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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trigun
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Mon Jan 26, 2009 11:33 pm

Image
Image

4" sch 40

32 in chamber

Pop-vent

80mm Pc Fan -18v power supply

no exposed wires or nuts and bolts

first time painting a cannon

cam-locks for easy barrel change and burst disks

off board metering system inspired by homedepotpro

Industrial BBQ starter- electric not piezo

homemade spark strip non-removable though so no pics sry

Feel free to ask questions
Last edited by trigun on Fri Feb 20, 2009 7:43 pm, edited 7 times in total.
EphOph
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Mon Jan 26, 2009 11:49 pm

Very nice with lots of features. I noticed you also used the Latke plug. That is a massive chamber; how long is the barrel you attach to it?
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trigun
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Mon Jan 26, 2009 11:51 pm

Yea the latke plug got kinda dangerous in testing stage but it was well worth the build.
For a barrels im getting 3" all the way to 1/2" at 7 feet
I had kinda cut up all my old one's and need to get new ones now hehe :twisted:
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starman
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Tue Jan 27, 2009 12:12 am

A new member but you have obviously been lurking some.

Very nice cannon you have there!...lots of chamber too. Hummm, some familiar things here and there I see..... :wink: You will have a lot of options operating this thing!

It's well thought out and constructed. I like all the electrics integrated into the handle. How did you mount the handle to the chamber? Why would you want to sell it? From the looks of this thing, it will last you a lifetime.

You could use the "direct link" that Imageshack provides and have them load up a little nicer in the post. I hate those thumbnails links.

Great job! and... Welcome to spudfiles!
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trigun
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Tue Jan 27, 2009 12:19 am

hmmm i'll have to look into the direct link thing but its getting late and my brain is fried from my college hw. For the handle i bought 8/32 threaded rod. Drilled holes into the chamber then screwed them in until it grabbed the spark strip. So i then drilled slightly larger holes in the handle so the handle easily slipped onto the rod. Put a small thing #8 washer and a nut tightened down and i was good to go. I'll try to upload more images tommorow :D

The handle and fueling are heavily inspired from your triple thunder cannons. :twisted:

on a side note i cant get the thumbnail to upload
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starman
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Tue Jan 27, 2009 12:46 am

trigun wrote:hmmm i'll have to look into the direct link thing but its getting late and my brain is fried from my college hw. For the handle i bought 8/32 threaded rod. Drilled holes into the chamber then screwed them in until it grabbed the spark strip. So i then drilled slightly larger holes in the handle so the handle easily slipped onto the rod. Put a small thing #8 washer and a nut tightened down and i was good to go. I'll try to upload more images tommorow :D

The handle and fueling are heavily inspired from your triple thunder cannons. :twisted:

on a side note i cant get the thumbnail to upload
Good idea using the spark strip bolts to also mount the handle. If you didn't tap the hole through the chamber, you should fill around it with JB weld or epoxy. That's a little bit of a weakness, drilling through only 1 layer of PVC. It would've been better to drill through at the coupler where there is 2 layers.

At Imageshack, you'll find the direct link when you click on "Show Adv Links".

I'm honored by your inspiration sir.... 8)
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trigun
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Tue Jan 27, 2009 12:50 am

I'm not to worried about the holes failing i tapped the holes. Pain in the A%@ by the way think tap is crap. Moving on yea i was worried about intefering with the chamber fan on the back so i comprimised so i made sure it was tight by on a spare piece old chamber tapped and i hooked it up to a vise and tryed to rip it out and failed.

The thing that worries me the most on this gun is the latke vent i built or gort vent what ever you want to call it.

i will edit my post tom. with the direct links and get more pics. I'll put a barrel in I pieced together so it looks pretty ugly but it will do. Starman what is your expierence with hybrids i think I'm going to spend my tax refund building one :twisted:
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starman
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Tue Jan 27, 2009 1:05 am

trigun wrote:The thing that worries me the most on this gun is the latke vent i built or gort vent what ever you want to call it.
Why don't you just configure a ball valve back there and call it a day? A 1" is plenty although others have been known to install larger ones.

I've never really trusted myself to get that Latke vent right.

Edit: I've not shown an official hybrid although in the testing of triple thunder, I "unofficially" tested it at 1.5x with a remote noise shot with no troubles.... :shock: ...yes monster loud, but I determined that fooling with trying to even low grade hybridize these for everyday use wouldn't be a good idea with a sced 40 build. I'm getting plenty of performance at 1x for its design with 3" noise stumps, long barrels and MAPP gas.

I have an artillery sized hybrid half built but on the back burner for the moment.
Last edited by starman on Tue Jan 27, 2009 1:17 am, edited 1 time in total.
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trigun
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Tue Jan 27, 2009 1:11 am

Yea i got the hole in with the largest rubber stopper i could buy. I did not however put any pressure on the stopper as in squishing it. So i loaded my burst disks 4-5 layers paper (works great). Fired the first shot and boom it worked great. Loaded second time 4 layers again. Held it to my side ignited it and whoomp?!?! The stopper and plunger fired through the hole and dented the garage door ( thank god it was the one my dad hit with the truck hehe). So i realized went wrong put it back and put two large washers and compressed the crap out of it. I've never had a problem since.

* on the thunder cannons how does the tape 4-5 layers hold 90 psi because i cant get the tape hold over 30 with 7 layers ? but paper at 7 layers does hold 90 psi ?
[/quote]
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starman
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Tue Jan 27, 2009 1:29 am

trigun wrote:* on the thunder cannons how does the tape 4-5 layers hold 90 psi because i cant get the tape hold over 30 with 7 layers ? but paper at 7 layers does hold 90 psi ?
I criss-cross the tape so the tape grains are running all different directions. Are you using the Scotch brand Blue tape?

On the 2" camlock breech, I use 3 layers of 2" Scotch Blue masking tape which I measured out consistantly around 65 psi with compressed air. I've tried to shoot 4 layers several times but 4 would occasionally fully contain the shot...you hear nothing...you think you have misfired, but you haven't. Open the vent and warm gases rush out. 4 layers measured out around 80-85 psi.

HGDT doesn't predict a vast difference in performance between them so I stuck to 3 layers.

On my 3" noise stumps, I have to use 7 layers of tape!
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trigun
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Tue Jan 27, 2009 4:16 pm

thanks starman for the help ill try the scotch brand blue instead of the generic maybe thats the problem.
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starman
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Tue Jan 27, 2009 4:46 pm

trigun wrote:thanks starman for the help ill try the scotch brand blue instead of the generic maybe thats the problem.
OK cool. You'll also find the Scotch tape to be a tad wider (really 2") than the competing brand (less than 2"). Here's what it should look like. I now actually put the tape pieces in 3 - 60 degree angles from one another rather than the 90 degree criss cross shown here.

Image
Image
Image
Image

BTW, what model of regulator did you use in your fueling setup?
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trigun
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Tue Jan 27, 2009 11:26 pm

the regulator is spare regulator my dad had laying around that he received for free with his air compressor. it has a weird inlet bushing and then 3 outlets. I'm going to purchase a husky regulator on my next trip to home depot.

Remember how you said you didn't trust those latke vents ? Well i decided shoot my cannon first time. Loaded my 70 psi paper burst disks and with empty barrel aimed straight up. Boom shot the plunger out again ! So i checked the plunger unscrewed the cap and relized it blew through by cracking the sch.40 cap into 3 pieces.

http://img220.imageshack.us/img220/4110 ... 060ed3.jpg

http://img220.imageshack.us/img220/1323 ... 061vj4.jpg
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starman
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Wed Jan 28, 2009 12:00 am

trigun wrote:the regulator is spare regulator my dad had laying around that he received for free with his air compressor. it has a weird inlet bushing and then 3 outlets. I'm going to purchase a husky regulator on my next trip to home depot.
Yowwie... :shock: Looks like you weakened the endcap too much making way for that pop-out vent. This is the kind of thing I was worried about. A burst disk causes chamber pressures to rise a good bit higher than usual so if you have a weakened chamber cap, it's going to be a serious problem there...lots of force on that back wall. I don't believe Latke or Gort used a burst disk on their units...at least the ones they use the pop-out vent on.

If that regulator is working well for you, I would just keep it. It looked rather industrial and I was jealous.... 8)
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trigun
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Wed Jan 28, 2009 12:05 am

Yea it works great only problem is that if i want to lower the pressure i have to let out some gas manually, besides that it works like a charm. :D
As for the plug yea i agree with you that i was pushing it. I really like the use of it though and on my new cannon i was thing i would take 4" male adapter and glue a normal cap on it and drill the hole through that. so i can still maintain the chamber and install fan on new piece so its easily fixable. P.S. so glad it didnt blow out my fan :shock:
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