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| Tsukiten |
 Posted: 11/17/2007 5:30 AM Post subject: Problems w/ Onboard Fuel Injection |
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Corporal
Joined: 12 Aug 2007
Posts: 68
224.94 Spud Bux
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Hey guys,
I started yesterday building some reliable mini, And I finally did that by using a onboard-fuel injection... But I found that the chamber was to weak, too fat and there were some big rips where the barrel goes in. So I decided to scrap the fat chamber and go for a thick walled, thin long chamber with no holes (some gluestick containter).
Here's the result:
But since I'm using that chamber...It doesn't fire at all!! 
I just can't get that mix right  It's true that I sometimes ajust the wheel that adjusts the butane flow but I returned it in it's original position I think, here's a pic of the fuel injection:
Maybe the insides got something to do with it? :
The cap where the piezo igniter is fixed on uses 2 nails that kinda 'float' above eachother, and are not next to eachother, does this matter? And since the whole chamber is from a gluestick, I can still smell the glue...does that change the athmosphere(?) or something? Here's another pic:
Oh and here's a size comparsion(?) of the 2 chambers...:
Would really appreciate help  I really wanna fire this thing off again (I miss smashing light bulbs with bb's...  ) |
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| wangpushups |
| Posted: 11/17/2007 5:35 AM Post subject: |
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Sergeant Major
Joined: 23 Sep 2007
Posts: 187
42.29 Spud Bux
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| Did you measure the chamber volume? |
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| hubb017 |
| Posted: 11/17/2007 5:37 AM Post subject: |
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Sarcasmo
Joined: 28 May 2007
Posts: 1323
269.90 Spud Bux
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On my mini (which is bigger than yours  ), I had the same trouble to begin with and here's how I fixed it.
First, I put the butane wheel to a suitable place and left it alone. Next, I just experimented, by seconds, the amount of butane needed. Mine (which was made from a small Gatorade bottle) holds a bout 7 seconds of butane, at about medium power (that's the wheel).
Since mine is larger, I would assume that yours would take less. Also, take a look at this thread. It may help as well. |
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| Tsukiten |
| Posted: 11/17/2007 5:38 AM Post subject: |
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Corporal
Joined: 12 Aug 2007
Posts: 68
224.94 Spud Bux
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| wangpushups wrote: | | Did you measure the chamber volume? |
Uhm... That is ((radius*2)*Pi)*hight ?? Forgot |
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| hubb017 |
| Posted: 11/17/2007 5:39 AM Post subject: |
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Sarcasmo
Joined: 28 May 2007
Posts: 1323
269.90 Spud Bux
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| pi * radius * radius * length |
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| Tsukiten |
| Posted: 11/17/2007 5:46 AM Post subject: |
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Corporal
Joined: 12 Aug 2007
Posts: 68
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| hubb017 wrote: | | pi * radius * radius * length |
Okay thanks
Old chamber: pi*1.5cm*1.5cm*5cm = about 35.3 square cm
New chamber: pi*1cm*1cm*8cm = about 25.1 square cm
Sure that's the formula? 0.o |
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| wangpushups |
| Posted: 11/17/2007 5:48 AM Post subject: |
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Sergeant Major
Joined: 23 Sep 2007
Posts: 187
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| No man the easiest and most accurate way to check your chamber volume is to fill it with water then measure it in millimeters. Then we could probably go from there... |
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| Tsukiten |
| Posted: 11/17/2007 5:59 AM Post subject: |
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Corporal
Joined: 12 Aug 2007
Posts: 68
224.94 Spud Bux
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| wangpushups wrote: | | No man the easiest and most accurate way to check your chamber volume is to fill it with water then measure it in millimeters. Then we could probably go from there... |
Isn't the formula enough or do you really want to know the water capacity?
Lol I just tought of fixing the big chamber ON the smaller one making 1 big badass strong mini AND whiping out the problem perhaps?? Plz reply |
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| hubb017 |
| Posted: 11/17/2007 6:07 AM Post subject: |
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Sarcasmo
Joined: 28 May 2007
Posts: 1323
269.90 Spud Bux
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| Did you miss my first post in this thread? |
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| Tsukiten |
| Posted: 11/17/2007 6:15 AM Post subject: |
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Corporal
Joined: 12 Aug 2007
Posts: 68
224.94 Spud Bux
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| hubb017 wrote: | | Did you miss my first post in this thread? |
Well not really but I gave up on experimenting because I spent ALOT of time with experimenting with clicks, seconds...It just doesn't seem to work with this chamber! |
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| jrrdw |
| Posted: 11/17/2007 6:36 AM Post subject: |
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Donating Moderator
Joined: 16 Nov 2005
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It could very well be a fume problem from the glue, sometimes i get lawnmowers were people get dumb stuff in the gas tank and they just wont fire the mixture until the system gets cleaned out. Sometimes less is more, meaning at least the smaller amount of fuel should fire even if it's a weak shot, untill it gets just rite, also meaning to much will dround the ignition, causing your problem, maby. Don't give up man, keep experimenting and good luck!
Edit: After a closer look at your eletrodes/nails, the points should be even. Sometimes a arc has a hard time crossing to a flat surface, the side of the nail, instead of the point.
Last edited by jrrdw on 11/17/2007 7:01 AM; edited 1 time in total |
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| Novacastrian |
| Posted: 11/17/2007 6:43 AM Post subject: |
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Bloody Aussie
Joined: 11 Aug 2007
Posts: 1622
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For a chamber that size you only need like 3cc of butane.
Use a syringe. |
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| Tsukiten |
| Posted: 11/17/2007 7:03 AM Post subject: |
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Corporal
Joined: 12 Aug 2007
Posts: 68
224.94 Spud Bux
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| Novacastrian wrote: | For a chamber that size you only need like 3cc of butane.
Use a syringe. |
Thanks for the idea, but sorry...  I rather work with a butane lighter injection. Number 1 reason is that you don't have to mess with opening the gun, using things like spray's and syringes... And I also think it's alot quicker to prepare for the next shot. Actually the concept of this gun was to use it in a classroom, and I rather get busted with a mini spudgun, than getting busted with a mini spudgun, a propane torch, and a syringe
I guess I'll continue experimenting.. |
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| jackssmirkingrevenge |
| Posted: 11/17/2007 7:06 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 6239
9329.59 Spud Bux
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| Tsukiten wrote: | Actually the concept of this gun was to use it in a classroom, and I rather get busted with a mini spudgun, than getting busted with a mini spudgun, a propane torch, and a syringe
I guess I'll continue experimenting.. |
I would really advise against using spudguns in the classroom, mini or not, except for officially sanctioned projects. |
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| wangpushups |
| Posted: 11/17/2007 7:08 AM Post subject: |
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Sergeant Major
Joined: 23 Sep 2007
Posts: 187
42.29 Spud Bux
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Oh my god dude you just made my day!!!  In the classroom... How old are you? |
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