Update

Okay, tweaks are done and the crossbow has been fired. So, on to the description:

I was going to give a detailed how to, but in this case it would take too long. The main things you (as budding maker of crossbow) need to know are actually rather basic:

  1. The bow. In this case, one of the leafspring sub-sections from a car was used. I ended up taking the second-largest spring, which ended up fitting a string of about 110cm. This then had its ends cut to take said string.
  2. The draw. The bow was mounted about 10cm down the stock (which was about 80cm long) once strung, it had a draw of about 60cm.
  3. the trigger. The trigger consists of a trigger plate and a lever to push the string off of it. The plate (represented by the very painty image below) should be canted inwards slightly so that the string rests properly:
    Trigger plate

    Trigger plate

    Multiple screws are a must on this one as the pulley and string both have a tendency to pull the damn thing apart. The lever consists of two planks held in place by pins and joined at the bottom by an arm. Here’s an even paintier side view:

    Side view

    Side view

    And a completely paint-tastic top view:

    top view

    top view

    The grey bit is the string…

  4. The winch. This is one thing that I urge you to buy. I made mine, using a drilled pipe, some pulleys and two thick steel pins. But I urge you to buy one all the same. Just in case, though:
    winch

    A winch

    The string is tied once at each end of the rod and passes behind the stock. The pulleys are attached to a bent piece of wire(5mm or bigger), which is used to hook the string. Note that the hooks face upwards, as otherwise they tend to get caught on things and horribleness occurs:

    A hook

    A hook

And that’s it for the build. Remember to over design  everything, as there ends up being a lot of tension of the string. Also, remember to never put anything you don’t want to lose in front of the string.

Mine eventually put a throwing spear (made with a throwing knife and a 15mm piece of pine rod) through a thick board (20mm) without breaking a sweat. For comparison, the best I could do with the spear was get it to stick in.

Have fun…

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