Grappling Hook Launcher

As surprising as it is, there really is no where on the internet where I found any decent instructions on how to make a grappling hook gun. Figuring it would not be that hard to make, I decided to design and make one myself.  After running into  many problems, obstacles, and a few prototypes, I think I finally have a really solid version that definitely will impress all who use/see/build it.  Naturally there are sure to be plenty of upgrades and other ways to accomplish what I did but I will share the parts and methods I used to make this particular launcher.    
  Although I call it a grappling hook launcher, it is basically a souped up version of any pneumatic gun.  I took the best aspects of many different spud guns to make one of the best possible systems doing my best to avert creating any weak spots and not using any dangerous PVC (which shatters when over pressured and does not work well in the cold).  This system is designed to be robust and efficient in every aspect of its construction.  It is not hard to build and the most trouble anyone would have is gathering all the materials needed.
       I tried my best to used parts locally avaliable (Home Depot, Lowes, etc) but a few i needed to order online. Feel free to ask me any questions you may have. 
     For everyones information, if you are really that concerned about why I didn't film myself climbing the rope,  you are missing the purpose of the video, to show you how it works.  The hook and rope combined for my gun weight 2lbs 2.1oz for anyone concerned that this device isnt practical.  Also, I launched the hook at 150 psi and you could go much higher to achieve greater heights.  
     A little background on myself; I am current a Mechanical Engineering Student at the Massachusetts Institute of Technology  (MIT) and have been building things for 14 years.  My personal blog has most of my creations (some of them made by following Instructables).  Enjoy.  

Step 1: Parts and Materials

My advice to you is you read through the entire instrutable first before beginning to build or obtain parts to make sure I have everything correct or if you see any modifications you would like to make.  Please do not hesitate to contact me with any comments/questions/concerns you may have.  


Parts Needed for Launcher Assembly

-Dry Chemical Fire Extinguisher
-N-Strike Raider Rapid Fire CS 35 Nerf Gun
-Black Spray Paint
-Air Tool 3/8" Hose 
-20 oz CO2 Canister
-Paintball Coil Hose
-1.5 feet 3/4" Copper pipe
-8 inch tie downs
-Blow Gun
-(3) 6" Hose Clamps
-(4) Adjustable 5/8" Hose Clamps
-QEV Valve
-Pressure Gauge (mine had 1/8" threads on it)
-Teflon Tape
-J-B Cold Weld


Brass Fittings
-3/4" garden hose to NPT thread adapter
-3/4" to 3/8" Reducer 
-3/8" Close Nipple
-3/8" to 1/4" Reducer
-(4) 1/4" Close Nipple
-1/4" Cross
-1/4" Tee
-1/4" Check Valve
-175 psi Safety Valve
-(4) 90 Degree Elbows (male x female)
-(2) 1/4"x1/8" Reducing Bushing
-(4) 1/4" thread  x3/8" barb Hose Barbs


Tools
14mm, 15mm, 16mm, 18mm
2 Adjustable wrenches
Copper Pipe Cutter (hack saw would be fine too)
Phillips and Flat head Screwdriver
Drill with set of bits
Dremel with bits (Sanding, a few grinding and the cutoff wheel)
Exacto Knife to cut hose
Propane Torch (Soldering copper pipes)

Some other basic tools that I'm sure you have 

Comments

[OS_Epsilon]

Are you willing to make one for me?

[stormneel]

wait what about the motor to ascending you faster so you don't have to climb

[crreed]

I mean sure, you could use one, I personally have not designed one.

[Chillawolff]

I tried to build this myself, but it won't work. I was wondering if you could build it for me. I know this defeats the purpose of this website, but I was wondering if you could do it for me.

[crreed]

Send me a picture of what you built and I will try to help you out

[de0509]

I get that the sound is one aspect to be taken into account for grappling hook guns. it is mostly used to sneak, but I would really like to ask if it would be good to use water bottle rockets to carry both the hook and the rope? water bottle rockets have large momentum and should be able to carry a sturdy hook and stronger rope to huge distances, provided the rope supplied is long as well.

[crreed]

Water bottle rockets would never have enough force to carry much of anything besides itself

[de0509]

Sir, Id rather have half my monthly allowances in exchange for your badass gun but I beg to differ. law of conservation of momentum will cause the bottle to have equal (sum of) momentum with the water thrown backwards. And we know that water is heavy and they splash very hard backwards, thus momentum forward is powerful as well. Also, people had been shooting water balloons(water is heavy) using a water bottle rocket. I may be too young to create such a gun, but Im at the gathering-ideas phase.

http://www.sciencetoymaker.org/waterRocket/WaterBalloonLaunch.htm

[crreed]

the water is minimal you put in the rocket. A gallon of wate ris about 8.33 lbs and the amount in a rocket is no where near that, more like a few ounces (as the bottles they launch are usually about 20oz and we can essentially consider the plastic massless). Although they have a high velocity, the water weight is minimal so the momentum is relatively low. However, the momentum is not particularly relevant, more of the force that is required to launch the projectile (the grappling hook). I havent done the math but the force is fairly high in order to launch a 3.5lbs object over 80 feet at a 70 degree (or greater angle). So you could probably calculate this all out and see, compared to a bottle rocket which is esentially massless once in flight, that the two forces are greatly different.

[xxcalebbxx]

water bottle rockets are extremely louder than this...then you would be soaked with water...

[iBite-kun]

I don't understand the purpose of having both a fire extinguisher and a CO2 tank. Why?

[qpatrick]

The fire extinguisher on it's own has no pressurized CO2 inside since you emptied it. Therefore you need to add some to it, hence the CO2 canister.

[xxcalebbxx]

or you could fill it with compressed air or propane

[iBite-kun]

does the fire extinguisher act as a secondary?

[crreed]

The CO2 in the canister is at a very high pressure (greater than 1000psi). This is too much for the launcher so only about 200psi is put into the fire extinguisher at a time which then, in turn, is used to launch the grappling hook.

[Ruminator]

Outstanding Ccreed, any idea what the muzzle energy is at 150psi?

[xprosario]

Osama is alive, paparulo.

[ro'keefe]

out of curiousity, what is the approx cost of this? im a college student (NCSU engineering!!) and dont have a ton of extra money, but this is just awesome and i really want to make one

[crreed]

really depends on how thrifty you are and if you can find old parts. to build it completely new would be about $125-$175

[twhitfield]

Anyone know if commercially available guns are unreasonably expensive? I'm thinking that this would make a good addition to a rescue team/firefighter tool set...not so much for climbing but with a "soft" grappling hook this could be used to get ropes to people stranded in flood water, etc. Just a thought for real world application....

[dblanchard]

A few kayakers I know, including myself, use the tennis ball throwers from pet stores for this. Accuracy is high, max distance is pretty consistent (and far), and the portability/reliability is unbeatable.

Just punch a hole through a tennis ball, put your line all the way through the ball, tie a stopper knot (http://en.wikipedia.org/wiki/Ashley_stopper_knot) on the tail of the line and start practicing.

Remember to never stand in the bight (don't position yourself where you could get tangled in the line). Also, only use line appropriate for your purpose. If you want to throw a safety line, make sure the line is a safe one (weight-tested, in good condition, etc.), you are just throwing a service line so that the distant party can then pull the heavier rescue line across, make that clear to them before throwing, and make sure they understand.

[jthomas42]

If you go to www.brooksequipment.com or any local fire extinguisher service place, they have whats called a hydro test adapter that has the proper threads to screw into the unit. On the adapter is a 1/4 F Npt thread to attach an air chuck used when testing these portable units. all you will need is the model of the unit of the fire extinguisher you are using and that is found on the sticker. most units have a 585 psi range they are tested and rated to.

[tinmanm]

I see you are using tissue paper as a packing for the grappling hook. Try a small amount of water 1/4 cup just ennogh to fill the valve. This works great for my air cannon that shoots ping pong balls.

[sniperHunted]

MIT! nice, dude. the 'ible is great!

[jtepper]

This is pretty cool! I have also used the extinguisher tanks for a number of nerf related projects. I find that in most cases, the male CGA-580 nut can be used with an appropriately sized o-ring. I have also been able to simply drill out the port in the fitting to 5/8" and solder in 1/2" copper pipe.

[timnterra]

I'm not familiar with the "QEV" in your design. Does it function on the back-pressure from the closed blow gun valve?

[crreed]

When pressure is released from the blow gun, it forces the diaphragm in the valve to switch directions and allow the air to flow from the tank to the barrel. If you google "QEV Valve," there are many good articles describing how it works.

[gezer2u]

I like it! Good job documenting your build. The only thing that bugs me is the Garden hose to NPT adapter. I've used my share of JB Weld. While it is pretty strong, I wouldn't trust it as the sole connection to the fire extinguisher. Especially having the fitting facing rearward. Air pressure does some amazing things. Maybe it's just me? :)

[bowmaster]

Badass. I want one, so I can be Batman.

[mitch and sean]

Magnificent dude...u now have another follower:)

[halzark]

Great project. I have a question though... why not just buy another paintball CO2 (smaller?) tank and simply use the paintball fittings to connect your "storage tank" instead of modifying a fire extinguisher? http://www.paintball-discounters.com/i/149/co2-tank-aluminum-24-oz.htm

[crreed]

The fire extinguisher was $10 cheaper, available at any home depot, and a tad bigger, but you could use a CO2 tank if you wanted.

[johnny3h]

NOTE TO ALL;  Those el cheapo fire extinguishers [like in the 'ible are more often than not, SINGLE USE devices, and instead of buying one, it's possible that maybe you could advertize of some of free/giveaway sites like freecycle (dot) com, and someone who had an "empty" just laying around may give it to you.

Not only that, but I being a "curbside discard" salvor, and a "dumpster diver," have picked up many, including a few discarded along the roadside at the point of use for a vehicle fire.

Not only are these very good "spun" aluminum cylingers but the come with other handy parts like a pressure guage and a fast acting plunger type valve which are all handy for all kinds of DIY projects.

[Blaik]

I notice that you're always holding the CO2 canister, which must make it more difficult in accurate aiming ( I realize a grappling gun need not have rifle accuracy). A lot of paintball markers incorporate the tank in the buttstock. I'll take a look at my son's CS-35 and see if there's anyway a tank like that could be adapted into the stock. That would mean you'd have both hands free for aiming.

Also, I was contemplating a means to deploy the rope. Maybe fashioning a spool on the side and a secondary trigger on the foregrip. Have a spring loaded clamp on the spool that is release via the secondary trigger. In that manner you can hold the gun at different angles w/o fear of the rope coming off.

If you wanted to get even more advanced fastening a catch mechanism (released by the secondary trigger) and a 'nock' on the the grappling hook would allow a person to load the grappling gun and then hold it at any angle prior to falling and not have to worry about anything coming loose.

Of course, these things would add to the complexity of the build, but they were things that I saw as mods or 'improvements I would/will attempt to include in my own build.

[slavik1]

Just giving you an idea, i dont know if this will really work or not or if it is strong enough. You could try attaching a bowfishing retriever reel. I havent tried this yet so i dont know if this will help or not, just an idea.

[crreed]

Yeah those all sound like good ideas. Im not really sure why I did not mount the CO2 canister in the back, I will try to come up with something in the near future. It should't be too hard to do, just need to anchor the regulator to the gun.

[tinker234]

wow hey ideas on how to make a small pistol verison small motor like mythbusters did

[anode505]

PSI, volume, flow rate, and dumping rate all vs. weight of hook/projectile.

Maybe a couple CO2 carts and a good dump valve (thought the pierce hole of a CO2 cart might be the limiting factor.)

[crreed]

Ive never seen it but it seems like it would be near impossible at this point to make one the size of a pistol unless you could find some very strong spring or other compressible device to create a spring force of some sort.

[gnarf_]

pistol crossbow?