Need help with mini combustion

EvilFish · Tue Aug 04, 2009 3:22 am

hello, I am quite new to spudgunning, and so far all i have made is a small pnumatic cannon. however, would like to get some help with my (quite ghetto) combustion.it has a pen tube as a barrel, and some "1 pipe as a chamber. it also has pizolectruc (cant spell it

) thingy from a long nosed lighter as ignition. i have opened up the back and sprayed in some fuel from a butane lighter, but when i press the pizelctrick buton, nothing happens. i am sure it is produceing a decents spark, (5 mm) so what could be wrong?

thanks for any help
may the FSM be with you

inonickname · Tue Aug 04, 2009 3:27 am

You have put too much fuel in, a common problem. Try use less fuel, blow some air in after fueling or shake your chamber to help mix the fuel.

EvilFish · Tue Aug 04, 2009 3:33 am

i have tried that, but i still cannot semm to get it to ignite, are there any other things that could be stuffing it?

jackssmirkingrevenge · Tue Aug 04, 2009 4:31 am

What you can do is measure the volume of your chamber and calculate the approx 4% of volume that you need for butane, meter this amount into a small 1mL syring and inject it into your chamber.

theBOOM · Tue Aug 04, 2009 4:38 am

Look simple way of getting a relaible mixture is... measure out your cannon with a small measuring cup (look at your moms medicine cabinet if she has one and find the small cups used for drinkable medicine ) after you've measured it out, get 4% of it.. for example if you had a 10 ml chamber.. you would need .4 mls of butane to get it to work... Once you've done this you will need a small syringe.. you can buy small ones for 2 dollars but ask your mom or dad if they have one.. my mom had like 6 ... Anyway once you have a syringe just insert the needle (I suggest you cut off the sharp tip with some pleirs) into the hose coming from the small little butane tank in your lighter and then let the syringe fill itself up with butane.. then inject it into your chamber and close it up again.. you should get reliable ignition with this method.. If not you probably have leaks in your chamber...
If you dont have the small butane tank ligther here is a sight that will help you modify a normal bic ligther : http://inpharmix.com/jps/Fuel%20Meter%2 ... ghter.html

Also your c:b ratio seems kinda off.. a 1" chamber with a 1/4" barrel that is probably 4 inches long... Maybe get a piece of 1/2 pvc pipe and have a short-ish barrel with a bigger diam.

Anyway I hope this helped if you have any questiones just PM me or ask them here..

EvilFish · Tue Aug 04, 2009 5:32 am

Thanks Everyone for the replies, i got it working, turns out i had WAY too much fuel

. my dads a vet, so i have a nice small syringe, and its working great. thanks again everybody.

theBOOM · Tue Aug 04, 2009 5:57 am

Sure thing, got you got it working and I home you dont quit on the art of spudding..

Need help with mini combustion

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