 Bolt Action Magazine Fed Air Pressure Nerf, update from NerfHQ |
|
|
| Dr. Nerf |
 Sep 8 2005, 04:41 PM
|
Member
Group: Members
Posts: 35
Joined: 7-September 05
Member No.: 1660
|
About a month ago I posted about my second Nerf homemade. The NerfHQ topic is available here.  Specifications Propulsion - Air Pressure Magazine Capacity - 4 Valve - Semi-Auto Homemade Length - 50 inches (4' 2") Maximum Range - 250 feet Accurate Range - 150 feet It is very accurate and has a fairly high rate of fire. It's rate of fire is not as good as it could be because I did not install an ejector yet and the bolt jams against the shells frequently. But it still has a very good rate of fire for an air pressure Nerf. Some other pictures: Picture of entire gunCloseup on Shells and MagazineSecond picture of entire gunBolt ClosedBolt Half OpenBolt OpenTell me what you think. Edit: An explanation of how the valve works is available here and quoted below. QUOTE I am surprised that I never actually explained my system in full before. The links are to pictures of the parts that I am talking about. The valve is a simple piston style valve. The chamber setup ( second picture, this time solvent welded together) encases the piston. To get a seal, the piston has O-ring mounts at three places. The first set seal the main valve (the "trigger valve"). Since this valve has semi-automatic capabilties, the setup set is the shutoff valve (to conserve the air in the reservior). The third set is just there to make sure that air does not escape out the back of the gun. When the piston is pulled back, air can then escape from the front out into the barrel and so on. However, only air from the chamber is released because the second set of seals prevents extra air from escaping. This diagram that I make should show exactly how the valve works.  The trigger system was just two bellcranks and some music wire ( second picture). After the piston is inserted in to the back of the chamber, you hook on a piece of music wire (to connect to the trigger system) and put in a spring and cap (to push the piston forward). Cap the end with an end cap and the valve is ready. I really like how my gun is really easy to work with and easy to repair. Unlike other homemade valve, this one is high flow and allows you to repair it easily (because you can remove the piston).
--------------------
|
|
|
|
|
|
| ompa |
Sep 8 2005, 05:17 PM
|
Introductinator
Group: Ambassadors
Posts: 2344
Joined: 11-March 04
From: Baltimore, MD
Member No.: 655
|
I'm impressed. Why all the extra distance between the chamber and the darts though?
~ompa
This post has been edited by ompa: Sep 8 2005, 05:20 PM
--------------------
"I love that the french are always starting trouble, but never have the balls to finish it. I mean, it must be pretty disheartening to be globally accepted as the most useless nationality on the planet. Seriously though, I'm really sorry you're french.
VACC"
|
|
|
|
|
|
| BloodMoon |
Sep 8 2005, 05:18 PM
|
Member
Group: Members
Posts: 95
Joined: 4-September 05
Member No.: 1650
|
First off, great job! That looks awesome! As a newbie looking at your ranges, that looks like a VERY powerful weapon. How did you test the ranges? Was that a level shot, and was there any dart skip? Does it hurt to get shot from a closer range (say 30')? Also, do you use all the pressure up in one shot, or does it only let out a little bit of pressure at a time, like in Osiris' homemade?
--------------------
We live in an age when pizza
gets to your house before the police.
|
|
|
|
|
|
| murakumo32 |
Sep 8 2005, 05:25 PM
|
Member
Group: Members
Posts: 420
Joined: 10-July 05
Member No.: 1553
|
No offense, but that thing needs to get a face lift. Other than that, ACCURATE UP TO 150FT!?!?!?!?!?!?!??!?!?!?!?!? Oops, overdid it on the !?
--------------------
QUOTE Nerfing, now fortified with vitamin C!
-or-
100% Nerf, for 100% pwnage. QUOTE
Nerf is a neutral weapons dealer. Anyone coughing up the dough can get armed.
QUOTE
and they're made of Foam... which makes them very Nerfy...
|
|
|
|
|
|
| Team_Slaya |
Sep 8 2005, 05:31 PM
|
Member
Group: Members
Posts: 614
Joined: 30-April 05
From: Massachusetts
Member No.: 1411
|
That thing, while not being very hot, is very hot. I especially like the trigger... but I don't know why  . Awsome power, with a sweet clip. I need to see bolt's analysis on this, I think he'd be happy to know that someone is up to par with his FAR. Did you get any inspiration from the FAR that went into the development of this gun? TS |
|
|
|
|
|
| NerfMonkey |
Sep 8 2005, 05:52 PM
|
Member
Group: Members
Posts: 1715
Joined: 24-November 04
From: Youngstown, OH
Member No.: 1141
|
Doctor Nerf, I've never been that crazy about homemades until I saw bolt's FAR, and now this...this has just inspired me to build one. Thank you.
As for the gun...sexy. Very, very sexy. How many shots can you get from that beast before needing to repump it? And also, couldn't you build a huge magazine with about ten rounds in it? I assume you used a leaf spring (think that's what they're called), in fact I know you used one. But on that magazine, is it like bolt's mag on his FAR, where you have two semi-/half circles of PVC, like you cut a length of 1/2" or 3/4" down the center and then just connected the two halves with balsa? I love it! Oh, and you used Sch. 80 PVC for the shells, correct? I really, really like it and now want to build something similar, meaning semi-auto, but I'd probably have a much smaller tank to make it usable in wars.
Very, very good job Nerf. It's a great looking gun.
This post has been edited by NerfMonkey: Sep 8 2005, 05:55 PM
|
|
|
|
|
|
| Doom |
Sep 9 2005, 02:16 AM
|
Member
Group: Members
Posts: 331
Joined: 27-November 03
From: Berwyn Heights, MD
Member No.: 440
|
The ranges are completely true. I'd know because I'm his brother, and I helped him out with most everything (not too much design though). The valve opens fast, the pressure chamber is huge, the pressure is moderate, the barrel is several feet long: it's a proven formula for range. If we increased the pressure from the moderate 15 or so PSI we use right now, it'd just be plain dangerous (or more than it already is). Already at barely 15 PSI we've had accidents involving glass...
The 250 foot shot is at least short. We never recovered the dart simply because it shot into a neighbor's yard, right over their house (it was an angled shot). We measured from inside our garage to their house and took that measurement (with a tape measure). The gun is perfectly capable of more with more pressure, but I wouldn't want to be near it.
Dr. Nerf and I don't use normal "stefans". Dr. Nerf had the idea to use small, relatively heavy screws in Nerf darts because we don't have to use hot glue given you can screw them into the foam. This is easier to make, cheaper and faster. I'd also like to say they perform better, but I bet if anything it's simply added the weight that helps.
| QUOTE | | What kind of spring did you use for the magazine? Just curious because I know how hard it is to come up with a spring good enough to use for a magazine. |
To the best of my knowledge, he used multiple springs. I bet you'd rather hear it from the horse's mouth though, as I'm not completely sure.
To clear up some confusion, this system can have potentially infinite shots. Right now he has the gun setup to be attached to the air compressor in our garage just like many air powered tools. I plan on letting him use my Constant air pressure water gun's air chambers after I build it - this should provide about 22 liters of compressed air stored at at least 100 PSI. I'd have to do some math to figure out how many shots that would be, but you get the picture.
I am glad that they finally let Andrew in here though... this was his third attempt at registration.
--------------------
|
|
|
|
|
|
| Dr. Nerf |
Sep 9 2005, 01:36 PM
|
Member
Group: Members
Posts: 35
Joined: 7-September 05
Member No.: 1660
|
First I must thank everyone for their compliments. On to answering the questions:
| QUOTE | | Why all the extra distance between the chamber and the darts though? |
The extra distance is there only because the bolt takes up that space when it is retracted. It is dead space when shooting though.
| QUOTE | How did you test the ranges? Was that a level shot, and was there any dart skip? Does it hurt to get shot from a closer range (say 30')?
Also, do you use all the pressure up in one shot, or does it only let out a little bit of pressure at a time, like in Osiris' homemade? |
I tested the ranges by standing in my garage and shooting out towards my neighbors house. I tested the weapon at about 10 to 20 psi (usually 15 psi). To test accuracy, I shot at my neighbor's garage door (about 150 feet away) and repeatably hit it. I shot 3 darts to find out the range. All three soared over my neighbor's house. I went into their backyard and could not find the darts, so I basically assumed that they at least made it to the fence that borders their backyard (the fence that led into their backyard). So I measured out to that fence, and it was 250' and I think 3".
So the gun was able to shoot about 250 max, but that kind of range is completely useless. I was more pleased that it could shoot 150 feet accurately (which is very good).
The gun does not use up all the pressure at one, but I basically was designed to. Because of the semi-automatic valve I put in it, when the trigger is pulled, all of the internals before the pressure chamber are sealed and not used, so only the pressure chamber is emptied.
The pressure chamber that you see takes up about 83% of the volume of the full chamber. All of the stuff before the chamber takes up 17% of the volume. So, you can get 2 shots per tank, one strong one, and one weak one. But I must say that I designed the gun to work with a pressured backpack (just a piece of pipe with an air regulator attached to it).
If you put the pressure up very high (say 40 psi or so) use could get two strong shots if you want, but I prefer low psi. I could modify the gun to allow it to get 4 or 5 shots per tank by extending the area behind the pressure chamber, but this would make the gun even more bulky and huge.
| QUOTE | Did you get any inspiration from the FAR that went into the development of this gun?
|
To tell the truth, yes the FAR did inspire me. I did not like how it was spring powered (no offense), but I loved the rate of fire. So I designed something to offer sort of a compromise between rate of fire and power. So to make it powerful, I made it have a huge (now that I think back, too huge) pressure chamber. The bolt action system fulfills my requirement for fast rate of fire. Also, a fast valve with a large internal diameter was necessary to allow the air to flow better. So I made a homemade semi-auto valve. These fulfilled my goal well.
| QUOTE | | How many shots can you get from that beast before needing to repump it? And also, couldn't you build a huge magazine with about ten rounds in it? |
I could build a magazine that could fit ten rounds, but it would be huge. Plus, it is pretty hard to load rounds into the magazine. I designed my magazine to fit 6, but I have never fit more that 4 in.
| QUOTE | | Oh, and you used Sch. 80 PVC for the shells, correct? |
Yes, just plain pieces of 1/2 inch Schedule 80 PVC. Each is 2 inches long.
| QUOTE | | Without an ejection system, how do you get the spent shell out? Just let it fall out by tillting the weapon? |
The ejection hole is large enough just to remove it with your finger. I was planning on using a standing ejector for it (check the bolt open picture, look at the mount hole for it), but the plan literally "fell through" (the ejector kept on falling out of the gun). I think that if I redesign the way I attached the standing ejector, I might be able to get it to work again. | QUOTE | | What kind of spring did you use for the magazine? Just curious because I know how hard it is to come up with a spring good enough to use for a magazine. |
The springs that I used probably aren't what I should have used, but they work well. NerfMonkey asked if I used leaf springs, but I don't think I did. I just went to my local hardware store and bought 4 compression springs. I had to pair them together to get 2 sets of two and they work great.
| QUOTE | | I am a bit skeptical about your ranges though. 250 feet is a bit high. I beleive there is an asymptotic limit for nerf darts slightly over 200'. I`m not saying you're ranges are BS but the amount of energy it takes to get a nerf dart to 250' is quite high and not attainable by the typcial homemade. How are you measuring your ranges? |
It is completely understandable why you say that a 250' is very hard to get, because it is. I think that a normal "stefan" homemade dart would have a limit of about 200'. But I weigh my darts heavily with screws. These heavy darts and the huge pressure chamber must really propel the darts well.
| QUOTE | | To clear up some confusion, this system can have potentially infinite shots. Right now he has the gun setup to be attached to the air compressor in our garage just like many air powered tools. I plan on letting him use my Constant air pressure water gun's air chambers after I build it - this should provide about 22 liters of compressed air stored at at least 100 PSI. I'd have to do some math to figure out how many shots that would be, but you get the picture. |
Well put. The gun was designed to use a compressed air backpack, and I have most of the parts to build a small backpack that could provide 8 to 12 shots (2 to 3 clips). A backpack should be no problem since it is filled with air and therefore not the heaviest thing in the world.
I hope that this answers some questions.
--------------------
|
|
|
|
|
|
| boltsniper |
Sep 9 2005, 01:58 PM
|
Member
Group: Contributors
Posts: 578
Joined: 27-February 03
From: Richmond, VA
Member No.: 130
|
| QUOTE (Dr. Nerf @ Sep 9 2005, 04:36 PM) | | I think that a normal "stefan" homemade dart would have a limit of about 200'. But I weigh my darts heavily with screws. |
Ahh, that would explain it. You could definitely get some high ranges with a substantially heavier dart. I can see that you have a massive amount of air propelling the dart but I was under the impression that you were shooting stock darts or standard sefans. I can`t say that I would want to get hit with anything heavier than a stadard dart though....
When I was playing with my combustion gun I was shooting stock darts and I never got much above 200' regardless of chamber pressure.
--------------------
|
|
|
|
|
|
| blink_182 |
Sep 10 2005, 06:22 AM
|
Member
Group: Members
Posts: 422
Joined: 22-November 03
From: Toronto, Canada
Member No.: 433
|
Do you think we could get a picture of the mag. I'm intrested in the design of how you placed the springs.
--------------------
New Price On Freedom, Buy Into It While Supplies Last...
|
|
|
|
|
|
| Ronster |
Sep 10 2005, 06:42 AM
|
Member
Group: Members
Posts: 514
Joined: 20-May 05
From: The Alamo
Member No.: 1469
|
How many times must you pump it in order to acheve 250'?
BTW: Very nice, dood!
Not too pretty but your ranges sure do make up for it.
--------------------
-I Nerf, there for I am. QUOTE(baghead @ Oct 25 2006, 09:55 AM)  Ronster reminded me that I should have warned you all Prepare your Bladder for Imminent Release!!!! |
|
|
|
|
|
| Forsaken_angel24 |
Sep 10 2005, 01:49 PM
|
Member
Group: Contributors
Posts: 2352
Joined: 9-July 05
From: Mississauga, Ontario
Member No.: 1551
|
| QUOTE (Doom @ Sep 9 2005, 02:16 AM) | | Dr. Nerf and I don't use normal "stefans". Dr. Nerf had the idea to use small, relatively heavy screws in Nerf darts because we don't have to use hot glue given you can screw them into the foam. |
| QUOTE (Dr. Nerf @ Sep 9 2005 @ 04:36 PM) | | I tested the ranges by standing in my garage and shooting out towards my neighbors house. I tested the weapon at about 10 to 20 psi (usually 15 psi). To test accuracy, I shot at my neighbor's garage door (about 150 feet away) and repeatably hit it. |
How is it your neighbour hasn't come home and killed you guys yet? With a screw (metal) protruding even slightly from foam would leave a dent, scratch or crater in this guys garage. My sniper that only reaches 100 feet straight still left dents in my shed door about the size of pinky finger print. My stefans had the weight protruding from the foam a bit but would still be covered in a dome of hot glue, spreading the impact a little more. Does he know you guys are shooting at his garage?
This post has been edited by Forsaken_angel24: Sep 10 2005, 01:55 PM
--------------------
Who wants to take on my most entertaining brute!?!? Go for it! |
|
|
|
|
|
| Dr. Nerf |
Sep 10 2005, 05:12 PM
|
Member
Group: Members
Posts: 35
Joined: 7-September 05
Member No.: 1660
|
| QUOTE | | Do you think we could get a picture of the mag. I'm intrested in the design of how you placed the springs. |
The magazine is made of 1" PVC, 1/2" PVC, cardboard (I did not have any wood thin enough), duct tape and 4 3 and 3/8" compression springs. The springs are placed in sets of 2 with one set on side to allow for easy compression and loading. At the top of the springs is a piece of 1/2" PVC with a cover of duct tape to space it more (I think that I could remove the duct tape though, it is sort of useless). If you would like to see how the springs are oriented, this picture should do. | QUOTE | | How many times must you pump it in order to acheve 250'? |
The gun does not use a pump, it was made to use a pressurized backpack setup (just a piece of pipe filled with pressured air) to allow for multiple shots without pumping. I did however make a PVC pump just incase, and it only needs 8 to 12 pumps to pump to a good enough pressure. I usually shoot this around 15 PSI, which is quite low, and that is enough to easily shoot 250', with a heavy enough dart. | QUOTE | | How is it your neighbour hasn't come home and killed you guys yet? |
First of all, I recess the screws I use as weights and glue them in if needed. This way, the foam is basically the tip with a screw head visible. And second, 150' is a far distance away, so I doubt it would do anything to their garage. I did check after the first shot and they did not have any marks at all, the darts just casually bounced back. It would however, seriously do some damage if I was not so far away. Edit: Now that I think back, it was a pretty dumb idea to shoot it at their garage. But that is in the past now and fortunately, nothing went wrong.
This post has been edited by Dr. Nerf: Sep 11 2005, 07:22 AM
--------------------
|
|
|
|
|
|
| Crappy Nerfer |
Sep 10 2005, 05:49 PM
|
Member
Group: Members
Posts: 149
Joined: 23-August 05
From: Kissimmee, FL
Member No.: 1627
|
Woah, I never knew one hundred fifty inches is a far distance. O_o
This post has been edited by Crappy Nerfer: Dec 9 2005, 02:17 PM
--------------------
"If one notices a patch of gangrene in a wound on the back of one's hand, one does not simply hope that it gets better over time.
One cuts that shit off at the wrist and learns to masturbate lefty."
- Death
"By BC do you mean Boston College?"
- nerfer34
|
|
|
|
|
|
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
