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The SEX (Scaled EXperimental) Pistol

Built a miniature cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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The SEX (Scaled EXperimental) Pistol

Unread postAuthor: dongfang » Tue Dec 25, 2007 10:54 am

Hi,

Well it's been too long since I last presented anything here.

Really, I have something, but it is not finished yet ... but it's time to show the prototype!

The SEX Pistol is a DFTV based gun; valve housing is a 32mm tee. For an explanation of the DFTV and of the terms used, see http://antennalaunchers.com/dftv19/.
The main difference from the plain DFTV is that the exit disc and the vent disc are the same diameter, that the turbo disk has been omitted, and that the bolt is a pipe and is used as equalization hole.

This is really the same as the S-DSTV I once mumbled about; that was a pilot valve for conventional large barrel sealers. I simply added a barrel and a chamber, and then it became a SEX Pistol. Scaled, because I have a much larger scale-up of this in the pipeline .... (and I had it in the drain line too, if any of you read my story about how I blew up a clogged drain with it, that's it).

The PVC hose over the chamber end of the 20 mm pipe that centers the bolt/plunger is an RSCV (Ridiculously Simple Check Valve). It is the same as an old-fashioned bicycle rubber valve - a flexible sleeve over a hole in a pipe. The PVC hose around the pilot chamber end is a recompression damper - it seals pretty well against the vent disk seat and has some mechanical friction too.

The performance of this tiny thing (exit valve diam. is only 25mm, or 1 inch) is quite impressive. I'll see if I can get some damage done and post it later.

Regards
Soren[/url]
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Attachments
DSC_0640.JPG
The complete parts line-up, before assembly. The thing above the tee is a 40mm bushing that fits over one branch of the tee (with a little heating).
DSC_0645.JPG
About half way through. Still need to put valves and dampers on the bolt, and drilling and tapping for the 8 bolts holding the vent seat in the bushing.
DSC_0646.JPG
The basic valve body, exit end.
DSC_0647.JPG
The basic valve body, vent end, closed position.
DSC_0648.JPG
The basic valve body, vent end, open position. The valve is reset by hand.
DSC_0078_small.JPG
Size comparison with its pump.
DSC_0085_small.JPG
OOOoo kay, I reveal it: Why it is called Scaled EXperimental. Its good performance convinced me to ge ahead with a larger, meaner motta fokka version. It has a quite short barrel and a very high pressure (it's all PN16, goes up to 230 PSI water), and it can pump golf balls through virtually anything. It still needs an improved damping system - it has cracked its vent seat / breech. I have a top secret solution for that underway, but I'm too lazy to get it built.
bolt.JPG
The bolt and the vent valve seat.

The exit "disk" is on the left (an end cap with a groove for an O-ring that was on vacation when the picture was taken). The larger O-ring in the center is the opener disk seal. On the right, inside the reducer, is the vent disk, similar to the exit disk.
DSC_0076_small.JPG
Breech end.
DSC_0075_small.JPG
The SEX Pistol.
Last edited by dongfang on Tue Dec 25, 2007 11:05 am, edited 1 time in total.
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Unread postAuthor: c19o » Tue Dec 25, 2007 11:02 am

Very nice, what porting is your "meaner motta fokka version"?
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Unread postAuthor: dongfang » Tue Dec 25, 2007 11:06 am

Hey,

50mm.

Regards
Soren
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Unread postAuthor: jackssmirkingrevenge » Tue Dec 25, 2007 11:13 am

Impressive, what pressures are you running at?
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Unread postAuthor: ALIHISGREAT » Tue Dec 25, 2007 11:18 am

ooh grey pvc goodness, i get the same colour in the uk, i think its EFFAST pvc... and thats a nice looking pistol and i'm curious as to what pressure you run at aswell. maybe to improve the looks you could use a smaller higher pressure chamber (not that it looks bad now :wink: )
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Unread postAuthor: dongfang » Tue Dec 25, 2007 11:54 am

Hi,

Yeah I did think about a stubbier chamber. Or a 90 deg elbow.

I have no pressure gauge on it, but I'd say somewhere between 6 and 8 bar.
It can take more, but the threaded connection to the chamber starts to leak before that. I need to either replace the chamber (then if I cement the chamber on, the valve can not be used as a trigger anymore) or just improve the seal.

Regards
Soren
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Unread postAuthor: hyldgaard » Tue Dec 25, 2007 12:09 pm

Very impressive. Did you built this in Denmark or Switzerland? not quite sure i understood where you normally live, as I have seen both countries mentioned as your location.
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Unread postAuthor: LikimysCrotchus5 » Tue Dec 25, 2007 12:20 pm

Very nice pistol :D

Nice job on creating the piston. I dont think i could do that. I would mess up somewhere.
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Unread postAuthor: Novacastrian » Tue Dec 25, 2007 12:53 pm

Looks very fun to use, cant wait to see what it can do. I like the "Sex Pistol" name too, very original :)
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Unread postAuthor: carter » Tue Dec 25, 2007 5:32 pm

looks super clean. nice name now can we see the damage
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Unread postAuthor: frankrede » Wed Dec 26, 2007 1:39 am

<a href="http://s30.photobucket.com/albums/c325/redensekjf/?action=view&current=mac_m11_9sl.jpg" target="_blank"><img src="http://i30.photobucket.com/albums/c325/redensekjf/mac_m11_9sl.jpg" border="0" alt="Photobucket"></a>
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Unread postAuthor: experament-u2 » Thu Dec 27, 2007 8:01 am

thats a nice looking gun chap
dont know why but i love the shape and nice job on the valve

great gun chap cant wait for the damage and the full scale version
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Unread postAuthor: dongfang » Thu Dec 27, 2007 11:16 am

Hi,

As for the color: I think that's an EU regulated code color, so it should be pretty much the same all over Europe (light gray is waste water above-ground and orange is waste water underground. Black is ??? So much plastic plumbing in Switzerland is black, however Switzerland is not in the EU).

Heeey Hyldgaard, another Dane here! Jeg er dansker men bor og arbejder pt. i Schweiz. Pistolen er.... et eller andet sted. (I´m Danish but I live and work in Switzerland. The pistol is ... somewhere).

The best ammo I have found is pieces of 25 mm pipe with some tape wadding around them and ice inside. I will try do some damage pics with that. And maybe also with a 25mm barrel.

Regards
Soren
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