon is a complicated task that probably can't be done without a lathe. 
Even then, most fields won't let you play with your homebrew weapon; spud guns that fire paintballs should be considered target-practice devices only.

[[Category:Projectiles]]

Butane

2007-02-25T02:03:08Z

Saladtossser: Benstern wanted me to change this so I did

[[Image:Butane.gif|frame|The butane molecule]]Butane is quite similar to [[propane]], but with a slightly lower [[stoichiometric]] value of 3.23%. Pure butane is found in lighter refill canisters.

Butane has a lower vapor pressure than propane, and its boiling point is -0.5°C (31.1°F), limiting it's use to higher temperature environments. It is most easily used the same way as [[aerosol]] fuels.

Disposable canisters with mixtures of butane, propane and (sometimes) isobutane is sold for camping gear and blowtorches, this gas evaporates at lower temperatures and can be used in cold weather.

[[category:fuels]]

Opening time

2007-02-25T01:59:53Z

Saladtossser: spelling

"Opening time" is the time it takes a valve to open, and as expected, is most important when the barrel dwell time is low. The approximate opening time of some valves:
* [[Burst disk]]s Practically instant... most likely under a millisecond.
* Pilot operated valves ([[diaphragm valve]]s, [[piston valve]]s): 3-5ms.
* [[Ball valve]]s: about 100 ms hand-actuated, maybe 20-30 spring-actuated.

The [[GGDT]] will give you a graph of your valve opening. (valve position vs. time or projectile position)

This author is confused as to what the number is when the valve [[honking|honks]], as this involves opening and closing rapidly - should one measure it from beginning of opening to end of honking, or from beginning to the most open part of the first vibration?

[[category:valves]]

Wadding

2006-09-15T19:48:30Z

Saladtossser: one spelling

'''Wadding''' is essentialy a [[sabot]] that mearly fits behind the projectiles, and it preforms essentially the same function, but is easier to construct than an enclosing sabot.

They are often used to keep a delicate projectile from exploding upon firing, and/or to seal up small power-sapping gaps between projectile and barrel. [http://forums.spudtech.com/topic.asp?TOPIC_ID=129 common waddings].

[[Category:Projectiles]]

Piston valve

2006-09-15T19:47:15Z

Saladtossser: /* Barrel sealing tee piston valve explanation and plans */ no off site images

A '''piston valve''' is a [[pilot valve|pilot]] operated valve. It is very similar to a [[diaphragm valve]] in theory, but replaces it's flexible diaphragm with a rigid cylinder. There are 2 varieties; barrel sealing and chamber sealing.

== Construction, barrel sealing ==

The piston is often a well fitting cup-shaped object, such as a end cap. To provide a sealing face, a piece of rubber is attached, typically with a bolt. Equalization is accomplished by simply allowing the air to leak past the piston and into the chamber. Some people will machine their own pistons, in which case they often build [[O-ring]]s into them. With the O-rings, you need to make a small equalization hole; sometimes this is fancied up to be a homemade [[check valve]].

Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, barrel sealing" diagram.

These valves are often used on [[coaxial]]s and [[over/under]]s. In an over/under, the valve is built in a "T" fitting. The barrel is put co-axially through one end, the pilot and piston are put in the opposite one, and a chamber is connected to the perpendicular opening with a 90° elbow.

== Use, barrel sealing ==
[[Image:Wpiston.PNG|frame|top=pressurized, bottom=firing]]
Operation:
#Air is added by filling behind the piston (C).
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the pressure to equalize] from the chamber.)
#More air is added, and leaks around the piston (or through a small equalization hole) and into the chamber (B), filling it to the desired pressure.
#The pilot valve (D) behind the piston is opened, the pressure in the [[pilot|pilot volume]] (C) drops, and the higher pressure in the chamber area pushes the piston away from the barrel.
#The air flows around from the chamber, and into the barrel, propelling the projectile.

The performance of these valves can be calculated with the [[GGDT]].
If your valve [[honking|honks]], it is probably a good idea to invest in a better [[pilot valve]].
[[category:valves]]

== Barrel sealing tee piston valve explanation and plans==

[http://www.magooffl.com/images/diagram.jpg Image]

The air is put into the gun from behind the piston. the piston is pushed into the rubber coupler, and it seals so no air can go out the barrel.

but air goes between the piston and pipe, and goes through the bottom of the tee, into the chambers. Okay, this is where the sprinkler valve comes in. Since there is air pressing on the front and back of the piston, but there is less surface on the front, the pressure on the back keeps it seated.

to fire, activate the solenoid, which vents the back of the piston, so there is much more more pressure pushing it on the front. This causes it to slam backwards, unseating the valve, and dumping huge amounts of air out the barrel at once.

this all actually happens instantaneously(instantly) at the near instant you hit the button.

NOTE:the 3 inch sch 40 end cap piston was sanded around the back, where you will find small ridges of extra PVC from when it was injection molded. buy the smoothest end cap and rubber coupler you can find, and it will seal

Barrel

2006-09-14T19:51:37Z

Saladtossser: deleted 2 words (oh, perfectly)

The '''barrel''' is the pipe used to launch the projectile, and is, along with the [[chamber]], the only component found in all launchers. The diameter determines what projectiles will fit in the launcher, and the length affects how much energy is transferred to the projectile.

Modifications and improvements to the basic barrel include [[sleeving]], [[rifled barrel|rifling]], [[hop-up]]s and flatline barrels.

There are many diameters of barrels popular in spudding, below are some that fit certain ammo:

* 4.5mm brakeline - fits bbs, good for [[BBMGs]]
* 6mm brakeline - fits [[airsoft bb]]s, a commonly used ammo in BBMGs.
* 3/4" CPVC, 3/4" sch 80 PVC (looser fit), or 3/4" sch 120 PVC - fits .68" [[paintball]]s
* 1/2" sch 40 PVC (.602" id) - fits "AA" batteries, marbles.
* 3/4" sch 40 PVC (.804" id) - fits 12g [[CO2 cartridge]]s, C batteries.
* 1" sch 40 PVC (1.029" id) - size [[C cell|"C" batteries]], smaller sized [[bouncy balls]].
* 1.25" sch 40 PVC (1.360" id) - Fits size [[D cell|"D" batteries]], [[film canister]]s
* 1.5" sch 40 PVC (1.590" id) - a common size, good trade-off between power and [[potato]] usage. [http://www.spudtech.com/components.asp Available rifled from the [[SGTC]]]
* 1.5" sdr 21 PVC (1.700" id) - fits [[golf ball]]s. Traditionally [[sleeving|sleeved]] within SCH-80 PVC.
* 1.5" sdr 26 PVC (1.734" id)- fits golfballs, but it is thinner than sdr 21, so the golfballs fit a little looser. Traditionally sleeved within 2" SCH-80 PVC.
* 2" sch 40 PVC (2.047" id) - fits caulk tubes and (large) potatoes.
* 2" sch 80 PVC (1.913" id) - fits 1.5" nominal pipe well, making it ideal for [[sleeving]] Also used as a golf ball barrel by itself, with the golf ball held in place by a rag patch, or other wadding. Also fits normal light bulbs! [http://advancedspuds.com/concreteballs.htm (Details)].
* 2.5" sch 40 PVC (2.445" id) - fits [[tennis ball]]s well.
* 3" sch 80 PVC (2.864" id) - fits many drink bottles well.
* 3" sch 40 PVC (3.042" id) - fits normal [[steel can|cans]], empty propane torch tanks, and gadorade bottles.
* 4" sch 40 PVC (3.998" id) - fits 29 oz. cans

Inside diameter (id) data from harvel.com
[[Category:Components]]

Piston valve

2006-09-14T19:49:53Z

Saladtossser: minor spelling

A '''piston valve''' is a [[pilot valve|pilot]] operated valve. It is very similar to a [[diaphragm valve]] in theory, but replaces it's flexible diaphragm with a rigid cylinder. There are 2 varieties; barrel sealing and chamber sealing.

== Construction, barrel sealing ==

The piston is often a well fitting cup-shaped object, such as a end cap. To provide a sealing face, a piece of rubber is attached, typically with a bolt. Equalization is accomplished by simply allowing the air to leak past the piston and into the chamber. Some people will machine their own pistons, in which case they often build [[O-ring]]s into them. With the O-rings, you need to make a small equalization hole; sometimes this is fancied up to be a homemade [[check valve]].

Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, barrel sealing" diagram.

These valves are often used on [[coaxial]]s and [[over/under]]s. In an over/under, the valve is built in a "T" fitting. The barrel is put co-axially through one end, the pilot and piston are put in the opposite one, and a chamber is connected to the perpendicular opening with a 90° elbow.

== Use, barrel sealing ==
[[Image:Wpiston.PNG|frame|top=pressurized, bottom=firing]]
Operation:
#Air is added by filling behind the piston (C).
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the pressure to equalize] from the chamber.)
#More air is added, and leaks around the piston (or through a small equalization hole) and into the chamber (B), filling it to the desired pressure.
#The pilot valve (D) behind the piston is opened, the pressure in the [[pilot|pilot volume]] (C) drops, and the higher pressure in the chamber area pushes the piston away from the barrel.
#The air flows around from the chamber, and into the barrel, propelling the projectile.

The performance of these valves can be calculated with the [[GGDT]].
If your valve [[honking|honks]], it is probably a good idea to invest in a better [[pilot valve]].
[[category:valves]]

== Barrel sealing tee piston valve ==

[[Image:
Image:http://www.magooffl.com/images/diagram.jpg]]
the air is put into the gun from behind the piston. the piston is pushed into the rubber coupler, and it seals so no air can go out the barrel.

but air goes between the piston and pipe, and goes through the bottom of the tee, into the chambers. Okay, this is where the sprinkler valve comes in. Since there is air pressing on the front and back of the piston, but there is less surface on the front, the pressure on the back keeps it seated.

to fire, activate the solenoid, which vents the back of the piston, so there is much more more pressure pushing it on the front. This causes it to slam backwards, unseating the valve, and dumping huge amounts of air out the barrel at once.

this all actually happens instantaneously(instantly) at the near instant you hit the button.

Paintball

2006-08-27T00:25:21Z

Saladtossser: spelling

A '''paintball''' is a small hollow sphere filled with a non-toxic, washable 'paint'. They are designed to splatter upon impact. 
They are commonly available for the game of paintball, and they are round and have a fairly uniform mass - generally good for accuracy in smoothbore barrels.

== Aerodynamics ==

Paintballs are assumed to have a Cd of about .5, as they are smooth spheres. 
They may be launched out of a curved barrel to increase range via the Magnus effect (the same at work in [[hop-up]] devices.

== Use and target performance ==

Paintballs are typically launched out of 3/4" CPVC, as that is the most commonly available that pipe that is a close match for their diameter. Some prefer 3/4" sch 80, and the ultimate is recognized as being 3/4" sch 120, although this pipe is extremely hard to find and not commonly used.
Sch 120 barrels are thicker and are a tighter fit, [http://forums.spudtech.com/topic.asp?ARCHIVE=true&TOPIC_ID=2772 decreasing sag and increasing velocity].

Paintballs are typically [[breech loading|breech loaded]], and their shape allows them to be stored in magazines/clips.

Upon impact with:

* A twig, a paintball typically ruptures.
* A water-filled milk jug, a paintball typically ruptures.
* A tree, a paintball ruptures.
* A rock, a paintball ruptures.

Due to their low sectional density, most launchers will fire a paintball too fast to be considered safe, which is generally considered to be 300 fps. Furthermore, actually making a reliable, accurate, and rapidly firing weapon is a complicated task that probably can't be done without a lathe. 
Even then, most fields won't let you play with your homebrew weapon; spud guns that fire paintballs should be considered target-practice devices only.

[[Category:Projectiles]]

Talk:555 timer

2006-08-19T16:43:26Z

Saladtossser: why?

== why? ==

why did u delete this? it is perfectly fine to copy from wikipedia, the GNU lets us.

Blowgun modification

2006-08-19T05:14:31Z

Saladtossser:

[[Image:BlowgunMod.PNG|frame|Stock vs. Modded: blowgun operation, explanation of mod #3 and #4]]
'''Blowgun Modification''' refers to the modification of a [[blowgun]] to increase flow.

There are 4 possible procedures; often, all 4 are carried out. Listed in order of difficulty.

==Nozzle removal==
The nozzle is the small piece on the front of the blowgun, which serves to focus the blast of air, frequently made of brass, steel, or rubber. It also happens to reduce flow.
Most of the time, it can be removed by simply unscrewing it.

==Removing slack in the mechanism==
Most blowguns use a lever to push down on the piston, and typically, this lever cannot depress the piston enough to allow full flow.
Easily remedied by sticking a spacer between the top of the piston and the lever. You can insert a Popsicle stick behind the lever.

==Enlarging the holes==
The inlet hole to the piston slide tube is typically smaller than it can be, and this (clearly) limits flow.
The solution is to grind or drill this hole to a larger size. The piston should be removed first, to prevent damage to it. (see diagram)

==Reducing the diameter of the piston==
The standard piston's diameter is too big to allow full flow around the piston.
Remedied by removing the piston, and reducing its diameter where the step exists currently. This can be done using a small file or a dremel tool. Be careful not to damage the O-ring. (see diagram)

[[category:valves]]

Honking

2006-08-15T20:25:51Z

Saladtossser:

'''Honking''', which can sound roughly like an airhorn, is the result of a valve that vibrates open and closed; the cycle is like this:
# The diaphragm/piston unseats, and due to the increase in differential force caused by the "new" area, is pushed back rather quickly.
# Air pressure in the pilot volume starts to build, as the diaphragm/piston moves, compressing it.
# The momentum of the diaphragm/piston keeps it going past the point where the pressures on both sides of the diaphragm/piston are equal.
# The higher pressure in the [[pilot]] volume now accelerates the diaphragm/piston back to where it started... and you can follow the steps from #2, but with the pressure in the pilot volume dropping.

If a valve is honking, it is most likely not opening fully, and this will decrease performance. Honking is often interpreted as a sign that you are using a [[pilot valve]] that is too small, and this occurs most often in un-[[Sprinkler valve modification|modified]] [[sprinkler valve]]s due to the extremely small stock pilot. This pilot also vents to the barrel instead of the atmosphere, which increases feedback.

[[Image:Honk.GIF]]

(Note the upwards trend in the valve position.)

[[category:valves]]

Sprinkler valve

2006-08-15T20:24:29Z

Saladtossser:

The next step up from a [[ball valve]], this is essentially a commercially produced [[diaphragm valve]]. However, they are unfortunately designed to open relatively slowly to prevent "water hammer", and the large number of internal turns decreases the flow of the valve (to roughly 60-70% of a piston/diaphragm valve with the same diameter). The performance can be improved by replacing the stock solenoid-valve vent with a [[pilot valve]] with more flow. Most often this is a blow gun, although for larger valves a ball valve or even a smaller sprinkler valve can be used. This operation is often called [[sprinkler valve modification|modding]] the valve.
You can download a video of how to modify a sprinkler valve [http://www.bcpneumatics.com/utopia/sprinkler.htm here]

===Troubleshooting===
If you are having problems with your sprinkler valve, these are some things to try
====Valve "Honks" or "sounds like an airhorn"====
You need a larger pilot valve. For more information, see [[honking]].

====Valve won't seal====
If your valve leaks air out the barrel, you should disassemble it and clean the diaphragm and seat. Check for any plastic chips that may have entered the valve. Smear the diaphragm and seat with lithium grease to promote a seal.

====Valve won't open====

[[category:valves]]

Primer

2006-08-15T20:23:58Z

Saladtossser:

A primer is a chemical substance used to prepare an object for painting or gluing. However, to potato-gun enthusiasts, primer is generally used in the process of combining PVC/CPVC fittings and pipes by preparing them for the gluing process.

== How to use Primer ==

Primer is to be applied liberally to all PVC/CPVC joints, pipes or fittings (by use of a brush) where they are going to be connected together. In many cases, a brush is supplied with the primer.

== Health and Safety ==

Primer is a mixture of methyl ethyl ketone, cyclohexanone, tetrahydrofuran, and acetone. Tetrahydrofuran is a known carcinogen in animals, so primer should be used outside, while wearing rubber/latex safety gloves. In addition, long term exposure of skin to these low-polarity solvents will severely dry your skin out, swallowing primer may result in death, and inhaling primer could most definitely kill more than a few brain cells. (as with most solvents)

Be sure to read warnings and instructions.

== Types of Primer==

There are two basic "types" of building primer commonly used with potato cannons: clear and purple primer(s). The difference is simply that purple primer has a dye added to aid in the enforcement of building codes. This dye is essentially impossible to remove, as it soaks into the pipe fairly deeply.

Both of these are manufactured by many various companies and can usually be found at your local hardware store. Purple primer is easier to see when applied, clear primer can often be hard to detect after in dries. However, purple primer often leads to messy and unsightly purple smears on and around the project you are working on, best prevented by a generous application of masking tape around the non-joint area prior to gluing. Both are equally effective at getting the job done; it is up to you to decide which to use.

== External links ==

Wikipedia article on primer: [http://en.wikipedia.org/wiki/Primer_%28paint%29]

Computer Applications

2006-08-03T21:30:20Z

Saladtossser: spelling

The certain members of the spudding community have written computer programs pertaining to spudguns:

==the [[GGDT|Gas Gun Design Tool]]==
Written by David Hall (D_hall of the [[SGTC]]), it is the most commonly used program to predict [[pneumatic cannon]] performance, and is free for the download at Hall's [http://www1.iwvisp.com/thehalls/ggdt/index.html website].

Accuracy of the predictions is typically within 5-10% of the actual value, although there has not been much testing of very long where the (unaccounted for) flow resistance due to barrel length is significant, or very high pressure launchers where the non-modeled liquefaction of the propeller gas(ses) may take place.

==[[CALM]]==
Standing for Compressed Air Launcher Model this is a Pneumatic Launcher simulator program by AKB of the [[SGTC]]. Since it is written in the Python programming language you can read the code and see how it works. It is not graphical, but produces tables of pressure, velocity, height, etc.

CALM can be downloaded at http://www.qsl.net/wb6zqz/calm.html .

==[[EVBEC]]==
EVBEC stands for Energy & Volume Based Estimator for Combinations. Written by boilingleadbath, it is based on [http://www.burntlatke.com Latke's] chamber:barrel test data.

==[[SpudTool]]==
A great spudding tool made by Boogieman. [http://www.advancedspuds.com/SpudToolonline.htm Click here to try it out]

==[[ProMeterSuite]]==
Spud Calculators galore. Requires Microsoft Excel. [http://www.spudfiles.com/Main/download_stuff/ProMeterSuite.zip Download]

==[[Unit Converter]]==
I just found this a long time ago and is really handy when converting metric pipe sizes to U.S. sizes. [http://www.spudfiles.com/Main/download_stuff/UnitConverter.zip Download]

==[[Launcher Range Calculator]]==
Predicts ballistic trajectory accurately taking into account both atmospheric and ballistic variables. [http://bb.1asphost.com/sigmarhaven/SSpictures/launchers/LauncherRangeCalculatorV2-2.xls Download]

==[[Other Calculators]]==
[http://www.burntlatke.com/calc.html http://www.burntlatke.com/calc.html]

[http://www.joshmadison.com/software/ http://www.joshmadison.com/software/]

[http://www.1728.com/diam.htm http://www.1728.com/diam.htm]

==Works in progress==

Beverage can

2006-08-02T21:13:12Z

Saladtossser: spelling

'''Beverage cans''', also known as '''beer cans''' or '''soda cans''', are disposable aluminum containers sold with a liquid content.
They are easy to fill with water, sand, or concrete.

==Barrels==
Very few [[pvc pipe|pipe]]s fit standard-sized beverage cans; with the only stock pipe being 2.5" [[SDR]] 26. Such pipe has a total gap of .035", which is a pretty good fit.

Alternatively, one can make their own barrel for soda cans, by [[sleeving]] a piece of 3" sch 40 pipe inside another piece of 3" sch 40 pipe using the "modified insert" method.
This yields a barrel with an estimated inside diameter of 2.61" (.01" gap).

Smaller cans, such as those of "energy drinks" are said to fit in 2.5" sch 40 pipe. (Which also fits [[tennis balls]])

For those that don't wish to go to the trouble of procuring a special barrel for beverage cans, it's always possible to use a [[sabot]].

==Use and target performance==
Soda cans can be filled with any fluid or small-particles solid including water, sand, or cement. A flap of material can be glued over the opening to keep its new contents inside.
Alternatively, they can be fired without consuming their contents; this effectively spreads the odor of the product.

(Need info on target performance)

Aluminum containers don't biodegrade very well. Pick up your trash.

==Specifications==
* Outside diameter: 2.6 inches
* Length: 4.8"
* Mass: 14 grams
* Wall thickness: .005"
* Volume: 355 ml
* Mass, water filled: 369g

[[Category:projectiles]]

Potato

2006-08-02T21:12:26Z

Saladtossser: spelling

[[Image:Potato.jpg|frame|Some standard potatoes.]]

The '''potato''' (aka '''spud''') is the original and most common ammo for a spud cannon. This is largely an effect of their low cost and availability.
Due to using a [[spud cutter]] to cut the potato to size, they have a nearly air tight fit, to the point where it can prevent loading. (a solution is offered [[muzzle loading|here]])

==Use and target performance==
Typically large and juicy ones are preferred, as the size is needed for larger barrels and the juice acts as a lubricant in the [[barrel]] when muzzle loaded.

Upon impact with:
*A twig, a potato typically survives.
*A water-filled milk jug, a potato is reduced to "potato crumbs"; small bits of potato only a few mm in size.
*A tree, a potato is reduced to "potato crumbs".
*A rock, a potato is reduced to "potato crumbs".

==specifications==
*Density: varies, although it is typically around 1.1 g/ml (16g or .58oz per cubic inch)

==external links==
[http://www.starch.dk/isi/starch/tm5www-potato.htm International Starch Institute: potato density]

[[Category:Projectiles]]

Golf ball

2006-08-02T21:11:42Z

Saladtossser: spelling

[[Image:Golf_ball.jpg|200px|right|]]'''Golf balls''' are commonly used as ammo in spudguns for a few reasons

*Uniform in shape and size
*Aerodynamic
*Availability

==Barrels==

Golf balls fit perfectly in 1.5" SDR 21 [[PVC]] pipe, but because of its thin walls, it should be sleeved inside 2" SCH 80.

Also fairly common is the construction of a hop-up device. These consist of a high-friction object on the top of the barrel which catches and puts a back spin on the ball. This backspin generates lift via the magnus effect, greatly extending the range of a golf ball. Also, it improves accuracy, because instead of a spin in a random direction pushing the golf ball off course, you have a consistent back spin.

==Modifications==

Mantle removal: By removing the outer covering (mantle) of the golf ball, you reduce the diameter which allows you to put it in 1.5" sch 40 pipe. This is best done with a chisel or such tool. However, this removes the dimples; they increase the magnus effect (responsible for lift) and decrease the drag. This means that the ball won't go as far.

"fin" insertion: By drilling a hole and inserting a nail/golf tee/stick, you prevent the golf ball from spinning. This improves accuracy by protecting the golf ball from the magnus effect.

==specifications==
* Diameter: 1.68 inches
* Mass: 46g

{{stub}}
[[Category:projectiles]]

Marble

2006-08-02T21:08:11Z

Saladtossser: spelling

'''Marbles''' are good solid projectiles, that can penetrate hard targets like wood and sheet metal. They are cheap easy to find and come in a range of sizes, the most common being 1/2", 5/8", 7/8" and 1 inch, or 12, 16, 22 and 25 mm. Larger marbles exist but are often too costly to be used in day to day shooting.

==use and target performance==
The manufacturing tolerances of marbles are often quite wide, so not all 16mm marbles will fit in a 16mm [[barrel]] for instance. If you go to the store to buy marbles, it is suggested to bring a piece of you [[barrel]] to test fit your ammo.

A marble hitting a hard target (such as a rock) is often crushed to harmless sand, but there are chances of getting sharp splinters and ricochets, and appropriate care should be taken. Because if their relatively consistent shape and size marbles are good projectiles to use in cannons with automatic loading mechanisms.

==specifications==
Diameter: 1/2, 5/8, 7/8, or 1" (12, 16, 22, or 25mm)
Density: glass is ~2.4-2.8 g/ml

[[Category:Projectiles]]

C cell

2006-08-02T21:07:45Z

Saladtossser: spelling

A C Cell is a 'C' size battery.

[[Image:ccell.jpg]]

== Use and target performance ==
They fit well in 1" SCH 40 [[PVC pipe]] with a gap of only ~.03" (.9mm).

The thick steel cases make them very robust, and they can often be reused if shot at softer targets, although impacts with unyielding objects (such as rocks and steel plates) will deform them to the point where they won't fit in the barrel anymore.

Alkaline batteries are not terribly toxic to the environment, but one should make reasonable effort to clean up after yourself.

== Specifications ==

Diameter: 25.3mm (.996")

Height: 50 mm

Weight: Varies; roughly 68-74g for Duracell alkaline batteries

{{stub}}
[[Category:projectiles]]

Triggered burst disk

2006-07-31T02:45:48Z

Saladtossser:

[[Image:Triggered_burstdisk.PNG|frame|The firing cycle of a triggered burst disk]]
A triggered [[burst disk]] system consists of two burst disks mounted between the chamber and barrel of a [[pneumatic cannon]], with a trigger chamber in between and a trigger valve that either dumps said chamber to the atmosphere, or connects it to the main chamber.

The burst disks must be dimensioned to break somewhere between half and full chamber pressure. The trigger chamber is filled to half the chamber pressure, and then the chamber is filled to full pressure. When the trigger valve is opened, one of the disks is subjected to the full chamber pressure and ruptures, in turn overloading and rupturing the second burst disk.

The design has the advantages of quick opening and full flow of a burst disk, and with the reliability and repeatability of normal [[pilot valve]]s. It has the other disadvantages of a burst disk system, as well as higher consumption of burst disks.

[[category:valves]]

Sprinkler valve modification

2006-07-31T02:45:21Z

Saladtossser: spelling

This refers to '''modifying''' a [[sprinkler valve]] to actuate via a [[pilot valve]] with a higher flow than the solenoid—typically a blowgun, although larger valves (1.5-2" and up) require something with more flow to preform well. The larger vent decreases [[opening time]], and does not require batteries like the stock solenoid. A step by step tutorial of the process is available at [http://www.spudfiles.com/forums/viewtopic.php?t=305 Spudfiles]

The faster and higher flow the pilot valve, the faster the actuated valve will open. This means that performance can be increased by using a [[QEV]], which offers the additional benefit of eliminating the human variable. This has been [http://forums.spudtech.com/topic.asp?ARCHIVE=true&TOPIC_ID=11028 shown] to yield muzzle velocities as much as 2 times as consistent.

Another modification that can be made is enlarging the pilot leak hole. If the Sprinkler valve is opened it contains a large diameter rubber disk (called the diaphragm). About 1/2-1" in somewhere around the diaphragm (in a often used [http://www.orbitonline.com/index.cfm?fa=watermaster.product&productid=201 Orbit Watermaster] sprinkler valve) will be a small white plastic piece poked through the diaphragm. If this piece is removed, the pilot area above the diaphragm will be pressurized instantly while the cannon is being filled, and so the valve will be more sensitive and will (in some instances) seat better.

[[category:valves]]
[[Category:Construction methods]]

O-ring

2006-07-28T03:00:54Z

Saladtossser: spelling

[[Image:O-rings.jpg|frame|Some small o-rings]]An '''o-ring''' is a rubber gasket with a round cross-section, and is usually used to create an airtight seal around moving parts, such as pistons and bolts. O-rings are cheap and come in a wide range of sizes. However they need to be mounted in a precisely machined groove for most applications, and a [[lathe]] is usually needed to achieve this, so they are not always a viable option.

An o-ring seal, when done correctly, can hold thousands of [[psi]].

For those with a lathe, the process for machining an O-ring groove is:
<ol><li>Chuck the workpiece well, ensuring that it rotates true.
<li>Gently measure the actual radial thickness of the O-ring.
<li>Using a cut-off tool or similar tooling that will produce a deep flat bottomed cut, cut a groove of the proper width to a depth that will put a 5-10% squeeze on the O-ring.
</ol>
This depth can determined by the formula O*(100%-S%) - 1/2(OD - ID) Where O is O-ring thickness, S% is the percent of squeeze (higher percents make tighter O-ring seals), OD is the outside diameter of the interior part, and ID is the inside diameter of the exterior sleeve.

Putting the O-ring on the exterior sleeve is not recommended, as it is harder to machine and tends to fall out if the interior part fails to press against it.

[[category:construction materials]]
{{stub}}

Supah-Valve

2006-07-18T01:54:30Z

Saladtossser: spelling

The Supah-Valve is a chamber sealing [[piston valve]] designed and made by the [[The Spudgun Technology Center]]. It is one of the best performing spudgunning valves on the market, and on the short list of valves that are actually designed for use with gasses, which combined with their excellent craftsmanship cause them to be very popular valves.

The marketing at the spud gun technology center's product page lists the opening time as equivalent to that of a [[Diaphragm valve]], but this is disputed - chamber sealing valves typically have slightly longer opening times than barrel sealing ones due to the lack of a surface under the barrel to expose upon cracking open.

[[Image:sv1.jpg]]

'''Specifications:'''
*Maximum Pressure - 120 psi
*2" porting (inlet and outlet holes)
*Exterior body made from a 3" PVC tee
*Nitrile O-ring sealed with nitrile face-gasket (1)
*static and dynamic bulkheads (1)

[[Image:supah001.jpg]]

[[Image:002.jpg]]

[[Image:003.jpg]]

[[Image:004.jpg]]

[[Image:005.jpg]]

[[Image:005.jpg]]

[[Image:007.jpg]]

[[Image:pwtee.jpg]]

[[Image:innards.jpg]]

sources: [http://web.archive.org/web/19960101000000-20030101235959/http://www.spudtech.com/supahvalveprod.html an old spudtech page]

[http://www.spudfiles.com/forums/viewtopic.php?t=2534&postdays=0&postorder=asc&start=15& Spudfiles topic]

[[category:valves]]

Talk:Supah-Valve

2006-07-16T23:53:14Z

Saladtossser: OMG

== OMG ==

Is this really a good idea?

Talk:Supah-Valve

2006-05-19T01:03:37Z

Saladtossser:

Spud cutter

2006-04-08T19:36:24Z

Saladtossser: the second example was a 404

A '''spud cutter''' or '''muzzle knife''' is used to cut produce to the diameter of the barrel. It can be made as an integral part of the barrel, or kept as a separate utensil.

It is made by beveling the outside of the barrel (or a pipe of the same inside diameter) until it forms a sharp edge. In [[combustion cannon|combustions]], is recommended that you add an inner chamfer to your launcher; this cuts a tighter fitting projectile, which increaes friction and therefore acts a bit like a [[burst disk]], allowing the pressure to build before projectile starts to move.

However, there are deficiencies in the typical PVC 'cutter, mainly that it is a relatively soft material and therefore can neither be sharpened very well nor hold an edge. Many have attempted to counter this by:
* Serrating their cutter. (Examples: [http://www.spudfiles.com/official_pics/loc_04.jpg])
* Making them out of steel. ([http://www.spudfiles.com/forums/viewtopic.php?t=775 at risk of promoting my own product...])

[[Category:Accessories]]

User:Spudmonster

2006-04-04T01:11:58Z

Saladtossser:

I'm hungry...
No you are not...

Quick-exhaust valve

2006-04-01T18:29:05Z

Saladtossser: better QEV picture

'''Quick-exhaust valves''' ('''QEVs''' for short) are ready-made piston or diaphragm valves, designed to quickly exhaust pneumatic cylinders. They work somewhat similarly to [[sprinkler valve modification|pneumatically modified]] [[sprinkler valve]]s, they are more expensive and harder to find, but also perform better.

QEVs need a separate [[pilot valve]] for triggering. They can be very sensitive, triggering at a pressure drop of a few psi, so care should be taken when filling with a [[schrader valve]] or other valves that will let out air when disconnected.

Most QEVs are designed to be filled from the pilot side, and will typically work well using a 3-way valve as the fill/pilot valve. Some QEVs will also work when filled from the chamber side.

Small QEVs are sometimes used as pilots for larger valves, often to allow the use of a [[blowgun]] as the trigger.

http://www.bpe950.com/becker/products/control-inst/accessories/QEV-productIMG.jpg

[[category:valves]]

Acetylene

2006-03-24T02:20:45Z

Saladtossser: spelling

'''Acetylene''' (chemical formula C2H2) is a flammable gas used for welding and cutting. It is far too powerful for a spudgun, and its use can result in injury or death. There are also dangers that are unique to acetylene, because the molecule contains an unstable and energetic triple bond that is easily broken.

Acetylene is a very reactive gas, with a flammability limit of 2.5 to 100% in air. It can decompose spontaneously with no air present, if there is an ignition source, or simply if the pressure of the gas exceeds 15 psi. Because of this it is more prone to [[detonation]] than any other gas. Acetylene is also very sensitive to static electricity, and it comes out of the tank dry which means that plastic materials containing the gas get charged easily.

In addition to these dangers, the gas doesn't even contain as much energy per volume as [[propane]], it's gross calorific value is 56000 kJ/m2 as opposed to propane's 101000 kJ/m2. The destructive power comes from the extremely rapid release of energy, which creates very high pressure spikes.

Talk:Combustion cannon

2005-11-19T07:50:30Z

Saladtossser:

Hey, where's that trouble shooting guide?

https://netfiles.uiuc.edu/hanson2/www/CLTG/start.htm

damn, bandwidth exceeded

why dont we leave that link alone?

Vogt-pattern

2005-11-13T19:58:27Z

Saladtossser: deleted dumbass link

Hybrid cannon

2005-11-13T19:57:37Z

Saladtossser: deleted "hi"

A '''hybrid''' launcher consists of seven basic elements:

*High pressure combustion chamber
*Pressure-triggered main valve (usually a [[burst disk]])
*[[Barrel]]
*Fuel system (usually [[fuel meter|metered propane]])
*Air filling valve
*powerfull [[Ignition source]]
*One or more [[pressure gauge]]s

A hybrid is a type of spudgun that combines principles of the [[combustion cannon|combustion]] and [[pneumatic cannon|pneumatic]] spudgun. It uses a pressurized mixture of fuel and air to get more power out of a given chamber volume. In order to fire, the operator first inserts a [[burst disk]], usually consisting of aluminium foil or plastic, between the chamber and barrel. A [[Cam lever coupling]] or [[union]] is used to hold the burst disk in place. The operator then loads projectile into the barrel, adds fuel to the combustion chamber, and then adds pressurized air. The amount of air depends on how much fuel was added, and is calculated to achieve a [[stoichiometric]] fuel/air ratio in the chamber. when the ignition source is triggered, the pressure from the combustion ruptures the burst disk and propels the projectile out of the barrel. The hybrid is capable of higher velocities than a combustion or pneumatic spudgun, projectiles fired by a hybrid have broken the sound barrier (Source). A hybrid using twice as much fuel and air as a comparable combustion gun is said to be using a 2X mix, higher mixtures can be used and will produce even higher pressures. The fuel and air needs to be measured and matched carefully to ensure reliable operation, pressure gauges and fuel meters are used for this. A pressure gauge with a check valve can also be added to record the peak chamber pressure of the gun.

===Safety===
A hybrid is the most dangerous launcher that can be built. It is advised to build with pipe that can handle the high pressure environment (200+ [[Pressure gauge|PSI]]) such as Sch. 80 PVC or metal. Remote ignition is a must, and the limit of a 4x propane/ 4 atmosphere mix should never be breached. If a higher mix is attempted, DDT (deflagration to detonation transition) can occur, causing an extreme pressure spike. Most pipe cannot handle the spike, and will shatter, launching plastic shards every where. Therefore utmost care must be taken with these launchers.

Talk:Honking

2005-11-11T00:00:55Z

Saladtossser:

omg, send me the gdt file for that plz!!

Talk:Piston valve

2005-11-02T01:55:12Z

Saladtossser:

Info on chamber-sealing piston is needed. --[[User:GalFisk|GalFisk]] 31 October 2005 06:51 (CST)

put up the 3 flash animations...
and find mine on spudfiles.

Safety valve

2005-10-26T17:15:06Z

Saladtossser: or not oe

[[Image:Pop_safety_valve.jpg|right|thumb|250px|A 125psi pop-safety valve]]A '''safety valve''', also known as a '''pop-safety valve''' or '''pop-off valve''' is a device installed on a chamber to prevent over-pressurization. They are available in a wide range of pressure ratings, from pressures lower than you'd want to use in a spudgun to pressures higher than a PVC chamber will hold.
These are most commonly installed when you are using a [[pressure regulator]], so that if it malfunctions it won't fill your chamber to the point where it fails, although no such event has been recorded.

{{stub}}
[[category:Valves]]

What is a spudgun?

2005-10-25T23:01:47Z

Saladtossser:

'''Spud guns''', '''potato cannons''', or '''produce accelerators''' are all recreational launching devices usually made of plumbing pipe. There are two common means to launch projectiles from a spudgun. The [[pneumatic launcher|first]] uses the energy stored in a compressed gas and the [[combustion launcher|second]], more popular method, uses the energy released by combusting fuel vapors to heat the air and cause it to expand. There is a quite rare mix of the two, a [[hybrid launcher|"hybrid"]], that combusts a pressurized fuel-air mixture. The object of these varieties is to propel "non-[[not a toy|destructive]]" projectiles in the direction of a designated (safe) target for fun. Common projectiles include: [[mandarin orange|mandarins]], [[potato]]es, [[tennis ball]]s, and [[golf ball]]s. They are a particularly popular home-made class of projectile launchers because of their low cost to build: a simple hairspray powered gun costs no more than $20 in PVC and glue, less if parts can be scrounged.

Sprinkler valve modification

2005-10-25T00:03:51Z

Saladtossser: than not then

This refers to '''modifying''' a [[sprinkler valve]] to actuate via a [[pilot valve]] with a higher flow than the solenoid—typicaly a blowgun, although larger valves (1.5-2" and up) require something with more flow to preform well. The larger vent decreases [[opening time]], and does not require batteries like the stock solenoid. A step by step tutorial of the process is available at [http://www.spudfiles.com/forums/viewtopic.php?t=305 Spudfiles]

The faster and higher flow the pilot valve, the faster the actuated valve will open. This means that performance can be increased by using a [[QEV]], which offers the additional bennifit of eliminating the human variable. This should yield more consistant muzzle velocities.

Another modification that can be made is enlarging the pilot leak hole. If the Sprinkler valve is opened it contains a large diameter rubber disk (called the diaphragm). About 1/2-1" in somewhere around the diaphragm (in a oftenly used [http://www.orbitonline.com/index.cfm?fa=watermaster.product&productid=201 Orbit Watermaster] sprinkler valve) will be a small white plasic piece poked through the diaphragm. If this piece is removed, the pilot area above the diaphragm will be pressurized instantly while the cannon is being filled, and so the valve will be more sensitive and will (in some instances) seat better.

[[category:valves]]

Tapping

2005-10-25T00:01:41Z

Saladtossser:

[[Image:Tap_set.gif|right|thumb|250ps|A set of pipe taps]]'''Tapping''' is the process of cutting [[thread]]s on the inside diameter of a hole with a tool called a tap. It is used to thread holes for mounting:
*[[Pressure gauge]]s
*[[Fuel meter]]s
*Electrodes (Bolts)
*[[Safety valve]]s
*Other

===Types of threads===

There are a few diffent thread systems that are used in spudgun construction

*[[NPT]] (National Pipe Taper)
*BSP
*NF (National Fine)
*NC (National Course)

===The process===

#Mark and drill an appropriatly sized hole
#*The hole should be in an area where fittings or pipe overlap (double thickness)
#*Find correct hole size with a [http://www.engineersedge.com/tap_drill_chart.htm Tap/Drill Chart]
#Insert the tap into the tap wrench
#*If you don't have a tap wrench, a normal crescent wrench can be used
#Cut the threads
#*Be careful to keep the tap straight or you will end up with crooked threads
#*If cutting anything other than plastic, use a cutting fluid to lubricate the tool
#*Apply downward pressure while slowly turning the tap clockwise 180 degrees, then back out 90 degrees counterclockwise to clear some shavings.
#*For tapered threads, stop as soon as the entire length of the hole is threaded

Tapping

2005-10-25T00:01:25Z

Saladtossser: backing out

[[Image:Tap_set.gif|right|thumb|250ps|A set of pipe taps]]'''Tapping''' is the process of cutting [[thread]]s on the inside diameter of a hole with a tool called a tap. It is used to thread holes for mounting:
*[[Pressure gauge]]s
*[[Fuel meter]]s
*Electrodes (Bolts)
*[[Safety valve]]s
*Other

===Types of threads===

There are a few diffent thread systems that are used in spudgun construction

*[[NPT]] (National Pipe Taper)
*BSP
*NF (National Fine
*NC (National Course)

===The process===

#Mark and drill an appropriatly sized hole
#*The hole should be in an area where fittings or pipe overlap (double thickness)
#*Find correct hole size with a [http://www.engineersedge.com/tap_drill_chart.htm Tap/Drill Chart]
#Insert the tap into the tap wrench
#*If you don't have a tap wrench, a normal crescent wrench can be used
#Cut the threads
#*Be careful to keep the tap straight or you will end up with crooked threads
#*If cutting anything other than plastic, use a cutting fluid to lubricate the tool
#*Apply downward pressure while slowly turning the tap clockwise 180 degrees, then back out 90 degrees counterclockwise to clear some shavings.
#*For tapered threads, stop as soon as the entire length of the hole is threaded

Talk:What is a spudgun?

2005-10-24T23:58:57Z

Saladtossser:

lets take some stuff from burnt latke

Talk:Gas Gun Design Tool

2005-10-24T23:03:45Z

Saladtossser:

y dont we put a few examples up?

Talk:Combustion cannon

2005-10-24T23:02:53Z

Saladtossser:

Hey, where's that trouble shooting guide?

https://netfiles.uiuc.edu/hanson2/www/CLTG/start.htm

damn, bandwidth exceeded

Talk:Main Page

2005-10-23T23:14:09Z

Saladtossser:

I moved (renamed) the entries on the different types of cannons to singular form ([[Combustion cannon]], [[Hybrid cannon]] etc), it's standard in wikis and makes linking much easier. Edit: removed capitalization in the titles as well, should not be used unless neccessary (such as in person names) since wiki is picky about capitals. I put redirects in place. --[[User:GalFisk|GalFisk]] 18 October 2005 04:22 (CDT)

== Formatting ==

Question: should the preferred formatting of lists be like that on the cannon pages
*item 1
*item 2
*etc
or the default one, like this

*item 1
*item 2
*etc

The second one is more common, but the first one has precedence on this page. I prefer the second one since it's more integrated with the rest of the text (same font/size) and think the other should be reserved for ascii drawings and the like that needs a monospace font. It would be nice to have a rule either way though, have the pages edited to correspond to that rule, and so set a consistant basis for future articles.
-- [[User:GalFisk|GalFisk]] 18 October 2005 09:04 (CDT)

== Whatever you please ==

If you think the second way is better then go with it. I'm still trying to get used to using a Wiki and it seems that you've been on more than be so you've had more experience.

Have fun :)

Thanks a lot.
:Ok, I'll change the formatting in the affected articles to the way I like it then. I've edited a bit on Wikipedia and I enjoyed it, I'll be adding/fixing stuff here whenever I feel like it.
:I see that the box formatting can creep in by simply custting and pasting from Wikipedia, it's created by adding a space in front of a line and that can creep in during that operation for some reason.
:You can sign your posts by putting three tildes (<nowiki>~~~</nowiki>) at the end, or sign it with date using four tildes. Remember to be logged in then of course. Preview is a good tool when trying out stuff.
:Result: [[User:GalFisk|GalFisk]] 18 October 2005 11:47 (CDT)

== duplicate articals ==

There are multiple articals that are exactly the same, but with slightly different names.
What's up with this?
:Some items redirect to other articles, if you search for [[ignition]] you're redirected to [[ignition source]] for instance. some articles were also renamed, when that is done a redirect is automatically placed on the old name. If you have been redirected, it will say so at the top of the page.
:The reason for having redirects is to make searching and linking easier, as well as not losing all previous links to a page if it gets renamed for some reason.
:If you find genuine duplicate identical articles, delete one and place a redirect from that to the other one. A redirect consists of the following text:

:<nowiki>#redirect [[article name]]</nowiki>

:--[[User:GalFisk|GalFisk]] 18 October 2005 17:35 (CDT)

== Some info on how Wiki handles capital letters: ==

The first letter in an article name will always be a capital letter. If you try to create an article on "psi" (which is the correct capitalization), it will be named "Psi".

When linking, the first letter is treated the same whether it is capital or not. Both <nowiki>[[psi]] and [[Psi]]</nowiki> will get you to the "Psi" article.

This is not the case with capital letters elsewhere in the article name though, a link to <nowiki>[[PSI]]</nowiki> will point to an article with the entire title in capitals.

To create more confusion, the search function is less picky, a search for both "PSI" and "psi" will send you to the same article.

Because of this, it's important not to use capital letters except where warranted. Valid cases are abbreviations ([[BBQ ignitor]], [[PVC]]), proper names, ([[The Spudgun Technology Center]], [[Gas Gun Design Tool]]), and other things that are normally written capitalized. If it's done both ways (many don't bother capitalizing either of these two), make a redirect from one version to the other.

As a rule of thumb, only capitalize when it looks wrong if you don't.

If you are unsure just go ahead and do it either way, if it's wrong someone will come along and fix it.

i think linking to a particular post on spudtech is a bad idea, people may have to sign up.

Talk:Pneumatic cannon

2005-10-23T23:12:06Z

Saladtossser:

Shouldn't there just be one page for modding a sprinkler valve?
:Probably should, it could also be put in the [[sprinkler valve]] article, but I think it's better that it has its own. Could be called [[sprinkler valve modification]] perhaps? --[[User:GalFisk|GalFisk]] 18 October 2005 13:48 (CDT)

:Ok, that seems good. --[[User:Wesman987|Wesman987]] 18 October 2005 17:46 (CDT)

It seams that changing "main valve" to "firing valve" could introduce confusion, as pilot operated valves... well, you fire the gun by oppening the pilot valve. Thoughts on this, saladtosser? --[[User:Boilingleadbath|boilingleadbath]] 23 October 2005 17:25 (CDT)

i dont know, but main gas release valve sounds fine, main valve could be anything. should have a vote on this one.

Venting

2005-10-23T16:02:06Z

Saladtossser:

Venting is the action of cleaning out combustion products and introducing fresh air to the chamber of a [[combustion cannon|combustion]] or [[hybrid cannon]]. This is neccessary to ensure that there is enough oxygen present to sustain the combustion of the fuel.

Venting can be done by simply opening the chamber by means of a threaded plug or cap, a large [[ball valve]], or a [[check valve]]; a [[chamber fan]] is often used to help exchange the gasses. Other venting methods include using a bike pump, [[compressor]] or [[mattress inflator]] to inject air into the chamber. Pressurized air from a scuba or HPA paintball tank can also be used, but with a regulator.

Spark strip

2005-10-23T14:06:52Z

Saladtossser: metalic dust field

A spark strip is used to provide multiple sparks to ignite the fuel/air mix in a [[combustion launcher]]. It is differs from multiple [[spark gap]]s in that a spark strip is mounted using two or even one [http://www.advancedspuds.com/his.htm (temp link)] hole. This is done primarily to ensure the integrity of the launcher, as drilling multiple holes weakens the chamber. Spark strips can also be used in [[coaxial]] launchers, where chamber space is more cramped.

A spark strip consists of several conductive objects in a row with a short gap in between, effectively forming a line of spark gaps. As with other spark gaps, the combined width of the gaps must be small enough for the [[ignition source]] to overcome.

There are several ways to achieve this:
* scratched conductive film:
By scratching thin lines across a conductive film (metallic paints, CDs) it is possible to get very large numbers of sparks out of a meager scource. A more sophisticated method consists of etching a spark strip pattern in a printed circuit board.

* wire method:
Small pieces of wire, BBs, nuts or other metallic objects are attached to the chamber wall. (either directly or indirectly).

* veroboard:
Veroboard is a ready-made circuit board with multiple copper strips or dots, a piece cut perpendicular to the copper strips will function as a spark strip.

* metalic dust field:
A cloud of iron and/or steel dust gathered from grinding, this creats an infinit number of paths for the electricity to travel through. This method is experimental as of the moment, but if done correctly, it will be able to cause the entire chamber to spark.

Examples: 
[http://www.spudtech.com/images/etc/sparkstrip.jpg BB spark strip] 
[http://www.burntlatke.com/strip.html Wire, etched and veroboard spark strips]

Pneumatic cannon

2005-10-23T14:01:32Z

Saladtossser: changed main to firing valve

Pneumatic launchers consist of five basic elements:

*Compressed gas storage reservoir ([[chamber]] for short)
*Filling valve (bicycle [[Schraeder valve]]s, [[quick disconnect]]s, etc.)
*Firing valve ([[ball valve]]s, [[sprinkler valve]]s, [[piston valve]]s, [[quick-exhaust valve]]s, and [[burst disk]]s are the most common)
*[[Barrel]]
*[[Pressure gauge]] (for safety & repeatable launches)

In order to fire, the operator loads a projectile into the barrel, fills the chamber with a compressed gas (air [[compressor]]s, hand pumps, [[Pressure regulator|regulated]] bottled gas, and 12 gram [[CO2 cartridge]]s are common filling methods), and activates the main valve thus dumping the air in the chamber to the barrel.

The expansion of the compressed gas propels the projectile down the barrel. The barrel length determines the amount of energy transferred to the projectile and ultimately the velocity of the projectile.

High performance launchers use techniques such as [[sprinkler valve modification|modifying valves]] for faster opening times, using homemade valves, and maximizing the amount of airflow through the valve.

The [[GGDT]] (gas gun design tool) is heavily recomended to those interested in pneumatic launchers.

Spark strip

2005-10-22T21:23:22Z

Saladtossser:

A spark strip is used to provide multiple sparks to ignite the fuel/air mix in a [[combustion launcher]]. It is differs from multiple [[spark gap]]s in that a spark strip is mounted using two or even one [http://www.advancedspuds.com/his.htm (temp link)] hole. This is done primarily to ensure the integrity of the launcher, as drilling multiple holes weakens the chamber. Spark strips can also be used in [[coaxial]] launchers, where chamber space is more cramped.

A spark strip consists of several conductive objects in a row with a short gap in between, effectively forming a line of spark gaps. As with other spark gaps, the combined width of the gaps must be small enough for the [[ignition source]] to overcome.

There are several ways to achieve this:
* scratched conductive film:
By scratching thin lines across a conductive film (metallic paints, CDs) it is possible to get very large numbers of sparks out of a meager scource. A more sophisticated method consists of etching a spark strip pattern in a printed circuit board.

* wire method:
Small pieces of wire, BBs, nuts or other metallic objects are attached to the chamber wall. (either directly or indirectly).

* veroboard:
Veroboard is a ready-made circuit board with multiple copper strips or dots, a piece cut perpendicular to the copper strips will function as a spark strip.

* Spray paint or CD etching:
(help me out here, i forgot the links)

Solvent welding

2005-10-22T21:20:31Z

Saladtossser: cannons not cannosn

Solvent welding is a method of joining plastic pipe, usually used on PVC and ABS to achieve a high strength joint. In the process, the plastic in the joined surfaces is chemically melted, and joins together to a solid piece when the solvent evaporates. A properly made solvent weld will have a pressure rating equal to that of the individual parts. The joints will take some time to achieve full strength, cannons should be left to dry at least 24 hours before use.

Solvent vapors are flammable and hazardous to your health, work should be done in a well ventilated area and away form ignition sources. The chamber of combustion and hybrid cannons should be vented before testing the ignition, accidents have happened when solvent vapors have ignited in newly constructed guns.

Schrader valve

2005-10-22T21:17:06Z

Saladtossser: schrader not schraeder, i think.

A schrader valve, often called a "tire valve", "tank valve" or "sniffler valve" because schrader is a brand name, is used in [[hybrid launcher|hybrid]] and [[pneumatic launcher]]s to allow you to fill them with air. They are also used, less frequently, in [[combustion launcher]]s, to allow you to [[venting|vent]] them.

They accept the standard air chuck used to fill tires, allowing you to fill them with a standard bicycle pump.
Alternative valves exist, most notably the [[quick disconnect]] which is more expensive, but has a higher amount of flow.

[http://en.wikipedia.org/wiki/Schraeder_valve more info]