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    Spacing for prod

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    jds6
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    Spacing for prod

    Post by jds6 on Fri Jan 27, 2012 10:25 pm

    Greetings All.
    I have a questions for the experts out there, When cutting out the tiller for the prod, does the cut out need to be the same size of the center of the prod? Any help would be great!
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    Re: Spacing for prod

    Post by mac on Fri Jan 27, 2012 10:42 pm

    jds6,

    Yes. The prod should be an nice close fit in the tiller. I suggest a clearance or no more than 1/32".

    I see from your other post, that you are awaiting delivery of a prod. By all means, wait till you have the prod in hand before you cut its seat in the tiller. Years ago, I took someones' word for the dimensions of the prods I was waiting for and went ahead and cut the seats on two tillers. I ended up cursing and making fillers to close up the space.

    You can make the stirrup while you wait... or fletch up some bolts. You can never have too many bolts.

    Mac

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    Re: Spacing for prod

    Post by jds6 on Fri Jan 27, 2012 11:05 pm

    Thanks mac for the info. one more question if i may? In most pics and drawings of the crossbow it looks like the the amount of stock between the top of the prod and the very top side of the tiller is in the range of about a half inch or so. Does it matter on how much is between the two? Thanks
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    Re: Spacing for prod

    Post by mac on Sat Jan 28, 2012 10:00 am

    Jds6,

    The vertical distance between the top of the prod and the upper surface of the tiller is a thing of some importance. The smaller this distance, the less will be the pressure of the string on the tiller. less pressure is better than more pressure; as this pressure results in energy lost to friction.

    I would consider 1/2" to the the maximum that you would want to use. I have just gone out to the shop and measured the four crossbows I have hanging from the rafters. It seems like I generally make this distance somewhere between 3/8" and 7/16".

    In general, modern makers tend to use a lot more wood in their tillers than our ancestors did. I'm not sure why, really. In any case, it's a think to watch out for.

    Mac
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    Re: Spacing for prod

    Post by jds6 on Sat Jan 28, 2012 1:49 pm

    mac,
    Thanks again for the info, it is a lot of help. Starting to draw out my next crossbow since I have time on my hands. I will be using a prod that is 1" in the center (slobows) does that not leave a lot of wood at the bottom of the tiller? How would you go about making it look appealing? Thanks again
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    Re: Spacing for prod

    Post by mac on Sat Jan 28, 2012 5:52 pm

    jds6 wrote:
    I will be using a prod that is 1" in the center (slobows) does that not leave a lot of wood at the bottom of the tiller?

    It need not. It's your tiller, and you are free to trim away anything you don't want or need.


    jds6 wrote:How would you go about making it look appealing?
    jds6

    Are you interested in an historical style of crossbow? If so, what do you have in mind?

    Mac
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    Re: Spacing for prod

    Post by jds6 on Sun Jan 29, 2012 6:36 am

    mac,
    Maybe to a certain degree, to me a lot of the European bows just seem to blend together. Its hard for me to figure whats what. Anyway I think my new project will be a Finnish bow , really like the look.
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    Re: Spacing for prod

    Post by mac on Sun Jan 29, 2012 8:50 am

    Jds6,

    Post a couple of pics of those Finnish bows. Let's see what we can do with them.

    Mac
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    Re: Spacing for prod

    Post by jds6 on Sun Jan 29, 2012 2:29 pm








    mac,
    dont have any pics of the crossbows myself. There is an example in Iolo"s First Book of Crossbows, also a pic of one on the site of New World Arbalest.






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    Re: Spacing for prod

    Post by mac on Mon Jan 30, 2012 8:18 am

    Jds6,

    OK, here's a picture I just pulled off of Geezers site. It's the one he is calling his Finnish bow.




    It's a pretty handsome crossbow. The tiller is nice and slim. The original that Geezer was working from probably had a prod that was "taller" in the middle, and he has kept the shape of the tiller the same even though the prod that he used is smaller. To my mind, this weapon would look even nicer if it were to lose a bit of the extra wood on the "chin".

    (Geezer, I hope you will forgive me for taking liberties here)

    In the end, it is a judgement call. Do you keep the authentic profile? ... or do you adapt it to accommodate the smaller bow? ....and if you do adapt it, where do you draw your lines and make your compromises?

    Mac


    Last edited by Ivo on Mon Jan 30, 2012 2:59 pm; edited 1 time in total (Reason for editing : Picture)
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    Re: Spacing for prod

    Post by Armbrustier on Mon Jan 30, 2012 8:49 am

    The picture don't work for me Mac! Crying or Very sad
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    Re: Spacing for prod

    Post by mac on Mon Jan 30, 2012 9:21 am

    Armbrustier wrote:The picture don't work for me Mac! Crying or Very sad

    hmmmm....I wonder what went wrong.....I can see it on my computer.

    Is anyone else not able to see the image?

    Here's the url http://www.crossbows.net/CuMine/albums/UploadPics/OurCrossbows/5F%20-%20The%20Finnish%20Bow/normal_DSCF1206.JPG

    Mac
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    Re: Spacing for prod

    Post by Geezer on Mon Jan 30, 2012 9:42 am

    Geezer here: Indeed, the original 5F pattern (taken from a Finnish-language article on replicating ancient Finnish/Nordic bows) had a 'taller' prod than the one I used. It also had a rather deeper prod-socket, with top and bottom material projecting more than mine. Anyhow, the question eventually comes down to preferences, and maybe to some extent reflects timber available to the original maker. I elected to leave the head of the stock pretty tall, but take a look at Padre Island bows... they have very little wood enveloping the prod, which makes the fore-plates necessary. And they look pretty cool, too.
    Geezer.
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    Re: Spacing for prod

    Post by mac on Mon Jan 30, 2012 10:09 am

    Geezer wrote:Geezer here: Indeed, the original 5F pattern (taken from a Finnish-language article on replicating ancient Finnish/Nordic bows) had a 'taller' prod than the one I used.
    Geezer.

    Geezer,

    Can you post the citation for that article? My knowledge of Scandinavian crossbows is limited to what is in Josef Alm's book.

    Mac
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    Re: Spacing for prod

    Post by septua on Mon Dec 03, 2012 8:09 pm

    The shot from my bullet bow clears top of prod by a little
    over 1/16”. I wanted the draw angle at a minimum, so I used the clamping method I’ve seen on some tournament bows.
    I

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