Help with a BL stainless steel

jdty · Fri Feb 18, 2011 10:15 pm

hey there,
have made a few simple cannons in the past. all combustion. i dont like messing with compressed air as its not very mobile.

my last cannon had 3 sparks and was pretty decent, untill i found spudfiles. and now that i have seen the BL series i am keen to build one.

having the barrel come back into the chamber is something i would have never thought of because i would have assumed it would be to hard for the pressure to find its way out nicely, obviously i was wrong. is there anything i should know before i start my build based on one of the BL series guns? for example does the back of the chamber need to be a dome shape to help direct the blast in and out the barrel? what distance should there be between the back of the barrel and the back of the chamber? can i make the gun out of stainless steel? because of my trade this is cheaper/easier for me to use, but everyone els seems to use pvc?
should i use 4" tube or 6" for the chamber and should i use 2" or 2.5" for the barrel? how long should the barrel be? and any other things i may have overlooked, i would hate to spend my time and money to find out i forgot one crucial part.

Crna Legija · Fri Feb 18, 2011 10:25 pm

idk if you know but they are for sale at ultimate spudguns.com might be a bit more expensive but hell of a lot ezyer

jackssmirkingrevenge · Sat Feb 19, 2011 1:16 am

Welcome to spudfiles

jdty wrote:for example does the back of the chamber need to be a dome shape to help direct the blast in and out the barrel?

It should be dome shaped to be able to better contain the pressure, but in terms of performance you wouldn't see a difference.

what distance should there be between the back of the barrel and the back of the chamber?

The minimum distance is 25% of your barrel diameter (so for say a 2" barrel, the distance should be at least 1/2")

can i make the gun out of stainless steel? because of my trade this is cheaper/easier for me to use, but everyone els seems to use pvc?

If everyone had access to stainless, they wouldn't use PVC at all

There are several metal combustions out there, here's a particularly attractive example.

The use of stainless also gives you the option of going hybrid, as Moonbogg did with hisCobra Venom.

should i use 4" tube or 6" for the chamber and should i use 2" or 2.5" for the barrel? how long should the barrel be? and any other things i may have overlooked, i would hate to spend my time and money to find out i forgot one crucial part.

The important parameter is the ratio between chamber volume and barrel volume. Have a look here, with combustions there's an ideal number for that ratio.

Gaderelguitarist · Sat Feb 19, 2011 12:22 pm

May I ask what you do that makes stainless steel cheaper than PVC?

What a lot of people don't do is plan the projectile as well. If you're going to emulate the BL series, I'm assuming you're going to have metered fueling, meaning that with the right projectile, you could have a serious cannon in your hands.

Potatoes are fine for "purists" and simple shooting. However since you have access to stainless steel so easily, you should look into making potentially reuseable rounds that have a stable flight pattern.

motorfixer1 · Sat Feb 19, 2011 8:45 pm

Building out of steel or stainless steel is the preferred method for safety. PVC is kids stuff. Just kidding, no but seriously anyone can build a launcher out of pvc from home depot, it takes skill to build one out of steel!

Technician1002 · Sat Feb 19, 2011 8:47 pm

It requires more tools. PVC requires little more than a saw and glue. Not so with stainless.

Remember, metal parts rob the combustion cannons of heat. For higher power, use PVC as it is more insulated than stainless.

jdty · Sat Feb 19, 2011 9:06 pm

as i say, stainless steel would be easier and cheaper for me. however i want to know witch is best and how to do it. i dont want to just build one thats average. i want a beast to be sitting on my shoulder, not a toy. also yes i like the BL series as it doesn't have the combustion chamber sitting underneath the barrel so it would be good looking as a shoulder launcher.

Gun Freak · Sat Feb 19, 2011 9:23 pm

In no way is steel easier to use than PVC. Use PVC for your launcher-- it will be simple and easy and with a little creativity you can make a sick launcher out of PVC. And as Tech said, you'd be better off power wise.

jdty · Sat Feb 19, 2011 9:55 pm

i have decided hybrid is the way i want to go.

Moonbogg · Mon Feb 21, 2011 5:33 pm

A cannon the size of a BL made of stainless would be way too heavy for shoulder fire. If you want a beast of a cannon like a BL in stainless for hybrid use, you either have to be really damn strong to hold it comfortably, or start thinking about tripods.
Another option is to make the cannon smaller.

Help with a BL stainless steel

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