Picture of IPAD 7 - Insanely Powerful Arrow Driver
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I built my first heavy crossbow when I was about 13 years old. It was a quite powerful device, powered by a rubber sling - a 10mm O-ring I just 'found' on a public worksite - and armed with custom wooden darts. Steel heads, explosive heads, too dangerous heads - in the hands of a small me. I'm sure the holes are still in the steel garage door of my parents.
No wonder that one of the first skills I learned was changing glass windows. Rapidly. Invisible. I became a pro.

My crossbows were a great source of pleasure in my youth.
And of cave arrest, also. Too bad - for my parents - there was a lot of beer stored in that cave, also.
That's how, for the first time, I got insanely drunk.
Resulting in more cave arrest, my hands powertaped. And the company of the neighbours dog to keep an eye on me.
Sweet youth souvenirs...

Resuming: in my youth I learned to love crossbows, I learned to love beer, I discovered the resistance of duct tape and I started to hate dogs. JUST KIDDING!!!
More than 20 years later I'm still on bows, crossbows & slingshot stuff. Target shooting. Long range. 'Run, doggy, run!'.
Since the 80's I've built six arrow-shooting devices. This is number 7, I guess.

But today I see things a lot bigger. Crossbow's Revenge.

This project is about building a real heavy powerful 'badass' scorpio-style arrow shooter. It's not a crossbow, not a speargun, not a scorpio and it's definitely not a slingshot. It's a prototype.
My wife calls it 'That Heavy Thing That Keeps On Hanging Around In The House'.

I built it gradually. 'Sometimes it's good to look at your work' a member said once. That's also what I told my wife because that's exactly how I build this weapon. It all started with a piece of wood and some scrap metal I had to integrate in the project.
In other words: I got the ingedrients, but no idea of the meal I was going to prepare.
Experimental building.

This instructable isn't about howto, it's about custom made hardware. I'm not going to explain how to work wood & metal.
I'm giving you the plans of each device. Your job to make it. Or to improve it. Open source.
Download the plans (click on the pictures & get access to the original files). No CAD-stuff - I'm an old school guy...

Total length (winch included): 128 cm (4 feet) - look at those kitties to compare!
Max. widht: 21 cm (2/3 foot)
Total weight: too much

This IPAD is made of  12 components:
- stock
- drum
- trigger
- trigger rod
- trigger protection
- 'double decker' aka roller device
- stirrup
- lock
- winch
- driver
- sling
- sight

One step, one component. Let's have a look at all those pieces!
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Attmos6 months ago

Very well written instructable on a very cool project. I'm researching ideas and methods for a project I'm working on. Thanks for the great detail, you've given me some new directions to think about.

bricobart (author)  Attmos6 months ago

Thanx, I'm looking forward to that amazing project of yours!

Amazing drawings, some of the best documentation I've seen yet on this site. And I love the amount of overkill: it's just ridiculous!
bricobart (author)  Speffeddude6 months ago

Overkill? Where did you see that?! ;)

Eldalote1 year ago

That's really epic! I was planning to make something similar as a weapon for steampunk larp.

bricobart (author)  Eldalote1 year ago

Wanna see that! Good luck with the build!

Eh Lie Us!1 year ago

"Resistant like ... the skin of married men"? Oh, if it's not it will be!

Great comment. Thought you'd slip that by and no one would notice, eh?

bricobart (author)  Eh Lie Us!1 year ago

I forgot I wrote that! The quote was too evil to keep it just for myself! ;)

Hey, this is really cool in fact its so coll it inspired me to make my own crossbow (no elastic) ibwas wondering if i could use your idea of a ratchet tie down (i assume thats what it is) winch in my own ible? I would of course give credit
bricobart (author)  Pokemon_Trainer_Dan1 year ago
That's cool mate! No need to give any credits, the idea of instructables is to share that knowledge. Looking forward to see that project!
Please excuse the typos im on my phone :/
DaveB131 year ago
Ditto googling
set triggers
Trigger sears

For development
REMOTE drawing / cocking
REMOTE release
To avoid a Darwin Award or high medical cost & permanent disability.

Reduce sheave mass, machine material to act as string guide on just the bearings.

block & tackle
Costruct miniature block & tackle so drive spring ( rubber or steel or air ) movement is small so inertia is small and arrow drive distance is as large as you want it. You may want to incorporate a cam to have draw & driving force continuous. Bow string materials and construction techniques are available online.

You may want to look at performance of most powerful production crossbow, as I recall very impressive.
Know that arrow accuracy becomes terrible with increase of distance compared to firearms.

Even with considerable safety factor built of power reduced from just below a loading factor that causes failure. Firing without an arrow will almost certainly break something.

Ipad.... I think that's great! It's the only kind of Ipad that will be working after the supposed TEOTWAWKI.... ;-}

bricobart (author)  keverett4584291 year ago

That's the spirit! IPAD 7 is build to resist and to last. Technology Won't Save Us, anyway... ;)

Quester551 year ago

A great idea, I to built my first (and last) HD Crossbow out of an old Leaf Spring from my dad's old Round bale maker & Piano Wire-cable, Plus one R/R Jack to cock it. & a 1" gas pipe for the main stock, For Arrows/Bolts, I used ground down Carbide Runners for Snowmobiles, With Welded Triangle Hay-more blades for the Arrow head.

However my dad found out & would let me fire it once before Chopping it to bits with his torch!

I can tell you, the arrow cracked a Flat Head on an old Dodge Truck engine, befor shaddering into a million pieces.

Good Luck with yours.

bricobart (author)  Quester551 year ago

That sounds really beasty! My father didn't go that far - possibly because he knew I would build something more dangerous after that!

Your right, However you've heard it before, " If I only Knew Then, What I know Now?, I'd have tried to build a " Spear Chucker " type Ballista (?) . Good luck with your builds & You might make a few bucks, Selling your Ideas.
holtt1 year ago

Gorgeous! Looks like something straight out of the Metro 2033 video game!

bricobart (author)  holtt1 year ago

Thanx - so you agree with me that it's really unfair my wife doesn't want it in our kitchen! ;)

Check out which is a very slowly moving build thread I'm doing with the Metro 2033 Railgun. Some real similar looks with the metal stock and bolts.

And my wife also doesn't like this in the kitchen ;)
ferjanyen1 year ago
Hi, nice instructable. Just one coment, the firing mecanism must be made of hard steel to advoid friction? Aluminium is just too soft to work well and at different power. Once sorted the next step is to do spme fancy work, see fire arms and deploy ideas.
bricobart (author)  ferjanyen1 year ago
You're right, thanx. A few members suggested to make the nut from bronze, which seems a very nice that I'm gonna try soon!
fidgety21 year ago

i would absolutely love to see a video of this in action it looks to be a excellently planned and very well thought out build.

good job,


bricobart (author)  fidgety21 year ago

Thanx! I'll try to mount my camera in place of the sight - or better, I'll mount my friend's camera in place of the target!

Which one do you prefer?

I could look at your drawings all day.

bricobart (author)  toekneebullard1 year ago

Thanx! But don't abuse - they could you make crazy ;)

I enjoyed your comments and monologue as much as the hardware aspect. I'm for any instructables with more creative engaging writing! Nice piece of work and I might consider brass fixtures/(bronze where needed as suggested) and it would be beautiful leaning against your fireplace or hanging over it. Lots of good suggestions so I have nothing to add. Just gave me a great feeling reading it and seeing all the brainwork involved....

bricobart (author)  keverett4584291 year ago

Very nice comment, thanx friend! I'm sure I had the same amount of fun writing it than you had reading it ;)

Jobar0071 year ago

I highly recommend the book called "The Crossbow" by Ralph Payne-Gallwey. It describes the history of the crossbow, use in military and hunting, and how to build one. A lot of good information is in there that would help you out if you were to make a mkVIII.

I like this build, but I have a few suggestions that might make a difference: first, ditch aluminum. While it is quite light for it's strength, when it fails in this kind of application it tends to explode. You would be better off with steel for everything but the nut (called the drum by you). Which leads to my second (that's kinda related to the first): make the nut out of bronze. Granted it is nearly four times as dense depending on alloys compared, but it is just as strong, and "self lubricating" to a degree. Aluminum is very sticky and doesn't slide well based on it's aluminum oxide layer. The sticky point could be a good reason your trigger takes a yak (get it?) to move it when loaded with more bands.

Crossbows didn't make armor obsolete, the firearm did. The Catholic church made crossbows illegal to use on Christians which is why it didn't revolutionize warfare in medieval Europe. For some reason they didn't do the same to gunpowder....

I agree with Jobar on his comments. Great project BTW!. You mention wanting the power of your 50 lb compound bow. That will require a draw weight upwards of 150 lbs. Reason being that the power stroke (the length the bow accelerates the arrow/bolt) is much shorter in a crossbow. To get the equivalent energy requires 3 times the draw weight (3 to 1 ratio).

Jobar suggested using bronze for the roller nut which is good! The lighter the better (more energy transfer to arrow/bolt), you might look into using Delrin rod with metal inserts for the bearing surfaces. Bone and horn are other materials that could be used also. Check out the Arbalist guild forum:

A lot of great information and projects there.

Have fun!

bricobart (author)  tnetcenter1 year ago

Thanx, that's a lot of useful info!

Great forum, by the way!

bricobart (author)  Jobar0071 year ago

Your idea of using bronze inpires me a lot, thanx! Got to break a roman statue down soon! ;)

mcmonte1 year ago

This is the ratchet from a tie-down?

bricobart (author)  mcmonte1 year ago

It is! I just couldn't find the right vocabulary, thanx!

this is not "insanely powerful" most cross bows operate in the 200lb draw weight

relbatto1 year ago

think i read something once about an arbalest... anyhow, this is really an ingenious use of your perfect winch and i love the peep sight. i want to make a crossbow using the rear spring from a small utility trailer, and make the arrows closer to the ones they used to shoot the guys in tin cans with.. about 5/8 inch dowel , two four inch length overall, including a cast metal pointy end... that lets you use a really strong spring, and a short pull., loved the concepts and execution.

bricobart (author)  relbatto1 year ago

Thanx friend. I saw a few videos of those car spring crossbows on the net and they look ferociuos! Don't forget to make an I'ble of it, I'd like to see that!

cw871 year ago

Fantastic! I gotta ask......What's your "day" job??

bricobart (author)  cw871 year ago

Thanx! At this moment I'm in the phase of starting up my own business of home renovation, repairs & that stuff. In the meantime I'm renovation our house - there's more than a lot of work to do. So there are few moments in a day where I don't have a tool in my hands ;)

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