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by octavioaugusto.oliveira Thu Apr 27, 2017 1:27 pm


    Carving out room for the roller nut

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    Arcuballista
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    Carving out room for the roller nut

    Post by Arcuballista on Thu Sep 01, 2011 8:40 am

    I have just started on my first medieval crossbow and I have decided on making a crossbow very much like this:



    or this



    The thing I find a little difficult is to carve out a perfect half moon hole for the rolling nut like shown here:





    Is there anyone in here who has dones this before? I did find one article on wikipedia but it was not the most beautiful work I have seen. I have just bought a spoon chisel and I might get a decent result if I`m careful?

    Thanks for any help!
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    Todd the archer
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    Re: Carving out room for the roller nut

    Post by Todd the archer on Thu Sep 01, 2011 1:45 pm

    From the pictures you posted, it should be noted the roller nut shown rotates on an axle therefore you can chisel a square or rectanglar socket. However medieval crossbows that I am aware of do not employ that design. They use a round socket either bored from the side or made as a separate unit then "dropped" in from above into a retanglar mortise.



    In the second example the roller nut bears against the socket not on an axle, in fact there is no need for an axle.



    What material do you plan to use for the nut. The one pictured appears to be steel.



    I have used the bore from the side method myself with good results. Can post pictures if you want let me know.



    Todd


    Last edited by Todd the archer on Thu Sep 01, 2011 1:50 pm; edited 1 time in total (Reason for editing : add info)

    Arcuballista
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    Re: Carving out room for the roller nut

    Post by Arcuballista on Thu Sep 01, 2011 2:19 pm

    Hi Todd, I will be using steel because it`s strikes me as the strongest material and therefore should be the best

    It seems strange that they did not use this simple design in the middle ages, I belive I have seen pictures of original medieval crossbows with this solution. I might just try to chisel out a hole for the nut on one of my crossbows just to try it out, my next will defenitly have a pre made nut socket

    Other opinions would be very welcome
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    Geezer
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    Re: Carving out room for the roller nut

    Post by Geezer on Thu Sep 01, 2011 3:09 pm

    Hi, Arcubalista: Geezer here. There are a number of reasons why medieval archers didn't cut a square nut-socket and hang the roller-nut on an axle. They mostly have to do with strength of the socket and wear on the axle. A bone-or metal reinforced round socket that fits the roller-nut is stronger and more wear-resistant than a square socket with axle. Simple axles tend to bend and wallow-their ends loose where they pass through the sides of the socket.
    Steel or brass rollers are certainly stronger than antler rollers, but they are also substantially heavier. Their greater intertia results in slower release, which costs power. Also metal rollers that aren't perfeclty balanced, particularly if they are hung from a simple axle will vibrate heavily on release. It's a really unpleasant phenomenon.
    Strength is an important issue, but not the only one. Geezer.
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    Re: Carving out room for the roller nut

    Post by juancheco on Thu Sep 01, 2011 7:21 pm

    Geezer, that nick in your avatar (Master Crossbowyer) fits you very well!!!!!

    Arcuballista
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    Re: Carving out room for the roller nut

    Post by Arcuballista on Fri Sep 02, 2011 10:45 am

    Hi Geezer and thank you for your advice too Wink

    I hoped to get a hole with the exact half diameter of the nut so that it would roll around nicely but it might be to hard to do, I do understad a square hole would be very wobbly. Any reason the two crossbow makers I have listed below made their crossbows like this?

    Tod at "Tod`s stuff" seems to know what he is doing and the price on the fairbowshop crossbow is a lot for something that should not last to long!

    http://www.todsstuff.co.uk/crossbows/battle-crossbows.htm

    http://fairbowshop.nl/index.php?main_page=product_info&products_id=82
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    Geezer
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    Re: Carving out room for the roller nut

    Post by Geezer on Fri Sep 02, 2011 11:38 am

    Arcubalista: Geezer here.
    Todd enjoys a very good reputation as a crossbow maker. I have no doubt his bows work very well, If he's making square sockets with nut suspended over-top on an axle, he's probably using a pretty strong axle and a fairly light prod. Even so, such a system will inevitably wear a bit faster than nut in tight-socket.
    As for the socket itself, you don't want a half-diameter hole, you want a 2/3 hole. Less than that gives you too little mass around the top of the socket (Payne-Gallwey suggests a 5/8 diameter hole. That works okay if you reinforce the edges of the socket, otherwise, I recommend 2/3) a 3/4 diameter hole will sink the nut so deeply, you will HAVE to insert/remove the nut through the side, rather than the top, as can be done with 2/3 or less. As long as you have enough of a lug sticking out the top to catch the string, 3/4 will work fine, it's just an assembly/disassembly problem.
    Geezer

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    Re: Carving out room for the roller nut

    Post by Arcuballista on Fri Sep 02, 2011 2:01 pm

    Thanks alot once again Geezer, crossbow building sure is facinating stuff perfected over a very long time

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