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Fully Automatic Stationary Gun

Mod Write-up completed!!

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#1 b00m13

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Posted 27 August 2007 - 12:40 AM

Okay as promised, here's the write-up for the F.A.S.G (Thank God I called it "stationary", lol)

1st off I'd like to thank anders for giving the most bashed gun a chance (MT20)
He turned a semi-automatic gun (That jammed like no tomorrow), into a "beautiful" 8 round fully automatic war machine that was just so inspirational. Check his mod out!!
I used a lot of the advice he gave (because he actually knows what he's doing), and added a few tweaks of my own.

The difficulity isn't not high at all, I'm pretty sure anyone can build one if they follow the diagrams.

Items needed:

Wood - (x1) 1/4" x 2 1/5" x 3'
(x1) 1/4" x 5" x 2'

(x2) I recommend Longshot front gun triggers (try to buy it from another member since hardly anyone uses that weak
gun, and a lot of members just integrate the front gun into the LS so their triggers are just collecting dust).
If you can't get your hands on a pair of LSFG triggers, then I suppose you could substitute with pull strings.

The motors from a Mech Tommy 20 gun.

The wires and the normally open connection from a Mech Tommy 20.

The metal pieces from the battery compartment of a Mech Tommy 20 and a Nite Finder.

A switch (Can be a button switch, light switch, turn switch, or like myself- a busted computer fan switch)

Copper/metal wires.

The Normally Open connection from a NF (The metal piece behind the trigger that completes the circuit and turns on
the lazer.)

A bunch of really thin cardboard, 8 1/2" x 14" (I got these from my office. They come with the stacks of printing paper.)

1' of 1/2" PVC

A handful of screws (Left over Nerf guns screws is best)

E-tape

Wood glue

Rotary tool/Dremel

Hotglue Gun+Hotglue


Optional piece(s):

The lazer from a NF

A pair of Door Hinges (They're usually sold in pairs from any hardware store for $2-$3)

A tripod (They sell these at Radio Shack from $30-$40, but you can use a kid's telescope tripod like I did.)

(x4) 2' x 3' (or larger) cardboard

(x2) Hefty or strong garbage bags (You could use really thin styrofoam, but it's easier to obtain several square feet of garbage bags.)

A handful of Popsicle sticks

(x6) Binder Clips (Medium - Large sized)

(x4) 3/16" - 1/4" screws

(x4) Washers (With an ID large enough to fit the 4 screws above)


The Battery storage pack

You can use the MT20's battery storage pack if you want, it might actually save you time since everything's done for you and you'd just have to cut out the square frame of it.

Or

If you want to do it my way...

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MT20 Motors

Just be careful when taking the motor out of the MT20.
When it's out there's very little modding needed to be done. Just sand down any nudges that juts out and might interfere with the frame of your gun, etc.
The 2 motors were designed to work with 3 AA batteries, (4.5 volts) but you can do as I did and push it up to 4 AA's (6volts). The speed of the spin of the motors works as you might think... more volts/power = faster spin. But growing up watching Home Improvement... more power =/= better/safer. Anders made his operate with just 4 AA's and I agree. Some of you suggest using a 9V battery which is much simpler to hook up to the motor, but doing that will kill your motors over extended use (I hooked it up to a 9V battery to see for myself, and it did spin a little bit faster/louder, but risking 2 motors to do it was not worth it. So just take Ander's and my advice, and STICK WITH JUST 6 VOLTS TOPS!!

For the wheels, I suggest wrapping a few layers of E-tape around them for a batter grasp.

The Dart Propelling Motor


I used a toy race track motor to propell my darts forward because it was all assembled for me. It was basically the same motor used in the MT20's (or hand held fans), hooked up to some gears connected to a rubber wheel. The motor I used had a small gear connecting to a larger gear, which meant that it actually spun the wheel much slower then the motor spun. If you want to make your own propelling wheel, connect the wheel directly to the motor. The wheel can be made out of anything... even a Gatorade cap with some E-tape wrapped around it.

The Internal Wirings

For those of you that have never worked with electricity before, either get an expert to help you or an adult will usually suffice.
In the Diagram, NONE OF THE WIRES CROSS EACH OTHER!! They might GO OVER ONE ANOTHER, BUT THEY NEVER CROSS EACH OTHER!!
ALL EXPOSED WIRING MUST BE SEALED!! Use wire connectors to connect wires if you have (ask your dad, most likely he'll have a few packs). Go to a store and buy them... they've only a few bucks for a pack,... but if you are that cheap and don't care about risking exposed electricity, as a last resort, atleast cover your connected wires with a few layers of E-tape.

It's been a while since I've had to draw circuit diagrams so please bare with me...

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Some of you might be wondering why I didn't ust connect the 3 motors to a single power supply... well I did... at first. When I was building the prototype, I had 6 volts of batteries all powering everything, and it seemed fine at first. Then when I loaded one of the prototype cartridges into the holder, the darts jammed (surprise surprise... a prototype having bugs). That showed me something else that was going to be a problem, when the darts jammed (too much weight for the wheel to handle), the wheel struggled to spin, and it exerted more and more energy to do it, which drained the energy going into the 2 MT20 motors. That was when I realized I needed a second power source, that way I can run 3 volts into a single motor, which gave it a hell of a lot more spinning power to propel the darts forward.

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The Frame of the Gun

Think "Shoe box" when trying to imagine the frame of the gun, because that's what mine came out as. Sure if you have a bunch of free time, you can design a super cool frame, but I'm all about simplicity (at least for this build, I am).
There's really no super hard work for making the frame, except physical hard work... hacking/sawing the wood. If you have access to a miter saw or a table saw... then I envy you, because I did all the major cutting by hand... and only the small cuts by rotary tool.

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The Measurements of the Cartridges, and the Holder that grabs onto the cartridge

Those thing I leave to you do decide because it's based on the dimensions of your darts.
Make sure when you're making the folds on your cardboards, that you'll leave enough room on the sides of the darts so they wont get stuck inside, each dart must be able to freely drop from the top to the bottom with no resistance (I recommend the space between the dart and the wall of the cartridge to be 1/16", Front to Back; Side to Side)
The Holder should grab onto the cartridge just right, NOT too tight, and NOT too loose. You could do as I did if it's too loose. Cut slits on the top of the holders where the ends of the cartridges would be, and insert a popsicle stick into the slit to grab onto the cartridge (See pics for reference).

Placement of the Clip/Clip Holder

This part is probably the most important part. It took me a week and a half to figure out why the ROF was so erratic. One moment it was spitting out everything in under 3 sec which sucked because the darts only went 6'... the next, it would have a 5 sec gap between shots, which allowed the motor to get back to speed, but the ROF was crap...
It was near the end of the mod when I realized that the position of the clips determined the ROF. If you placed the clip farther back, so that the wheel would touch the head of the darts, then you'll have a SUPER HIGH ROF (I mean 26 darts in under 3 sec), if you place it so that the dart's mid section touches the wheel... the wheel would have to spin a few times to drag the dart forward enough to be propelled. So just do some test run until you find your own "sweet spot" (where you get the greatest ROF but don't sacrifice too much distance).

Adding a Tripod


Since not everyone has a tripod, or have similar tripods... I'll have to leave it up to you to determine how to attach it. For myself, I used some door hinges and screwed it to the belly of the gun, that way, if I were to store it away, the flaps would be able to fold up (See pics for reference).

Super Shields

This is not really required... but it's a great advantage if you're up against Titan users in "capture the flag" games.
The garbage bags is just 1 material you can put between the 2 layers of cardboard, you can put anything lightweight in it... like bubble wrap, silk... etc.
Besides making the shields anti-armor piercing, you can also take advantage of the large size of it, and attach clips to the walls facing you. Just attach some 1LB magnets to the walls and tape some washers to the sides of clips, and you'll have yourself an easy to detach wall of spare clips.

Posted Image

As always... the low quality pictures...

Posted Image

And now, even LOWER quality videos

Explaining some neat features of the gun - This video is dark because we were filming it after the Sun was setting.

Being silly

EDIT: Adding this new video of the F.A.S.G

Just shooting a few rounds at a plastic bag.

Hope you've enjoyed em, if you are curious, the range for a single shot is about 50ft at around 10 degrees, and for the whole clip... it's anywhere from 25-40ft (It decreases a lot since the motors are being slow downed by each dart it's trying to squeeze off). Although the 2nd video doesn't seem to show the gun firing very accurately, that's my fault for making inaccurate stefans. When using stock darts, the spread is very small.

Thanks for reading ^^)


PS

BTW, this counts as a Mech Tommy 20 mod, *hint hint* FA24

Edited by b00m13, 29 August 2007 - 10:08 PM.

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#2 philadel Elite

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Posted 27 August 2007 - 12:52 AM

thats pretty cool!

By the handle it looked like a Scout.
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#3 Z-man12

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Posted 27 August 2007 - 01:06 AM

So thats what all those electronics questions were for. Now I get it.

Nice job now you just have to slap it in a good shell. (PM me I might be able to send you in the right way for that.) The clips are amazingly simple. Now you just have to figure out how your going to make it so that the motors don't slow down so much after each dart fired.

I really think this sould be in homeades though unless you actualy used a MT20

Edited by Z-man12, 27 August 2007 - 01:10 AM.

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#4 Forsaken angel24

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Posted 27 August 2007 - 01:39 AM

Awesome, Just awesome. It would be cool to up the range on that thing though. It also doesn't look very accurate.
I was thinking of doing something like this with 2 lawn trimmers back when I first got into modding.
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#5 Prometheus

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Posted 27 August 2007 - 08:42 AM

Now you just have to figure out how your going to make it so that the motors don't slow down so much after each dart fired.


Flywheels.

I was thinking of doing something like this with 2 lawn trimmers back when I first got into modding.


holy shit, we're not trying to shoot lawn darts here... that type of power, people would run shitting their brains out just because you'd started it up.
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QUOTE(VACC @ Jan 24 2008, 06:12 AM) View Post
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#6 anders

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Posted 27 August 2007 - 10:15 AM

If you want to achieve higher accuracy with a gun like this you can use to conveyor belts instead of just wheels. That way your darts wont be able to wobble sideways when they pass the wheels. I was about to build a gun like that after my second electric gun but on my way to the workshop i decided to build a snap instead.
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QUOTE(VACC @ Aug 16 2007, 03:52 AM) View Post

Does posting in agreement somehow validate your standing in the community? Personally I think it just makes you look like a tool.


the el snapo again

#7 b00m13

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Posted 27 August 2007 - 12:25 PM

Good afternoon guys!!

I have a few minutes to address some replies, so here goes..

P-Elite - Thanks, those trigger handles are actually 2 Longshot front gun triggers. (1 from my friend's LS that I modded, and 1 of my own).

Z-man - Yep, that's why I asked those electrical questions. Someone mentioned about using a classic gameboy adapter as the power source, (6Volts) and I actually tried to try it out. I had a spare dual adapter (Gameboy original and pocket), but instead of the regular red/black wires... I got orange yellow and white. I was going to bust out the ol' multimeter to figure out which connected to which, but I decided to save that til the end and just substitute with 4 AA's until then. By the time I finished, using 4 AA's for the projectile motor didn't seem so bad so I just stuck with it (The 2nd motor used to propel the dart forward has 2 AA's for itself because powering 3 motors with just 4 AA's was weakening the performance dramatically).
I did use a MT20's motors and wires for this mod so that's why I posted it in mod, but yeah, there was a LOT of stuff that was homemade.

FA24 - I'm sorry that the video didn't do it justice, but please take my word for it.. the gun is VERY accurate. When planted on carpet, I can hit a target 20ft away with each shot hitting the target within 6 inches of each other (I was shooting a fan, and 85% of the shots hit the center plastic circle, while the rest hit the metal frame/cage of the fan). In the first video, when I was shooting the gun, my friend was 25 ft away from me, and had the camera zoomed in. The shots that seemed like it went far into the right of the screen were actually only 5-7inches from the camera (I dropped my head at the end because I was trying to hold in my laughter from shooting my friend in the head so many times).
In the second video, when my friend shot me, the gun was stationed on his bed so it was not stable. We had to set the gun on autofire, and target with our left hands on the right hand trigger (because we used our right hands to film the vid), so during half way into the firing, he said he accidentally shifted the turret and didn't realize it so the 2nd half of the cartridge hit the door instead of me.

Also, if you were to do this and wanted to use an improved motor, might I suggest you save a few bucks and use window fan motors. Window Fans usually come with 2 fans each unit, and they're pretty cheap, the motors are larger then those cheap ones on most toys, and they're a hell of a lot more powerful too. Not to mention that they're already set up for 120volts, so you can plug it into an outlet, and they can go for an insanely long time w/o stopping (I planted a window fan in front of my room's vent; to suck in and blow more cool air towards me, and it's been on for weeks (turned off only for a few hours when it's too cold each day)).

Anders - Dude, thanks again for your mod. As for the accuracy, it's very accurate already, the video's don't do it justice as I said above. I thought about a conveyor belt propeller at first too, but I scarped the idea because simpler is usually better, and I've had no problems with the way things are. That final propelling motor was the biggest pain of the whole mod. It took a week and a half to figure out how to make cheap simple clips that would work with it; how to prevent the clips from hindering the motor's performance; where exactly to put the clip, so when it's turned on, the darts wont stress the motor out... etc.
If I could make one change for it, I'd make the frame of the gun much longer, so it can carry several more clips in it's rail.. 78 1.5" stefans is ok... but I rather use a few hundreds since this thing spits them out in seconds...


Edit : PS I would have wanted to do more performance videos, but as you could tell from the 1st video, we were losing daylight fast, and I couldn't find 25% of the stefans, the camera's batteries were dead by the time we've transfered it to the PC, and a whole bunch of other problems aroused (damn mosquitoes). The 2nd video clip was made because I wanted you guys to see a 1st person view of the gun firing (since the first clip was hard to see), and we were going to do it in a larger space, but it would have gotten in the way with his family, so we confined it to his room)... I would have liked to do another video... but I don't have a digi cam, only webcams and those qualities suck... (not to mention I don't have a clue about creating homemade vids... my friend did all the work)

Edited by b00m13, 27 August 2007 - 12:36 PM.

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#8 Shorty

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Posted 27 August 2007 - 09:44 PM

Yeah, I would like to see how strong it is so could you either tell me or more likely post a video with you shooting a cardboard .

Thanks
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#9 Nonsense Man

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Posted 27 August 2007 - 11:27 PM

This thing is pure awesomeness. Also is there any chance of any kind of writeup or maybe just a thread filled with helpful information??

Edited by Nonsense Man, 27 August 2007 - 11:28 PM.

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QUOTE(1lastnerfgun @ Apr 19 2008, 08:39 AM) View Post

40 shots for 40 cocks


#10 nerfsharpie6

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Posted 28 August 2007 - 01:21 PM

If you build a second one of these instead of using some wheels or conveyor belts try a plunger tube with opening at the end like with an electric air soft gun uses. It may give it more range if its large enough while adding some power behind it. But it is a cool gun. Good for indoor battles.
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#11 b00m13

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Posted 29 August 2007 - 01:58 AM

Ok the write-up is now completed and a super craptacular vid has been uploaded... have fun.
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#12 Recruit

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Posted 29 August 2007 - 04:24 AM

Funny I had a similar idea. Thanks for doing the experimenting for me. :D :D
Most nicely done.
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#13 precisionnerfer

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Posted 29 August 2007 - 05:41 AM

Hey boom my very first mod was something like that, except the tommy parts were mounted on a mav shell. If you wanted to make that shoot farther, yes it would be more complicated but not too much. Grab a hotwheels track and take it apart, then take the wheels and put the just as far apart as you did to your tommys. It is a bit more powerful! Also you could you etape to coat the track wheels with.
Nice mod!
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#14 Senor Wolfwood

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Posted 29 August 2007 - 06:41 PM

I'm not trying to rain on a parade or anything, because I really like the stationary gun deal, but this isn't anything new. I've done this myself and mounted it inside of a superiorly fucked Vortex Tornado. May I offer a bit of advice: Replace the motors. I started with some 1.5-3 Volt Motors from Radio shack, with around 8000 RPM, and they work fantastically. They do loose a bit of power, but they keep it up quite a bit. 12 specially crafted darts out in about 3~5 seconds isn't that bad, if I may say so.
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QUOTE(Forsaken_angel24 @ Oct 23 2007, 12:13 AM) View Post

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#15 b00m13

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Posted 29 August 2007 - 10:15 PM

Bump for the new video links (if you want to see part 2, just check my youtube list).

PS I'm uploading vids I made for my other guns atm so watchout for those too ;)
(LS+DTB vid is next.. then my BS, then finally the GB)
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#16 zaphodB

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Posted 30 August 2007 - 10:14 PM

I have a suggestion.

You said the darts lost range later on in the burst becuase the wheels lose speed. The solution is very simple (or at least fairly simple). Make the wheels heavy. Make 'em really heavy. I think washers would work well if you could find a bunch of big ones, or some lead circles. (Golf shops have lead tape for adjusting the weight of drivers, so maybe that would work, but those are relatively lightweight (5, 10, 15 grams), so you'd have to layer, and I don't know how much that would cost. Basically, if the wheels are heavy, they won't slow down as much, and there are many ways to make them heavier.
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#17 Thom

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Posted 31 August 2007 - 01:16 AM

Heavy wheels would take bigger motors.
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#18 six-five-two

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Posted 31 August 2007 - 02:29 AM

Forsaken_angel24: Are you going to add this one to your Modification directory or should I add it to homemades? He did basically modify a Tommy 20, but the whole body, etc. was homemade.
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#19 zaphodB

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Posted 31 August 2007 - 11:19 PM

Heavy wheels would take bigger motors.


Only if you want them to spin up in the same amount of time. The final speed would be pretty much the same, it would just take longer to spin them up. That's the trade off. Longer spinup time for smaller decrease in speed in between shots.
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#20 b00m13

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Posted 01 September 2007 - 04:52 AM

You'd think that, but there's not real "in between" shots with this gun. Well there is, but it's so small, there's no way it could build it's speed back up so far.
There are 27 rounds fired off in this clip.
I understand your washer idea, and I've seen it put to work. In fact, the propelling wheel that pushes the darts forward uses a circle metallic plate next to it. But a washer of that size wont do it. Generally due to it's low mass, to do it right, I'd suggest another heaver metal.
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