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"In the world of spuds today"

A place to ask general spud cannon related questions.
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Unread postAuthor: MrCrowley » Mon Jun 04, 2012 7:34 pm

Fnord wrote:Crowley,

I've also noticed carbon buildup in hybrid chambers. Long ago when I did the sealed 2" sch40 test, I noticed some grime on the walls, having put perhaps 20 'shots' through it at various mixes. Ye olde piston hybrid accumulated it to a lesser degree, just not as much as you've shown.
Yeah my piston hybrid doesn't accumulate much except for a blackening of the chamber walls. I think it has to do with not bursting the disk in a burst disk hybrid; which isn't a problem you get with piston hybrids. I think a majority of the build up clears out with a successful shot, it just so happened that the last shot in my BD hybrid didn't burst the disk and I didn't air out the chamber before opening it up.
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Unread postAuthor: DYI » Thu Jun 07, 2012 12:33 pm

50 MHZ is not a common frequency. An easy to obtain frequency is 4, 8, or 16, which is easily divided to 1 Mhz reference for break wire clock. My time base for calibration checks is divided to 1 KHZ. Mechanical spacing error is orders of magnitude higher than the crystal 0.005%.


Tech, I'm measuring an event which will, at the upper end of the timer's designed performance (a projectile at 5000m/s measured over a gap of 5cm), last approximately 10μs. I'm not the designer of the timer electronics. The frequency is whatever common frequency was close to 50 MHz. There was no issue with finding a source for these oscillators - everyone stocked them. The issue was finding a source for less than ten thousand of them :lol:

@Jack: the high speed camera was totally blinded by emission in the visible spectrum for the duration of any event you would find interesting. The frames you're interested in were blank white squares :wink:
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Unread postAuthor: Labtecpower » Thu Jun 07, 2012 1:10 pm

got some nice stuff :)

First some 316 l stainless pipes, 22mm OD 14 mm ID barrel and a 33mm OD and 27mm ID chamber pipe :)

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and the 316l 1" union

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I want to turn this into a 28x mix hybrid, I have to make a nice design for it :)


A friend of me got this from his work;

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if we put these in a bank (if they still work correctly) they will put out about 1300 joules. Enough to have some fun like a very crude ETC?
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Unread postAuthor: ramses » Thu Jun 07, 2012 7:00 pm

DYI wrote:@Jack: the high speed camera was totally blinded by emission in the visible spectrum for the duration of any event you would find interesting. The frames you're interested in were blank white squares :wink:


I wonder how many ND filters you would need for them to become interesting...
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Unread postAuthor: Fnord » Sun Jun 10, 2012 1:56 pm

Sweet Jesus look what finally descended from the heavens today!


Ten minutes later and I have a working drill press again (That's not counting the three and a half months it collected dust).

Edit, I guess I could also post this while I'm here...

A *proper* non-ferrous metals crucible, made from graphite clay/mulite composite.
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Now I have an excuse to cut the excess of hair I grew during the downtime.
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Roughly a liter of capacity, rated for 2900F
Last edited by Fnord on Sun Jun 10, 2012 6:39 pm, edited 1 time in total.
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Unread postAuthor: Labtecpower » Sun Jun 10, 2012 3:56 pm

this is for the head spindle of the drill press?

nice to have some good tooling at home :)
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Unread postAuthor: Brian the brain » Mon Jun 11, 2012 2:37 pm

I want to turn this into a 28x mix hybrid


It's a good thing you're not living in a country where that would be illegal.

In my country this would be considered a firearm.
A pneumatic is quite a different matter wich is why I stick with those.
This is what the law says about it.
It's in Dutch so you probably can't read it.. :wink:

(Wet wapens en munitie, Artikel 1, onder 3) Het voorhanden hebben van dit soort wapens (feitelijk er over beschikken) wordt door artikel 26 lid 1 WWM als verboden beschouwd en door artikel 55 en 56 WWM als misdrijf aangewezen. De sanctie welke op het voorhanden hebben van een spudgun staat is maximaal 9 maanden gevangenisstraf of een geldboete van maximaal €18.500,- (artikel 55 lid 1 WWM

In case you decide to move to my country, you should be aware of this.

Ahem...
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Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Labtecpower » Mon Jun 11, 2012 3:40 pm

:D :D

Of course I don't live in the Netherlands, and it'll be a nail gun, so no problem at all :wink:

bird scarer is also an option..
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Unread postAuthor: MrCrowley » Mon Jun 11, 2012 5:13 pm

In that case, I don't live in New Zealand either. I suggest that all hybridists join together and seize Sealand for our cause!
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Unread postAuthor: Technician1002 » Mon Jun 11, 2012 6:22 pm

I recently acquired a new (to me) air cannon hauler with a 4.8 KW electric generator. :D This summer's launches will be using the bigger compressor. I can now haul a barrel over 20 feet long.

Pictures later. Brand Itasca.
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Unread postAuthor: Spud Destruction » Mon Jun 11, 2012 6:58 pm

20 ft barrel wow. if i only had a barrel that long :wink: :wink:
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Unread postAuthor: MrCrowley » Thu Jun 21, 2012 10:21 pm

Noticed this when inspecting my hybrid barrel:
Image

It's actually far more defined than the photo lets on. It also has a uniform twist and runs the entire length of the barrel. I'm thinking maybe a golf ball caused it as they're pretty much the only sabot-ed projectiles I fire from it.
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Unread postAuthor: jackssmirkingrevenge » Thu Jun 21, 2012 11:48 pm

Rifling by fire :)

That's what you get when you use shítty sabots :D
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Unread postAuthor: MrCrowley » Fri Jun 22, 2012 12:18 am

jackssmirkingrevenge wrote:That's what you get when you use shítty sabots :D
Any ideas?:D

Still not sure what I can use for golf balls. Tech's soda bottle method probably wouldn't work (finding a bottle that fits/deforming in the barrel), anything too hard usually flies too far (one shot/ricochets), anything too soft will deform in the barrel (angry JSR).

Actually, I've got some dry wall tape that I've used to sabot D cell batteries in the past. Perhaps I can make a cup sabot out of that (similar in design to your BB aluminium sabot) and line the inside with cardboard to prevent the ball sticking. Doubt I'll get more than one or two shots out if it but better than using old socks :oops:
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Unread postAuthor: jackssmirkingrevenge » Fri Jun 22, 2012 12:55 am

MrCrowley wrote:Doubt I'll get more than one or two shots out if it but better than using old socks :oops:


If you're using old starched wank socks then that would more than explain the scratches in the barrel :)

I don't think that at the velocities you're firing, a reusable sabot is really feasible, so you should be on the lookout for something cheap and plentiful.

If you can get your hands on some UHMWPE rod that is the same diameter as your barrel (shouldn't be too expensive) you can use a band saw to quickly cut it into 1/4" or so thick slices which can then be used as pusher plates.
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