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    newbie to crossbows here a few questions

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    blades7558
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    newbie to crossbows here a few questions

    Post by blades7558 on Wed May 25, 2011 11:53 am

    ok so I made my first crossbow, it had a 15 inch power stroke (im guessing)I shot 11/32 arrows they are 15 inches long (again im guessing) it has a rolling nut style trigger and i made the bow from red oak backed with linen. It came out to 50 pounds at 20 inches. It has since taken a lot of set and im dissapointed in its performace.

    now on to the questions:
    i plan opn using leaf springs for the prod, do i have to heat treat the prod fter shaping it?
    can i leave it strung? i hope so since it will be ALOT heavier than a bow
    what are some good dimensions for bolts?
    i have a lathe and a fully stocked wood shop and metal shop so no suggestions are out of question
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    mac
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    Re: newbie to crossbows here a few questions

    Post by mac on Wed May 25, 2011 12:02 pm

    Blades,

    It's a pretty big jump from a 50lb bow to a leaf spring. You might do well to introduce an intermediate step or two in your progress. A fiberglass 150lb prod would be a good next step.

    If you do use leaf spring, you will have to reheat-treat if you forge the spring to a different shape. If you grind it to shape, and take care not to let is overheat during the process, its original heat treatment will serve you well.

    Mac

    blades7558
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    Re: newbie to crossbows here a few questions

    Post by blades7558 on Wed May 25, 2011 1:55 pm

    thanks mac I plan on making the prod only 75 to 80 lbs if i can help it and i dont plan on heating recurves or any thing into it so thats a relief that i dont have to heat treat it.
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    Basilisk120
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    Re: newbie to crossbows here a few questions

    Post by Basilisk120 on Wed May 25, 2011 4:38 pm

    If you haven't looked at it already there are some plans for making a leaf spring prod in the Crossbow building Wiki: http://crossbow.wikia.com/wiki/Plan_for_a_simple_leaf-spring_prod
    Just be careful as used leaf springs may have taken a beating of there life and have small cracks and pitting in them which will shorten there life span as a bow prod.

    I belive that the leaf spring prods can be tillered similiar to a board bow in that material can be carefully removed from the sides to get a good tiller.

    How long was your red oak prod? It sounds like it may have been a little too short. there are crossbows with wood prods but the prods are longer than metal or horn/sinew prods. Sorry that it didn't work out better but do you ahve pictures.



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    blades7558
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    Re: newbie to crossbows here a few questions

    Post by blades7558 on Wed May 25, 2011 5:00 pm

    thanks basilisk i have been spying on the wiki for a while, i plan on taking the dimensions from alchem prods and trying to recreate it. i plan on welding a small piece of allthread or rebar to the center of the spring. the wood prod was only 50 inches long. i know it was over strained in hind sight i would have used a better wood like beech or hickory but it was an experiment and i had plenty of oak sitting around.

    also another question came up, how does one go about initially stringing these things? just like a bow with a stringer?
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    Re: newbie to crossbows here a few questions

    Post by mac on Wed May 25, 2011 8:32 pm

    Blades,

    If you weld anything to the spring, you will alter the heat treatment of that area. You can probably get away with it if you tiller the bow so the welded place does not flex.

    Pay heed to Basilisk's admonition abut used springs. Start with a new one. I once tried to forge an old spring fragment that I fond on the road into a dagger. There was no end to the cracks that showed up as the work progressed. I had to abandon the project because the material was so treacherous.

    Mac
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    Basilisk120
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    Re: newbie to crossbows here a few questions

    Post by Basilisk120 on Wed May 25, 2011 10:00 pm

    As for stringing the crossbow.
    There are a few different ways. If the bow is designed right a classic style stringer would work but the ends on most bows are two small.

    Next is a bastard string with clamp ends. Could explain it but this will explain it so much better: http://www.crossbowbook.com/page_115.html
    That is from Payne-Gallway's "the Crossbow", its a good book and worth reading but its not correct on everything for example I believe the bastard string in the book is not the best way of doing that.

    Third is to bend the crossbow with your body and one end of the prod on a piece of wood on the ground. There is a quick desctiption in the back of "Iolo's First Book of Crossbows" (downloadable here: http://crossbows.net/ifboc.php) which was written by Geezer. Another good read and this one is quicker.

    fourth method is to a cross jig. Basically a cross made of wood with some thick wooden dowels at the end of the crossbar. A jack is at the base. The crossbow is loaded so the butt of crossbow is on the jack and is then jacked up so the dowels bend the prod. Geezer uses one in his shop and there pictures some were I just couldn't find them right now.

    Hopefully that helps get you started.



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