constant flow full auto :)

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 26179
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 543 times
Been thanked: 319 times

Donating Members

Tue Jan 06, 2009 10:51 am

The older members will remember my quest for a full auto valve from a constant air supply that sometimes were epic fail and other times came closebut not quite.

I've long been a proponent of self-made fittings, but recently spotted a couple of adjustable safety valves and decided to buy them for the heck of it to see what they could do. Long story short, I hooked one up to a blowgun attached to my compressor and after tweaking the spring tension a little:

[youtube][/youtube]

I think it's safe to say you can expect another attempt at an auto project pretty soon :D
User avatar
POLAND_SPUD
Captain
Captain
Posts: 5402
Joined: Sat Oct 13, 2007 4:43 pm
Been thanked: 1 time

Tue Jan 06, 2009 11:01 am

so when are you going to turn it into a gun...

I've never really undestood your persistence with all this constant flow thing... could you explain what are main advantages of it or how powerful gun you can buld with it??

BTW you should have titled the topic as 'I has constatant flow fullauto' :wink:
Children are the future

unless we stop them now
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 26179
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 543 times
Been thanked: 319 times

Donating Members

Tue Jan 06, 2009 11:26 am

POLAND_SPUD wrote:so when are you going to turn it into a gun...
It exhausts from two slots, all I need to do is block off one of them and attach the other to a blow-forward breech, given the joys of epoxy casting that shouldn't be too much of a chore :)
I've never really undestood your persistence with all this constant flow thing... could you explain what are main advantages of it or how powerful gun you can buld with it??
I suppose it's carried over from starting out with cloud or vortex BBMGs, where all you need to do is inject air from a blowgun into the system et voila, full auto. While the rate of fire is obviously less, incorporating some sort of "pulse" valve into the loop will usually give you the benefit of faster opening time and more flow.

The valve has 1/4" porting so it should be perfect for a 6mm BB/pellet machinegun :)
Attachments
safetyvalve.jpg
safetyvalve.jpg (4.74 KiB) Viewed 6570 times
User avatar
jitup
Specialist 2
Specialist 2
Posts: 251
Joined: Wed Nov 12, 2008 1:40 pm
Location: North east Ohio

Tue Jan 06, 2009 11:36 am

very cool. maybr I will give something a try (maybe not, I am working on quite a few things)
if you live in Ohio join the Ohio Spud Gun and BBMG Association at http://www.ohiosga.webs.com
User avatar
ALIHISGREAT
Staff Sergeant 3
Staff Sergeant 3
Posts: 1778
Joined: Sat Aug 25, 2007 6:47 pm
Location: UK

Tue Jan 06, 2009 12:11 pm

sounds pretty cool, although i suspect performance won't be mind blowing, hopefully the flow is adequate for airsoft bbs though?
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 26179
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 543 times
Been thanked: 319 times

Donating Members

Tue Jan 06, 2009 12:14 pm

ALIHISGREAT wrote:hopefully the flow is adequate for airsoft bbs though?
That's what I'm hoping, working on a way to attach it to an existing 6mm blow-forward breech as we speak :)

Here's what it's looking like, one port blocked off and a flattened brass tube on the other port to feed into the breech, all that's left is to encase it in epoxy for strength and we should be good for testing in 24 hours :)
Attachments
safetyvalvemod.JPG
User avatar
psycix
Sergeant Major 4
Sergeant Major 4
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands

Donating Members

Tue Jan 06, 2009 3:28 pm

Impressive!
So easy and yet you converted a constant flow to a pulsed one.

On the valve you used:
What kind of safety valve is it?
What is it normally used for?



EDIT

2000 posts!
Call in the unnecessary yet celebrative emoticon wave!
:wav:
Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
ALIHISGREAT
Staff Sergeant 3
Staff Sergeant 3
Posts: 1778
Joined: Sat Aug 25, 2007 6:47 pm
Location: UK

Tue Jan 06, 2009 3:56 pm

we should be good for testing in 24 hours
hopefully this one won't explode :wink: :D
PVC Arsenal 17
Staff Sergeant 3
Staff Sergeant 3
Posts: 1762
Joined: Mon Mar 27, 2006 4:18 pm
Location: United States

Tue Jan 06, 2009 4:38 pm

Saladtosser did this many moons ago.

A pop-off on its own wouldn't really be of any use. It would have to be used as a pilot valve. Lots of people have thought about this but it's too finnicky to waste time on. At least in my opinion. Of course it is possible though.

Wow... I was an idiot back when Atlantis posted this...
THUNDERLORD
Sergeant 3
Sergeant 3
Posts: 1264
Joined: Fri Mar 28, 2008 1:42 pm

Tue Jan 06, 2009 4:54 pm

jackssmirkingrevenge wrote:The older members will remember my quest for a full auto valve from a constant air supply...

...I think it's safe to say you can expect another attempt at an auto project pretty soon :D
I almost forgot :roll:

I hope you keep us posted.
Just ducked into an internet connection, and with earphones, the sound effect is awesome when played in combination with this!
Anyway, I'll be waiting for the follow up on this
BTW, more details on the safety valve, where can I get one ?
-----SPEED,STRENGTH, AND ACCURACY.-----
"Procrastination" is five syllables for "Sloth".
Theopia 8)
Born To Be Alive!
iknowmy3tables
Staff Sergeant
Staff Sergeant
United States of America
Posts: 1596
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Has thanked: 3 times
Been thanked: 9 times

Tue Jan 06, 2009 5:12 pm

PVC Arsenal 17 wrote:Saladtosser did this many moons ago.

A pop-off on its own wouldn't really be of any use. It would have to be used as a pilot valve. Lots of people have thought about this but it's too finnicky to waste time on. At least in my opinion. Of course it is possible though.

Wow... I was an idiot back when Atlantis posted this...
using a saftey relief valve as a pilot has been done plenty of times before, and it's also been used as a pilot for full auto, but this is different it's just using the relief valve as a pulsing valve for a full auto bbgun, previously this has not been done before because of difficulties in making the valve pulse while maintaining a strong output in those pulses, but If jack's has tweaked this right then there is a lot of potential for this

edit:
BTW Jack you have pretty good craftsmanship, but for me I find getting the back of the bolt alined to pop in and out of the input pipe tricky so I'm recommending this design
Image
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 26179
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 543 times
Been thanked: 319 times

Donating Members

Wed Jan 07, 2009 12:31 am

PVC Arsenal 17 wrote:Saladtosser did this many moons ago.
Not quite the same thing is it though, he's using the pop-off as a pilot. The guy who had done something similar to this was Brian the brain with his snap valve.
A pop-off on its own wouldn't really be of any use. It would have to be used as a pilot valve. Lots of people have thought about this but it's too finnicky to waste time on. At least in my opinion. Of course it is possible though.
I'm quite confident it will, it does move a lot of air - you can see the blowgun recoiling in the video - and we're talking 1/4" porting for a 6mm barrel.

The valve was purchased off eBay so is no longer listed, but it's nothing special, works just like any other pop-off only the top is threaded to allow you to adjust the spring tension. alternatively one could buy a standard pop-off with a fixed pressure and change springs.
BTW Jack you have pretty good craftsmanship, but for me I find getting the back of the bolt alined to pop in and out of the input pipe tricky so I'm recommending this design
Good idea there but for now I'll be using the one I made here ;)

Image

and it should work something like this:

Image

*crosses fingers*
hopefully this one won't explode


wanker. :D
User avatar
i-will
Specialist 2
Specialist 2
Posts: 245
Joined: Tue Jul 22, 2008 3:04 am

Wed Jan 07, 2009 1:55 am

so how strong is each air burst? that recoil kinda gives me an idea. what kinda fps do u think u'll get with 6mm barrel and 0.2g bbs? i trust that u've been doing this kinda thing long enough to give a reasonable estimate. i'm sorry if u think this is a dumb question.
WHY PAY FOR IT WHEN U CAN MAKE IT?
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 26179
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 543 times
Been thanked: 319 times

Donating Members

Wed Jan 07, 2009 1:59 am

No clue what performance will be like to be honest, but I'm very optimistic. Now that it's directed through one port only it should be pretty significant. Can't wait to get home and have a play with it, I'll post results as soon as I have them :)
User avatar
frankrede
Sergeant Major 2
Sergeant Major 2
Posts: 3220
Joined: Thu Jul 20, 2006 9:47 pm
Has thanked: 1 time
Been thanked: 1 time

Wed Jan 07, 2009 7:57 am

This looks to be promising, and with an even better blowgun you could maybe up the pressures?
Current project: Afghanistan deployment
Post Reply