How to Make a Crossbow

How to Make a Crossbow

by Splint

How to Make a Crossbow

Supplies:

1 Piece of wood to make the stock

( a 2x4 will not be big enough, 2x6 should work, if you can find one.)

1 Leaf spring from car

(only one section is needed)

1 Cable to use as spring

( The break cable from the same car you got the spring out of would be perfect. If not bow string will work also.)

Hammer and nails

Material for bolts( wooden dowels, construction type bolts, large nails, ect.)

Welding equipment (optional) if you don't have any, or can't borrow any some epoxy glue sould work.

Lets get started.

Take the piece of wood you are using for the stock and cut it into roughly this shape:

Sorry about the picture, but I hope you get the idea, it should look like a rifle without a barell, in fact you could even use a rifle without a barell if you wanted to, but it would have to have wood running a good distance along under the barell. A play rifle, like the type you get at Disneyland would work to. The overall length of the wood should be about the same as the length of the leaf spring you plan to use.

Now take your nails and hammer in a support for the spring (leaf spring from car). It should be located about 3 inches from the front of the stock.

The spring will be in front of this, so you might want to make it slightly curved, make sure you use ALOT of nails here, as all the pull of the spring will be working against them.

It wouldn't be a bad idea to reinforce the nails with more nails like this:

Hammer in the reinforceing nails first(the diagonal ones) then put the straight ones right infront of them.

Now a word about the leaf spring:

You can get a leaf spring off almost any car, ideally it will be one found in a junkyard,or one of the ones you see striped, along the freeway. You might be able to find one just lying around in a juckyard or wreaking lot also.

Any way, when you get it, it will be a lot of leafs all bound together to make a spring. You have to cut this binding, of just pry it off, and seperate one leaf. Depending on the size of the spring you get. You will probably want one of the small or medium sized leafs. Remember, the bigger the leaf the more powerful the crossbow, but also the bigger and heavyer it must be. I would go with a small leaf.

Now to string the leaf. First you will want to file some grooves, about an inch in from both ends of the leaf, and about half a centimeter deep:

Now take your cable or string, if it is a bowstring, it will already have loops at each end, if you are using some other type of thin flexible cable( like break cable ) you will have to make loops at each end. You can do this by welding or with items you can get at a hardware store, I mean the things where you tighten a nut and it keeps two strings together. It would be found near where you can buy rope. Make sure you get some that are small enough. Also it wouldn't be a bad idea to get 4, 2 for each end, just to be sure they don't come apart. The length of the string should be slightly shorter (1/2 to 1 inch shorter) than the resting length of the leaf.

To string the leaf place one loop of you string or cable on one end of the leaf so that it fits in the grooves, then put this end on the ground preferably a hard surface like rock or cement. Stick one foot in between the string and the leaf, but make sure the loop stays in its grooves. Now comes the hard part. While pushing down with your foot, to keep the leaf in place, pull down on the top of the leaf, and slip the other loop of the string over the end and into its grooves. This is kind of tricky, but keep trying, you'll get it eventualy.

Now take your leaf, and set it in front of the nails. Push it in tight against the nails and hammer more nails in front of it to hold it in place, you don't need as many nails here, but use quite a few for stability anyway. Make sure the nails keep the leaf tight against the other nails.

Now for the trigger. Pull the bow( which is what I will now call the strung leaf ) string back as far as you can, or as far as you want it to be while in the cocked position. Mark this spot, but let go of the spring first.

(The method I will explain for making the trigger mechanism is easy to make and fix if it breaks, but it is not a very good system. If you can think of a better way. I encourage you to use it.)

Drive a nail through the spot you marked. The wood must be thin enough here for the nail to go completely throuhg with atleast a third of an inch sticking out of each side. I said to just drive the nail in, but don't. Hammer the nail in a little bit then take it out, then do this at an angle. The nail will have to be able to pivit within the wood. When you have enough room nailed out so the nail will pivit, but not loosely, hammer the nail in so the point comes out the top of the stock.

With about a third of an inch sticking out each end if there's more nail than that have the extra stick out the bottom. Test the nail to make sure it pivits, but not loosely. Now file the point of the nail, which sould be at the top of the crossbow, so that its blunt. Now hammer a nail in, solidly, about 2 inch from the nail you just put in, on the bottom of the crossbow. Put many rubber bands between this nail and the other. The rubber bands will have to be strong enough to counteract the pull of the bow. Now test the arrangement by pulling the bowstring back and putting it over the blunted nail end. Add or remove rubberbands as needed until you can pull the trigger nail with your finger and relese the string.

If the trigger is to far forward to do this while the stock is against your sholder, tie a strong string to the trigger, and make a loop at the end of this string so the loop is where you would have liked the trigger. Then you can just pull the loop. You can avoid this by planing better in advance.

Now you are pretty much done, you might want to file a groove in the exact middle of the bow so the bolts(which are the ammo of a cross bow) have a path to travel along. You might even want to put a channel for them to travel along. In fact you probably will.

Well thats about all. Experiment with your crossbow and add anything you thing will make it perform better.

NOTE: THE TRIGGER SYSTEM ON THIS CROSSBOW IS NOT VERY STABLE. DO NOT POINT IT AT ANYTHING YOU DON'T PLAN TO SHOOT!