Electro-pneumatic BB machine gun video

Innovator · Sat Jan 22, 2011 3:55 am

Thought this might be of interest for other as well:
BB machine gun based upon a 2kg fire extinguisher.

and

jackssmirkingrevenge · Sat Jan 22, 2011 4:43 am

Interesting, though $79 just for plans seems a bit steep.

I like the torsional spring magazine. The use of a geared motor and coaxial tubing - "the 7/32 tubes outer diameter is a perfect sliding fit inside their ¼ brass tube, which is very convenient in this design." - suggests an electrically powered reciprocating bolt, likely connected to a constant air supply but possibly even the valve is reciprocating.

ilovefire · Sat Jan 22, 2011 5:18 am

jackssmirkingrevenge wrote:Interesting, though $79 just for plans seems a bit steep.

about $1 a page... glad they dont charge that much for books like harry potter

django · Sat Jan 22, 2011 8:30 am

Nice find 8) seems to have really decent power too, Id like to find out how it works but Im not paying $79.00 to find out!!

Technician1002 · Sat Jan 22, 2011 8:52 am

Electro seems to simply be a laser pointer added to it. If you watch his channel, the BB magazine is spring fed. The details on the machine gun are left to those wishing to bite the bait and spend the money.

jackssmirkingrevenge · Sat Jan 22, 2011 9:05 am

Technician1002 wrote:Electro seems to simply be a laser pointer added to it. If you watch his channel, the BB magazine is spring fed.

If so what's the motor for?

django · Sat Jan 22, 2011 9:08 am

jackssmirkingrevenge wrote:
Technician1002 wrote:Electro seems to simply be a laser pointer added to it. If you watch his channel, the BB magazine is spring fed.
If so what's the motor for?

Exactly!! that motor and gearing must be for some sort of reciprocating bolt like an AEG

Hotwired · Sat Jan 22, 2011 9:43 am

django wrote:
jackssmirkingrevenge wrote:
Technician1002 wrote:Electro seems to simply be a laser pointer added to it. If you watch his channel, the BB magazine is spring fed.
If so what's the motor for?
Exactly!! that motor and gearing must be for some sort of reciprocating bolt like an AEG

Except instead of applying force to the BB by compressing air with force from the spring, it uses the spring to propel a hammer into a hammer valve on the chamber.

jackssmirkingrevenge · Sat Jan 22, 2011 10:05 am

Hotwired wrote:Except instead of applying force to the BB by compressing air with force from the spring, it uses the spring to propel a hammer into a hammer valve on the chamber.

I would suggest there is no hammer valve but constant flow - ie, the only valve is the extinguisher valve itself - and the motor simply serves to reciprocate a bolt which loads individual BBs.

If you look at this video of it firing without BBs, you can hear a rush of air even when the bolt is not working:

[youtube][/youtube]

Also available for free download are instructions for a tube-fed simple BBMG, but the complaint is always the same

The simplicity comes with a cost; the rate of fire is excessive, >100BBs/sec

I had been pondering an electronic solution to the issue from the spudtech days, this was one of my earliest designs and likely similar to the subject of this thread:

I also made this design using a solenoid instead of rotational motion, but never got it to work, even after revisiting the idea.

Kudos to the guy who did, it's bulky but clearly functions very well and performance is quite impressive

Gaderelguitarist · Sat Jan 22, 2011 10:41 am

Also it looks as though he's got it timed with circuitry for a 7 round burst, unless the sound in that video is off. He releases the trigger and it continues firing until 7.

However it works, I like it. It would definitely be a show stopper at any skirmish. It could almost be done up to look like Big baby from Hellboy 2.

EDIT: BB gun, not airsoft gun

! Not good for skirmishes.

Hotwired · Sat Jan 22, 2011 12:00 pm

jackssmirkingrevenge wrote:
Hotwired wrote:Except instead of applying force to the BB by compressing air with force from the spring, it uses the spring to propel a hammer into a hammer valve on the chamber.
I would suggest there is no hammer valve but constant flow - ie, the only valve is the extinguisher valve itself - and the motor simply serves to reciprocate a bolt which loads individual BBs.

If you look at this video of it firing without BBs, you can hear a rush of air even when the bolt is not working:

[youtube][/youtube]

I'm hearing static in the sound feed not air flow.

You can see him squeezing the extinguisher handle before pressing the electric switch. My guess is still on that charging a hammer valve and the AEG style mech powering a bolt/hammer.

jackssmirkingrevenge · Sat Jan 22, 2011 1:23 pm

Hotwired wrote:You can see him squeezing the extinguisher handle before pressing the electric switch. My guess is still on that charging a hammer valve and the AEG style mech powering a bolt/hammer.

It could also be that the bolt blocks off the airflow like so:

nature-boy · Sat Jan 22, 2011 2:38 pm

By looking closely at these pictures, I might have found out a few things.

The gear wheel (not in the picture but here) does at least 2 things per turn:

First: It drives a pipe with a hole in it, that receives a bb from the mag
and puts it into the pipe (inline with the barrel,
or even the barrel itself?) beneath it.

Second: It presses a electronic-lever-switch.
(Maybe for a solenoid as the main firing valve?)

Furthermore you can see that the big short white tubular-shaped thing on the left, (around the barrel) moves between one cycle.

I'm still not sure what the screw in the back of the brass elbow is for.
Or is it just for reducing/adjusting flow?
But it would be hard to make the screw airtight AND movable...

And I wonder what thisis for.
The pipes are not connected to each other, although there seems to be a pinhole in the longest part. Perhaps it is the "axis-pipe", driven by the gear wheel, which I mentioned above.

...I am about to get the feeling of getting eye-cancer by staring at these bad resolution pics, trying to see more details in them...arrgh...

@Innovator: Since this is your first post, are you the inventor of this BBMG ?

Innovator · Sat Jan 22, 2011 6:21 pm

Brilliant analyze, spot on!
I’m so sorry to hear about your eye cancer...it was totally unintentional on my behalf.....

I have been passing by as a guest from time to time and always been mighty impressed by the positive spirit and enormous creativity in the spud files forum.

The video clips posted here by me was mainly intended to be inspirational and not as “teasers”, since most people on a forum like this want to conceive their own ideas rather than just follow a step by step building instruction.
Never the less, feel free to ask questions, I will try to answer them as best I can.

The bolt is functioning as a valve retainer, once adjusted it is sealed with CA.
The airflow is controlled by a hammer valve.
The barrel with its permanent magnet assembly acts as a hammer.
The system is surprisingly efficient.

nature-boy · Sat Jan 22, 2011 7:45 pm

The self made solenoid-hammer-valve, triggered by the loading mechanism is really innovative and smart IMO.
I really appreciate that you share your project/invention with us, especially regarding the fact that you sell the plans!

So the barrel is forced/accelerated backwards trough the coil, closes the breech and hits the valve in the back of the loading-mech?

Do you drill out this piece from the top after soldering it together?

Is there a spring in the back of the valve (in the elbow) keeping it closed, or does it close from pressure?

Why is the gun still shooting a few shots even though you already removed your finger from the trigger? Is it because the motor is still turning from inertia?
If that is so and if you don't like that, you can maybe avoid that by having the solenoid in the same circuit as the motor, so the solenoid would not be able to work after you stopped pushing the trigger.
Just a thought.

I wish you good luck with the sale of your plans!
It's always great to earn money with something you enjoy doing!

Electro-pneumatic BB machine gun video

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