SpudFiles

Nice job Peeto, Looking forward to seeing it rip up my paintball field.....you could easily add a tripod and use it as a mortar with sabots and paintballs , or my artillary rounds......I would keep that one with the steel chamber as a mortar and just make another for a LAW...... Nice.

I like it! What type of barrel supports are those on the barrel? They look like some sort of thermoplastic hangers?

Also, I would agree with everybody else in disagreeing with replacing the chamber with plastic pipe. While plastic is suitable for hobby cannons which are treated gently, I don't think a piece of scenario equipment should be plastic. I would suggest either keeping the steel chamber and just getting over the weight, or replacing the steel pipe with aluminum.

potatoflinger wrote:...you should keep the chamber metal...

nope. will be too heavy. i'm keeping the pressure down near 60 psi (max so far), and the gas supply will be double-regulated. i probably will do the chamber in sch 80, though. i'll keep the metal chamber as backup .

plus, i still have to look in to how much $ to build an aluminum chamber - alum would be operated at higher pressure, so it could be physically smaller, so cost may not be bad...

Isomer wrote:...seems pricey with the two QEVs.

that's what i thought at first - but they weren't really that much! at McMaster-Carr, the 3/4" is ~$18 , and the 1/4" is ~$12.

with 1" sprinkler valves at $15, the 3/4" QEV alone beats it for price/performance (i think). to spend another $12 doesn't seem too bad to get that much more out of it (IMO anyways).

i'll do up a complete price & source list.

EGOed wrote:Nice job Peeto, Looking forward to seeing it rip up my paintball field.....you could easily add a tripod and use it as a mortar with sabots and paintballs , or my artillary rounds......I would keep that one with the steel chamber as a mortar and just make another for a LAW...... Nice.

thanks, Ed , and thanks for the help. i'm looking forward to see what you're gonna do with your 2" piston valve - artillery across the entire scenario field! nowhere is safe!!!

Ed's field: http://www.highenergypaintball.com

markfh11q wrote:...thermoplastic hangers?

yup - from the Electrical Dept. at my local Lowes - they were a surprise find for me, never seen em before last week. was using galv. steel rings separated by thrded rod, but these are much cleaner & the action is much smoother.

thanks again everyone for the great feedback.

ok, i've looked into the cost of using an aluminum chamber buying parts from mcmaster (sch 40, fittings rated to 150 psi):

(pipe lengths 12", guesstimating chamber length ~14" incl. 90d elbow)

2" dia chamber: Cap $13, Pipe $25, El $20, Bushings (2"-3/4") $17
Total: $75

1-1/2" dia chamber: Cap $9, Pipe $16, El $14, Bushing (1-1/2"-3/4") $9
Total: $48

GGDT is telling me that 14" chamber of 1-1/2" pipe will reach the speeds i want at 75 psi with an 18" barrel. perfect!

ok, potatoflinger, i think i'm going with a 1-1/2" chamber! will be a few weeks before i get all the parts, but i'll post back the progress.

Nice cannon.

I too play paintball and live the demo/engineer role. I’m also a resident Nerf Nerd for a few local Carolina fields, aka I do inspections and crono LAWs for scenarios.

Not sure if you play in the States, but many fields in the southeast will not allow plastic chambers; even schedule 80 or 120. Most national promoters will not allow them in their scenarios either.

Have you given thought to using a fire extinguisher for your pressure chamber?

Bluemax wrote:Nice cannon...
...Have you given thought to using a fire extinguisher for your pressure chamber?

thank you! no, i hadn't thought of that - what a good idea.

i assume you have used them before for this application?
1) what are the thread specs? (NPT?)
2) what diameter of the threads i could typically get?
3) have any suggestions as to where to obtain them? or recommendations on make/model?

thanks again

1) The threads you usually can't use. Chances are you'll have to get it welded like I did.

2) They're about 3/4 +- but again they usually don't work. In the odd occasion you may find one that has NPT threads.

3) Weld.

I got two welded and made them into chambers here:
<A HREF="http://www.spudfiles.com/forums/viewtop ... html#56422"> DSGR</a>

MrCrowley wrote:I got two welded and made them into chambers here:
<A HREF="http://www.spudfiles.com/forums/viewtop ... html#56422"> DSGR</a>

ok - thanks for the info. nice gun there - where did you get the extinguishers? or brand info pls...

I got them of http://www.trademe.co.nz and they're 1kg Dry Powder fire extinguishers. I'm in New Zealand so you'll probably have different brands.

I've been screwed over by the no pvc rules at local feilds too
If I were going to make a LAW I'd just use a qev and fire extingisher

I am not sure whether this would help you but when fire extinguishers don't pass inspection they are recycled. You could probably grab a couple from a junkyard if your willing to deal with slight leaks.

so, with your experiences, would officials accept an all-metal cust. built aluminum chamber? (no plastic except for the barrel, all Al pipe and fittings rated to 150 psi)

add to the consideration if you slip the the guy $5 and a... oops, uh,... i mean if the law appears well thought-out and well constructed, and has additional safety features? (safety switch (valve), double-regulated CO2 (CO2 (800-1500 psi) --> Palmers Stab --> 120 psi --> Palmers Micro-Rock --> 75 psi (expected op. pressure)))

i think that for maybe a little more than i'd expect to (find and) pay a welder, or have a machine shop make me one, i could just buy the parts i found on McMaster & build me a lighter, smaller chamber - even if i found a FE cylinder for free...

My current rig for paintball

Are you in the States? I tapped this FE with only a crescent wrench with a double male threaded adapter from Lowe's. If you have a Lowe’s near you I can get the part number for you.

Bluemax wrote:...I tapped this FE with only a crescent wrench with a double male threaded adapter from Lowe's. If you have a Lowe’s near you I can get the part number for you.

that's a sweet rig - how do you fill? by remote? very sleek!
i thought i read somewhere here that FE tanks are left-theaded - was yours?
and do you know anything about the brand?
tia,
p

The double thread connector: Watts A-524, 7/8" Tube to 3/4" MI Connector with insert compression. Just throw away the insert and compression nut.

FE: I used a Kidde 10BC Kitchen, but I'm sure a Kidde 1A 10BC Recreational will do and a bit cheaper.

Tapping: The thread count of the FE is huge, around 5 per inch. I could never find anything close to that count. Slowly tap the FE with the 7/8" threaded end. The brass threads will cut in to the aluminum (what you want), just take it slow.

To seal: Use a glob (glob being the proper engineering measurement) to seal the connector and the aluminum bottle. I used JB Weld.

HTH and good tapping

*edit*
Yes I fill via a remote line. I run two remotes, one to my cannon and one to my marker. The cannon fills faster than I can breech and load a Nerf. [toot own horn] I can accurately fire 8 Nerfs from my LBV in about 12 secs [/end toot] The tanks love me when I go to a Scenario *insert evil laugh*