Sign In Sign-Up

Welcome!

Close

Would you like to make this site your homepage? It's fast and easy...

Yes, Please make this my home page!

No Thanks

  Don't show this to me again.

Close

-On Sept. 2 I made it and bought the parts

-Spent $50.43 on all of the pipe fittings and valve ( including $25 for the valve) all at home depot.

-Spent $3.44 dollars for the two switches at Active Electronics on Oct 14 .

-I got the bicycle valve for free from Canadian Tire because they were mixed up about how much I was supposed to pay for it. That was nice of them.

I also bought a switch from Canadian tire on Sept 3 for a total of $6.89 but it never did work.

I went from one Canadian tire another and home hardware looking with One of my friends but they never had anything- accept the bicycle valve. Finally I went to Home Depot and they had it all. That is where I will go from now on

September sometime soon after building it

As I recall: After I built it, it was hard to get the solenoid to work but I tried it on a 12 volt car battery and it worked, even though it's a 24 V valve. I used a switch from a car window but found out that it leaks current and shorted the batteries - a while after I used up some batteries. The valve leaked so I returned it and got another one. The new one leaked for a time but I held it upside-down while pressurizing the tank it and it stopped.

I load the gun by cutting the potato first, with the extra length of tube.

I went to a friend's house with a ammo thing made of ice and we fired it at a tarp. It worked rather well but we had to use the manual valve. 

-On September 14 I bought the parts and assembled it accept for the lighter

-It cost $20.40 at home depot plus $3.43 at giant tiger for the lighter on Sept 16. NOTE: the lighters were labeled as 4 dollars and some, oh well. I could also use one of the flint lighters that my dad got . They would probably work well but I would have to take it out to replace the flint.

-Early April The Spudgun Fund paid for a real BBQ sparker-$13.95, give or take a few sense.

Right after building it

I taped the lighter in place and started testing fuels for the first time I tried propane, butane and ether, and WD40, the last one didn't=t work at all. It got pretty loud and the Idiot next door got all mad.

I was trying it in the shed, after putting the silencer on and was shooting potatoes at the pillar. I was having lots of fun, since it was raining and there was nobody around. Finally the bitch next door said she would call the police if she heard it again. I was hardly making any noise either, I found the right mixture to make it burn rich and shoot the spuds out with a sucking and kersplat!. I once or twice shot it at full power and it was really loud.

   ** Editors note: The silencer is a hole bunch of holes drilled into the barrel near the end, then fiberglass insulation wrapped around that and some plastic and duct tape around that to hold and protect it. It doesn't work that great and it kind of comes apart from the blasts of the gun after a while. When it started to fall apart, I took it off and didn't bother replacing it.

I went with a friend to Hardwood lake and brought the combustion gun. We had a hard time working out the fuel but eventually we could get it to go rather far, like almost out of site. Then I plugged up the lighter with a piece of potato by accident. It didn't=t work so we cut it out for the rest of the day.

About a week or something my dad brought me a present that is a piezoelectric sparker though it sparks more than once when you press the lever down. Getting the potato plug out of the gun sparker has become almost moot as I wait for the glue gun and time to do it, and now I'm just going to install the new  lighter. 

Yesterday my dad offered to take me to mud lake on Saturday to go spudding and take any friends who could come. Some guy in my class, Garrit, wants me to make him a gun but I am not so sure about him- he seems to have a short attention span and he may not be interested long. He just asked me about Athose big cannon things@ out of the blue one day in Business class, first period.

today I replaced the sparker and am getting ready for tomorrow. i.e., calling people.  I also cleaned the gun today, just the chamber, since the ether leaves some carbon dust around the inside of the chamber.  I hope all works out tomorrow.

Today I put the new 6 volt batteries on. My dad got me two and it=s a good thing too because one won=t open the valve. He actually got me three, one with a flashlight attached to it, that is to say that it came with it when bought.  I will be back after the outing to enter stuff.

The Aouting@ sucked. My gun didn't=t work. When I tried the air cannon I forgot to bring the piece to cut the potato with so I cut it with my knife and it just got lobbed a few yards. When I got back, I reshaped the cutting piece on the end of the gun so that I don=t need the separate cutting piece. I'll go look up the stoichiometric value to find out how much fuel I need for my combustion gun air to fuel mixture. I'll start out looking for it for propane. My dad tells me that the propane to air mixture is 40 to one.

270 times compressed in liquid form

formula = C3H8 

about 40 to one is ideal mixture?

boiling point : -42.1 C

http://www.propane.ca/Safety/defin.html - lots of info

Cubic feet(mtrs) of air required to burn 1 cubic ft.(mtr) of gas. 23.5

Lower and upper percentage of flammability : 2.4 to 9.5

my chamber is 3" wide (inside), round and 18" long.

Therefore the volume is: v = piR^2 * H

Therefore v= 3.1415926535 * 1.5 *1.5 * 18

which is equal to 127.23450246675

but let's just say 127.23 inches cubed

Which means that the volume of my chamber is about 127.23 inches cubed

Which means that it is about 127.23 * 2.54 cm cubed (127.23 * 16.387064)

which means that the chamber volume is2084.92615272 cm cubed (lets say 2084.92 cm3)

and since I need 2.4 to 9.5 percent of that (lets say 5 percent to start)

that means I need 104.246 cubic cm to make a good mixture.

that means I need 104.246 (lets say104) cc.of propane.

formula : C2H5OC2H5

- couldn't find much else

Whooo hoo! it I made the device to fill it up with propane and it works very well. First I took off the end piece of the nozzle of the torch (the part that mixes propane with the air), it screws off, but you might need some WD40. Then I took a small, soft piece of tube and put it on the end of the torch. All I do is take the 60 cc syringe (the biggest conventional one) and hold the end of the syringe against the end of the tube, turn on the torch and it fills up the syringe. I use two syringes at once, fill them both up one at a time and inject them into the chamber at the same time, if I had a third, I would do the same with all three to make loading faster. Be careful when you take the nozzle off because there is a small piece between the nozzle and the brass tube that it attaches to. This small piece is only held between the two parts and it will fall off when you take the air mixing part off. Save this piece because you won't be able to turn the torch back to normal afterwards if you don't have it, it has a small hole in the middle of it and is used for making the propane come out fast, so it can pull air in with it and mix with the air (the Venturi effect). The rubber hose has a friction fit with the brass propane valve. As for getting the rubber hose, the stuff I have is black and has thick walls. It is used in car radiators, washing machines for high pressure tubing (this stuff is reinforced) and sometimes in dehumidifiers. You could salvage it off one of these items or probably buy it from a large hardware store like Canadian Tire, or in Ottawa, Preston Hardware since it is used for lots of utility uses as well. It comes in different sizes but only one will fit the torch, so bring the torch to make sure it fits.

Click for bigger image.

click for a close up

The plan is to go to the experimental farm or some other place like mud lake and try out some different amounts of propane with it.

Try: (rounded to nearest cc)

Note: this would only work if there is a potato in it, thus blocking off the barrel and letting the propane fill only the chamber. Or you could hold the end shut and put twice as much in (the barrel volume happens to be the same size as the chamber). 4.4 percent (92cc)gives the maximum temperature, which is probably what I want.

I just tried this neat trick: fill the syringe with propane, light a lighter, and squirt the propane into the flame; a Mini Flamethrower! It won't blow up the syringe because there is no air in it. Push the propane out fast enough or you'll melt the end of you're syringe.

(Tuesday) I went out with my dad to the experimental farms on the south east corner and it is a wonderful spot. We spend around two hours and 10 minutes (18:30 to 20:40) there. Sparky (my dog) came but she got cold sitting there for most of the time. Dad was very helpful because he held the gun while loading and directed the process, basically. Only about five people came around in that time. Two dog walkers and two cars. and the last one scared me and annoyed dad because we thought it was a cop but it was just the guy from the farm coming to say that they were closing the gate soon so that we better leave soon. He was nice and dad told him about what we were doing and the guy suggested that we use a welder lighter, a "tweezer like" thing, but with "very high grade" flint. All together we concluded that it was probably a mixing problem. This is because the firings were very erratic and scarce (5 the whole time) I thought that may be I needed a new lighter( bigger) because that is the only difference that I could think of from mine and a regular one (like one on the net) Some things that my dad suggested are a pipe with tubes in it and attached to the plug. or with fins or something so that when you turn it mixes the gases. I will also need to attach the sparker to it more sturdily. I thought a wooden cradle to support it with a hose clamp around the pipe ( I think I can get one this big.) since it is a mixture problem, may be shooting the gas in faster would work better. I noticed that it is difficult to fill the syringe in the dark or quickly because you have to center it to get a good seal. I will try to fix that. Here are the notes that I took (typed and edited a bit because they were in point form):

Note: sometimes when we tried the same thing twice it didn't work the second time, but did the first.

Percentage amount of cc Comment (result)

3% propane about 67 cc

4% about 83 cc

5% about 104 cc

6% about 125 cc

7% about 146 cc

8% about 167 cc

9% about 188 cc -Worked once when "diluted" (dad opened the trap and let the propane flow out while sparking it.

- tried 180 CC and it worked

-The last time we tried it we put in about 7 syringes and waited about 10 minutes (we were trying it when the truck came up and then dad was talking to the guy and the second time he tried it while showing if it would work or not to the guy, it went off.)

- We think that it is a mixture problem

-5 syringes, wait 10 seconds and it worked

that's all the notes.

I just found out that the flashlight that I brought was left on. The batteries are dead.

Since it snowed a lot today- 30cm, I tried firing snow from the pneumatic but it kept leaking. I found out that the solenoid gets, not frozen, but stuck somehow, possibly from frost, from the cold that my shop is in (my workshop isn't heated). I took it apart (the valve) and found that once it was warmed up a bit by my hand, it worked all right. The little metal part that the solenoid moves is the part that gets stuck, it's really the only moving part. This only works for a little while though because it soon gets cold again. The trouble is that I have to take it apart to warm it, which is very annoying to do for every shot. I also had a thought today: may be the nine volt batteries don't supply enough peak current when it is cold. but do when it in warm. My dad says that the voltage drops as it gets colder but perhaps the ability to draw peak current drops also, since I measured the voltage at 27 volts.