SpudFiles Wiki - User contributions [en]

Compressed air regulator

2007-02-04T20:15:57Z

BillyBobJoe:

A '''compressed air regulator''' is made for regulating air from compressors or similiar sources. The input pressure can range from anywhere from 0 to several thousand [[psi]], and output pressure can be either predefined or adjusted within a certain range.

Air regulators commonly found at hardware stores are relatively cheap, but have a somewhat limited use because of the low input pressure.
Compressed air regulators have been used successfully to regulate [[propane]], though they are not made for this and could potentially be damaged. An air regulator may vent to the atmosphere when the pressure dial is being turned down, and vented propane may pose a fire hazard. Liquid propane entering the regulator may damage it as well. Nevertheless spudgun enthusiasts commonly use such regulators on propane [[fuel meter]]s.

Compressed air regulator

2007-02-04T20:15:22Z

BillyBobJoe:

A '''compressed air regulator''' is made for regulating air from compressors or similiar sources. The input pressure can range from anywhere from 0 to several thousand [[psi]], and output pressure can be either predefined or adjusted within a certain range.

Air regulators commonly found at hardware stores are relatively cheap, but have a somewhat limited use because of the low input pressure.
Compressed air regulators have been used successfully to regulate [[propane]] for [[fuel meter]]s, though they are not made for this and could potentially be damaged. An air regulator may vent to the atmosphere when the pressure dial is being turned down, and vented propane may pose a fire hazard. Liquid propane entering the regulator may damage it as well. Nevertheless spudgun enthusiasts commonly use such regulators on propane [[fuel meters]].

Aerosol

2007-02-04T20:11:32Z

BillyBobJoe:

'''Aerosol''' propellants come in cans, you can buy them at any grocery or department store, and they do not need any auxillary hardware (like a [[fuel meter]]) to use. As such, they are quite popular.

It is recommended that you avoid using hairspray, as it will leave an undesirable residue in the combustion chamber. Deoderant is much better - "Right Guard" in the brown can was the generally recommended aerosol fuel until recently, when the formula was changed to use a non-combustible propellant. Any spray with flammable propellants will work, look for compounds such as [[propane]], [[butane]], isobutane and/or [[starter fluid|ether]]).

Because the amount of fuel cannot be measured accurately (the usual procedure is timing the spray duration by feel), it does not yield the performance that [[fuel meter|metered propane]] does - the pressure generated during a [[closed chamber]] firing is estimated to about 30-40 [[psi]], as compared to 40-50.
If your cannon is not firing, or is firing weakly and you have a flammable fuel (verified by spraying over a flame): check the [[ignition source]]. If you are getting a spark, you are most likely spraying too much fuel in; experiment with varying amounts of fuel until successful results are achieved. And always remember to [[venting|vent]] the combustion chamber between successful and unsuccessful ignitions.

[[category:fuels]]

Aerosol

2007-02-04T20:10:32Z

BillyBobJoe:

'''Aerosol''' propellants come in cans, you can buy them at any grocery or department store, and they do not need any auxillary hardware (like a [[fuel meter]]) to use. As such, they are quite popular.

It is recommended that you avoid using hairspray, as it will leave a sticky residue in the combustion chamber. Deoderant is much better - "Right Guard" in the brown can was the generally recommended aerosol fuel until recently, when the formula was changed to use a non-combustible propellant. Any spray with flammable propellants will work, look for compounds such as [[propane]], [[butane]], isobutane and/or [[starter fluid|ether]]).

Because the amount of fuel cannot be measured accurately (the usual procedure is timing the spray duration by feel), it does not yield the performance that [[fuel meter|metered propane]] does - the pressure generated during a [[closed chamber]] firing is estimated to about 30-40 [[psi]], as compared to 40-50.
If your cannon is not firing, or is firing weakly and you have a flammable fuel (verified by spraying over a flame): check the [[ignition source]]. If you are getting a spark, you are most likely spraying too much fuel in; experiment with varying amounts of fuel until successful results are achieved. And always remember to [[venting|vent]] the combustion chamber between successful and unsuccessful ignitions.

[[category:fuels]]

Starting fluid

2007-02-04T20:07:26Z

BillyBobJoe:

'''Starting fluid''' is normally known as ether, diethyl ether, or ethyl ether. All types are powerful, some people believe they produce more power than propane. Ethers are incredibly easy to over-fuel however. the upper flammability limit is about the same as the LOWER flammability limit of propane.

Some starter fluids contain oil, which can collect in the combustion chamber and disable [[lantern sparker]]s. It may also be corrosive to certain plastic and rubber materials. The fluid can be tested for oil by spraying some on a piece of paper. Any oil will leave a grease stain after the ether has evaporated.

[[Image:00165.jpg]]

[[category:fuels]]

File:00165.jpg

2007-02-04T20:05:24Z

BillyBobJoe: Cans of starting fluid.

Cans of starting fluid.

Starting fluid

2007-02-04T20:03:24Z

BillyBobJoe:

Butane

2007-02-04T20:02:30Z

BillyBobJoe:

[[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 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]]

Quick disconnect

2007-02-04T20:01:23Z

BillyBobJoe:

[[Image:Quick_disconnect.jpg|right|thumb|250px|A quick-disconnect plug and coupler]]A '''quick disconnect''' is a device that allows you to split an air line at a point without having to unthread components. Always place the coupling (the female side) on the upstream side and the plug (male) on the downstream side.

Quick disconnects are often used as high speed filling valves (in place of a [[schrader valve]]) on larger cannons.

{{stub}}

Quick disconnect

2007-02-04T20:00:58Z

BillyBobJoe:

Primer

2007-02-04T19:59:17Z

BillyBobJoe: /* Use as a Dye/Paint */

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. Application of primer should be done immedatly before the application of PVC cement. As always, the directions on the can provide the best advice on the process of [[solvent welding]].

== 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 in a well ventilated area. Gloves can be worn, but care should be taken to avoid spilling primer on them, as acetone penetrates through latex and rubber gloves, where it is absorbed through the skin. In addition, long term exposure of skin to these low-polarity solvents will severely dry your skin out, possibly leading to dermatitis. Swallowing primer may result in death, and chronic inhalation of primer fumes can cause damage to several vital organs including the central nervous system, liver, and kidneys. Symptoms of acute (short term) overexposure include dizziness, headache, nausea, confusion, vomiting, and unconciousness.

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.

==Use as a Dye/Paint==

The unsightly stains caused by purple colored primer can be made to look less noticeable by covering the rest of the PVC pipe/fitting with primer also. Multiple coats may be necessary to achieve the desired shade. This dyeing method is especially resistant to scratching and was used in this .25 caliber piston valve cannon made by BillyBobJoe of the [[Spudtech]] forum.

[[Image:Primercannon.jpg]]

It should be noted that this rifle suffered a fracture in the rear female adapter, which was most likely caused by an overtightened SCH. 80 plug. The primer only penetrates the surface of the pipe/fitting and once it has had time to dry and dissipate, overall strength of the finished product should not be compromised.

== External links ==

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

12 gram CO2 cartridge

2007-02-01T00:32:48Z

BillyBobJoe:

12 gram '''CO2 cartridges''' are used primarily as a portable way to provide pressurized gas to a [[pneumatic cannon]]. They cost roughly $0.50 a peice, and are typically connected via an adapter, which can be purchased for about $10 USD.
Once empty, they are often used as projectiles - they have a high mass, are quite sturdy, and fit in 3/4" SCH. 40 PVC.

The following is a chart outlining the chamber size (in cubic inches) vs. pressure in (pounds per square inch) using a 12 gram CO2 cartridge:
<table>
<tr><td>Chamber Size (ci)</td><td>Chamber Pressure (PSI)</td></tr>
<tr><td>10</td><td>420</td></tr>
<tr><td>20</td><td>210</td></tr>
<tr><td>30</td><td>140</td></tr>
<tr><td>40</td><td>105</td></tr>
<tr><td>50</td><td>84</td></tr>
<tr><td>60</td><td>70</td></tr>
<tr><td>70</td><td>60</td></tr>
<tr><td>80</td><td>53</td></tr>
<tr><td>90</td><td>47</td></tr>
<tr><td>100</td><td>42</td></tr>
</table>

To calculate the pressure for any non-given value, use this equation, but note that the pressure can't go above 800 PSI (the vapor pressure of CO2).

4200/Chamber Volume In ci=Chamber Pressure in psi -OR- 4200/CV=CP
For example:
You have a chamber volume of 41.3ci.
So it can be said that 4200/41.3=CP
4200/41.3 is equal to 101.6949152542373 For simplicity's sake we will round this to 101.7
This means that CP=101.7 PSI
Your 41.3ci chamber will have a pressure of 101.7 PSI when filled with one 12g CO2 cartridge.

12 gram CO2 cartridge

2007-02-01T00:32:31Z

BillyBobJoe:

12 gram '''CO2 cartridges''' are used primarily as a portable way to provide pressurized gas to a [[pneumatic cannon]]. They cost roughly $0.50 a peice, and are typically connected via an adapter, which can be purchased for about $10 USD.
Once empty, they are often used as projectiles - they have a high mass, are quite sturdy, and fit in 3/4" SCH. 40 PVC.

The following is a chart outlining the chamber size (in cubic inches) vs. pressure in (pounds per square inch) using a 12 gram CO2 cartridge:
<table>
<tr><td>Chamber Size (ci)</td><td>Chamber Pressure (PSI)</td></tr>
<tr><td>10</td><td>420</td></tr>
<tr><td>20</td><td>210</td></tr>
<tr><td>30</td><td>140</td></tr>
<tr><td>40</td><td>105</td></tr>
<tr><td>50</td><td>84</td></tr>
<tr><td>60</td><td>70</td></tr>
<tr><td>70</td><td>60</td></tr>
<tr><td>80</td><td>53</td></tr>
<tr><td>90</td><td>47</td></tr>
<tr><td>100</td><td>42</td></tr>
</table>

To calculate the pressure for any non-given valve, use this equation, but note that the pressure can't go above 800 PSI (the vapor pressure of CO2).

4200/Chamber Volume In ci=Chamber Pressure in psi -OR- 4200/CV=CP
For example:
You have a chamber volume of 41.3ci.
So it can be said that 4200/41.3=CP
4200/41.3 is equal to 101.6949152542373 For simplicity's sake we will round this to 101.7
This means that CP=101.7 PSI
Your 41.3ci chamber will have a pressure of 101.7 PSI when filled with one 12g CO2 cartridge.

Legal issues

2007-02-01T00:28:59Z

BillyBobJoe:

==United States of America==
===Letter from the ATF===
The bureau of alchohol, tobacco, and firearms sent the [[SGTC]] the following letter.
Another version with pictures can be found [http://www.spudfiles.com/Other/are_they_legal.php here].

<blockquote>
Department of the Treasury

Bureau of Alcohol, Tobacco, and Firearms

Washington, DC 20226

As defined in section 921(a) (3) of Title 18, United States Code (USC) the term "firearm" means --

* (A) any weapon (including a starter gun) which will or is designed to or may readily be converted to expel a projectile by the action of an explosive;
* (B) the frame or receiver of any such weapon;
* (C) any firearm muffler or firearm silencer; or
* (D) any destructive device. Such term does not include an antique firearm.

As defined in 26 USC subsection 5845(f) (2) the term destructive device includes any type of weapon by whatever name known which will, or which may readily be converted to, expel a projectile by the action of an explosive or other propellent, the barrel or barrels of which have a bore of more than one-half inch in diameter, except a shotgun or shotgun shell which the Secretary or his delegate finds is generally recognized as particularly suitable for sporting purposes; and (3) any combination of parts either designed or intended for use in converting any device into a destructive device as defined in subparagraphs (1) and (2) and from which a destructive device may be readily assembled. The term 'destructive device' shall not include any device which is neither designed nor redesigned for use as a weapon; any device, although originally designed for use as a weapon, which is redesigned for use as a signaling, pyrotechnic, line throwing, safety, or similar device; surplus ordnance sold, loaned, or given by the Secretary of the Army pursuant to the provisions of section 4684(2), 4685, or 4686 of title 10 of the USC; or any other device which the Secretary of the Treasury or his delegate finds is not likely to be used as a weapon, or is an antique or is a rifle which the owner intends to use solely for sporting purposes.

It is unlawful for anyone to make or possess a destructive device which is not registered in accordance with the provisions of the National Firearms Act.

We have previously examined that certain muzzle loading devices known as "potato guns." These potato guns are constructed from PVC plastic tubing. They use hair spray or a similar aerosol substance for a propellant, and have some type of spark ignitor. We have determined that these devices, as described, are not firearms provided that they are used solely for launching potatoes for recreational purposes. However, any such devices which are used as weapons or used to launch other forms of projectiles may be firearms and destructive devices as defined.
</blockquote>

===Interpretation of the ATF letter===
"other forms of projectiles" is typicaly interpreted to mean flammable, and/or explosive projectiles; ie, that "potatoes" were an example of an acceptable projectile, and not the only option.

===State, County, and City laws===
These vary. It is generally illegal to shoot a spudgun inside city limits.
The owner of the SGTC provides the following advice: "If it is OK to shoot a shotgun in your particular location....you will have no problem with your spudgun."

*In Glendale, Arizona and Phoenix, Arizona combustion spudguns are considered firearms.
Subject: RE: potato gun legality
The legality of potato guns are as follows. If the potato is expelled
by the use of air it is OK. If any explosion occurred from gas, powder,
etc. it is illegal and cannot be fired. The "firearm" definition is
what dictates this.

==Other countries==

=== Australia ===

Information taken from my (Julz) posts on Spudfiles Forums. This information is as accurate as possible, however, may not be entirely correct as I did not speak to anybody of authority, I gained my information only from government web sites.

Please note, nowhere did I read that spudguns were definantly legal. Assumptions that they are legal are made on the basis that in a detailed list of prohibited weapons spudguns were not mentioned.

I am not responsible for any trouble you get into as a result of this information.

For the original posts, see [http://www.spudfiles.com/forums/viewtopic.php?p=1305&lighter=&#1305 here]

Victoria---->Legal? - I could find no referance to spud guns etc in this page, detailing prohibited weapons.
[http://www.justice.vic.gov.au/CA2569020010922A/OrigDoc/~AF15C6429D88D005CA256C1D0016321D?OpenDocument&1=0-Safety~&2=0-Crime+Prevention~&3=0-Information+about+Prohibited+Weapons~ Long Link]

New South Wales---->Illegal - Requires a permit that cannot be gained without a legitemate reason for possessing the cannon.
Quote:
Item 2(3) Any device that is designed to propel or launch a bomb, grenade, rocket or missile by any means other than by
means of an explosive, including a device known as a PVC cannon.

http://www.police.nsw.gov.au/__data/assets/file/5232/Prohibited_Weapons_General_Permit.pdf

Australian Capital Territory---->Legal? - I could find no referance to spud guns etc in this page, detailing prohibited weapons.
http://www.legislation.act.gov.au/b/db_14541/19960829-16540/pdf/db_14541.pdf

South Australia---->? I could find no referance to spud guns etc in this page, detailing prohibited weapons.
http://www.sapolice.sa.gov.au/firearms/prohib_weapon/weapon_type.shtml

Northern Territory---->Illegal

Western Australia----> Legal if the projectile is expelled
by the use of air it is OK. If any explosion occurred from gas, powder,
etc. it is illegal and cannot be fired.

Quote: F23 Can I have a spud gun?

No, as a spud gun is deemed to be a firearm within the definition of a firearm under the Firearms Act 1973 amended 1996.

http://www.police.wa.gov.au/Services/FirearmsandWeapons.asp?FrequentlyAskedQuestions#F23

Queensland---->Unknown I could not find any page detailing what weapond are prohibited.

Tasmania---->Unknown I could not find any page detailing what weapond are prohibited.

update on 2006/02/04 by Mountaineer
Under Australian Law, a spud gun would be considered either a Compressed Air Gun (Class 'A') or a Muzzle Loading Firearm (Class 'B') depending on the propellant being used in the individual device.
This is something of a moot point however as any home-made firearm falls under Prescribed Firearms legislation.
Other examples of Prescribed Firearms include fully automatic weapons, modified firearms (sawn-off etc), silenced firearms, disguised firearms and firearms designed to fire explosive or incendiary devices such as bazookas and mortars.
There are a few exception to the Prescribed Firearms legislation, mainly related to weapons made and used in theatrical productions.
Theoretically, a registered gun owner with (for example) a Class 'B' license could have a gunsmith make a spud gun for them which could then be registered and legally used under purpose 2 (Target Shooting - unsupervised) of Australian law. However I find it hard to imagine anyone doing that when they could simply buy a "real" gun.
I got all this information from "Firearms & the Law in South Australia" (c) 2004 Regency Publishing ISBN: 1 86393 404 9 which I am currently studying for my own license.

Tennis ball

2007-02-01T00:25:13Z

BillyBobJoe:

'''Tennis balls''' are hollow, pressurized balls of vulcanized rubber, with a fuzzy felt-like covering, approximately 2.6" in diameter. They are sold in many retail stores (including Wal*mart) for use in the game of tennis. 
Somewhat smaller (and significantly cheaper) alternatives with the same basic construction exist, and are marketed as "fun balls" or pet toys.

== Aerodynamics ==

The fuzz on the ball increases air resistance above what would be expected of a sphere, to a Cd of about .6 at high velocities. 
(See this [http://www.aeromech.usyd.edu.au/15afmc/proceedings/papers/AFMC00075.pdf research])

This, coupled with the low sectional density of approx. 10.5g/inc^2 exterior the launcher, cause the unmodified tennis ball to be a short range projectile; range is limited to about 150 yards (150 meters), even with a powerful launcher. 
It should be noted that this is not necessarily a bad thing.

== Modifications ==

The friction required to load a tennis ball in a 2.5" sch 40 barrel is about 12 pounds [http://forums.spudtech.com/topic.asp?TOPIC_ID=14446]. If one finds this excessive, they generally correct the problem by burning the fuzz off.

Additionally, one may seek to increase the range or damage capabilities of the tennis ball. This generally entails weighting the tennis ball by injecting water, or inserting pennies or other small, dense objects. [[Optimal mass]] increase may be calculated with repeated trials using the [[GGDT]]'s integral ''external ballistics calculator''.

== Use and target performance ==

Tennis balls are typically launched out of 2.5" sch 40 pipe, and they may be either muzzle or breach loaded. Some recommend putting an inside chamfer on the pipe to facilitate loading.

Due to having to reduce the OD of the tennis ball from ~2.6" to 2.445", there is a significant amount of friction (2.1 - 2.7 [[psi, average and median of 2.5 psi, for a force of about 12 pounds (54 newtons). This complicates loading, slightly reduces muzzle velocity, and during launch will scorch the fuzz on the ball.

The inexpensive "fun balls" are slightly smaller, and thus have reduced friction.

As an alternative, some use [[SDR]] 21 or 26 2.5", which have IDs of 2.581" and 2.635" respectively.

== Specifications ==

Diameter, unsqueezed: 2.6" (65mm) 
Mass, unfilled: 57g 
Friction; in 2.5" sch 40: 2.5 psi; 12 pounds (.18 k/cm^2; 54 newtons) 

[[Category:Projectiles]]

Paintball

2007-02-01T00:24:14Z

BillyBobJoe:

A '''paintball''' is a small hollow sphere filled with a non-toxic, washable 'paint'. They are designed to splatter upon impact and typically .68 caliber. 
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]]

Paintball

2007-02-01T00:23:30Z

BillyBobJoe:

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 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]]

Cannon construction

2007-02-01T00:23:02Z

BillyBobJoe:

It is important to construct your launchers with care. This includes:

* Using pressure rated (NSF-PW or NSF-61) fittings and pipe, especialy in a [[pneumatic cannon]].
* [[Solvent welding]] [http://www.burntlatke.com/weld.html correctly]
* Using pipe of the proper pressure rating, eg. sch 80 in a [[Hybrid Cannon]].
* Only [[tapping|tap]] through a double layer of pipe where the pipe and a fitting is joined (for bolts, pressure gauges) .

[[Cell-core]] or unsleeved thinwall [[PVC]] pipe should not be used in the making of cannons. Cellular-core pvc can be used in low-power, aerosol combustions, but remember, cellular-core pvc is nothing more than laminated foam.

You may also want to make a design of your cannon first. Sketches and dimensional drawings are both very helpful. You may find out ahead of time that your design will not work, saving precious money. [[3d models]] are some of the most effective visual representations. A limited library of parts (~115) for potato gun construction is currently completed and will be available soon.

See also: [[:Category:Construction materials]], [[:Category:Construction methods]]

Cannon construction

2007-02-01T00:22:51Z

BillyBobJoe:

It is important to construct your launchers with care. This includes:

* Using pressure rated (NSF-PW or NSF-61) fittings and pipe, especialy in a [[pneumatic cannon]].
* [[Solvent welding]] [http://www.burntlatke.com/weld.html correctly]
* Using pipe of the proper pressure rating, eg. sch 80 in a [[Hybrid Cannon]].
* Only [[tapping|tap]] through a double layer of pipe where the pipe and a fitting is joined(for bolts, pressure gauges) .

[[Cell-core]] or unsleeved thinwall [[PVC]] pipe should not be used in the making of cannons. Cellular-core pvc can be used in low-power, aerosol combustions, but remember, cellular-core pvc is nothing more than laminated foam.

You may also want to make a design of your cannon first. Sketches and dimensional drawings are both very helpful. You may find out ahead of time that your design will not work, saving precious money. [[3d models]] are some of the most effective visual representations. A limited library of parts (~115) for potato gun construction is currently completed and will be available soon.

See also: [[:Category:Construction materials]], [[:Category:Construction methods]]

Linear

2007-02-01T00:22:25Z

BillyBobJoe:

A linear launcher (also called an "inline") is a type of cannon in which the barrel is directly in front of, and pointing in the same direction, as the chamber. Such a configuration is slightly cheaper than the over/under configuration, but only by the cost of 2 90* elbows. The linear design is most often used in [[combustion launcher]]s, and this is considered the most basic launcher design. It's also the simplest to assemble, requiring no special tools or fittings.

The linear design is often considered slightly more powerful than over-under configuration as the traveling gasses dont have to make a 180* turn thus slowing the speed of them.

Most pneumatics are not linear because of there increased chamber length and piston valve arangment.

Bulk tank regulator

2007-02-01T00:20:26Z

BillyBobJoe:

[[Image:Pressure-regulator.jpg|thumb|right|300px|A high-pressure bulk tank regulator]]
A '''bulk tank regulator''' is used to regulate down the output pressure of bulk gas tanks, such as CO2 or scuba tanks. They are made in many different designs for use in welding, cutting, scuba diving, carbonization of beverages etc.

Some regulators regulate flow instead of or in addition to pressure, a pure flow regulator is not useful in most spudgun applications, since it doesn't drop the output pressure from the tank to a safe level.

A pressure regulator is ESSENTIAL when filling a PVC chamber from a bulk tank to prevent a rupture. Also, an adequate pressure release valve should always be used in the event of a regulator seal failure.

Compression fitting

2007-02-01T00:17:42Z

BillyBobJoe:

Compression fittings are mainly used on copper pipe, they are very simple in function. An olive, a small ring of brass not unlike in appearence to a wedding ring, fits over the copper pipe. Then when the fitting around it is tightened they will deform the olive so it grips the pipe.
Compression fittings are usually stronger than solder fittings by a small margin but are harder to airtight and dont look as nice. Compression fittings are also alot more expensive, some as much as 3 times more expensive in larger copper sizes.

An example of a cannon that uses compression fittings is pictured here:
[http://bb.1asphost.com/sigmarhaven/Ragnarok/DCP00932.jpg Behemoth]

Compression fitting

2007-02-01T00:17:16Z

BillyBobJoe:

Compression fittings are mainly used on copper pipe, they are very simle in the way they work. An olive, a small ring of bras not unlike in appearence to a wedding ring, fits over the copper pipe. Then when the fitting around it is tightened they will deform the olive so it grips the pipe.
Compression fittings are usually stronger than solder fittings by a small margin but are harder to airtight and dont look as nice. Compression fittings are also alot more expensive, some as much as 3 times more expensive in larger copper sizes.

An example of a cannon that uses compression fittings is pictured here:
[http://bb.1asphost.com/sigmarhaven/Ragnarok/DCP00932.jpg Behemoth]

Lantern sparker

2007-02-01T00:15:40Z

BillyBobJoe:

[[Image:sparker.jpg|frame|Replacement lantern sparker]]'''Lantern sparkers''' are a method of ignition and are usually cheaper and more arguably reliable than [[BBQ ignitor]]s or [[stun gun]]s. They work by spinning a knurled wheel connected to a rod of steel. A piece of flint pressed against a rifled section of the steel by a spring. When the wheel is spun rapidly, pieces of the flint material are
shaved off and ignite spontaneously, causing a shower of sparks that are ideal for igniting a combustion mixture.

==Disadvantages==
The main disadvantage of lantern sparkers is that they have the tendency to not spark when wet. AXE, hairspray, and [[starting fluid]] will all stop a lantern sparker from working if they should get on the flint/steel sparking assembly. They are very cheap however, and the flints are replaceable. If you can afford it, a GOOD (usually expensive) [[BBQ ignitor]] or [[stun gun]] is superior.
the lantern sparker is mounted through a single hole in the chamber. It protrudes into the chamber, and may therefore be impractical or impossible to use in [[coaxial]] launchers.

[[Category:Ignition sources]]

Lantern sparker

2007-02-01T00:15:20Z

BillyBobJoe: /* Disadvantages */

Lantern sparker

2007-02-01T00:13:25Z

BillyBobJoe:

[[Image:sparker.jpg|frame|Replacement lantern sparker]]'''Lantern sparkers''' are a method of ignition and are usually cheaper and more arguably reliable than [[BBQ ignitor]]s or [[stun gun]]s. They work by spinning a knurled wheel connected to a rod of steel. A piece of flint pressed against a rifled section of the steel by a spring. When the wheel is spun rapidly, pieces of the flint material are
shaved off and ignite spontaneously, causing a shower of sparks that are ideal for igniting a combustion mixture.

==Disadvantages==
The main disadvantage with lantern sparkers is that they have the tendency to not spark when wet with ANYTHING! Axe, hairspray, and [[starting fluid]] will all stop a lantern sparker from working if they should get on the flint/steel sparking assembly. They are very cheap however, and the flints are replaceable. If you can afford it, a GOOD (usually expensive) [[BBQ ignitor]] or [[stun gun]] is superior.
the lantern sparker is mounted through a single hole in the chamber. It protrudes into the chamber, and may therefore be impractical or impossible to use in [[coaxial]] launchers.
[[Category:Ignition sources]]

Lantern sparker

2007-02-01T00:13:05Z

BillyBobJoe:

[[Image:sparker.jpg|frame|Replacement lantern sparker]]'''Lantern sparkers''' are a method of ignition and are usually cheaper and more arguably reliable than [[BBQ ignitor]]s or [[stun gun]]s. They work by spinning a knurled wheel connected to a rod of steel. A piece of flint pressed against a rifled section of the steel by a spring. When the wheel is spun rapidly, pieces of the flint material are
shaved off and ignite spontaneously, causing a shower of sparks that are ideal for igniting a combustion mixture.

The main disadvantage with lantern sparkers is that they have the tendency to not spark when wet with ANYTHING! Axe, hairspray, and [[starting fluid]] will all stop a lantern sparker from working if they should get on the flint/steel sparking assembly. They are very cheap however, and the flints are replaceable. If you can afford it, a GOOD (usually expensive) [[BBQ ignitor]] or [[stun gun]] is superior.
the lantern sparker is mounted through a single hole in the chamber. It protrudes into the chamber, and may therefore be impractical or impossible to use in [[coaxial]] launchers.
[[Category:Ignition sources]]

Lantern sparker

2007-02-01T00:12:29Z

BillyBobJoe:

[[Image:sparker.jpg|frame|Replacement lantern sparker]]'''Lantern sparkers''' are a method of ignition and are usually cheaper and more arguably reliable than [[BBQ ignitor]]s or [[stun gun]]s. They work by spinning a knurled wheel connected to a rod of steel. A piece of flint pressed against a rifled section of the steel by a spring. When the wheel is spun rapidly, pieces of the flint material are shaved off and ignite spontaneously, causing a shower of sparks that are ideal for igniting a combustion mixture.

The main disadvantage with lantern sparkers is that they have the tendency to not spark when wet with ANYTHING! Axe, hairspray, and [[starting fluid]] will all stop a lantern sparker from working if they should get on the flint/steel sparking assembly. They are very cheap however, and the flints are replaceable. If you can afford it, a GOOD [[BBQ ignitor]] or [[stun gun]] is superior.
the lantern sparker is mounted through a single hole in the chamber. It protrudes into the chamber, and may therefore be impractical or impossible to use in [[coaxial]] launchers.
[[Category:Ignition sources]]

Lantern sparker

2007-02-01T00:11:57Z

BillyBobJoe:

[[Image:sparker.jpg|frame|Replacement lantern sparker]]'''Lantern sparkers''' are a method of ignition and are usually cheaper and more arguably reliable than [[BBQ ignitor]]s or [[stun gun]]s. They work by spinning a knurled wheel connected to a rod of steel. A piece of flint pressed against a rifled section of the steel by a spring. When the wheel is spun rapidly, pieces of the flint material are shaved off and ignite spontaneously, causing a shower of sparks. The main disadvantage with lantern sparkers is that they have the tendency to not spark when wet with ANYTHING! Axe, hairspray, and [[starting fluid]] will all stop a lantern sparker from working if they should get on the flint/steel sparking assembly. They are very cheap however, and the flints are replaceable. If you can afford it, a GOOD [[BBQ ignitor]] or [[stun gun]] is superior.
the lantern sparker is mounted through a single hole in the chamber. It protrudes into the chamber, and may therefore be impractical or impossible to use in [[coaxial]] launchers.
[[Category:Ignition sources]]

Schrader valve

2007-02-01T00:08:40Z

BillyBobJoe:

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.

[[Image:Schrader.jpg‎‎]]

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

[[category:valves]]

File:Schrader.jpg

2007-02-01T00:08:10Z

BillyBobJoe: A schrader valve with a 1/4" NPT rear fitting.

A schrader valve with a 1/4" NPT rear fitting.

Schrader valve

2007-02-01T00:06:19Z

BillyBobJoe:

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.

[[Image:B0006VN78U.01-A2PTFH552V4E7G._AA280_SCLZZZZZZZ_.jpg‎]]

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

[[category:valves]]

File:B0006VN78U.01-A2PTFH552V4E7G. AA280 SCLZZZZZZZ .jpg

2007-02-01T00:03:38Z

BillyBobJoe: A schrader tire valve with a 1/4" NPT back.

A schrader tire valve with a 1/4" NPT back.

Paintball

2007-02-01T00:01:30Z

BillyBobJoe:

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.
* 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]]

Paintball

2007-02-01T00:01:09Z

BillyBobJoe: /* Use and target performance */

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.
* 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]]

Valve

2007-01-31T23:27:32Z

BillyBobJoe:

A '''valve''' is any device that can be used to control the flow of a liquid or gas. It is an essential component of [[pneumatic cannon]]s, where a wealth of different designs are used depending on price, complexity and performance.

Valves are used in many other applications as well, such as [[fuel meter]]s, in [[venting]], and sometimes as part of a loading mechanism.

The efficiency of a valve is indicated by it's [[Flow coefficient]] or CV.

For a current list of articles on different valves, see [[:Category:Valves]]

{{stub}}

Paintball nitrogen tank

2007-01-31T23:26:58Z

BillyBobJoe:

A paintball '''nitrogen''' or '''HPA''' (High Pressure Air) tank is used as a pressure source for paintball guns, as an alternative to [[CO2 tank]]s. The pressure is usually 3000 or 4500 psi, and the tanks are filled from bulk tanks or special compressors. A regulator is necessary to reduce this high pressure to that acceptable for PVC chambers.

{{stub}}

Sabot

2007-01-31T23:24:43Z

BillyBobJoe:

'''Sabots''' are typically used to improve the seal of projectiles in the barrel, be they slightly undersize or much smaller.

The improved seal (or larger area for the gasses to push on) improves [[muzzle velocity]], and a smaller projectile flies farther and penetrates better.
Foam is the most commonly used sabot material because it is strong enough for most spudding applications and it's light weight means that less energy is wasted accelerating it.

==Manufacture==
There are two primary kinds of sabots; ones that enclose the projectile and those that merely sit behind it (also called "[[wadding]]").

Both are commonly made out of foam, being either insulation foam cut with a [[muzzle knife]] or expanding foam cast in a segment of barrel-sized pipe. 
After this initial step, the sabots that simply sit behind the projectile are done, but the enclosing sabots need to have the hole cut out and possibly be cut into 2 or more pieces.

==Use==
Foam sabots don't travel very far, typically about 15 feet, and can easily be found.

Other than that, sabots can be used many times unless '''sabot collapse''', in which the projectile exerts too much force on the sabot (breaking it), occurs. 
Such an event can be avoided by putting a hard covering on the sabot, protecting the sabot with padding, or lowering the pressure (and thus forces) used.

==Common Materials==

• Caps from minature spray paint cans make an acceptable sabot for a 2" SCH. 40 PVC barrel. A slit may need to be cut down the side for a proper fit.

• Rags or paper towels can be used are are more effective when damp (which reduces the chance of catching fire in a combustion spudgun).

[[Category:Projectiles]]

Safety

2007-01-31T23:21:27Z

BillyBobJoe: /* Ammo Safety */

Spudguns can be very dangerous if built or used improperly. However, if they are respected, they can be great fun.

==Launcher safety==
*As a very basic summary- DON'T BE AN IDIOT WITH THESE THINGS!!!!!
*Use good, safe [[cannon construction|construction methods]] and materials.
*Follow the rules of basic gun safety: never point the cannon at anything you don't want to destroy, and treat it as if it's loaded at all times. Never look down the barrel.
*Always make sure you are firing in a safe direction that is free of people, pets, livestock, cars, houses and other property. Use a solid backstop or make sure you have a clear landing area.
*Don't look into the chamber of a [[combustion cannon]] that has failed to fire. Fresh air can make a rich gas mixture lean enough to ignite.
*Don't use PVC cannons in cold weather. Sub-freezing temperatures makes PVC brittle and increases the chances of catastrophic failure.
*Don't use a cannon that is cracked or heavily scratched, or has been dropped on a hard surface. Joints may be weakened and the pressure ratings on damaged parts cannot be trusted.
*Don't use excessive pressure in a [[pneumatic cannon]]. [[PVC]] pipe is not rated for pressurized air because of the shrapnel risk, so use in a pneumatic gun is considered to be outside pipe specifications in the first place. Never exceed the pressure rating of the lowest rated part.
*Don't use overly powerful fuels in a [[combustion cannon]]. Solid fuels and very reactive gases such as [[hydrogen]] or [[acetylene]] are not suitable for use in spudguns. Don't use oxygen to enrich the mix in a PVC cannon.
*Use hearing protection when firing loud combustion and hybrid cannons, especially in an enclosed space. Use eye protection if there is a chance of splinters or other debris from the projectile hitting the target.

==Don't shoot living things==
A typical spudgun is capable of launching a potato weighing 50-150 grams a couple hundred yards with the muzzle energy of a powerful handgun. Longer distances are easily achieved with rocks, PVC darts, golf balls, and other aerodynamic projectiles.

This energy, even when carried by a projectile as fragile as the humble tuber, is easily capable of killing someone, or at least breaking bones or putting out eyes. As to property damage, most launchers can put a vegetable through a piece of 1/2" plywood, and many can put it through 3/4" - which is very significant considering the construction of most residential buildings.

The same applies to short/and or small-bore launchers too.

Despite their great potential to do harm, it is not looked upon well if you (attempt) to use your launcher as a hunting instrument. They are often hard to aim, leading to a low probability of a clean (humane) kill - plus; it is illegal to do so.

Some people don't take the extreme danger of a projectile fired from a potato cannon seriously enough. There are frequent news articles about people injured by potato guns firing projectiles other than vegetables, or people being accidentally shot while handling the gun.

Accidental discharges are the most likely cause of injury however some individuals lack the mental capacity to keep their guns pointed away from others at all times. When a potato gun is pointed at a human being the dangers are extreme. Do not under any circumstances let the barrel of a potato gun point towards another human, even if the gun is not loaded.

The bottom line is: don't aim a spudgun at anyone, at any time, even if you think it's not loaded.

==Ammo Safety==
Some advise against shooting bolts, coke cans full of concrete, and other hard objects out of your gun; saying things along the lines of:
"Anything that is much harder than a spud can cause grievous bodily harm if shot at another person, or any animal for that matter."
...in actuality, even a tater will cause "grievous bodily harm" if shot at another living being. The danger lies in an increased chance of ricochet when using sturdy ammo - use common sense, and don't fire non-shattering ammo at close targets.

Some caution should be taken with shooting loose sub-munitions, specifically gravel or stones, with a [[sabot]] behind them - there is a significant probability of them jamming up, and the barrel being overstressed when the sabot tries to keep moving through the blockage, leading to a failure. Always wrap your lose projectiles in something - paper towels, old socks, and plastic bags are all acceptable.

Shooting water or other heavy objects from a cannon can overstress barrel fittings from the excessive recoil created. A sound grip must also be used when holding such a cannon as it can easily be blown out of one's hands.

Gasoline

2007-01-31T23:15:22Z

BillyBobJoe:

==Use as a Fuel==

Gasoline is used in some combustion cannons. It can be metered like propane, but instead using a syringe. Gasoline provides a powerful combustion, but will very easily flood the chamber.

==Myths==
Gasoline will not damage PVC chambers as proved in a test by a well-respected Spudtech forum member Freefall.

==Safety==

An exessive amount of gasoline in a combustion launcher will not fragment a properly contructed chamber, but can drip out, causing burns to the operator and fire hazard. A surprisingly small amount of gasoline is necessary for proper combustion.

Gasoline

2007-01-31T23:13:13Z

BillyBobJoe:

==Gasoline==

Gasoline is used in some combustion cannons. It can be metered like propane, but instead using a syringe. Gasoline provides a powerful combustion, but will very easily flood the chamber.

Gasoline will not damage PVC chambers as proved in a test by a well-respected Spudtech forum member Freefall.

SpudFiles Wiki:Community Portal

2007-01-31T23:10:43Z

BillyBobJoe: /* '''PVC''' */

== '''ABS''' ==

'''Pros :'''

1) Chemical resistance, so can stand up to the average weekender going crazy experimenting with every different thing that can be found in an aerosol can.

2) Light weight, even the weakest of us has no reason to heft and bear these devices.

3) Low cost, it can be obtained almost anywhere, in the correct dimensions.

'''Cons:'''

1) NOT PRESSURE RATED! This material has been proven to be acceptable, but standard pipe is not certified for any pressure service above those found in gravity drain applications, typically not above 10 psi. The term "cellular core" means that millions of tiny air bubbles were whipped into the plastic before it was run through the extruder. The end result is a very light weight material that in effect is nothing more than a piece of hard foam in the shape of a tube. This hard foam can be strong but inevitably an unfortunate configuration of bubbles can cause catastrophic failure.

2) If it fails, it will fail. When it goes, it will turn into many little shards of sharp plastic that will invariably find you in some way.

3) Decomposition products are nasty! If you have ever taken a whiff after firing it a few times, you will get a burning in your nose. This caustic gas is not good for you!

== '''PVC''' ==

'''Pros:'''

1 )Inexpensive, the pipe is almost free. Fittings are where the money is dropped, but well worth it

2) Multitude of dimensions to chose from. Pretty much any configuration of pipe fitting can be found somewhere in PVC, but get out your checkbook! 6" sch 80 will run you right around $40 for a 10' piece.

3) Pressure Rated. What you see is what you get. The rated pressure on the side of the pipe is already conservative, so you don't need to incorporate safety factors, unless you want to. Fittings are always stronger than bulk pipe, as long as the glue joints are made and allowed to cure properly and are Schedule 40.

'''Cons:'''

1) Limited Chemical Resistance. Aldehydes and ketones are out, as these readily dissolve the polymer, as in a glue joint, just read the label on the can: Acetone, THF, MEK. Some fuels should be totally avoided such as carb cleaner and insect repellant as they decompose ABS.

2) More brittle than ABS, but by not using oxygen and just burning fuel and air....should never be a problem.

3) Cellular core PVC is common at many hardware/home improvement stores. Make sure you buy SCH 40 pipe with a pressure rating printed on the pipe. If the pipe is not specifically marked with a certain PSI rating (ie, 330 PSI, depending on diameter), IT IS NOT PRESSURE RATED!!

[[''Source taken from www.spudtech.com'']]

THIS IS UNACCEPTABLE!!
http://www.spudfiles.com/spud_wiki/index.php?title=Special:Deadendpages
Look at the number of dead end pages! Not Cool!

SpudFiles Wiki:Community Portal

2007-01-31T23:10:18Z

BillyBobJoe: /* '''PVC''' */

== '''ABS''' ==

'''Pros :'''

1) Chemical resistance, so can stand up to the average weekender going crazy experimenting with every different thing that can be found in an aerosol can.

2) Light weight, even the weakest of us has no reason to heft and bear these devices.

3) Low cost, it can be obtained almost anywhere, in the correct dimensions.

'''Cons:'''

1) NOT PRESSURE RATED! This material has been proven to be acceptable, but standard pipe is not certified for any pressure service above those found in gravity drain applications, typically not above 10 psi. The term "cellular core" means that millions of tiny air bubbles were whipped into the plastic before it was run through the extruder. The end result is a very light weight material that in effect is nothing more than a piece of hard foam in the shape of a tube. This hard foam can be strong but inevitably an unfortunate configuration of bubbles can cause catastrophic failure.

2) If it fails, it will fail. When it goes, it will turn into many little shards of sharp plastic that will invariably find you in some way.

3) Decomposition products are nasty! If you have ever taken a whiff after firing it a few times, you will get a burning in your nose. This caustic gas is not good for you!

== '''PVC''' ==

'''Pros:'''

1)Inexpensive, the pipe is almost free. Fittings are where the money is dropped, but well worth it

2)Multitude of dimensions to chose from. Pretty much any configuration of pipe fitting can be found somewhere in PVC, but get out your checkbook! 6" sch 80 will run you right around $40 for a 10' piece.

3)Pressure Rated. What you see is what you get. The rated pressure on the side of the pipe is already conservative, so you don't need to incorporate safety factors, unless you want to. Fittings are always stronger than bulk pipe, as long as the glue joints are made and allowed to cure properly and are Schedule 40.

'''Cons:'''

1) Limited Chemical Resistance. Aldehydes and ketones are out, as these readily dissolve the polymer, as in a glue joint, just read the label on the can: Acetone, THF, MEK. Some fuels should be totally avoided such as carb cleaner and insect repellant as they decompose ABS.

2) More brittle than ABS, but by not using oxygen and just burning fuel and air....should never be a problem.

3) Cellular core PVC is common at many hardware/home improvement stores. Make sure you buy SCH 40 pipe with a pressure rating printed on the pipe. If the pipe is not specifically marked with a certain PSI rating (ie, 330 PSI, depending on diameter), IT IS NOT PRESSURE RATED!!

[[''Source taken from www.spudtech.com'']]

THIS IS UNACCEPTABLE!!
http://www.spudfiles.com/spud_wiki/index.php?title=Special:Deadendpages
Look at the number of dead end pages! Not Cool!

SpudFiles Wiki:Community Portal

2007-01-31T23:08:17Z

BillyBobJoe: /* '''ABS''' */

== '''ABS''' ==

'''Pros :'''

1) Chemical resistance, so can stand up to the average weekender going crazy experimenting with every different thing that can be found in an aerosol can.

2) Light weight, even the weakest of us has no reason to heft and bear these devices.

3) Low cost, it can be obtained almost anywhere, in the correct dimensions.

'''Cons:'''

1) NOT PRESSURE RATED! This material has been proven to be acceptable, but standard pipe is not certified for any pressure service above those found in gravity drain applications, typically not above 10 psi. The term "cellular core" means that millions of tiny air bubbles were whipped into the plastic before it was run through the extruder. The end result is a very light weight material that in effect is nothing more than a piece of hard foam in the shape of a tube. This hard foam can be strong but inevitably an unfortunate configuration of bubbles can cause catastrophic failure.

2) If it fails, it will fail. When it goes, it will turn into many little shards of sharp plastic that will invariably find you in some way.

3) Decomposition products are nasty! If you have ever taken a whiff after firing it a few times, you will get a burning in your nose. This caustic gas is not good for you!

== '''PVC''' ==

'''Pros:'''

1)Inexpensive, the pipe is almost free. Fittings are where the money is dropped, but well worth it

2)Multitude of dimensions to chose from. Pretty much any configuration of pipe fitting can be found somewhere in PVC, but get out your checkbook! 6" sch 80 will run you right around $40 for a 10' piece.

3)Pressure Rated. What you see is what you get. The rated pressure on the side of the pipe is already conservative, so you don't need to incorporate safety factors, unless you want to. Fittings are always stronger than bulk pipe, as long as the glue joints are made and allowed to cure properly and are Schedule 40.

'''Cons:'''

1)Limited Chemical Resistance. Aldehydes and ketones are out, as these readily dissolve the polymer, as in a glue joint, just read the label on the can: Acetone, THF, MEK. Some fuels should be totally avoided such as carb cleaner and insect repellant, don't say I didn't warn you!

2)More brittle than ABS, but by not using oxygen and just burning fuel and air....should never be a problem.

3)Cellular core PVC is common at many hardware/home improvement stores. Make sure you buy SCH 40 pipe with a pressure rating printed on the pipe. If the pipe is not specifically marked with a certain PSI rating, IT IS NOT PRESSURE RATED!!

[[''Source taken from www.spudtech.com'']]

THIS IS UNACCEPTABLE!!
http://www.spudfiles.com/spud_wiki/index.php?title=Special:Deadendpages
Look at the number of dead end pages! Not Cool!

Primer

2007-01-31T23:06:29Z

BillyBobJoe: /* Use as a Dye/Paint */

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. Application of primer should be done immedatly before the application of PVC cement. As always, the directions on the can provide the best advice on the process of [[solvent welding]].

== 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 in a well ventilated area. Gloves can be worn, but care should be taken to avoid spilling primer on them, as acetone penetrates through latex and rubber gloves, where it is absorbed through the skin. In addition, long term exposure of skin to these low-polarity solvents will severely dry your skin out, possibly leading to dermatitis. Swallowing primer may result in death, and chronic inhalation of primer fumes can cause damage to several vital organs including the central nervous system, liver, and kidneys. Symptoms of acute (short term) overexposure include dizziness, headache, nausea, confusion, vomiting, and unconciousness.

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.

==Use as a Dye/Paint==

The unsightly stains caused by purple colored primer can be made to look less noticeable by covering the rest of the PVC pipe/fitting with primer also. Multiple coats may be necessary to achieve the desired shade. This dyeing method is especially resistant to scratching and was used in this .25 caliber piston cannon made by BillyBobJoe of the [[Spudtech]] forum.

[[Image:Primercannon.jpg]]

It should be noted that this rifle suffered a fracture in the rear female adapter, which was most likely caused by an overtightened SCH. 80 plug. The primer only penetrates the surface of the pipe/fitting and once it has had time to dry and dissipate, overall strength of the finished product should not be compromised.

== External links ==

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

Primer

2007-01-31T23:06:07Z

BillyBobJoe: /* Use as a Dye/Paint */

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. Application of primer should be done immedatly before the application of PVC cement. As always, the directions on the can provide the best advice on the process of [[solvent welding]].

== 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 in a well ventilated area. Gloves can be worn, but care should be taken to avoid spilling primer on them, as acetone penetrates through latex and rubber gloves, where it is absorbed through the skin. In addition, long term exposure of skin to these low-polarity solvents will severely dry your skin out, possibly leading to dermatitis. Swallowing primer may result in death, and chronic inhalation of primer fumes can cause damage to several vital organs including the central nervous system, liver, and kidneys. Symptoms of acute (short term) overexposure include dizziness, headache, nausea, confusion, vomiting, and unconciousness.

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.

==Use as a Dye/Paint==

The unsightly stains caused by purple colored primer can be made to look less noticeable by covering the rest of the PVC pipe/fitting with primer also. Multiple coats may be necessary to achieve the desired shade. This dyeing method is especially resistant to scratching and was used in this .25 caliber piston cannon made by BillyBobJoe of the [[Spudtech forum]].

[[Image:Primercannon.jpg]]

It should be noted that this rifle suffered a fracture in the rear female adapter, which was most likely caused by an overtightened SCH. 80 plug. The primer only penetrates the surface of the pipe/fitting and once it has had time to dry and dissipate, overall strength of the finished product should not be compromised.

== External links ==

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

Primer

2007-01-31T23:05:57Z

BillyBobJoe: /* Use as a Dye/Paint */

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. Application of primer should be done immedatly before the application of PVC cement. As always, the directions on the can provide the best advice on the process of [[solvent welding]].

== 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 in a well ventilated area. Gloves can be worn, but care should be taken to avoid spilling primer on them, as acetone penetrates through latex and rubber gloves, where it is absorbed through the skin. In addition, long term exposure of skin to these low-polarity solvents will severely dry your skin out, possibly leading to dermatitis. Swallowing primer may result in death, and chronic inhalation of primer fumes can cause damage to several vital organs including the central nervous system, liver, and kidneys. Symptoms of acute (short term) overexposure include dizziness, headache, nausea, confusion, vomiting, and unconciousness.

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.

==Use as a Dye/Paint==

The unsightly stains caused by purple colored primer can be made to look less noticeable by covering the rest of the PVC pipe/fitting with primer also. Multiple coats may be necessary to achieve the desired shade. This dyeing method is especially resistant to scratching and was used in this .25 caliber piston cannon made by BillyBobJoe of the [[Spudtech forums]].

[[Image:Primercannon.jpg]]

It should be noted that this rifle suffered a fracture in the rear female adapter, which was most likely caused by an overtightened SCH. 80 plug. The primer only penetrates the surface of the pipe/fitting and once it has had time to dry and dissipate, overall strength of the finished product should not be compromised.

== External links ==

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

Supah-Valve

2007-01-31T23:04:57Z

BillyBobJoe: /* sources */

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]]

Primer

2007-01-31T23:02:50Z

BillyBobJoe: /* How to use Primer */

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. Application of primer should be done immedatly before the application of PVC cement. As always, the directions on the can provide the best advice on the process of [[solvent welding]].

== 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 in a well ventilated area. Gloves can be worn, but care should be taken to avoid spilling primer on them, as acetone penetrates through latex and rubber gloves, where it is absorbed through the skin. In addition, long term exposure of skin to these low-polarity solvents will severely dry your skin out, possibly leading to dermatitis. Swallowing primer may result in death, and chronic inhalation of primer fumes can cause damage to several vital organs including the central nervous system, liver, and kidneys. Symptoms of acute (short term) overexposure include dizziness, headache, nausea, confusion, vomiting, and unconciousness.

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.

==Use as a Dye/Paint==

The unsightly stains caused by purple colored primer can be made to look less noticeable by covering the rest of the PVC pipe/fitting with primer also. Multiple coats may be necessary to achieve the desired shade. This dyeing method is especially resistant to scratching.

[[Image:Primercannon.jpg]]

It should be noted that this rifle suffered a fracture in the rear female adapter, which was most likely caused by an overtightened SCH. 80 plug. The primer only penetrates the surface of the pipe/fitting and once it has had time to dry and dissipate, overall strength of the finished product should not be compromised.
== External links ==

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

Primer

2007-01-31T23:00:46Z

BillyBobJoe:

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 in a well ventilated area. Gloves can be worn, but care should be taken to avoid spilling primer on them, as acetone penetrates through latex and rubber gloves, where it is absorbed through the skin. In addition, long term exposure of skin to these low-polarity solvents will severely dry your skin out, possibly leading to dermatitis. Swallowing primer may result in death, and chronic inhalation of primer fumes can cause damage to several vital organs including the central nervous system, liver, and kidneys. Symptoms of acute (short term) overexposure include dizziness, headache, nausea, confusion, vomiting, and unconciousness.

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.

==Use as a Dye/Paint==

The unsightly stains caused by purple colored primer can be made to look less noticeable by covering the rest of the PVC pipe/fitting with primer also. Multiple coats may be necessary to achieve the desired shade. This dyeing method is especially resistant to scratching.

[[Image:Primercannon.jpg]]

It should be noted that this rifle suffered a fracture in the rear female adapter, which was most likely caused by an overtightened SCH. 80 plug. The primer only penetrates the surface of the pipe/fitting and once it has had time to dry and dissipate, overall strength of the finished product should not be compromised.
== External links ==

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