SpudFiles

First off I would like to say hello.......Awsome forum and very helpful people.
I've been a "Lurker" for a few months and decided to join so I can get a few questions answered....

A little about my gun...Its a basic 4in X 16in chamber that reduces to a 2in X 18in barrel. Using a standard Grill igniter (red push button) that is mounted flush right in the middle of the chamber. At first I was using good ol hairspray as my propellant and the results where awsome!! I was getting a good 100 to 150 yards easy with spuds. Only problem was the residue from the hairspray caused the pvc glue to give way on my end cap, which is a 4in female with threaded cap, and blew it off while shooting it. Thus turning me on to propane....

So I made the conversion to propane but have yet to get it to fire like it was before. Basically I want to know is a fan needed inside to help with ignition??
Im running the basic blue torch bottle with brass fitting hooked to a rubber line that connects to a 90d elbow that enters the chamber right above the igniter. Im barely opening the valve for a 2 mississippi count and i get nothing. I open my end cap to release the built up gas and while doing that i click the igniter and still get nothing. Until I blow in it then click the igniter ill actually get fire. So im thinking a fan?? do I need to move the air in my chamber to help with proper air fuel?? or do I need to get more air into the chamber to begin with??

I've done reading on this sight and others and didnt find a deff answer.

A fan is not necessary, but it helps. You need a meter for you propane if you want to have it fire reliably every time. Do some searches on propane meters and how they work. I would start with that wiki button on top.

If you insist on sticking with simply blowing the torch, it is obvious that you are using way too much propane. The propane is a lot more concentrated than the hairspray so you will need a lot less. Try a few things. I suggest blowing the torch into the chamber for less time. After every shot the chamber needs to be vented (that fan helps a lot here). Experiment, if your 2 seconds didnt work the first time, it probably wont work again.

Also, I am concerned about your pvc cement job. A properly primered and cemented joint will NOT get weaker from anything in the hairspray. If you did not use primer, or used the wrong type of "glue" you will most likely see this same issue again.

Jook; I think he means that the hairspray gummed up the threads and that caused it to blow off.

A fan will ONLY ensure proper mixture of the fuel already IN the chamber. As it seems you are probably using a "rich" mixture (excess of fuel). Propane is stored at quite high pressures and is more pure than any hairspray, this is why your cannon wont fire.

For the most ideal mixture, you should use a propane meter. Try this, this and this.

Note that after combustion you will have non flammable gasses (with the exception of certain mixtures- co). Make sure it is vented adequately.

Jook; I think he means that the hairspray gummed up the threads and that caused it to blow off.

I hope so. I have had that problem where the threads got all gummy and I couldnt tighten it enough.

Its this quote, "residue from the hairspray caused the pvc glue to give way " That made me feel it needed to be mentioned.

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chrissilvermancs wrote:try here for all your propane questions http://www.burntlatke.com/.

The links I gave him where to Bl's site, specifically the propane metering section

If you want to use propane without a meter, get a complete propane torch and use that. The venturi will give you a close to ideal mix, but seen as a propane torch is designed to have a fairly long flame the mixture will nbe slightly rich. There are cannons in the showcase which use this system built-in.

xxxlblackmag wrote: Im running the basic blue torch bottle with brass fitting hooked to a rubber line that connects to a 90d elbow that enters the chamber right above the igniter. Im barely opening the valve for a 2 mississippi count and i get nothing. I open my end cap to release the built up gas and while doing that i click the igniter and still get nothing. Until I blow in it then click the igniter ill actually get fire. So im thinking a fan?? do I need to move the air in my chamber to help with proper air fuel?? or do I need to get more air into the chamber to begin with??

You need less fuel, that's why it'll fire after you blow into it, you flushed out some of the excess fuel. A combustion gun won't ignite if there is too much fuel in the chamber.

Cheapest, easiest and most accurate fueling meter is a syringe. You might have one laying around from an inkjet refill kit. Or, get a 60cc plastic syringe from a farm supply store for a couple bucks.