Problems with mini

[Rogue]

Ok I just attempted to make a mini combustion with the pill bottle and pen tube method. Except my piezo thingy does not click anymore.

But when i did get a spark in between the screws it would not light. So far i have used Axe and Bod. How much fuel do i put in there? Like a .5 second squirt or like a 1 second 1/2 half squirt?



Ahh help please

[psycix]

The big rule of thumb on combustion fuel problems:
You got too much fuel
The big rule of thumb on mini combustions:
You always have too much fuel!

Put in the smalles spray you can, wave it forth and back a few times and then close it.
Experiment with the amount of times waving it.


OR use a syringe to measure out fuel.

[Rogue]

ok thanks ill try that

[CpTn_lAw]

4% of gaz is very small....you really need to shake it back and forth...

[Rogue]

now i switched over to a little butane thing from a lighter. how long should i depress that thing for(gas). then how many times should i wave it???

[CpTn_lAw]

that depends...i suggest you try to inject 1/2 second of gas, then a little more if it isn't enough...try by increment of 1/4 second.

[Rogue]

when i move my screws back more i get a larger purplish spark. keep it like that or should i move them so they are very close together for a small bright blue spark?

[Tom]

You can also use a long nosed lighter, take out the nozzle, fuel hose and the gas tank(including valev). Glue the nozzle in the barrel as close to the spark-gap , connect the rubbe hose from the long-nosed lichter to the lichter itself and the nozzle that is glued in your combustion chamber . This wil have a result that you can put the feul in more accurate.
GR.Tom

[Rogue]

i am going to move to a glue stic one. ty tom

[Rogue]

GRRRR... i made another one out of a glue stic and i got it to work the first 2 times, one bod one butane.



should i let the chamber vent??

[Rogue]

UPDATE!


got it working. needed more fuel.


thanks guys


roguE

[f.c]

try using metholyted spirits. just one drop should be ample for a decent and reliable shot.

[jimmy101]

You can convert a standard disposable butane lighter to a more accurate metering system like this.


Even without a syringe, it'll work better than an un-mod'd lighter since you can get the small piece of tubing well up into the chamber.

One challenge with a mini is getting the fuel to mix well. Kind of hard to put a fan in a chamber that small. A couple of BBs can be added and then the chamber shaken to try to help mixing.

Another challenge with a mini is getting anywhere near a reasonable CB ratio. For 1/4" ID copper tubing as the barrel, and using a typical pill bottle that is what maybe 1"x2", you have a chamber volume of ~1.5 in³. For a 1:1 CB the barrel would have to be 30 inches long. A 6" barrel gives a CB of 5. The BIC pen body has an even smaller ID than 1/4" pipe so a BIC barrel would need to be even longer. A grossly too large chamber (CB too big) will significantly drop the performance of a gun.

The size of the spark doesn't make any difference, small spark, big spark, are all the same.