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How Cool Would it Be?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Would you have any interest in an OTC, lathe-less, semi-automatic 2" gun?

Poll ended at Mon Aug 11, 2008 11:49 pm

Yes
10
100%
No need for another semi-auto design.
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Total votes : 10
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Unread postAuthor: mobile chernobyl » Mon Jul 28, 2008 3:14 pm

socoj2 - Sorry to be a nag, but could you please delete your animations? The only one that really relates to my design in anymore depth than the fact that its a spool valve is the Shocker SFT, you may keep that one if you would like. The animations just clutter stuff up and add "Kewl" bait to what I'm hoping will be more of an intellectual conversation.
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Unread postAuthor: socoj2 » Mon Jul 28, 2008 9:34 pm

Does anyone have a reccomendation of a lube that will help seal o-rings to the inside walls of PVC, but not break down either compound? I've actually heard waterbased works the best lol


The Dow 33 lube that comes with paintball guns is what i use, it works well.


thats a negative on the diagram. Sadly the front and rear blocks i made for the overly large autococker where expensive...
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Unread postAuthor: Mr.Sandman » Mon Jul 28, 2008 9:48 pm

i think it is really hard to make new designs nowadays when you have people like ant who can replicate actual on the market air guns with a soda bottle and some bits of metal. :D but i think it will be considerd a cost effective cannon venture. cheers :D
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Unread postAuthor: mobile chernobyl » Mon Jul 28, 2008 10:26 pm

socoj2 wrote:
Does anyone have a reccomendation of a lube that will help seal o-rings to the inside walls of PVC, but not break down either compound? I've actually heard waterbased works the best lol


The Dow 33 lube that comes with paintball guns is what i use, it works well.


thats a negative on the diagram. Sadly the front and rear blocks i made for the overly large autococker where expensive...


Hey its cool, Do you have any pics of the finished gun by chance? When you say autococker, did you go with a ram operated "bolt" and some sort of valve? I would assume not a hammer valve, but something more along the lines of a piston valve?

I'll check and see if I still have any Dow33 left from one of my two shockers lol. The eclipse shocker used that sh!t up like it was food. I loved the overly complex structure of the old shockers haha.

Oh and sorry about double posting the last post I made, Some times at work I get forum lag, and I don't see the post's I've made until 10-20 minutes later, so I go ahead and post again thinking it didn't post originally when it did.

...................................

No CAD drawing tonight, sorry guys. I was shooting 1 gallon at my friends house today and it was so much fun shooting at his old, now retired Geo Prism - we shot until 8 pm. Then some more friends came over and we had a bon fire, and I'm just getting home now. After last night, I need some sleep so I don't nod off at "Initech" tomarrow lol. Peace spudders 8)
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Unread postAuthor: socoj2 » Tue Jul 29, 2008 6:14 am

Its not finished yet. I fired about 50-60 shots through it this summer, but the electronics were done all analog with 555 timers and they were finicky. I have scrapped them and went to a full Microprocessor and wrote the whole thing in C.

For the bolt it uses a 5/8ths Ram controled by a 4 way solenoid. The valve is a 1.5" Pulse valve. *XBOX HUEG QEV*
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Unread postAuthor: starman » Tue Jul 29, 2008 8:06 am

mobile chernobyl wrote:Does anyone have a reccomendation of a lube that will help seal o-rings to the inside walls of PVC, but not break down either compound? I've actually heard waterbased works the best lol


Have you tried plumbers grease? Vaseline? motor oil?
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Unread postAuthor: mobile chernobyl » Tue Jul 29, 2008 8:13 am

starman - Yes actually. Up in my first post I described a spool valve I made in college, and we tryed all those before I actually did research.

Motor oil - breaks down PVC, and alot of common o-ring compounds. Works OK in a static application, but in a dynamic it will deteriorate rapidly, If I tryed to use it on my 10" travel spool with 8 dynamic sealing orings, it would not work well

Vaseline - It's viscosity breaks down when used in a dynamic sealing manor over like 1". It works great as a lube for short throw dynamic seals like a common piston valve. It also works perfectly fine in a static operation.

Never tryed plummers grease. I can't imagine theres a need for greese and PVC, so I'm geussing its for valves or metal piping? I may be wrong though.

I'll look into it more. Water based lubes are save on pvc, they don't break it down, but they themselves break down and change viscosity quick with use.


Your project sounds cooler and cooler the more you describe it socoj2.

Ultimately I want to make this design a balance spool so I can tweak it manually, and not worry about programming in a .1 ms dwell time or something crazy that I could never do consistanly by hand. Then once I get it firing constistanly all I need to do is either add a homemade 4 way, or (the more I think about it now) 2 QEV's for the forward/backward spool motion, and nothing for the air inlet since its always on (beauty of a spool), and voila, electro-pneumatic semi-automatic spud gun.

I've never fiddled with 555's, instead I went strait to PICAXE microcontrollers when I started at college. We were assigned to build a fully autonomous machine in pretty good depth for a 2 credit 1st year course (this would typically be a 3rd year course, they were running a pilot with our year), so we got to learn full immersion style. It was great because I got to fool around with what it would take to program a picaxe to control something simple like a paintball gun (trigger, eyes, solenoid, on/off) and the timing and all on the side of our project. I never built the board for a paintball gun, but I'm sure if I had to I could now. I was using the predator morlock as inspiration, but I would obviously have to scale up the physical size since it wasn't going to be using printed circuitry. For a spud gun, size wouldnt be a factor and I could make something conviently. A cool project (even though its already been done in hardwire form by another tech website, sorry don't remember) would be to synch up a spud gun with video capturing target aquisition to a laptop computer and have it be able to fire wirelessly "The Jackal" style via touch pad. To have it recognize a target would be cool, but also manual control would be cool and alot easier. Pnuematic would be the ticket since you could have a pressure switch to regulate tank pressure and accomadate for distance. The GPS Guided spudgun project in the showcase section did just this, and that is a kickass project as well. Since my design would be easy to have a huge hopper of ammo, loading could be done manually no problem so that wouldn't need to be programmed in at all.

Unfortunatly I need to put a bigger timeline on this gun (months, not weeks) than any I've done in the past since it will undoubetdly need larger doses of tweaking.

Has anyone done a balanced spool valve on spudfiles before ?
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Unread postAuthor: starman » Tue Jul 29, 2008 8:45 am

mobile chernobyl wrote:Never tryed plummers grease. I can't imagine theres a need for greese and PVC, so I'm geussing its for valves or metal piping? I may be wrong though.

I'll look into it more. Water based lubes are save on pvc, they don't break it down, but they themselves break down and change viscosity quick with use.


Yeah usually used in o-ring seals in standard household valves and such. There's obviously not normally and need for grease and PVC. However, you are pressing the inside dimension of PVC pipe into a service for which it wasn't designed, so normalcy has already been thrown out the window... :wink:

While initially effective, I would think water based lubes would dry out fairly quickly. How about a silicone based one?
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Unread postAuthor: mobile chernobyl » Tue Jul 29, 2008 8:56 am

starman wrote:However, you are pressing the inside dimension of PVC pipe into a service for which it wasn't designed, so normalcy has already been thrown out the window...


'Tis the life of a spudgun fabricater. We are going down an unbeaten path of accelerating inanimate objects, and run into many bumps on the way haha.

I'll look into the silicon greese idea. I think we just ended up using a machine greese with teflon additive in the end because the project deadline was fast approaching and there really was no sound testing done on sealing anything to the INSIDE walls of PVC like you say. It worked OK, but if left sit it needed almost twice the pressure to initially "break it free" And it grew as we let it sit. I think they kept our project cause we actually won the competition, and I'm sure if they tryed to use it again, the valve might be siezed :shock: lol. I need to prevent swelling at all costs, or else this valve will need to be cycled day in and day out to prevent settling, if not it will be a fancy and heavy piece of 4" pvc with stuff inside.

Whatever I use, I'm like 99% sure its gotta be a grease, because its got huge sealing sufaces and an oil would just settle on the bottom of the valve.
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Unread postAuthor: mobile chernobyl » Thu Jul 31, 2008 3:06 pm

Well I got all the PVC fittings drafted up in solidworks last night. I figured I'd just draft them myself because I couldn't easily find a solidworks file online for the fittings, and they were going to have their stops sanded out anyways.

I also simplified the design alot, as well as put everything into scale, and it's looking like the spool section will be about 5" long. I sized the spool to be 2:1 C:B ratio to an 8' section of 2" PVC. No longer is there any expoying needed as well. I have picked out the O-rings from mcmaster - two difference sizes. Total there will be around $30 (they are not your normal o-rings, they're LARGE and thick haha). I'm trying to figure out an easy fabrication process for cutting the slots in the 2" PVC section of the spool. This could be done SUPER easy on a Mill, but that's not the point of this gun - its to be made easily, and pack quite a whallop. Semi automatic, 500cu in, 2" bore barrel, and LARGE AMMO, not 'dem cute wittle golf ballz. BAM! haha.
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