Pipe Tapping Question

[Hubb]

For my next project, I was looking at constructing a pneumatic. I have contemplated on several different options and finally decided to go with something similar to The Bergles Cannon.This design is pretty neat but mine will not be mounted. It will be handheld (yes, it is being built for paintball).

The question: I was wanting a 2" chamber with a 3/4" barrel. I was wanting to drill a hole through the 2" coupling / pipe to thread a 3/4" street elbow. Would this be a bad idea to put such a large hole in the chamber?

[williamfeldmann]

You want to drill through what coupler now?

If you making this a handheld/fired you don't need the cross system which is used for the mount (Whoohoo less $ spent on fittings).

I assume you are looking at the shortened version of the action. If you are doing this to locate an schrader valve or other hardware I would come out of the 2" tee to a smaller tee (3/4"), one direction to the valve the other to fill and gauges.

[Hubb]

It will look something like in the pic. I was wanting to keep a low profile with this and that's why I didnt' want to add a 2" tee, then go to the 3/4" elbow.

[williamfeldmann]

So you want to use one of the threaded street tees?

I have had good luck putting schraders and other brass fittings through double walled joints like that, but brass is stronger and can thread itself. I don't know if the PCV would be able to thread iteslf in like that.

You could use galvanized parts but that would increase your cost pretty significantly. Your other choice might be look for 2" tee that has a 1 inch or 3/4" offshoot. I know they make them cause I have used them before. It won't be super lowprofile but will be less so than a 2x2x2 tee. and probably stronger than threading in a tee.

Maybe someone else on here has done somthing like this.

ps. You are using this for paintball, single shot or shotgun loads?

[Hubb]

I was going to drill the hole with a hole saw, then used a galvanized pipe nipple to cut the threads.

ps. shotgun loads.

[HaiThar]

EDIT: Oh okay... the elbow was because I'm guessing thats the equivalent to having a street elbow...

[Hubb]

I agree with William...just use one of those with an offshoot and then a 45 degree elbow...

Where did the 45 degree elbow come in at? Anyway, threading and / or tapping pipe is no problem. Neither is obtaining a fitting that was described (that was my second option). I just want to know if anyone has ever tapped pipe like this and, if so, what is the outcome?

[williamfeldmann]

Another option:

From the front coupler go to 1 1/2" or 1 1/4" bushing and then smaller tee. The barrel will go through the new tee and it will save you more than an inch either way.

It is more fittings and you would need an inch or two of the appropriate pipe (you might have it laying around) but probably sturdier and safer than threading the piece into the chamber like you proposed. I know those sizes of tees also come with smaller offshoots, you can actually probably find one in 1" or 3/4".

BTW what size valve are you using. You will get the best performance out of a 1" sprinkler, and I found today a 1" threaded to 3/4" slip pipe connection you could use on the outboard side of your valve.

Nice integral stock design, you gonna load through the butt of the gun? If so you might wanna shorten that up.

[Hubb]

Thank you. I don't know why I didn't think of that. The valve will be a piston valve built into a 1" tee (GGDT predicted 260fps @ 70psi). The cannon will be loaded via a magazine fed system and pump action.

Just so that I am clear, you mean like this right:

[windshrike]

Try building a really small chamber(this is not supposed to be part of you gun!!), tapping it, put in the elbow, and pressure test it to see if the threads are close enough before you risk your entire cannon.

[williamfeldmann]

Yeah that is what I was talking about. Sure it uses some extra fittings and pipe but it will get you a nice low profile. So are you going to run 1" around to the rear tee (piston?)? You should be able to get a tee that sizes down to 1 inch.

Are you going to use that rotating clip feed I saw somewhere on here (can't find it right now)? How is your pump action going to work, just sliding the clip forward and back or an actual sliding bolt? I'm interested, cause I have never come up with a good pump clip loader. You have piqued my interest.

[Hubb]

No rotating anything. The original design was of a revolver with eight loads. I have opted to go with a magazine fed (mag with five rounds) to get more firepower. Also, I was going to make it into a bullpup configuration (I want a small profile) so the revolver would get in the way.

(Confused? How can I get more shots with a five round magazine then I could with an eight round revolver? I'll have more than one magazine )

It is going to be similar to Boltsniper's SCAR-N.