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Help with an inline vortex BBMG
Posted: Sun Aug 21, 2011 2:20 pm
Hey, I've recently been having trouble with my BBMG with regards to getting it to fire. I pump the air chamber I have constructed out of pressure rated PVC pipe up to 120 PSI through a shraeder valve I have installed in one of the end caps of the pressure chamber, but when I pull the trigger of my blow gun valve, I hear air rushing out of the barrel, but no BBs. My device uses a vortex block made out of wood that is inside of 2" diameter pressure rated PVC like my air chamber. The plunger system connects to a threaded adapter on the end of my gun by screwing into it. I have tested my system for leaks but I have found none. What am I doing wrong?
Posted: Sun Aug 21, 2011 2:28 pm
I cannot see how the vortex block works. I really can't help without more details.
Posted: Sun Aug 21, 2011 2:39 pm
Either there is a problem with the block or the bbs are jamming. Try taking the plunger off or loading less bbs. Give it a shake before you fire it.
Posted: Sun Aug 21, 2011 3:45 pm
Remove plunger, try firing in different orientations and shaking.
Add plunger again. If it does not fire, use the weakest spring you can find.
Posted: Sun Aug 21, 2011 4:16 pm
Could be as simple as a slight crimp in the beginning of the barrel, preventing any BBs from coming out.
Posted: Fri Oct 14, 2011 6:44 pm
Great news guys! I fixed the problem on my own. It turned out I was simply adding too much ammunition to my gun, which resulted in the inability for agitation to be reached, and in turn, no venturi effect. It works great now and fires about 100 rounds per second! Thank you for the feedback! I will post pictures and maybe a video in the photo gallery sometime soon. Thanks again!
Posted: Sun Jan 08, 2012 6:54 pm
OK, I now have a working gun that I have upgraded by installing a longer metal barrel, and a new backpack set up with an air tank constantly being charged by a 12 volt air compressor powered by a rechargeable battery. I have also installed a pressure gauge between the blowgun trigger and gun so I can quickly see the pressure in the tank. However, despite all these upgrades it takes a long time for my gun to reach significant pressure for firing (75 psi and up). How can I achieve greater power/recharge time?
Posted: Sun Jan 08, 2012 8:53 pm
Is the tank still pvc?
You don't want the pump running constantly if you don't have a pressure switch to kill the power once it tops off. It's easy to get distracted in a combat game.
Battery power is not really fast or efficient, so you'll either need to get some lithium batteries and a better pump or just use a CO2 setup.
Posted: Sun Jan 08, 2012 9:24 pm
Yes the tank is still PVC, but I have a safety cutoff switch built into the air compressor. I'm interesting in a setup that would still use high pressure air for the propulsion system. I was thinking of maybe getting one of those high pressure metal or carbon fiber paintball tanks that can take about 3000 psi and regulating down, but I have no idea how I would charge any tank beyond 150 psi (the limit of my air compressor). I have considered using a refrigerator compressor, but the price of such devices is beyond my current capabilities. Any suggestions?
Posted: Mon Jan 09, 2012 2:00 am
If a HPA or CO<sub>2</sub> air source is beyond your budget, you might want to consider making the most of what air you have by optimising your launcher parameters, I see yours needs it
that tiny barrel for example is not doing you any favours, and I'll wager the BBs are a loose fit too. What is your upgraded barrel like?
This thread is most helpful: http://www.spudfiles.com/forums/dvs-off ... 18159.html
Also if your tank is in a backpack, it seems you can afford to make it much bigger.
Consider large (2 or 3 litre) soda bottles, they should be safe filled to 75 psi or so.
Posted: Mon Jan 09, 2012 6:36 pm
Thanks for the help guys! My new barrel is about a foot long and has a tighter inner diameter. Something I have been wondering about though is how to create a simple homemade hop-up. I hear the backspin generated from such would increase my range and accuracy. How would I go about doing this?
Posted: Mon Jan 09, 2012 7:03 pm
For hop up I have used a slot cut in the top of the barrel with an o-ring around the slot so it goes into the barrel a bit on the inside. Crude, but it works
Posted: Tue Jan 10, 2012 12:56 am
Xenophile wrote:Something I have been wondering about though is how to create a simple homemade hop-up. I hear the backspin generated from such would increase my range and accuracy.
My comments on the subject from the other thread:
Hop-up isn't there for stability, the gyroscopic effect is not along the same axis as that applied to a bullet fired from a rifled barrel but rather is tangential to the line of flight. What hop-up does is trade velocity for lift through the magnus effect.
Davidvaini wrote:Things of importance for accuracy:
weight of BB
consistency of velocity
barrel quality and tolerance.
High velocity is also an important factor for accuracy, indeed it would be much better to fire heavy BBs at high velocity than to have hop-up. The latter is required because of the low velocity and woeful sectional density of airsoft BBs which give them a howitzer-like trajectory at anything past a few yards range.
I understand that if you want to have an airsoft gun for skirmishing, safety considerations will limit the performance, but otherwise stress should be made on obtaining the highest possible velocity with the heaviest possible BB. The former will ensure a flatter trajectory and shorter time to target, while the latter gives better velocity retention due to high sectional density while making the projectile less vulnerable to environmental factors.
The importance of barrel tolerance cannot be overstated, the "golfball in a drainpipe" analogy applies here.
Davidvaini wrote:Things of importance for for range:
weight of BB
barrel length, quality and tolerance.
Barrel length in itself will not give you longer range, it is the higher velocity usually supplied by a longer barrel that contributes to this. However, if you can achieve velocity without resorting to a longer barrel, this is better in terms of accuracy. Essentially it means that the time interval between trigger being pulled and projectile leaving the muzzle is shorter, so there is less time for gun or target movement during this delay to be a factor.
Posted: Tue Jan 10, 2012 6:51 pm
Thanks guys! I have reconsidered the possibility of running on a compressed air paintball tank assuming that I can find a place to refill it with compressed air. Would a sporting goods store (Where I would buy the tank) offer services where I could refill my tank? Does anyone here have experience running a BBMG off of said method?
Posted: Tue Jan 10, 2012 6:55 pm
Sporting good stores usually fill CO<sub>2</sub> tanks, I'm not sure about HPA tanks though. You might have to find a dive shop for HPA refills.