24 replies to this topic

[jediaelthewise]

Update: The mod is completed. Details and pictures on page 2.

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I am doing a variation of a mod by Captain Slug on my magstrike. (Thanks by the way for your tutorials!)

This will be my HvZ loadout for next fall's game.

WARNING ON PVC AIR TANKS:

I am not going the PVC tank route because PVC is NOT RATED FOR AIR PRESSURE. THe rating on PVC pipe is rated for WATER PRESSURE. Water pressure and air pressure have different properties and you cannot put the same air pressure as its water pressure rating. IT IS NOT THE SAME. It's dangerous because the PVC can shatter, explode and send shrapnel flying and really hurt or even kill someone. I asked for advice on this mod from my dad and his coworker who are working on the latest nuclear power plant project in north carolina so these guys are all very high level engineers. Their advice was to go with a prefabricated tank built for air pressure to be safest. I trust their advice and so I'm passing that warning onto you guys. DON'T MAKE PVC AIR TANKS.

Anyways, here is the tank I plan on buying and using for a portable supply.



For the four ports I will have:
1. A gauge directly on the tank to monitor air pressure

2. A safety valve to bleed air if it gets over compressed above 100PSI

3. A 1/4in screw on air inlet valve that can be filled with an automatic tire pump

4. Quick disconnect (Female end goes onto the tank)


The Gun end will have the quick disconnect male end, a regulator to change air flow and then the modded gun itself.

I am looking to modify a 2nd magstrike so I can dual wield them for the game so when I do the second one I will update this thread with a walk thru of the gun mod.

I plan on running the system at 100PSI make. Air regulators are capable of slipping air pressure so I do not want to exceed the pressure rating of my coupling and hose which is 100PSI. The magstrike CAN run at 100PSI but I'm afraid of the plastic parts breaking from such a high fire rate. I also don't feel like emptying the entire magazine in 1 trigger squeeze anyways so I can conserve ammo.

I only needed 3 parts from mastermccar for this project. I removed the pump internals and used coupling 9087K61 from the mccar catalog with this hose 5006K64.
The coupling attaches the internal hose to the external hose. I cut a circle notch and made it smooth with a soldering gun to place the coupling in a stable solid position as shown here.



I bought 10 feet of the hose and cut 2 4 foot length for the gun to regulator sections. I bought this 1/4 threaded push to connect fitting (MCCarr 9087K12) for the other end of the hose to connect to the regulator.

Here is a video of me testing the gun.
http://www.youtube.com/watch?v=IiAuFG1DUDI

I'll be sure to update this thread with a detailed walkthrough of the gun mod as well as a full system test once I acquire the rest of the parts.

Edited by jediaelthewise, 30 June 2012 - 08:44 AM.

[hamoidar]

And what proof do you have that PVC air tanks are dangerous? I personnally know quite a few nerfers who have used PVC air tanks for years without a problem: including myself! Water; is an incompressible substance. For instance, a simple water pistol uses air to force the water out of the tank. Why? Because compressing the water alone is impossible. If you were to have a PVC pipe with on end closed off, with a pump pushing water into the open end, the pipe would explode before the water compresses. Although a welded metel air tank can hold higher pressure than a PVC tank, you usually do not need over 100 PSI for nerf applications: A pressure which is not even close to dangerous to a well-made PVC tank. I am not saying your dad does not know what he is talking about, I'm just saying that PVC tanks work fine under air pressure. Maybe a long length of pipe would have trouble dealing with high pressure, but a small length with end caps will not. I have a PVC gun which I use for testing darts. It is made out of 2" PVC and a couple of valves. I have been using it regularly for almost 3 Years! It has been pumped up to 180 PSI many times, without a problem. People use large PVC for potato cannons, some of which use commbustibles, also without problems.

[jediaelthewise]

THe point I was attempting to make is just because you can do it and pull it off, doesn't mean its really dangerous. PVC is not NOT DESIGNED for air pressure, at least pvc 40 is. Some PVC80 is designed to take air pressure and if you are using that that is fine. The majority of the time though I see people just get the cheap regular PVC40 at home depot or otherwise to make their tanks and while they can build it and make it work, it doesn't mean you should do it.

Here is some info for you consideration. I looked up some official records from OSHA , the Occupational Safety & Health Administration. If you don't know who OSHA is, they are a federal organization and monitors workplace safety hazards and set out rules and codes for every kind of occupation for people's safety. They have had numerous documented cases of PVC compressed air setups exploding and causing severe injury. It is documented in several public letters that OSHA strongly states to not use regular PVC40 for compressed air because it is not designed for it.

Here is a section on their website containing a series of letters of this occuring and their stance on it: OSHA stance on PVC and Compressed Air

You're lucky and other people are lucky to not have an accident and thats all fine. But my point is basically, just because can, doesn't mean you should and isn't inherently dangerous by design. If you want to make one and don't get hurt, that entirely your responsibility and up to you. I just want to pass on a warning to my fellow nerfers to keep them safe.

If you don't feel like reading that whole page, here one such official warning:

Hazard Alert

For more information, call: 1-800-423-7233

FOR IMMEDIATE RELEASE May 26, 1988


PVC pipe not to be used in compressed air systems

OLYMPIA -- The Department of Labor and Industries warned today that plastic polyvinyl chloride (PVC) pipe cannot be used in compressed air piping systems without the risk of explosion.

When PVC piping explodes, plastic shrapnel pieces are thrown in all directions.

"We're seeing more incidents of explosive failure, and we're citing more employers for using PVC air system piping," said Paul Merrill, senior safety inspector in L&I's Spokane office.

"It's probably just a matter of time before someone gets seriously injured in one of these explosions unless everyone pays more attention to the manufacturer's warnings," Merrill said.
Last year, a section of PVC pipe being used for compressed air exploded 27 feet above a warehouse floor. A fragment of the pipe flew 60 feet and embedded itself in a roll of paper. Fortunately, nobody was in the area at the time.
A PVC pipe explosion in a new plant in Selah broke an employee's nose and cut his face.

PVC piping buried 3 feet underground at a Yakima manufacturing plant exploded, opening up a crater approximately 4 feet deep by 3 feet across.

Only one type of plastic pipe has been approved for use with compressed air. That pipe, Acrylonitrile-Butadiene-Styrene (ABS), is marked on the pipe as approved for compressed air supply.

By law, employers must protect their workers by avoiding the use of unapproved PVC pipe in such systems. Existing compressed air systems which use PVC piping must be completely enclosed, buried or adequately guarded according to specifications approved by a professional consulting engineer.

NOTICE TO EMPLOYERS: If you have questions about the suitability of a material for air system piping, call Labor and Industries at the number listed above for a free consultation.

NOTICE TO EMPLOYEES: If you suspect that a pressurized PVC piping hazard exists, bring it to the attention of your employer. If you do not obtain satisfactory results, you may file a confidential complaint with the Department of Labor and Industries. Complaints are investigated promptly.

THE INDUSTRIAL COMMISSION OF ARIZONA
DIVISION OF OCCUPATIONAL SAFETY & HEALTH
P.O. BOX 19070
PHOENIX, ARIZONA 80005-9070

Edited by jediaelthewise, 01 May 2012 - 07:53 PM.

[arfink]

This whole PVC tank thing has been beaten to death in the spud gun world, mostly because in their hobby they actually have to deal with high pressures.

If your Nerf gun's hard tank is running over 80 PSI there is something very very seriously wrong with your design. Like, face-destroyingly wrong.

I built a JSPB with a PVC air tank and a bike pump. I even did a "throw it off the second story onto concrete while pressurised" test and it held just fine.

But I would agree, if you're planning on using an air compressor other than a hand pump maybe you shouldn't be using PVC. But maybe you shouldn't be playing Nerf with it either.

[roboman]

The point I was attempting to make is just because you can do it and pull it off, doesn't mean it's not really dangerous.

There, I fixed it for you.

I've had PVC airtanks explode before, and it's by no means fun.


That was a 2" cannon I made a few years ago. It exploded while I was holding it between my legs. The barrel kicked back and upwards into my crotch, and PVC shards flew everywhere. I have a scar on my right foot as a result of one of the shards penetrating my shoe and slicing the top and side of my foot.

I was incredibly lucky and stupid. The explosion was due to the "water hammer effect," which happens when you try to move a large amount of water very quickly. This particular cannon had a 4' long x 2" diameter barrel filled completely with water at the time of failure.

Pressure is pressure. If a piece of pipe is rated for 200 psi, it can handle 200 psi, whether it's water, air, or any other fluid. The difference between air and water is that water is not compressible, as hamoidar said. In fact, SCUBA tanks and other high-pressure tanks are routinely "Hydro tested," which involves filling the vessel with water, then pressurizing it to the working pressure. Typically, a dye is added, so leaks can be easily found. That, however, is not the primary reason for using an incompressible fluid - since it cannot compress, it does not expand when depressurized. That means that if the pipe was to fail, it would just crack or pop, rather than exploding violently. The reason PVC pipe is not considered safe for compressed air by OSHA is that in an industrial environment, air lines can be subjected to unusual forces, such as sudden blows, drops, or sharp bends, which create weak points in the plastic's structure. These weak points eventually become failure points, which are the causes of explosions when operating within the maximum pressure rating of the pipe.

You can haul around that bigass (read: heavy) steel tank at your HvZ game, but I can guarantee it will get pretty old in a matter of minutes.

[Draconis]

And what proof do you have that PVC air tanks are dangerous? I personnally know quite a few nerfers who have used PVC air tanks for years without a problem: including myself! Water; is an incompressible substance. For instance, a simple water pistol uses air to force the water out of the tank. Why? Because compressing the water alone is impossible. If you were to have a PVC pipe with on end closed off, with a pump pushing water into the open end, the pipe would explode before the water compresses. Although a welded metel air tank can hold higher pressure than a PVC tank, you usually do not need over 100 PSI for nerf applications: A pressure which is not even close to dangerous to a well-made PVC tank. I am not saying your dad does not know what he is talking about, I'm just saying that PVC tanks work fine under air pressure. Maybe a long length of pipe would have trouble dealing with high pressure, but a small length with end caps will not. I have a PVC gun which I use for testing darts. It is made out of 2" PVC and a couple of valves. I have been using it regularly for almost 3 Years! It has been pumped up to 180 PSI many times, without a problem. People use large PVC for potato cannons, some of which use commbustibles, also without problems.

May the Lord have mercy upon your soul when you finally succeed in killing yourself by doing something exceptionally stupid instead of listening to smart people who are trying to keep you safe. Why do you still have posting privileges? The next time you want to call in to question a SAFETY recommendation made by someone, REGARDLESS of who they are, why don't you stop and ask yourself whether you are qualified to advise on such matters? Are you a materials engineer? Are you a plumber? Are you even bright enough to listen to a browser such as the one which is right now telling me VEHEMENTLY that I should fix your spelling errors? How about this... I'll make it really easy for you. If you decide that you need to spout off and some young (though likely too bright for his own good) nerfer builds something unsafe upon YOUR recommendation and injures himself or someone else... I will track you down. I will find you and I will make sure that you face legal ramifications for your idiocy. Or you could just learn to fucking listen.

[NeverWriteTwice]

According to google, that tank weighs around 6.5lbs and is about the size of a football (around 10"x5"). That isn't too bad, except that isn't all you'll be carrying. You'll also be carrying a compressor, several extra magstrike clips (which are light, but also awkward and bulky), and a crapton of darts. All while playing a game that requires you to run a lot.
I'm not saying it can't be done, it just doesn't sound like you've thought this through.

[roboman]

If you're absolutely hell-bent on using something other than PVC (not that I particularly LIKE using PVC as an air tank), these are quite handy. They're rated for 125 psi working, 500 psi burst with compressed air, and are made of polypropylene, which does not tend to fragment upon failure. They are, however, substantially more expensive than a piece of PVC of a similar size.

Basically, PVC pipe is cheap, readily available, and works just fine for our purposes. I would never dream of taking a piece of 2" Sch. 40 past 120 psi, and certainly nowhere near the labeled burst pressure.

Working with compressed air is inherently dangerous. One simply needs to take appropriate safety precautions and apply common sense to the situation to avert many of the potential dangers. Don't ever throw, drop, or otherwise cause a PVC tank (or one made of any other material) to encounter a sharp impact. Don't freeze your tanks or take them outside of their operating temperature range.

If you ARE looking to include a compressor on your rig, good luck. You're going to need a very large, heavy battery to power such a compressor for a substantial amount of time, and it will take an inordinate amount of time to refill a tank like the one you were planning on using initially, especially with a small compressor. Smaller compressors, such as those intended for use on ATVs, do not have a very high duty cycle, generally in the 5-10% range, sometimes even lower than that. The 90C from Viair is probably one of the smallest compressors for its output that you'll be able to easily find. Still, it weighs 2.5 lbs, not including the battery or a tank. That's not particularly practical for an HvZ game.

[jediaelthewise]

Thanks for all the feedback, I appreciate that you guys arent afraid to give me some counter arguments.

I may opt for the 1/2 gallon tank perhaps if it proves to be too bulky for an HvZ game. I planned on taking an old backpack and putting the tank inside that with holes cut for the fittings or if I can figure out something minimalist for transport it, I will do so.

The large tank is rated for 125PSI but i would run it no higher than 100PSI.

If your Nerf gun's hard tank is running over 80 PSI there is something very very seriously wrong with your design. Like, face-destroyingly wrong.

As far as using a tank over 80psi, I am also following CaptainSlug's advice in his DIY air tank. So if you could elaborate further why it's 'face destroyingly wrong,' I'd like to hear your opinion on that.

3. For this type of tank it's best not to fill beyond 100psi. If you want a higher capacity tank, purchase a purpose-made tank with a higher rating.

And finally on the point of people saying "its not practical/its too heavy." Everything has its trade offs. I'm not a fan of running constantly so my personal preference is to trade off a little mobility for high fire power. For the majority of our game, zombies have a 15 minute stun time. As for missions with shorter re-spawn times, the humans hardly had to do lots and lots of running in our game if you were smart about where you walked. If anything, I mostly was sneaking as a human instead of running. I played a human and a zombie on my campus and I almost never was running the time I played human.

Thats just my preference.

Edited by jediaelthewise, 02 May 2012 - 03:39 AM.

[HasreadCoC]

I'm still personally a fan of using an empty fire extinguisher as the air tank supply. Yes, heavy-ish, but you have it in a pack of some sort on your back, running through a tube to the blaster. It made to handle pressure, and I believe many/most already have threads that can be worked with, and used for fittings.

Just buy an empty one online from someone who just wanted to buy one to spray around with, maybe not one that's like 10 years old though.

[Langley]

And what proof do you have that PVC air tanks are dangerous? I personnally know quite a few nerfers who have used PVC air tanks for years without a problem: including myself!

Wow. Only a few hours out of your suspension and you manage to shit all over this poor guys's thread. While some of the discussion of air tank safety has been on the level, I think it's time to get back to the topic of the modification itself.

[Draconis]

I'm still personally a fan of using an empty fire extinguisher as the air tank supply. Yes, heavy-ish, but you have it in a pack of some sort on your back, running through a tube to the blaster. It made to handle pressure, and I believe many/most already have threads that can be worked with, and used for fittings.

Just buy an empty one online from someone who just wanted to buy one to spray around with, maybe not one that's like 10 years old though.

Occasionally I have found them at thrift stores and used tool shops for cheap. I have posted a couple of builds using the small ones for ball guns. They work quite well.

[Buffdaddy]

If you're set on your setup, then easiest thing would be mounting two smallish air tanks on either side of a large bike pump, and wearing that as a backpack. Keeps things balanced, gets rid of the compressor/battery problem, and if you need to, you can retreat and pump it up, do so between rounds, etc.

[Exo]

My experience with battery powereds has been less than fun. I would suggest a bike pump (minimized or with collapsible feet) to pump up the rig, just pull it off of the harness and pump, then put it back up and run. Or, you could attatch the tanks and pump to the blaster itself, heavy blasters are preferable to heavy backpacks with no space in them.

But in all honesty, a full-fill capable magstrike can fill in about 60 pumps, and drains three clips. If you were to make a homemade pump, with at least 2x the stroke, you could fill the bladder much faster, and if you increased the width, even fewer pumps than that.

Also, blasters that fast dual wielded? You will waste the majority of your ammo, and dual-wielding isn't all it's cracked up to be.

Edited by Exo, 02 May 2012 - 02:57 PM.

[jediaelthewise]

Also, blasters that fast dual wielded? You will waste the majority of your ammo, and dual-wielding isn't all it's cracked up to be.

That's why I haven't gotten to modding the second gun yet. I may opt to just use the single gun because they I can reload, pick up darts and generally have a hand free.

I think that might be better in the end. Just having the two for the opening ceremony and general badassery showing it off is all the dual wielding would be for =P

[zx532]

Disregard

Edited by zx532, 03 May 2012 - 12:43 AM.

[jediaelthewise]

Update on testing:

Tested the gun with the regulators on an air compressor with a 4 gallon tank. Got around 150 magazines worth out of a 4 gallon tank. It will not scale exactly by a 1/4th with a 1 gallon tank but if I'm conserving my shots and not just blowing off full mags every time like when I tested it, I should get a decent amount of magazines out of a small 1 gallon tank. I anticipate around 30 magazines full auto wastefully shooting or perhaps 30-40 conservatively shooting. This was tested outside at about 67 degrees Fahrenheit.

Of course it will vary depending on air temperature at the time of use, control of leaks and such but all in all it sounds like a good number.

I'll be getting the 1 gallon air tank next and filling it with the air compressor and test the actual number once I get it under various circumstances.

Also looking at different options for mobile top-off/fill-up as well. I'll keep you all posted.

[hamoidar]

Update on testing:

Tested the gun with the regulators on an air compressor with a 4 gallon tank. Got around 150 magazines worth out of a 4 gallon tank. It will not scale exactly by a 1/4th with a 1 gallon tank but if I'm conserving my shots and not just blowing off full mags every time like when I tested it, I should get a decent amount of magazines out of a small 1 gallon tank. I anticipate around 30 magazines full auto wastefully shooting or perhaps 30-40 conservatively shooting. This was tested outside at about 67 degrees Fahrenheit.

30-40 mags on one gallon! Wow, that's alot! How many PSI are you filling the tank to?

EDIT: Is the regulator you mention here the same as the one in the original post? If so, I guess that would mean you are filling the tank to 100 PSI. Right?

Edited by hamoidar, 27 May 2012 - 02:09 PM.

[jediaelthewise]

30-40 mags on one gallon! Wow, that's alot! How many PSI are you filling the tank to?

EDIT: Is the regulator you mention here the same as the one in the original post? If so, I guess that would mean you are filling the tank to 100 PSI. Right?

I did leave out a few details. Here is the full run-down

4-Gallon Tank filled to 120psi (compressor default). Air Temperature was 67 Degree Fahrenheit

Regulated to 40 psi output off the compressor.

Gun regulator hooked up to compressor hose as toned to 40PSI as well.

Shot until magazine was fully extended, removed and reloaded (no darts, just mag).

Did that a total of 150ish times with all of that. My estimation with a 1 gallon tank is possibly up to 30 mags.

I plan on filling up my 1 gallon tank to 100/120psi using the compressor and testing how many I actually get.

[Crater]

if I'm conserving my shots and not just blowing off full mags every time like when I tested it, I should get a decent amount of magazines out of a small 1 gallon tank. I anticipate around 30 magazines full auto wastefully shooting or perhaps 30-40 conservatively shooting.

I think you'll actually get more shots using full auto all the time. When you release the trigger, the remaining air in the piston is vented, causing more air to be wasted the more you try to control your shots. (That's why you can't use a MS trigger as a fill valve without an additional check valve.) I couldn't find a great reference, but there's this:

With 45 pumps I can get about 25 shots off in full auto.
I can get 22 single shots off for single fire. at 45 pumps.

[jediaelthewise]

This is true. So for instance in a humans vs zombies game if I'm goin for longevity without havin to recharge my air tank; it may be better to shoot more darts at once then just short bursts. I can kind of cover for that by having many magazines available to reload with. I'll definitely have to test that with the full system and see if there is a dramatic difference. If its negligible, then I'll just go with short bursts to not wastefully shoot off ammo and to make less noise.

[jediaelthewise]

The wait is over! I finally got the rest of my parts in for my Magstrike Air Tank mod and went to work testing it today. I did realize one big error I made in the process though: I got a bleeding type air regulator instead of a non-bleeding type so when I have the valve open I very slowly start leaking air which is a big problem. For now I have opted to go without the regulator and go straight off the tank (which is pumped to 100psi at max fill) and it works just fine.

I test fired in short controlled shots for this test and got 18 magazines straight off the tank before the PSI was too low to advance the clip. If I do full auto all the time to minimize air loss then I could possibly get 20-22ish. Off course theres also other factors like air temperature, leakage over time, etc. All in all though I am very happy with this modification and there is lots of room for adjustments and changes.



Without further ado, here is the video of my test run:

http://www.youtube.com/watch?v=RvSoNZCMtWI

Edited by jediaelthewise, 29 June 2012 - 03:18 PM.

[Zorns Lemma]

I got a bleeding type air regulator instead of a non-bleeding type so when I have the valve open I very slowly start leaking air which is a big problem.

From my understanding, a basic nonrelieving regulator does not shut off flow from the primary when the secondary reaches the given pressure. When air is flowing (before blockage) the downstream pressure will be what you set it to, but will slowly increase over time after a blockage, such as with a tank.

Since you already have a shutoff valve to the magstrike tank (in the form of the trigger), the nonrelieving one is probably the way to go, but in a lot of other semi-auto applications the nonrelieving regulator may cause your secondary tank to eventually leak/explode.

[jediaelthewise]

From my understanding, a basic nonrelieving regulator does not shut off flow from the primary when the secondary reaches the given pressure. When air is flowing (before blockage) the downstream pressure will be what you set it to, but will slowly increase over time after a blockage, such as with a tank.

Since you already have a shutoff valve to the magstrike tank (in the form of the trigger), the nonrelieving one is probably the way to go, but in a lot of other semi-auto applications the nonrelieving regulator may cause your secondary tank to eventually leak/explode.

I didn't actually consider that and I would've ended up ruining my gun (quicker haha) and that would've sucked. Thanks for pointing that out.

Since I can't return the regulator now (I purchased it a while back now), I'll just hold onto it in case I hook up to a compressor where I don't have to worry about losing air. For my purposes I think this set up will work just fine. The only place where I can see that it wouldn't be enough is like the final mission on HvZ or some absurdly long game. I had the idea for really long missions where I may want to conserve my air supply, I'll use one of my unmodded magstrike during slower or lesser crazy moments and just use the tank fed magstrike for periods when I need that fast reload/ready to fire moments.

I still have my modded maverick with 2 extra barrels and my single shot/front load dart tag gun as additional backups. =)

Edited by jediaelthewise, 29 June 2012 - 04:58 PM.

[jediaelthewise]

Some more pictures of the full gear rig. I used some paracord and my knotting skills to make a quick release loop to secure the magstrike to the side of the messenger bag. I also carry in the bag extra tubing (should any rupture), various extra 1/4" NPT attachments of all sorts, teflon tape and an adjustable wrench for any kind of emergency field repairs.

I found a nice old navy messenger bag in goodwill that has a nice hole for the tubing to go thru neatly.



In addition I took a large foam pad from an old DDR pad and custom cut it and strung it with some elastic to make a nice protective covering for the gauge and Schrader Valve in case I fall over or knock it into anything and cause a component to crack or bust and cause a blowout.




The side on the Schrader Valve can be pulled up for more open access to refill if need be.




And lastly I'll show my backup guns. A maverick with the barrel to come out freely like a clip with 2 extra barrels from other mavericks. And then attached to it I have a nerf crossfire dart tag gun which is front load, single shot. The reason I went with the crossfire is simple because it has the rail attachment clips on it that I can clip onto my magstrikeor maverick for easy carrying. Both backup guns obviously have all air restrictors removed for good range.

Edited by jediaelthewise, 29 June 2012 - 05:17 PM.