SpudFiles Wiki - User contributions [en]

Main Page

2008-06-03T19:16:50Z

Hotwired: /* Combustion Launchers */ linking hybrids

== The Spudding Handbook ==
Welcome to The Spudding Handbook! This wiki format handbook contains all of the information you will ever need to build spudguns, and much more besides. The purpose of this handbook is to explain the principles of spudguns and how they are built and operated. All of the information contained in this handbook is free and available to anybody who wishes to view it.

Look around and enjoy your stay.
--[[User:BC Pneumatics|BC Pneumatics]] 02:13, 31 May 2008 (EDT)
[[Image:Cannon.jpg|frame|An Advanced Combustion Cannon]]
==What is a Spudgun?==
''Main article: [[What_is_a_spudgun%3F|What is a spudgun?]]''

There are many different names for spudguns. They are called potato cannons, spud launchers, potato guns, spud cannons, and a host of others. Whatever you decide to call it, all of the aforementioned describe the same type of device: a device used to accelerate a potato down the barrel, and launch it some distance. While it may offend some purists, the humble little potato is quickly losing favour to other ammunitions such as golf balls, tennis balls, and other cheap, uniform projectiles.

==Types of Spudguns==

=== [[Pneumatic_launcher|Pneumatic Launchers]] ===

These use the energy stored in compressed gas to launch a projectile. The launchers chamber is pressurised and the gas held back from the barrel by a valve. When the valve is opened the gas is allowed to rapidly expand and escape down the barrel forcing the projectile out before it.

=== Combustion Launchers ===

* '''[[Combustion_launcher|Regular Combustions]]'''

These find the energy needed to launch a projectile from the combustion of a gaseous fuel and air mixture. The fuel is added to the air already in the chamber, the chamber is sealed and the mixture ignited. This combustion creates a pressure spike that forces the projectile out through the connected barrel.

* '''[[Hybrid_launcher|Hybrid Launchers]]'''

Hybrid launchers are a special type of combustion launcher that use a pre-pressurised fuel/air mixture. This results in a higher pressure and hotter combustion on ignition, thereby transferring more energy to the projectile.

==Important & Related Links==

[[Index|Glossary/Index]]

[[BCARMS]]

[[Useful construction links]]

[[Launcher configuration]]

[[Computer Applications]]

[[IPLA|International Potato Launching Association]]

[[Safety]]

[[Ammunition]]

[[Legal issues]]

[[History]] (A Brief History of Spud Guns)

[[SpudFiles forum guidelines]]

==External links==

*[http://en.wikipedia.org/wiki/Spud_gun Wikipedia's page on spudguns]
*[http://www.bavetta.com/aircannon.html Air Cannon Barrel Length Numerical Analysis]
*[http://www.thehalls-in-bfe.com/GGDT Gas Gun Design Tool, simulation program for pneumatic guns]
*[http://www.spudfiles.com/forums/viewtopic.php?p=13324#13324 ATF Correspondence concerning spud gun legality]
*[http://www.spudfiles.com SpudFiles Forum (aka The Spud Cannon Database)]
*[http://www.BCARMS.com BCARMS - Spud Cannon Parts, Accessories, Kits and Launchers]

BBMG

2008-06-03T12:19:21Z

Hotwired: BBMG link to BB machine gun

See [[BB machine gun]]

Strafer

2008-06-03T12:18:32Z

Hotwired: Strafer link to BBMG

See [[BB_machine gun|BBMG]]

Main Page

2008-06-03T12:01:08Z

Hotwired: Trimming. If the front page is for an overview it shouldn't contain details such as fuels to use - specifics are better suited for their respective cannon pages.

== The Spudding Handbook ==
Welcome to The Spudding Handbook! This wiki format handbook contains all of the information you will ever need to build spudguns, and much more besides. The purpose of this handbook is to explain the principles of spudguns and how they are built and operated. All of the information contained in this handbook is free and available to anybody who wishes to view it.

Look around and enjoy your stay.
--[[User:BC Pneumatics|BC Pneumatics]] 02:13, 31 May 2008 (EDT)
[[Image:Cannon.jpg|frame|An Advanced Combustion Cannon]]
==What is a Spudgun?==
''Main article: [[What_is_a_spudgun%3F|What is a spudgun?]]''

There are many different names for spudguns. They are called potato cannons, spud launchers, potato guns, spud cannons, and a host of others. Whatever you decide to call it, all of the aforementioned describe the same type of device: a device used to accelerate a potato down the barrel, and launch it some distance. While it may offend some purists, the humble little potato is quickly losing favour to other ammunitions such as golf balls, tennis balls, and other cheap, uniform projectiles.

==Types of Spudguns==

=== [[Pneumatic_launcher|Pneumatic Launchers]] ===

These use the energy stored in compressed gas to launch a projectile. The launchers chamber is pressurised and the gas held back from the barrel by a valve. When the valve is opened the gas is allowed to rapidly expand and escape down the barrel forcing the projectile out before it.

=== Combustion Launchers ===

* '''[[Combustion_launcher|Regular Combustions]]'''

These find the energy needed to launch a projectile from the combustion of a gaseous fuel and air mixture. The fuel is added to the air already in the chamber, the chamber is sealed and the mixture ignited. This combustion creates a pressure spike that forces the projectile out through the connected barrel.

* '''Hybrid Launchers'''

[[Hybrid launcher]]s are a special type of combustion launcher that use a pre-pressurised fuel/air mixture. This results in a higher pressure and hotter combustion on ignition, thereby transferring more energy to the projectile.

==Important & Related Links==

[[Index|Glossary/Index]]

[[BCARMS]]

[[Useful construction links]]

[[Launcher configuration]]

[[Computer Applications]]

[[IPLA|International Potato Launching Association]]

[[Safety]]

[[Ammunition]]

[[Legal issues]]

[[History]] (A Brief History of Spud Guns)

[[SpudFiles forum guidelines]]

==External links==

*[http://en.wikipedia.org/wiki/Spud_gun Wikipedia's page on spudguns]
*[http://www.bavetta.com/aircannon.html Air Cannon Barrel Length Numerical Analysis]
*[http://www.thehalls-in-bfe.com/GGDT Gas Gun Design Tool, simulation program for pneumatic guns]
*[http://www.spudfiles.com/forums/viewtopic.php?p=13324#13324 ATF Correspondence concerning spud gun legality]
*[http://www.spudfiles.com SpudFiles Forum (aka The Spud Cannon Database)]
*[http://www.BCARMS.com BCARMS - Spud Cannon Parts, Accessories, Kits and Launchers]

BB machine gun

2008-06-03T01:50:52Z

Hotwired: /* Common Designs */ smidge more editing

A '''BB Machine Gun''' (BBMG) is a device designed to shoot a large volume of small diameter [[ammo]], typically plastic airsoft or steel BBs. BBMGs are pneumatic guns but unlike single shot [[pneumatic launcher|launchers]] they require a constant gas supply to function. The common use of a large air [[compressor]] restricts mobility for the majority of BBMGs although models using CO2 systems have been successfully built as portable units.

== Common Designs ==

* A [[cloud chamber]] agitates the BBs in the ammunition chamber by means of the air inlet blowing upwards through them. The agitated BBs then get sucked into the [[barrel]] with the outgoing air stream.

* A [[vortex block]] uses the air inlet to swirl the BBs around a circular or semi-circular cutout in a block placed in the BB chamber and out through a BB sized hole in its side leading to the barrel.

* A [[vortex cap]] works on an identical principle to a vortex block but instead of a cut-out in a block placed within a large BB chamber it uses the circular internals of a pipe endcap in which to swirl the BBs allowing for a smaller diameter chamber. This potentially allows for a smaller overall design. It was designed by Gatorlangman AKA DavidVaini.

== Design Characteristics ==

The performance of a BBMG, as with any gun, depends on specific characteristics. For BBMGs, perhaps the most important are;

* Air supply [[pressure]]
* Sustainability of the supply pressure
* Air flow from supply to barrel
* Barrel length
* The fit of the BBs in the barrel

Most of the characteristics that make a good pneumatic spudgun also apply to BBMGs. As with any pneumatic gun, the higher the reservoir pressure and the longer the barrel (up to a point) the greater the [[muzzle velocity]]. Because of the large amount of compressed gas that is wasted in a typical BBMG, the air supply needs to be fairly substantial. For air supplies with a resevoir such as compressors this can mean [[CB ratio]]s of 100:1 to 1000:1. Note that, for a BBMG, the "[[chamber]] volume" includes the volume of the compressor's reservoir.

The BBs should fit the barrel well enough to minimize leakage of air around the ammo ([[blowby]]) but not so tightly that friction is excessive.

The chambering and firing of BBs in a BBMG appears to be a coupled process. Usually, when a BB is passing through the barrel the reduced air flow through the gun inhibits the loading of the next BB into the barrel. When the first BB leaves the barrel the increase in air flow "chambers" the next BB. As a result it appears that there is rarely more than one BB in the barrel at a time. This suggests that the muzzle velocity and ROF of these types of BBMGs are linked. The ROF for a gun would appear to be often very close to the reciprocal of the barrel transit time for a BB.

For example, a 3 foot barrel that fires at 300 FPS has an average barrel velocity of ~150 FPS and a transit time of ~20mS. The ROF would be expected to be about 1/20mS = 50 RPS. Design changes that alter the transit time would be expected to also change the ROF.

== Typical Performance ==

The rate of fire for the average gun is very high, in the vicinity of 30 to 100 rounds per second (RPS), 1800 to 6000 rounds per minute, comparable to that of a [http://en.wikipedia.org/wiki/Minigun Minigun] which clocks in at 33~66 RPS.

BBMGs in general are not usually capable of sustained full performance fire as most air sources cannot provide an adequate flow of sufficiently high pressure air. To reduce air consumption, maintain muzzle velocity and to reduce the rate that the ammunition is expended they are typically fired in short bursts lasting a few seconds at most.

'''Airsoft BBMG Performance'''

Airsoft BBMGs are known for their especially high rate of fire. This is in the region of 30 to 115 rounds per second (RPS), 1800 to 6900 rounds per minute. This is useful in Airsoft skirmishes for laying down suppressive fire or clearing out multiple targets up close. The projectile speeds of around 250-400 Feet Per Second(FPS) are comparable to higher end Airsoft Electric Guns or AEGs. The advantage of the high ROF is quite clear in skirmishes however the consumption of such a high volume of pellets can be expensive.

Other disadvantages of using BBMGs in airsoft lies in their portability and range. Portability can be fixed by using an external CO2 setup for the gas supply however it can be costly. The other problem of range is due to the lack of a hop-up system which creates backspin on the BB and so increase the distance they can fly. Although possible to add a hop-up they wear down quickly because of the high ROF.

'''Non-Airsoft BBMG Performance'''

These BBMGs are unregulated by airsoft limitations of plastic pellets as they are not intended to be fired at other people.

With 3 foot length of 1/4" OD (3/16" ID) stainless steel tubing, a 120 PSIG 3 gallon shop compressor and firing standard copper or steel BBs, a typical vortex BBMG has a muzzle velocity of about [http://www.inpharmix.com/jps/Jims_chrono.html 330 FPS]. This is about the same as a cheap commercial single shot BB gun. The muzzle energy for an 0.177" metal BB (0.33g) at 330 FPS is 1.2 foot-pounds (1.7J). Despite the relatively low projectile speed, the abrasive effects of a large number of hard BBs striking a target in a short period of time can be quite destructive.

The high ROF can consume pellets at an expensive rate. A six pound container of 6000 metal BBs costs about $15. At 50 RPS that six pound container will last for two minutes of firing.

== Links ==
[http://www.burntlatke.com/bb.html Latke's BBMG]: An excellent write-up on how to build a Vortex BBMG.

Compressor

2008-06-03T01:26:19Z

Hotwired: a quickie

A '''compressor''' is a mechanical pump that compresses gas. They range from small 12 Volt emergency compressors with relatively high [[pressure]] but very low volume, to shop compressors with large air tanks for storage, and scuba compressors that can deliver thousands of [[psi]] to fill high pressure cylinders.

== Pros/Cons of each type ==
'''12 Volt Emergency Compressor:'''

''Advantages:''
* Quite cheap to buy
* Light
* Theoretically capable of 200-300 psi

''Disadvantages:''
* Low flow
* Poor duty cycle - as low as 20% (the other 80% is for rest) is not uncommon.
* Prone to malfunction and often have a very short life.
* Requires power source (Car battery, car battery charger, or Mains to cigarette socket transformer)
* Noisy

'''Tool/Shop Compressor:'''

''Advantages:''
* Reasonably cheap to run
* Fast.
* Won't run out, unlike [[gas bottle]]s.
* Can provide a mobile pressure supply if gasoline powered.

''Disadvantages:''
* Requires power socket (if electrical).
* Requires fuel (if [[gasoline]] powered).
* Heavy.
* Typically limited to 8 bar/120 psi but 10 bar/145 psi types are available.
* Can be costly to buy initially.
* Noisy

'''Scuba Compressor'''

''Advantages:''
* Very high pressure (typically 2500-4500 psi)
* Can be used to fill gas bottles.
* Moderate flow

''Disadvantages:''
* Very large.
* Very expensive.
* Noisy.
* Power socket required.

==Types of compressors==
*'''Reciprocating''' - Uses a reciprocating piston to draw gas in through a [[valve]] and force the drawn gas into a storage tank or through a smaller orifice. They are available with single or multiple cylinders, depending upon the pressure and volume required. Reciprocating compressors are referred to as positive displacement compressors. (1)
*'''Rotary Screw''' - Two intermeshing helical rotors in a twin bore case are used to compress between one convex and one concave rotor. The trapped volume of gas is decreased while the pressure is increased. Rotary screw compressors are referred to as positive displacement compressors. (1)
*'''Centrifugal Compressor''' - Unlike the reciprocating and rotary screw compressors, centrifugal compressors do not make use of positive displacement. Gas enters the center of rotation of an element and is forced outward. The element can use curved blades, radial blades, or backward blades. The acceleration of the gas causes the pressure to rise. (1)

sources:
(1) http://www.ctrlsys.com/library/applications/compressors-2.php

BB machine gun

2008-06-03T01:01:03Z

Hotwired: General editing* - finished going through, shuffled a lot of text about and put the generic stuff together to cancel some repetition.

A '''BB Machine Gun''' (BBMG) is a device designed to shoot a large volume of small diameter [[ammo]], typically plastic airsoft or steel BBs. BBMGs are pneumatic guns but unlike single shot [[pneumatic launcher|launchers]] they require a constant gas supply to function. The common use of a large air [[compressor]] restricts mobility for the majority of BBMGs although models using CO2 systems have been successfully built as portable units.

== Common Designs ==

* A [[cloud chamber]] agitates the projectiles by means of the air inlet blowing upwards through them. The agitated BBs then get sucked into the [[barrel]] with the outgoing air stream.

* A [[vortex block]] uses the air inlet to swirl the BBs around a circular or semi-circular cutout in a block placed in the BB chamber and out through a BB sized hole in its side leading to the barrel.

* A [[vortex cap]] works on an identical principle to a vortex block but instead of a cut-out in a block placed within a large BB chamber it uses the circular internals of a pipe endcap in which to swirl the BBs allowing for a smaller diameter chamber. This potentially allows for a smaller overall design. It was designed by Gatorlangman AKA DavidVaini.

== Design Characteristics ==

The performance of a BBMG, as with any gun, depends on specific characteristics. For BBMGs, perhaps the most important are;

* Air supply [[pressure]]
* Sustainability of the supply pressure
* Air flow from supply to barrel
* Barrel length
* The fit of the BBs in the barrel

Most of the characteristics that make a good pneumatic spudgun also apply to BBMGs. As with any pneumatic gun, the higher the reservoir pressure and the longer the barrel (up to a point) the greater the [[muzzle velocity]]. Because of the large amount of compressed gas that is wasted in a typical BBMG, the air supply needs to be fairly substantial. For air supplies with a resevoir such as compressors this can mean [[CB ratio]]s of 100:1 to 1000:1. Note that, for a BBMG, the "[[chamber]] volume" includes the volume of the compressor's reservoir.

The BBs should fit the barrel well enough to minimize leakage of air around the ammo ([[blowby]]) but not so tightly that friction is excessive.

The chambering and firing of BBs in a BBMG appears to be a coupled process. Usually, when a BB is passing through the barrel the reduced air flow through the gun inhibits the loading of the next BB into the barrel. When the first BB leaves the barrel the increase in air flow "chambers" the next BB. As a result it appears that there is rarely more than one BB in the barrel at a time. This suggests that the muzzle velocity and ROF of these types of BBMGs are linked. The ROF for a gun would appear to be often very close to the reciprocal of the barrel transit time for a BB.

For example, a 3 foot barrel that fires at 300 FPS has an average barrel velocity of ~150 FPS and a transit time of ~20mS. The ROF would be expected to be about 1/20mS = 50 RPS. Design changes that alter the transit time would be expected to also change the ROF.

== Typical Performance ==

The rate of fire for the average gun is very high, in the vicinity of 30 to 100 rounds per second (RPS), 1800 to 6000 rounds per minute, comparable to that of a [http://en.wikipedia.org/wiki/Minigun Minigun] which clocks in at 33~66 RPS.

BBMGs in general are not usually capable of sustained full performance fire as most air sources cannot provide an adequate flow of sufficiently high pressure air. To reduce air consumption, maintain muzzle velocity and to reduce the rate that the ammunition is expended they are typically fired in short bursts lasting a few seconds at most.

'''Airsoft BBMG Performance'''

Airsoft BBMGs are known for their especially high rate of fire. This is in the region of 30 to 115 rounds per second (RPS), 1800 to 6900 rounds per minute. This is useful in Airsoft skirmishes for laying down suppressive fire or clearing out multiple targets up close. The projectile speeds of around 250-400 Feet Per Second(FPS) are comparable to higher end Airsoft Electric Guns or AEGs. The advantage of the high ROF is quite clear in skirmishes however the consumption of such a high volume of pellets can be expensive.

Other disadvantages of using BBMGs in airsoft lies in their portability and range. Portability can be fixed by using an external CO2 setup for the gas supply however it can be costly. The other problem of range is due to the lack of a hop-up system which creates backspin on the BB and so increase the distance they can fly. Although possible to add a hop-up they wear down quickly because of the high ROF.

'''Non-Airsoft BBMG Performance'''

These BBMGs are unregulated by airsoft limitations of plastic pellets as they are not intended to be fired at other people.

With 3 foot length of 1/4" OD (3/16" ID) stainless steel tubing, a 120 PSIG 3 gallon shop compressor and firing standard copper or steel BBs, a typical vortex BBMG has a muzzle velocity of about [http://www.inpharmix.com/jps/Jims_chrono.html 330 FPS]. This is about the same as a cheap commercial single shot BB gun. The muzzle energy for an 0.177" metal BB (0.33g) at 330 FPS is 1.2 foot-pounds (1.7J). Despite the relatively low projectile speed, the abrasive effects of a large number of hard BBs striking a target in a short period of time can be quite destructive.

The high ROF can consume pellets at an expensive rate. A six pound container of 6000 metal BBs costs about $15. At 50 RPS that six pound container will last for two minutes of firing.

== Links ==
[http://www.burntlatke.com/bb.html Latke's BBMG]: An excellent write-up on how to build a Vortex BBMG.

BB machine gun

2008-06-02T23:33:54Z

Hotwired: General editing* - not fully complete

A '''BB Machine Gun''' (BBMG) is a device designed to shoot a large volume of small diameter [[ammo]], typically plastic airsoft or steel BBs. BBMGs are pneumatic guns but unlike single shot [[pneumatic launcher|launchers]] they require a constant gas supply to function. The common use of a large air [[compressor]] restricts mobility for the majority of BBMGs although models using CO2 systems have been successfully built as portable units.

== Common Designs ==

* A [[cloud chamber]] agitates the projectiles by means of the air inlet blowing upwards through them. The agitated BBs then get sucked into the [[barrel]] with the outgoing air stream.

* A [[vortex block]] swirls the BBs around a circular or semi-circular cutout in a block placed in the BB chamber and out through a BB sized hole in its side leading to the barrel.

* A [[vortex cap]] works on an identical principle to a vortex block but instead of a cut-out in a block placed within a large BB chamber it uses the circular internals of a pipe endcap in which to swirl the BBs allowing for a smaller diameter chamber. This potentially allows for a smaller overall design. It was designed by Gatorlangman AKA DavidVaini.

== Design Characteristics ==

The performance of a BBMG, as with any gun, depends on several characteristics of the gun. For BBMGs, perhaps the most important are;

* Air supply [[pressure]]
* Sustainability of the supply pressure
* Air flow from supply to barrel
* Barrel length
* The fit of the BBs in the barrel

Most of the characteristics that make a good pneumatic spudgun also apply to BBMGs. As with any pneumatic gun, the higher the reservoir pressure and the longer the barrel (up to a point) the greater the [[muzzle velocity]]. Because of the large amount of compressed gas that is wasted in a typical BBMG, the air supply needs to be fairly substantial. For air supplies with a resevoir such as compressors this can mean [[CB ratio]]s of 100:1 to 1000:1. Note that, for a BBMG, the "[[chamber]] volume" includes the volume of the compressor's reservoir.

The BBs should fit the barrel well enough to minimize leakage of air around the ammo ([[blowby]]) but not so tightly that friction is excessive.

The chambering and firing of BBs in a BBMG appears to be a coupled process. Usually, when a BB is passing through the barrel the reduced air flow through the gun inhibits the loading of the next BB into the barrel. When the first BB leaves the barrel the increase in air flow "chambers" the next BB. As a result it appears that there is rarely more than one BB in the barrel at a time. This suggests that the muzzle velocity and ROF of these types of BBMGs are linked. The ROF for a gun would appear to be often very close to the reciprocal of the barrel transit time for a BB.

For example, a 3 foot barrel that fires at 300 FPS has an average barrel velocity of ~150 FPS and a transit time of ~20mS. The ROF would be expected to be about 1/20mS = 50 RPS. Design changes that alter the transit time would be expected to also change the ROF.

== Typical Performance ==

'''Airsoft BBMG Performance'''

Airsoft BBMGs are known for their high rate of fire (ROF). This is in the region of 30 to 115 rounds per second (RPS), 1800 to 6900 rounds per minute. This extremely high ROF helps in Airsoft skirmishes for laying down suppressive fire or clearing out multiple targets up close. The projectile speeds of around 250-400 Feet Per Second(FPS) are comparable to higher end Airsoft Electric Guns or AEGs. The advantage of the high ROF is quite clear in skirmishes however the consumption of such a high volume of pellets can be expensive.

Other disadvantages of BBMG's lie in their portability and range. Portability can be fixed by using an external CO2 setup for the gas supply however that can be costly. The other problem of range is due to the lack of a hop-up system to create backspin on the BB and so increase the distance they can fly. Although possible to add a hop-up they wear down quickly because of the high ROF. A truly bitter sweet situation.

'''Copper/Steel BBMG Performance'''

Copper/Steel BBMGs, even if very simply constructed from readily available materials, are capable of very high rates of fire (ROF). The ROF for typical guns is in the vicinity of 30 to 100 rounds per second (RPS), 1800 to 6000 rounds per minute. This rate of fire is much higher than military machine guns, which fire at ~9 RPS. Only the military [http://en.wikipedia.org/wiki/Minigun Minigun], a modern Gatling machine gun, with a ROF of 33~66 RPS fires this fast. So, BBMGs are very impressive in terms of their ROFs.

The muzzle velocity of typical Copper/Steel BBMGs is much less impressive than their ROFs. With 3 foot length of 1/4" OD (3/16" ID) stainless steel tubing, a 120 PSIG 3 gallon shop compressor and firing standard copper/steel BBs, a typical vortex BBMG has a muzzle velocity of about 330 FPS (data from [http://www.inpharmix.com/jps/Jims_chrono.html here]). This muzzle velocity is about the same as a cheap commercial single shot BB gun. The muzzle energy for an 0.177" copper/steel BB (0.33g) at 330 FPS is 1.2 foot-pounds (1.7J). Even though the muzzle velocity of most BBMGs is relatively low, the large number of BBs that strike the target in a short period of time can do a fair amount of damage.

The very high ROF of most Copper/Steel BBMGs consumes BBs at an alarming rate. A six pound container of copper/steel BBs costs about $15 and contains 6000 BBs. At 50 RPS that six pound container will last for two minutes of firing.

Most Copper/Steel BBMGs are not capable of sustained firing since the air source cannot provide an adequate flow of air at sufficiently high pressure. To reduce air consumption (and hence maintain muzzle velocity), and to reduce the rate that the ammos is expended, Copper/Steel BBMGs are typically fired in short bursts lasting a few seconds at most.

== Links ==
[http://www.burntlatke.com/bb.html Latke's BBMG]: An excellent write-up on how to build a Vortex BBMG.

User:Hotwired

2008-06-02T21:54:22Z

Hotwired: MAH PAGE!

=UK Spudgunner=

==Published cannons==

===Copperhead Prime===

* 15mm x 1m copper barrel
* 22mm x 60cm copper chamber
* 1/2" piston type [[QEV]] as the main valve
* 1/4" [[blowgun]] as the pilot valve
* 1/4" mini [[Ball_valve|ballvalve]] as a safety valve
* 15 to 400psi operating pressures

It utilised a unique bullpup configuration regarding the valve positioning, is breech loading and has a custom moulded grip.

Copper pipe

2008-06-02T21:37:30Z

Hotwired: General editing*

Copper pipe and fittings are popular spudgun construction materials due to their common availability in DIY stores. It is especially popular in countries such as the UK where pressure rated plastic piping is only available by order.

==Pros/Cons==

The primary advantages of copper pipe are that it is rated to much higher [[pressure]]s than PVC, and has better failure characteristics due to it's high malleability which results in splitting rather than shattering. This makes it well suited for making high pressure [[pneumatic cannon]]s and [[hybrid cannon|hybrid]]s. The pressure ratings have a safety factor of around 7.

Copper piping is typically very smooth and consistent, which combined with it's high rigidity makes it exceptional [[barrel]] material. The consistent internal diameter also makes it popular for construction of [[combustion cannon]] [[fuel meter]]s.

For comparable sizes of [[PVC]] it is around four times the price and considerably heavier, it is therefore only a viable alternative to plastic for small calibres of around 1" or less.

For comparable sizes of [[Steel]] it is has a lower pressure rating and again is more expensive. However due to the thinner walls it is comparatively light and it is cheaper to make non-mechanical joins with.

==Types & Use==

Copper pipe is usually joined by [[sweating]], using [[compression fitting]]s, or [[Copper epoxy]].
Compression fittings are much more expensive than soldering ones but require minimal tools to use (a spanner or two), copper epoxy uses the same solder fitting as for sweating but replaces the solder to make the join therefore requiring no blowtorch.

The threaded fittings for copper pipe are made of brass or less commonly, corrosion resistant/coated steel as they have better mechanical strength than pure copper.

Copper pipe comes in two tempers, annealed and drawn. Annealed pipe is very soft, is sold in coils and can usually be bent by hand. Drawn pipe is rigid, sold as straight lengths and will flex rather than bend (to a certain limit). Bending drawn pipe without causing it to flatten out requires bending springs or mechanical bending devices which force the pipe over curved forms to create the desired shape without unwanted deformation.

Drawn pipe is the most useful in spudgun construction for chambers and barrels, since it will keep its shape and not get damaged as easily. It is also rated to about twice the pressure as an annealed pipe of the same size. Small bore annealed tubing has a place in areas such as pilot tubing from the main valve to the pilot valve where it's higher malleability allows for pilot valve positioning.

==Safety==
Copper or Brass pipe/fittings should not be used with [[acetylene]] gas, as copper alloys can act as a catalyst to the explosive decomposition of the gas.

Due to it's relatively thin walled nature, potentially dangerous sharp ends can exist on pipe ends that have not been cleaned, and anybody using it should be aware of this.

Cutting of copper has a high attrition rate on rotary multi-tool abrasive discs, which will wear down at a high rate, and break apart regularly. Use of safety goggles is recommended

[[category:construction materials]]