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serviceable piston

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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serviceable piston

Unread postAuthor: no-limit » Sun May 25, 2008 10:36 pm

OK so I'm aking a lot of questions. This will be my 5th one and I am gettting tired of making them and them not working good.

I could solve my main problem if I can find a way to make the piston serviceable. Looking for ideas.
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Unread postAuthor: clide » Sun May 25, 2008 10:41 pm

There are many ways. I personally prefer a female threaded fitting on the tee and then a threaded bushing or threaded plug to close it up. Others make bolt-in plugs or caps. Just look at the piston valve guns in the showcase section. Almost everybody makes them serviceable.
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Unread postAuthor: MrCrowley » Sun May 25, 2008 11:32 pm

I use these:
Image

The pipe goes on the inside, not outside, like a normal fitting. There should be a tiny rim in the middle of the fitting which you just grind out, then your piston can fit through. And yeah just stick a threaded plug on the end.
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Unread postAuthor: no-limit » Sun May 25, 2008 11:41 pm

Oh yeah, I want to use a 1" spinkler valve to pilot it.
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Unread postAuthor: Biopyro » Mon May 26, 2008 3:30 am

You can still do that, you just have to make a hole in the plug where you would usually put it in the endcap.
What I'm doing with my current cannon is having it serviceable until it works then I think I'm gonna seal it off, because having a serviceable piston attached by screws is giving me serious pains with leaks.
For my next piston cannon I will definately be using a threaded cap and plug, they just make this so much easier!
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Unread postAuthor: no-limit » Mon May 26, 2008 2:03 pm

Then do you use a 1" hole saw to make the hole in the cap?
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Unread postAuthor: MrCrowley » Mon May 26, 2008 2:17 pm

If you use the fitting I showed you, say you were building a 2" piston valve, this is what you do...

Cut a piece of 2" pipe that is long enough to fit all the way in both sockets (the tee and the fitting), then dremel or file out the small 'lip' or 'ring' in the threaded fitting above, so that your piston can fit through.

Glue the pipe in the tee and to the fitting, stick your piston in, get a 2" bushing that has 2" male threads on the outside and 1" female threads on the inside. Then hook your sprinkler valve and fill setup to that.

And you're done.


It's that easy.

Best thing to do is just go down to HomeDepot and see for yourself, otherwise we're gonna be here all day with you asking more and more questions that are self-explanatory.
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Unread postAuthor: MaxuS the 2nd » Mon May 26, 2008 6:32 pm

A piston is only as good as the person who builds it.
Build it well and it'll work well, it's not the piston's fault that it doesn't work.
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Unread postAuthor: no-limit » Mon May 26, 2008 9:58 pm

A piston is only as good as the tools a man has. I'm going to get this one right. If I only had a lathe!
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Unread postAuthor: MrCrowley » Mon May 26, 2008 11:19 pm

no-limit wrote:A piston is only as good as the tools a man has. I'm going to get this one right. If I only had a lathe!
Not exactly. You can build o-ring pistons perfectly fine without a lathe.

Had my first go on a lathe today at school, almost finished my piston. Though I don't like how I had to use plywood. I might ask if I can use somethign else, plywood is terrible for pistons.
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Unread postAuthor: biged » Tue May 27, 2008 5:47 am

Serviceable 3 inch chamber, 2.375 porting. A tennis ball barrel was welded on later.
Image
I have to use a vice and a 2 foot pipe wrench to get inside to the piston. It also eats about half a roll of tape sealing it.
Image
Even doubled-up lock washers loosen over the span of 200+ shots.
Doubled-up lock washers and locking nuts seem to be holding.

///ed///
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Unread postAuthor: LikimysCrotchus5 » Tue May 27, 2008 2:54 pm

I like what you have 8)

I want to build one now, it makes a inline design easier.
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Unread postAuthor: no-limit » Tue May 27, 2008 3:51 pm

So how do you put on an o-ring without a lathe to make the grove to seat in?
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Unread postAuthor: Biopyro » Tue May 27, 2008 3:53 pm

Use an abra file, or even just a hacksaw - it is harder, but if you need one it's worth it!
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Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety. -Benjamin Franklin
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Unread postAuthor: no-limit » Wed May 28, 2008 11:37 pm

On a lathe all I would have to do is touch the file to it and it would file a perfect circle for the o-ring. How do I get that circle without it, is the abra file a circle file?
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