SpudFiles

so this is our first cannon completed 1.5:1 C:B ratio

here is the chamber itself

here are the screws we have meeting in the chamber to create the spark (hooked up to BBQ sparker)

Ever since this morning the spark has been occurring less and less frequently. Now we are lucky to get 10 sparks in a row without failure. To sum it up, it is very unreliable. Sometimes we'll get a big and blue spark. i don't understand why it only sparks half the time. its not the fuel mixture either, we have that pretty much down, just no spark. We got a new one but it doesn't work any better than the one we got off of an old rusted grill. We put washers on the screws to try to get a better distance between the tips inside and placed the sparker wire in between the washer and the heads of the screw to try to increase conductivity, still having problems. Does anyone have any ideas?

Hmmm, Im not that all into combustions, but, you might just want to buy a whole new igniter instead of taking them off of old rusty grill. Also, check if your igniter needs batteries, and replace them. Make sure that the igniter isnt sparking any where that it shouldnt. BTW nice gun. Is that clear PVC for the chamber?

the peizo isn't the problem, it's the electrodes, they are probably gunked up, get a rag and wipe off the tips of the screws, that should get you better sparks

edit: yay!! 300 w00t...ok smilie time :violent1: :headbang: :hello1: :happy4: :happy3: :blob8: and the ever popular :wav:

Looks like the gap is a bit far apart. Close it down to 1/4" or so with longer screws or bend them together some.

Also, be sure you are airing the chamber out good.

I have noticed somthing strange with piezo sparkers.... I seem to get the brighest, most blue sparks when the electrodes are only barely close enough to spark. When they are very close, the sparks are usually weak and sorta orangy-purple colour, and fairly dim. Seeing as you said that the sparks you do get are very bright ones, I would suggest moving the electrodes closer. The sparks won't be as impressive but it should be more reliable.

Besides moving the electrodes closer to eachother, is there a chance they are getting gummed up by hairspray?

we've been using starting fluid and after every shot we brush off the electrodes with a small wire brush. the pvc for the chamber is just a different color but still pressure rated .

AJChambers91 wrote:we've been using starting fluid and after every shot we brush off the electrodes with a small wire brush. the pvc for the chamber is just a different color but still pressure rated .

Close the gap some....

Close the gap a lot. Kind of hard to tell from the photo but it looks like the gap is more than 1/2 inch or so. Close it down to ~1/8". The gap does not have to be very big. If you can see a spark it'll ignite the fuel. A bigger, longer, hotter spark won't increase the performance of the gun.

Also check that your wires are all well separated. The insulation on the wire won't stand up to the several thousand volts the sparker generates. Since the insulation can't handle the voltage you basically want to use air between the wires as added insulation.

Shortening the spark gap will make it less likely that you get sparking through the insulation.

I agree that your gap is too large. I don't think you need to clean the electrodes after each shot if you are using starting fluid - there shouldn't be anything in there to gunk anything up.

try riggin 2 or 3 sparkplugs at diffrent parts of the ignition chamber and wire then to all fire at once off the ignighter

I'd suggest investing about $20 into a cheap stun gun in the near future.

You'll never have another ignition problem again, even with a less than ideal mixture.

I've been having this exact problem with my new combustion. Although I am using hairspray. Any suggestions?

Would that be your new cannon looking cannon? You never did show us the guts of that thing. What does your spark setup look like? Chances are you're:

- using too much fuel
- spark gap is too wide
- not airing out between shots

1 or all of the above.

I'll get some pics up later but yes that would be my new cannon looking cannon.