Nerf Gun: Design Change

Creating a new design that will be pneumatic powered. With an actual trigger system. It should be a lot easier to design, implement, and build.

Leaks in the Air Pump

Title is self-explanatory. There seem to be leaks in the air pump. School is restarting and robotics season is kicking up so this will probably be worked on over a long while. T_T

O-Ring Fault

There's a design flaw with the pump. Spring and everything installed, everything works. I need to see what's the problem with that O-Ring inside the pump and install a trigger system. The problem is that it compresses air, but leaks if the motion of the plunger stops -- problem.

New Spring Design for Nerf Gun

After some mishaps with two springs that did not work as planned, I changed the spring design to accommodate a pulling spring nested in the middle of the firing plunger. I also doused all connections in cyanoacrylate and hot glue. :D

Homemade Nerf Gun: Part II

Some more pics of what's been going on.

T-Joint and couple-inch section of 1/2" pipe. Will be used to cock the gun. Also pictured is a ring made from a PVC end cap that will be used as a stopper.

I had taken out the cracked pump to repair. To accommodate new designs, I shifted that pipe mount (that used to be a couple notches back) up. You can also see how I stuffed that 1/2" pipe into the pump -- by melting it. >=D

New firing anchor for new design. Gorilla glued to two PVC pipe mounts.

The firing anchor is temporarily mounted this way to provide the Gorilla glue with the "clamping" that it needs to set properly.

Formerly cracked pump. The crack was pumped full with Krazy glue (ethyl cyanoacrylate) and then electrical-taped for sturdiness. Once the Gorilla glue sets on the firing anchor I can put it back in.

Right now this looks mumble-jumbled but I do have a set plan. I'll upload it later. Handwriting is horrible on it, though.

Homemade Nerf Gun: Prototype 1

New project: Homemade Nerf Gun.

This idea started with a toy pump used for pumping up an air-powered airplane. I attached a length of 1/2" PVC pipe to the end to accommodate Nerf darts, and rigged up a system to power the entire mechanism via bungee cord. It was a basic bow and arrow, and was operated in the same way.

General view of the gun. The black pump, white PVC barrel, steel reinforcement are clearly visible. As is the bungee cord, which hooks onto the bent metal thing on the end of the barrel.

Back view of gun -- reinforcement visible.

A bolt on the handle serves to stop the plunger from impacting the PVC barrel inside the pump, as doing so propels the barrel out from the frame like a bullet.

The connection between pump and barrel. Both were whittled and filed down to fit each other, as it is a dry fit.

Front view of gun -- barrel, reinforcement, and bungee anchor are visible.

The result of firing the gun with the bolt on the handle in place. It placed all the stress on the outer casing of the pump, and it cracked a few inches.

I'm currently working on a new design that will be considerably more complex and will be spring-powered.

Update

Haven't shown my face in a while. Again.

What has happened since my last update? My dad and I have installed an auxiliary input to my dad's 2005 Corolla, with a 6-CD Changer. We followed some instructions online which put us in the right direction, but had to do a little tinkering and testing to get it right. Now his iPhone is acting up and refusing to output to the headphone jack when it is plugged into the car. Not sure why that is yet.

And I have revamped my Crayola marker butane gun. Made it into a two-Crayola marker butane gun. Except that the firing isn't all that reliable nor is it any more powerful. I need to find an increased diameter, not an increased length (which is what I did) in order to make it more powerful. Project on hold.

With the boredom of summer, I'm going to research and build a proper HHO generator. Hopefully.

Recent Fun on the Computer

For the past few weeks I've split my hard drive into its fourth and final partition, formatted in HFS+ (those who know what that is probably know what I'm doing ;]) (Partition 1 = Windows XP SP3, Partition 2 = swap, Partition 3 = ext3 for Ubuntu 8.10, for those who are curious). I've been wrestling with this operating system, getting Time Machine working was no biggie but I still don't have Wi-Fi (3945ABG wireless card not supported...drivers are being developed as we speak though), line-in/internal microphone, or the built-in Thinkpad Active Protection System working. Sleep doesn't work either. I tried to get that to work and the result was first a kext error and then a kernel panic. Joyous. I then reinstalled using iATKOS 5i and got rid of all the crapware that I had installed. It seems stable now, but I still wish sleep worked.

In the physical world, I took apart 3 hard drives and harvested monstrous neodymium magnets and 3 spindle motors. And lotsa shiny aluminum disks.

I also tried cauterizing nerve endings on a painful sore/cut wound. I used a piezoelectric igniter (lighter-grade), grounded another finger, and zapped the wound. The pain was white-hot but it became numb afterwards.

Not much more happening b/c of FRC season. Just random shooting moths with plastic BB guns. Planning on revamping that butane gun made from a crayola marker, making the combustion chamber a bit bigger to make it a bit more menacing. Hee hee.

Projectile Launcher

I regularly look on the Instructables website (esp. the tech section) for various hacks and projects that I can pursue. One such Instructable was the butane-powered "gun" (more like miniature cannon -- it's not very strong) made from a Crayola marker and a Bic pen. And a lighter. So several weeks ago, I built it. It works. Barely. It works exceedingly well with the right projectile (rubber o-ring thingy with a screw through the middle). Pencil erasers are especially good projectiles -- they fit perfectly in the Bic pen barrel. However, it is not efficient nor is it strong enough to be of any practical use other than proof-of-concept. I'll post pictures and link to the Instructable later.

Jam Jar Jet Update

Hi.

I've found some 3/8 drill bits and HAND-drilled (meaning turning the stupid bit around by hand and with nothing else) a single hole in a tomato sauce glass jar cap. And widened it using a can opener. Funfunfun. I've got the thing to ignite using the same rubbing alcohol and have it run for a couple seconds before it chokes itself out.

Possible reasons for choking out:
-gets too hot too fast; liquid alcohol evaporates quicker, messes up fuel/air ratio. there actually seems to be a certain temperature range that makes the thing go better.
-hole is of a bad size. i don't think so, because i've been slowly carving my way up from 3/8 to near 5/8 holes.
-no diffuser. probably not the main reason, but may contribute to the problem. alcohol gets pretty agitated by the constant barrage of explosions inside the jar.

It's fun to ignite. At first, when igniting a cold jar, the flame propogates from the top of the hole where it was ignited, running down the inside wall of the jar in a ring of fire until it gets to the bottom. Then, it coughs and starts to run like it's supposed to. It actually sounds like a car engine, starting slow then slowly speeding up. Then it chokes itself out. If the jar is warm/hot when it is first ignited, there is a HUGE jet of hot gas that BURSTS forth before it starts up. The problem is, if it is too violent of a starting jet, it doesn't start and just sits there. Dunno why.
The exhaust (especially leftover in the jar from running it) smells funky. The cut edge of the cap and several metal shavings in the bottom of the jar have both turned red from corrosion.