Spud-Gun Launcher Project BD-5

[PineRidge]

These are the two fiberboard spacers that I cut and the stainless steel band kit that will attach the main body of the launcher to the magnetic LP holder/battery box.

More later as I'm hitting the rack. Goodnight all!

 

[PineRidge]

You may remember me saying that we were going to use the electronics taken from a common 60,000 volt stun-gun for the ignition spark on the launcher.

It is important to maintain the same air-gap on the project that was used on the original design of the stun-gun. A spark normally jumps from point A to point B on the original gun. It is necessary to measure the distance between these two points and use the measurment to construct another air gap that can be used within the electronics box and still not short everything else out within the box should the spark jump within.

If this air gap is not constructed the stun-gun could be short lived.

 

[PineRidge]

Basically we took a small wood dowel and used it to construct the spark gap. Made a trip to Radio Shack and picked up a small roll of probe wire to handle the 60,000 volt output from the stun-gun electronics. This wire is nice to work with since it is very flexible.

I then took two pieces of the probe wire twisted them together and tinned them with solder so they would remain ridgid. I made two sets of these and taped them to the dowel rod using elecrtical tape so the gap between our home-made electrodes was the same as those that were used in the original stun-gun design.

 

[PineRidge]

Now I thought that it was a good idea to insulate the homemade air gap since it will be in close proximity to other electronics within the project box. I searched the house looking for a small non-conducting tube that might be used for this purpose and came up with a perfect solution. Turns out that a Blistex (wax for your lips) container fit so I pulled the innards from it and slipped it over the air gap being careful not to disturb the pre-set gap. I also used a bit of RTV sealant on the ends of the Blistex tube to seal it. (probably overkill)

This is the finished air gap ready to go in the electronics project box.

 

[Big Dog]

Mike,

I don't know why, but I'm thinking that Blistex tube ain't gonna last. Help change my mind?

 

[Doc]

Great job documenting all this and explaining your pics. Very cool project!!!!

 

[Archdean]

Someone once told me "I had way too much time on my hands"!!!
They obiviously haven't met you guys!!!!!

Well Done PineRidge!!

Dean

 

[PineRidge]

Well the Blistex tube wouldn't fit into the project box so it had to be stripped off the air gap. Guess I'll just have to be careful how I mount the gap to protect the other components within the box.

I also ran into a bit of a snag with the CCU. Bob Reeves a member of the other site fabbed up the CCU for me. It worked fine on the preliminary testing but today failed to cycle the brushless fan off after the predetermined time lapsed (it was like the Energizer Bunny. It kept running, and running, and ....) Bob Reeves is exploring the problem a bit further and I'm confident that he'll come up with a solution.

I'm also still waiting to see the clear PVC combustion chamber and the rifled PVC barrel, they haven't shown up as of yet and it's now going on 3 weeks since they were ordered from SpudTech.

I did come up with a very small piezo buzzer that I can add to the CCU so that I'll have an audible tone when it is first enigerized, and also found a neat "dead man switch" that I may be able to incorporate into the venting stand.

Special thanks to Bob Skurka who had a bit of machining done to a one way valve that will be incorporated into the launcher (more on that later). I also appreciated that fact that Bob Skurka used candy instead of packing peanuts when he sent the part back to me. Boy do I have a sweet tooth!

Glad to share this project with you guys, and we're having some fun putting it together. Besides when Bob Skurka sees this baby shoot he's going to want one for himself.

 

[PineRidge]

Here we are making ready the components to assemble the one-way endcap check valve. We took a PVC schedule 80 threaded plug and had Bob Skurka punch a hole in it to match the taper of the rubber plug. I then shortened up the stock plug by cutting the first 1/2" of threads off. Bent up some flat stock steel by using the oxy/acet torches while holding them in the vise. Now I'm off to the hardware store for some all-thread rod and a few nuts and bolts.

 

[PineRidge]

Here's a shot of the now completed one-way endcap check valve. I spring loaded it to the closed position. My plans are to have the valve automatically open when the launcher is placed on the loading base.

 

[PineRidge]

The clear piece of schedule 40 PVC that will be used for the combustion chamber arrived today. This is what it looks like fitted up.

It is now ready for the combustion fan, propane injection, and the spark strip to be installed.

 

[PineRidge]

Here's how we're coming with the venting/parking stand for the launcher. Once the launcher is placed on the stand the micro switch will be depressed from the weight of the launcher starting the boxer fan, while the end cap valve opener will automatically allow the carbon manoxide to be quickly vented from the launcher while it is being reloaded.

I need to get over to Radio Shack and pick up a fan guard to cover the opening in the box for the boxer fan.

 

[PineRidge]

Here's what the bottom side looks like before the cover is placed on the base to seal the box.

 

[PineRidge]

Here we test fit the chamber to the propane bottle holder so that we could see where we needed to mount the spark strip. We wanted it to fall within the junction of the chamber and the propane bottle holder.

 

[PineRidge]

Looking through the clear PVC combustion chamber you can now see the mounted spark strip.

 

[PineRidge]

Here's another shot looking into the bottom of the combustion chamber. Here you can easily see the spark strip. We used brass knurled thumb nuts so that it could be changed easily.

The other two terminals shown with brass acorn nuts will be the power source for the fan that will also be mounted within the combustion chamber..

 

[PineRidge]

Just finished up the final assembly today. The graphics aren't done yet but my children are coming to town for Christmas so we're sure to do a bit of field testing and let you know what happens. I did squeeze one shot off today as a test and the recoil really surprised me.

 

[PineRidge]

Closer.....

Check out the laser sight.

 

[PineRidge]

You can also see more here http://www.pineridge7.com/MJE/bd-5.htm

 

[BadAttitude]

That thing looks LETHAL Pine!!...probably need a permit for it too

Nice work!!
wanna build one for me

 

[PineRidge]

Legal? Here's what the Feds say about them:

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.





Bureau of Alcohol, Tobacco, and Firearms

Firearms Technology Branch, Room 6450

650 Massachusetts Avenue NW

Washington, DC 20226



Sincerely yours,



(signature)



Curtis H. A. Bartlett Acting Chief, Firearms Technology Branch