Herminator

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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starman
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Wed Jan 28, 2009 12:16 am

Those fans are almost indestuctible if you keep debris out of them. Amazingly, they don't seem to mind the shock of combustion.

Why don't you just build out a rear plug like mine. I thought about it a long time too and that's really one of the best solutions I could come up with, with standard parts that is.

4" threaded male - 4" socket PVC
4" - 2" spig - socket reducer bushing PVC
2" spig - 1" female threaded PVC
1" steel close nipple
1" threaded PVC ball valve

Yeah it's a little bulky but very solid. I think you are well beyond screw-in endcaps at this point.
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trigun
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Wed Jan 28, 2009 12:20 am

[
4" threaded male - 4" socket PVC
4" - 2" spig - socket reducer bushing PVC
2" spig - 1" female threaded PVC
1" steel close nipple
1" threaded PVC ball valve
couldn't i just go 2" to 2"pvc ball valve or is the 1" worth it

Starman i really have to thank you i am glad i can join and find someone that is intelligent to talk 2 :lol: .
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starman
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Wed Jan 28, 2009 1:11 am

trigun wrote:couldn't i just go 2" to 2"pvc ball valve or is the 1" worth it.
You could certainly. The 2" is a little large-ish and can be difficult to hand open and close. You'll want to vaseline lube it to help you some.
trigun wrote:Starman i really have to thank you i am glad i can join and find someone that is intelligent to talk 2 :lol: .
:oops: You're welcome and thanks ... :oops: but, you are asking good questions and learning things for yourself. I'm just reciting things from rote... :wink:
EphOph
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Sun Feb 08, 2009 11:47 pm

Sorry for the late reply, but hopefully this will help. Here is the vent I will be using on my next combustion project. This is an NSF-PW 4" plug. It was marked SCH80 but my supplier told me that it is actually SCH40. The ball valve is a 1" PVC valve with the threads removed from one side (for low profile). It is attached via a 1" MPT x 1.25" slip adapter; most of the 1.25" side has been removed. I chose this fitting for the surface area. Assembly was simple: I drilled a hole in the center of the cap and then used a dremel sanding drum to enlarge the hole to accommodate 1" threads. The ball valve is cemented to both the back of the cap and to the threads (the adapter had a generous helping of cement between it and the cap as well). This probably isn't quite as solid as starman's solution, but it is less of an extension to the chamber and I feel that it will hold up nicely to combustion pressures.
Attachments
Outside of cap showing 1" PVC ball valve.
Outside of cap showing 1" PVC ball valve.
cap_outside.JPG (31.99 KiB) Viewed 1892 times
Inside of cap showing 1"MPTx1.25"slip adapter.
Inside of cap showing 1"MPTx1.25"slip adapter.
cap_inside.JPG (24.83 KiB) Viewed 1892 times
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starman
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Mon Feb 09, 2009 12:05 am

That sir, is one beautiful endcap solution!! I love it! Weighs a lot less than mine too. I believe it will easily hold 1x combustion just fine.

One little tip about shortening the PVC valve...your valve handle, when open, now becomes a stress point and a target for damage during handling.

Otherwise, excellent work. Great post and photos!
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trigun
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Mon Feb 09, 2009 12:37 am

Wow that looks very nice ! i will post pics tom. Of the gun now after new plug in the back. Sorry it took so long to make i was working on my hybrid and that.

No hockey tommorow so it will be up.
Side note i won regionals and going to state now ! 8)
EphOph
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Mon Feb 09, 2009 10:41 pm

starman wrote: One little tip about shortening the PVC valve...your valve handle, when open, now becomes a stress point and a target for damage during handling.
This is true, however, I think it depends on the user. I did the same thing on my spray & pray almost a year ago and it has held up fine without incident, but I am very careful with my cannons. Shortening the valve would definitely not be recommended for those who are a little less conservative in the treatment of their launchers. I'm glad you like it.

trigun: looking forward to seeing the new plug and damage pics! Congrats on winning regionals.
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trigun
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Mon Feb 09, 2009 11:30 pm

Image
By trigun03, shot with Canon PowerShot A540 at 2009-02-09

Image
By trigun03, shot with Canon PowerShot A540 at 2009-02-09

Image
By trigun03, shot with Canon PowerShot A540 at 2009-02-09

Image
By trigun03, shot with Canon PowerShot A540 at 2009-02-09

All it is
Plunger
4" male adapter
4" to 2" reducer
needs to be repainted really bad



Image
By trigun03, shot with Canon PowerShot A540 at 2009-02-09
I'm the one holding it
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starman
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Mon Feb 09, 2009 11:48 pm

EphOph wrote:Shortening the valve would definitely not be recommended for those who are a little less conservative in the treatment of their launchers.
While I am a very careful handler of my cannons, I carry one of them in the back seat of my truck all of the time and it gets pinned in all kinds of ways back there with all the other stuff there as well. It's the things I don't have control over than concerns me not the stuff I do!... :wink:

BTW, if it's stamped sched 80, it is. I have a sched 80 cap just like it, it's gray while yours is white. Your supplier is confused...just because it's white doesn't make it sched 40. It has the exact sched 80 dimensions.

@trigun

Your endcap looks good! Much better photos this time.... :wink:

Congrats on the hockey championship!!
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vardas
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Wed Feb 11, 2009 4:59 am

hey man, a great looking cannon ! i hope you get all the bugs worked out so we can see some damage pics soon
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trigun
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Thu Feb 12, 2009 11:15 pm

The bugs are all worked out I just need some free time and then the weather to warm up.
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