Help Building "V3" advanced combustion

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
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metallover
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Wed Feb 11, 2009 9:55 pm

I just got done wiring the stun gun. Oh good god it turned out GREAT.

I didn't have any trouble at all soldering it. I used a good amount of flux and clamped everything down when I soldered. I never expected it to turn out so good.

Next on my list is:
-fitting fan into chamber
-making spark strip
-finishing barrel
-Compacting and installing the propane meter
-install propane cyllender holder
-... that should be about it. I hope to have it online by this weekend. It's a 4 day weekend for me!!

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metallover
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Wed Feb 11, 2009 10:10 pm

One more pic. That last one was a little blurry... I put a little bit of CA glue (super glue) to hold the default spark gap in place. I also wraped some electrical tape around the top part to get it back together better.

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I am astounded on how everything is going. It all looks really good. I hope I can finish it this good. This project is turning out to be a ton of fun. :D
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trigun
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Wed Feb 11, 2009 10:13 pm

How big is the gap in your chamber going to be ? I ask this because it appears that the guns default gap seems really close.
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metallover
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Wed Feb 11, 2009 10:15 pm

I'll keep the gap in the chamber pretty small. If I ever need it bigger I might take a dremel to the default spark gap. I think the default gap being smaller will help with the overall life of the gun. It's a cheap one... 16.99 shipped on fleabay. :lol:
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roboman
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Wed Feb 11, 2009 10:17 pm

It looks really clean so far... keep up the good work!
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Radiation
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Thu Feb 12, 2009 12:17 am

Looking good. Are you planning on just using the switches on the stun gun as your ignition? If not it's really easy to wire in a momentary switch and an on/off switch as a safety. It makes for a great way to have easy ignition using handles.

Also, Definitely dremel down those spark gap test leads... As a matter of fact what you should have done is just remove them completely and attached the wires directly to your monster cable speaker cables.
I void warranties.

The Gauntlet of Clara Ann
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metallover
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Thu Feb 12, 2009 7:59 am

I plan on using the switches already on the gun. the big switch on the top picture has a spring in it or something which makes it impossible to leave it in the on position. There is also another switch on the other side for on/off action. :)

With the default spark gap, I think I'll dremel it to 10-12mm to start. The latke one was 15mm, but I want to stay safe and make sure my nothing stupid happens to my stun gun. I would never remove them completely... That's just asking for trouble.

Tonight I hope to fit the fan in if I have time and possibly do a little wiring. I want to get the propane meter mounted before I mount anything else on the outside of the gun. I need to pick up a couple parts for that... 8)
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Thu Feb 12, 2009 10:14 am

Good, you got the case open without totally destroying it. You did a good job with it, just plan to keep the HV leads separated as much as possible. If you haven't yet completely unzipped the 2 wires apart from each other, now would be a good time to do it.

Keep up the good work!
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metallover
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Thu Feb 12, 2009 11:49 am

I forgot to mention how I got the case open. I dremeled about half an inch off at the bottom where the battery goes then I was able to pry the rest open with a flathead screwdriver.
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Thu Feb 12, 2009 3:26 pm

Radiation wrote:Also, Definitely dremel down those spark gap test leads... As a matter of fact what you should have done is just remove them completely and attached the wires directly to your monster cable speaker cables.
Definitely do not dick with the default gap. The manufacturer put it there to protect the guts of the stun gun. If you widen the default gap, and then have a problem with your igntion gap(s), you'll cook your stun gun.

Best thing is to cover up the default gap with a slice out of PVC pipe.

Here is how Latke did it;
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from http://www.burntlatke.com/stun.html
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metallover
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Thu Feb 12, 2009 5:54 pm

I just dremeled some of the gap away not having read that post. The default gap is now about 9-10mm, which still isn't very much. IIRC Latke used a 15mm gap.

I'm just about to install the fan. It's supposed to be blowing towards the muzzle, right?
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metallover
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Thu Feb 12, 2009 6:30 pm

I just installed the fan. It's blowing the right way too. I dremeled it to fit the threads and it screws in and mounts like that. I think it turned out great. My next order of business will be the propane meter. I don't know if I'll get to that tonight or not.

-One question. Is there a circut to increase the voltage of my 9.6v rc pack to a healthy 12v? I would attach this to not increase the voltage to the stun gun, but only to the fan. That makes me think I should limit the voltage to the stun gun too... A fully charged pack is well over 10 volts.

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EDIT. triple post would be bad.


I found a site with voltage regulators - http://www.eidusa.com/Electronics_Voltage_Regulator.htm

The way I'm seeing things is that one described as "+5v voltage regulator" will increase voltage to 5 volts. If one is described as "-5v voltage regulator" it will decrease the voltage to 5v. Do I have this right?

If I am, I plan on getting a -9v and a +12v. Do I need any fancy resistors or capacitors or anything?
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Radiation
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Thu Feb 12, 2009 7:39 pm

jimmy101 wrote: Definitely do not dick with the default gap. The manufacturer put it there to protect the guts of the stun gun. If you widen the default gap, and then have a problem with your igntion gap(s), you'll cook your stun gun.
You may have blown out your stungun, I'm not saying its impossible, but trust me this blanket statement you are making is not any sort of rule that must be adhered to. I have a lot of experience with electronics and circuits. I am more than comfortable with "dicking around" with spark gaps and high volt circuitry. The Gauntlet has nothing more than the guts of a stun gun, no default gap, no casing, just the guts. I have to date never had any problem with not having a default gap because I always have made sure the gap that is there is sufficient enough to allow for a jump. Even the times when I thought it was sufficient but wasn't the spark has not damaged the stungun. I know all this stuff is cheap chinese crap, so your results may vary.

Let's put it this way, if the stungun misfires, don't keep firing it, adjust the gap and try again. If it misfires and you keep pushing the trigger well of course you might damage it. Again I'm not saying a blow out impossible, but lets not make blanket statement rules or generalizations that are not true. Personally I find not having a big ugly stungun slapped on to my design quite nice and elegant. Just a preference thing I suppose. All that said Metallover has done a good job integrating the stungun here so let's move on.

Now back to your fan question. you can up the voltage using a regulator is you want, it is so not necessary though. 9.6 volt on the battery pack you are using should be more than adequate.

EDIT: FYI that "default gap" is put their on a stun gun to test the gun and to threaten potential assailants.
Last edited by Radiation on Thu Feb 12, 2009 8:13 pm, edited 1 time in total.
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metallover
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Thu Feb 12, 2009 7:44 pm

My battery is currently at 10.5v. Would this be too much for the stun gun designed to run on a 9v battery? The RC battery is even closer to 11v when fully charged. I wouldn't know but a regulator sounds in order.
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Radiation
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Thu Feb 12, 2009 7:55 pm

ehhh that should be fine. Any type of electronic device usually operates within a range when it comes to voltage. For instance an iPod may run anywhere between 4 volts and 1.5 volts and still operate. 10.5-11 volts should pose no problem for either your fan or stungun.
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