cartridge fed combustion build log

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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Lentamentalisk
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Thu Jan 21, 2010 11:39 pm

JSR:
How are you fueling the cartridges? I was thinking that one way to make them easy to fuel, assuming you can air them out well enough, would be to epoxy the refueling check valve from a lighter into the base of the cartridge. Then, just press it onto a butane lighter fuel can for a predetermined time, and you should be set. This could also in theory work for a hybrid cartridge, if you hack apart an empty butane refill, and hook it up to a compressor.
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jackssmirkingrevenge
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Fri Jan 22, 2010 4:15 am

Lentamentalisk wrote:How are you fueling the cartridges?
Same as always:

Image

Simple and reliable ;)
hectmarr wrote:You have to make many weapons, because this field is long and short life
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jackssmirkingrevenge
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Fri Jan 22, 2010 12:04 pm

Here's what the breech looks like now, just about ready for single shot testing once the epoxy cures - conceptually identical to my original design.

I hope to have some action videos (not high speed yet, camera's still stuck at bloody customs :evil: ) tomorrow, if that goes well I'll start thinking about a magazine.
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Cartridge removed
Cartridge removed
Cartridge chambered
Cartridge chambered
hectmarr wrote:You have to make many weapons, because this field is long and short life
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JDP12
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Fri Jan 22, 2010 12:53 pm

Love it!

Can't wait to see some video of it in action
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Fri Jan 22, 2010 2:15 pm

JDP12 wrote:Can't wait to see some video of it in action
You're going to have to wait a bit more for some proper action, I just blew it apart :roll:

[youtube][/youtube]

Moar epoxy + moar patience to stop me from testing it before it's full cured...

At least I know that the ignition contact interface between bolt and cartridge is working well :D
hectmarr wrote:You have to make many weapons, because this field is long and short life
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USGF
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Fri Jan 22, 2010 2:24 pm

jackssmirkingrevenge wrote:
JDP12 wrote:Can't wait to see some video of it in action
You're going to have to wait a bit more for some proper action, I just blew it apart :roll:


Moar epoxy + moar patience to stop me from testing it before it's full cured...

At least I know that the ignition contact interface between bolt and cartridge is working well :D
JSR, setbacks build character. :cry:

USGF
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Fri Jan 22, 2010 2:29 pm

USGF wrote:JSR, setbacks build character. :cry:
And Jack has LOTS of character. :wink:

Wait a second.... :lol:

Very good self control Jack...not one four letter word on the clip, I'm pretty certain there would be (at least one) if it was mine. :)
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Fri Jan 22, 2010 2:35 pm

Nice going JSR you broke it! About the camera, how is 30 fps high speed? It says 30 fps right on the front... :shock:
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jackssmirkingrevenge
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Fri Jan 22, 2010 2:37 pm

USGF wrote:JSR, setbacks build character. :cry:
Easy to say from your high end workshop :D but you know what they say, "if at first you don't succeed, you're probably JSR and you will invariably throw more epoxy at the problem" ;)
:D :D :D
Very good self control Jack...not one four letter word on the clip, I'm pretty certain there would be (at least one) if it was mine
Would you believe that it's exactly what I thought when I saw the video after uploading it, "People must think that this happens so often that it doesn't even phase me any more".

Well, not too far from the truth I suppose :P

Repairs in progress, I think I'd better start on something else so I can leave this project be until it can take the strain...
jrrdw wrote:About the camera, how is 30 fps high speed? It says 30 fps right on the front... :shock:
30 fps is the "burst photo" mode, as to video it can do 210, 420 and 1000 fps.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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jrrdw
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Fri Jan 22, 2010 2:43 pm

JSR wrote:30 fps is the "burst photo" mode, as to video it can do 210, 420 and 1000 fps.
Cool, I was wondering. How long of a video clip can you take at 1000 fps?
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Fri Jan 22, 2010 2:59 pm

jrrdw wrote:Cool, I was wondering. How long of a video clip can you take at 1000 fps?
I don't know first hand yet but from a review:
Encircling the Movie button is the Movie Mode switch, which can be set to either High Definition / Standard movies or High Speed Movies. Starting with the former mode, the EX-FC100 can record standard quality movies at 640x480 pixels at 30fps in the AVI format, or High Definition quality movies at 1280x720 pixels at 30fps. You can even pre-record up to 5 seconds of footage using the Prerecord Movie Best Shot mode, and shoot up to 10 still images (6 megapixels) whilst recording a movie simply by pressing the shutter button.

There are some limitations to the EX-FC100's HD movies though. The AVI format choice results in some massive file sizes that quickly fill up your memory cards, and the length of a movie is bizarrely limited to only 10 minutes
hectmarr wrote:You have to make many weapons, because this field is long and short life
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JDP12
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Fri Jan 22, 2010 3:51 pm

Wow..... well impressive nonetheless. It looks like it will have no problem working the blowback action... once you rebuild it
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Fri Jan 22, 2010 4:15 pm

blog JSR linked to wrote:This extreme slow-motion effect is initially very appealing and sure to impress your friends, but as with the HD movie mode, there are some drawbacks to be aware of. You can't use the optical zoom, sound isn't recorded at all, horizontal bands can appear as the lighting fluctuates, and the actual sizes of the recorded movies are pretty small, especially the 224x64 pixel, 1000fps mode.
This is what I thought. Should be able to get some good shots though.
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Fri Jan 22, 2010 7:56 pm

jrrdw wrote:
JSR wrote:30 fps is the "burst photo" mode, as to video it can do 210, 420 and 1000 fps.
Cool, I was wondering. How long of a video clip can you take at 1000 fps?
On mine I've never managed to reach a limit on the high-speed, so I assume it'll keep going till the card fills up. The one benefit of low-resolution high-speed is that it can be written to the card as quickly as it is recorded, provided you have a fast enough card. I'm using SanDisk Ultra II's and they've worked perfectly for me.

In a few minutes though I will start up a 1000fps and see how long it runs though, just to make sure it's not using it's internal buffer to record to. Either way, you don't want really long high-speed vids because then it takes forever to sift through it and cut it to size, at least with the in-camera editor.

EDIT: On a partly-used 4GB card, when recording at 1000fps it told me I had a bit over 16 minutes of recording left (16 minutes in real time). If my maths is correct, that would be over 8 hours of video when watched normally. So basically, more recording time than your ever likely to need.
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Fri Jan 22, 2010 11:12 pm

@jsr
if it wasn't for people like you we'dd feel much less successful :D

uhmm sorry that was mean but it proves that it might be a good idea to invest more in some tools (like a drill press, or a mini lathe). IMO it has got slightly too dangerous and time consuming since you got that HPA tank (yeah I know it was a combustion)

you could probably find some decent (but cheap at the same time) second hand stuff
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