370 replies to this topic

[SHADOW HUNTER ALPHA]

Commonly Hunted:
I was going to try for 100th post in my own forum, but that would merit reprocussions from Piney for double-posting. (Although this is technically the 100th reply.)

Back on topic:
I am working on a scale-dimension draft of my blueprints on a 2-D CAD program, so I will probably be done with almost all of my design work and detailing by the 17th, accounting for the time I need to take out for homework, school, and studying. I hope to see blueprints from as many other contributors to this topic as possible, so we can all build different, yet hopefully effective, models.

Edited by SHADOW HUNTER ALPHA, 09 December 2006 - 10:34 PM.

[LastManAlive]

I might start the top loading mechanism and the barrel around christmas. I wouldn't be that hard to join it with the cocking mech and the plunger assembly afterwards.

[Meaker VI]

After considering space and part sizes and such, I've decided to flip my design and go back to bottom-loading. Mostly because fitting a trigger mech onto the bottom of this thing would require adding space to the bottom, which might make it look unbalanced. Although I still don't have the PVC sizes, so the design is just a design and not construction documents yet, so I might change my mind back again. Right now, with 8 or 9 shells, the thing is 3' 7" long. That's a little big, it might get cut down a bit.

I'd like to see everyone else's plans in order to help work some things out with mine. And if you don't have plans, a description of what your idea is; details like which loading style, chamber setup (carrier, ramp, elevator), and ejector system. Especially the ejector system, right now I like mine since it's simple: the carrier forces the new shell through the old one, which flys out a trap door on top.

[SHADOW HUNTER ALPHA]

I was going to use an extractor similar to what boltsniper used on his SCAR-N. I posted a pic of a prototype self-contained ejector a while back, probably on the top of the 6th page, and I was going to use a more powerful and updated prototype of that for the actual shell ejection system. (The new ejector can propel itself 85 cm far when released from 50cm high and parallel to the ground.) If you are using a rotating bolt lockup like I am, you'll also have to make sure that you align the ejector and extractor to be parallel to each other and the port on the side of the gun where the empty brass can be released. I also might go searching for some brass and PVC sizes next weekend at the town Lowe's. Let's hope I fand something so I can get back to you.

[Meaker VI]

Actually, my plan didn't involve a "bolt." It was more of a plunger nozzle. It'll push the plunger back and then come forward and seal against the back of the shell, and the shell itself will work as the chamber. That's how I expect to use the carrier as the ejector, when the plunger nozzle disengages the shell it'll be loose and get knocked out of the gun. Hopefully.

I'm following the K.I.S.S. principle as much as I can. That way I can build confidence for more advanced stuff later.

[SHADOW HUNTER ALPHA]

Meaker VI, on Dec 10 2006, 09:40 PM, said:

I'm following the K.I.S.S. principle as much as I can. That way I can build confidence for more advanced stuff later.

It looks like you might need the confidence if you're not using a bolt. You'll need to be able to get the seal to be prefect with each shell and every reload if this concept is going to work. Another thing is that since you don't have a bolt, you can't have any kind of lockup that will ensure a seal until the grip is pulled back. Your design seems like you would have to hold the grip forward at all times for any seal between the shell, nozzle, and chamber walls to be formed. That's just too much work, and it makes it more realistic and practical to have a lockup and bolt. However, if you can get a model to work, then share how you did it. There could be some useful concepts in it for all of us.

[Meaker VI]

Unless I can somehow nest the PVC sizes inside eachother... Which is why I need to get ahold of some materials to work with. This week is going to drive me nuts, I've finished my first final, written a paper, and now I've pretty much got nothing to do but wait untill friday when I take my next final. Unfortunately, I don't really have access to materials or tools here, though I might bite the bullet and go on a bus-riding adventure to find parts.

The ideas I was considering involved flat rubber/neoprene washers in the contact areas, and possibly beveling both ends of the shell so that it forms a good seal but doesn't need to stick. I was also considering making the thing spring-loaded, so that it would lock forward. And now that you bring it up, I probably need to swipe a device from an airsoft gun of mine to keep the plunger from going off before the nozzle is in the forward position.

These are exactly the kinds of things I was hoping you'd bring up for me to think about, now I've got some work to do to bring my design up to par. Maybe I'll make some kind of bolt after all...

[SHADOW HUNTER ALPHA]

It may be more work, but I think that the bolt is worth it compared to all of the work that you're going to have to do with the seals. Then again, the ideas that you have to solve the problems are creative, and should work if implemented properly. When you decide, tell us and maybe we can all contribute to the design.

Also, I am probably going to go hunting for some parts as well, hopefully within the week.

[King Of Butt Land]

Orrrrrrrr, you could not spend billions of dollars on something thats not going to work and buy a nerf gun.

-Butt

[SHADOW HUNTER ALPHA]

King Of Butt Land, on Dec 11 2006, 05:07 PM, said:

Orrrrrrrr, you could not spend billions of dollars on something thats not going to work and buy a nerf gun.

-Butt

Who said these won't work or that they're going to be that expensive? I haven't seen you contribute anything, and unless you're going to, then keep comments like this out of my thread. We get homemades to work by trying, and there's proof in the works of boltsniper and Carbon, and I've never seen anyone tell them that they should give up.

Edited by SHADOW HUNTER ALPHA, 11 December 2006 - 06:02 PM.

[Meaker VI]

Alright, here's the first re-design.

Black= Barrel
Grey= Chamber
Yellow= Shell
Whatever color that is on the bottom left= Mag. Tube
Orange= Carrier
Blue= Bolt
Dk. Blue= Ejector, Plunger chamber, plunger head.
The paint looking scribble is my trigger setup; a shortened, streched (height-wise), Boltsniper setup.

The system: 1) The Magtube holds the shells (duh), which are passed onto the carrier. Note that the shells are 1/2" PVC and the tube is 1" thinwall PVC, so there should be wiggle room, this is important but may mess me up when I'm building. They are stopped by a peice slanting from the top of the gun into the magtube, which can be pushed out of the way by the downward movement of the carrier; it's not shown because it would get in the way and look like a box in this view.

2) The plunger moves backwords, somehow bringing the carrier to it's upmost position, which would tag the shell on the front of the stationary plunger tube and push it toward the top of the gun, and it would then be far enough forward to catch on the top of the chamber and begin to level itself out.

3) While this is happening, the bolt pushes the plunger head back and locks it into postion.

4) On the return stroke, the bolt disengages the plunger head and engages the shell, with the carrier still holding it.

5) Continuing forward, the carrier drops as the bolt forces the shell into the chamber and locks it's extractor claw onto a rim I have yet to add to the design of my shell. I'm hoping that the shells will nest 1/2" CPVC inside 1/2" PVC, so that I don't need to lathe anything. If that doesn't work, I'll run a bolt through the shells and mount them to a drill press to lathe them.

6) Fire and repeat, on the outstroke the ejector pin forces the shell out some hole in the casing (casing not shown, hole position not determined).

Presently I need to figure out how the pump engages the carrier. I've considered a pulley system (I don't like it), a second pump rod, and levers. I think gears might actually work here too; if I get spring to force the carrier up and then a round gear and a rack-and-pinion on the pump to force it back down...

All suggestions welcome (Except those from members without suggestions relevent to the betterment of the design).

Edited by Meaker VI, 12 December 2006 - 12:35 AM.

[Commonly Hunted]

Meaker VI, I think that your design looks a lot like mine now and it makes more sense too. Even my trigger is similar. But I'm using 3/4" PVC thin-walled for the mag tube. My Lowe's has every size of PVC that we use in thick and thin walls so I'm going to be buying some of that this weekend. I think it should fit the shells fine. If not, I'll cut the end of the mag tube at an angle to give the shells space to move up the ramp that is my carrier.

The shells you are thinking of can be made. I have already made one out of 1/2" PVC and 1/2"CPVC and they PVC only needed a little bit of boring. What is cool about these shells is that they can be used for micros or, if you change the shape into something like Bolt's SCAR-N shells, you can use megas (with the correct barrel of course). When I get home I'll post a pic of my shell and dimensions. But if I can find brass at a hardware store, I'm going to make brass shells and barrels and the whole deal.

I will also be using the depression tab to hold my shells in the mag tube but it will most likely be attached to the bolt and at the top of the mag tube so that when I cock the gun, it will allow shells up the ramp. If I can figure a way to time this kind of thing correctly, I can make it so that the depression tab only allows one shell to pass which will lower the chances of a jam (but I'd have to use the lifting carrier like you guys--don't want to). I think that can happen using something like the cam system that Carbon used in the SNAP-4. The ramp will use a spring to keep it down or there will be a long tab of 1" PVC thin-wall to make the bottom of the ramp flex back down into the normal position while loading shells.

For the pump to plunger/bolt connection, I think I'll use music wire or something stronger like in the NTS's slide. If not that, then I can figure a way to use something like the pump action in the SCAR-N.

More details to come...

[Meaker VI]

Commonly Hunted: Excellent, it's good to know many of my plans will actually fit. That means less re-designing. I don't know if I mentioned it, but everything in my last post uses PVC/CPVC sizes to the best of my knowledge. I'm using the 1" magtube to allow the shells some freedom (as I said before), but I won't be able to do any construction 'till next week (assuming I ever get home) and won't know for sure 'till I get that started.

More importantly, I've figured out (I think) that the carrier will be "L" shaped, and the top of the "L" will hit the bolt and be spring loaded so that it's down when the bolt is forward and up when it's back. This doesn't facilitate easy loading, so I'll work on that. I was considering top-ejection so that I could have the pump connected on both sides of the gun, right now I've got a 1/8" x 1/4" peice of something attaching the two and I'd feel so much better if that was a bit bigger. Or more than one.

[SHADOW HUNTER ALPHA]

I'm following everything about the bolt and the mag tube on your design, Meaker VI, but the carrier description is kind of confusing. However, the pump is not usually directly attached to the carrier, rather the movements of the bolt influence the rising / falling of the carrier.

As for my own plans, I will probably copy the design for the carrier / bolt arrangement found here at howstuffworks.com. However, I will replace all of the bolt and firing pin arrangements with a plunger and bolt of boltsniper's design. I will also have a stock that is in line with the barrel to house the plunger and plunger tube as well. The shells will probably hold micro stefans and be made of 17/32" brass like boltsniper's as well.

[Commonly Hunted]

Meaekr VI, here's my shotgun shell.

It is 1/2" CPVC inside of 1/2" PVC. The black part is electrical tape because I over bored the rim of the shell. but I think it will look cool with that part black on all of the shells. The entire shell is 2" long. So is the CPVC that runs throught the entire thing for micros and only under the rim (like the SCAR-N shells) if you wan't megas. The front section of 1/2" PVC is 1.6" and the back part is .2". The black part between the body and rim of the shell is .2".

Sorry for the shitty picture.

[Meaker VI]

Excellent... Things appear to be coming togeather nicely...

SHA: I was looking at the picture on that site for a long time while making my design, and the only problem I have now is that my bolt moves into the plunger tube (The plunger and the bolt have the same diameter, like in Bolt's NTS. The Bolt has a seal and the plunger has a seal; the plunger will also be floating, which was something Bolt was considering for the NTS). That makes relations between the bolt and the carrier difficult. My current plan for the carrier is pretty much like the thing Anders posted a few pages back from the buzzbee rifle.

CH: My shells will be between 1.5" and 3" because I'm planning on using stock micros, airsoft BB's with wadding for shotgun fire, airsoft BB sabots, and possibly someday building mirco stephans. I might also use rocks, steel berings, and whatever else fits into the shells (For target shooting only). Ahh, the glories of shotguns....

[edit] Oh right, this design was done with an 870 Tactical as the construction picture. The end of the plunger tube will have a stock (ideally extendable) attached to it.

Edited by Meaker VI, 12 December 2006 - 09:46 PM.

[Commonly Hunted]

I designed my shotgun after the one in the game BLACK. I think it is called the Remington 870 but I prefer the rifle stock over the combat one. But my design will also allow you to somehow attach a pistol grip and it will be just like a combat shotgun.

Here's my stock in lines and fills. If the links ask for a password it is vanilla gorilla.



I want my homemades to look like the real things like how Bolt does them.

Will add the rest of the gun when I finish it.

Edited by Commonly Hunted, 12 December 2006 - 10:01 PM.

[Ronster]

I just started on the gear system yesterday. Woo! Finally, I have some free time...

Just for kicks, I found some cool shotguns we could base aesthetically off of.

[The Crackerjack Man]

Those pictures kick ass that would look awsome to base it off of that.

[six-five-two]

Oh, I don't know if anyone has shown you the link in the last 8 pages but you should check out Torque's Boomstick.

http://nerfhaven.com...?showtopic=6867

Scroll down for pics of the complete gun.

This is one of my favourite homemade nerf guns on this forum... except there isnt that much details on the gun or schematics for it.

[Commonly Hunted]

Ronster, if I were to design my shotgun aesthetically based on those, I'd prefer the bottom one because it is more compact. But they are both nice.

Six-five-two, Meaker didn't post the link but he did mention it in the 7th page and told us where to find it. The boom stick is very nice but Torque said that he couldn't get it to work. I really wonder how he got the shells to eject without rims unless they were gravity ejected.

Edited by Commonly Hunted, 14 December 2006 - 04:45 PM.

[Meaker VI]

Torque said he couldn't get it to work because he had the wrong size material, it was either an o-ring or tubing. But I think he said the mechanisims all worked; I'm pretty sure it was all gravity fed/ejected though. I'm not a fan of gravity, it's not very reliable; which is why this project is still in the works.

More seriously though, the gravity feed would work fine, but I would prefer the knowledge that the thing was feeding no matter which way it was held to hoping I had it oriented properly.

Ronster, those things are pretty slick, I'd love it if one of these turned out kinda like that and then gave us a write up. I'm not sure I'm a fan of the length of either of them, they look kinda short - especially since the amount of ammo we can put in depends on how long the thing is. I'm planning on building a working prototype to make sure everything works, and then either modifying the prototype to be stronger, more effective, have better seals, and be better looking; or making another one that is all those things. We'll see if I can keep myself interested long enough to get anything done though.

[SHADOW HUNTER ALPHA]

Meaker VI, on Dec 12 2006, 09:44 PM, said:

SHA: I was looking at the picture on that site for a long time while making my design, and the only problem I have now is that my bolt moves into the plunger tube (The plunger and the bolt have the same diameter, like in Bolt's NTS. The Bolt has a seal and the plunger has a seal; the plunger will also be floating, which was something Bolt was considering for the NTS). That makes relations between the bolt and the carrier difficult. My current plan for the carrier is pretty much like the thing Anders posted a few pages back from the buzzbee rifle.

My bolt will also move back into the plunger tube. The bolt will simply push the plunger back into a locked position when the grip is pulled back, since the grip is connected to the bolt.

Edited by SHADOW HUNTER ALPHA, 15 December 2006 - 03:49 PM.

[Commonly Hunted]

SHA, I also have the same thing for my plunger/bolt setup. But I was thinking of making it more like Ompa's version of the SCAR-N (in size at least). I just can't think of how to connect the bolt to the pump-action securely without getting it in the way of the ejection port and mag tube hole.

And I think you meant the pump ("grip" in your words) is connected to the bolt. You said plunger.

Edited by Commonly Hunted, 14 December 2006 - 05:39 PM.

[six-five-two]

I am thinking of making my own shotty, but I don't know. All my homemades so far have failed. And I have still in the design phase of the ejector problem.. I also would make my shotty use a 1 1/4" rubber washer plunger instead of a o-ring. And I know it won't make the gun as awesome, but has anyone considered not having shells? It would be hella easier except it won't look all that realistic. But think about it:

With shells:
Pros
-Awesome
-More realistic

Cons
-Hard to make ejector system

Without shells:
Pros:
-Way easier to make

Cons
-Not as cool
-Bullets in tube clip may mess up somehow.

Edited by six-five-two, 14 December 2006 - 06:30 PM.