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    taking off from where others left off

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    panne
    Fresh Blood

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    Fresh Blood Doesn't meanI'm new to crossbows

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    taking off from where others left off

    Post by panne on Tue Dec 04, 2012 8:10 am

    i picked up this mix of jayhawk parts when my dad retired from teaching industrial arts. i decided to start with the most complete crossbow that had a broken stock. it was broken flush with the bottom of the tiller, so i screwed, glued and filled a section of mahogany that i could either cut down to a pistol grip or add onto to create a stock later.

    i then added some osage orange trim pieces to cover the patch work and the previous person's lack of patience and skill. i shortened the tiller to achieve an 8" draw from the 3.5" brace height. i polished the aluminum trigger, nock points and rails, then sprayed the whole thing with 6 coats of black lacquer, then rubbed it out until it was slightly matted.

    i'm presently working on a trigger guard, foot stirrup and bolt retainer. the bolts in the top pic are a 262 gr bamboo, a pieced together broken cedar arrow and an vw beetle aluminum push rod shaft with a standard screw on broad head.

    i'm still trying to design the foot stirrup so that it's solidly mounted to the tiller without interfering with the prod. i considered mounting it to the prod bolt, but not sure if it would be too much of a load. the 1/4" prod bolt is screwed into a birch dowel that is glued into the tiller crossways, so it may be ok to mount the stirrup there. any suggestions?






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    B.Cheers
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    Re: taking off from where others left off

    Post by B.Cheers on Tue Dec 04, 2012 8:43 am

    You could mount it to the prod bolt but it would need rubber washers inbetween the stirrup and prod so it does rattle off or loosen and i good nilock nut yet there are other ways.

    panne
    Fresh Blood

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    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 46
    Join date : 2012-10-21
    Location : abbeville, la

    Re: taking off from where others left off

    Post by panne on Tue Dec 04, 2012 11:58 am

    i've been searching online in a futile attempt to find the working load limit of the 1/4" lag bolt. i did find one source that claims 500 pounds if the pull has no angle, but find this to be a bit high. i may just bolt it in with the prod bolt and see what happens. i doubt it will pull the threads free the way it is run through the cross grain hardwood dowel and if it does, i'm sure i can figure out a way to repair it.

    it's a bit of a pain to span it with a short stock section. i figured out that the easiest way is to place the stock on the ground, facing the business end and push it down. with a stirrup i could probably span it single handed.
    avatar
    B.Cheers
    Tinkerer

    If there is a will, there is a way.


    TinkererIf there is a will, there  is a way.

    Posts : 60
    Join date : 2012-10-08
    Age : 28
    Location : Austrailia Brisbane

    Re: taking off from where others left off

    Post by B.Cheers on Tue Dec 04, 2012 8:49 pm

    You could also do the stirrup like my bull-pup crossbow but cut a slot in ether side of the stirrup so it slots into the prod and would act as a brace if you know what i mean.

    As for your short stock you will find once you have a stirrup mounted that it will be easier to cock since i have no troubles cocking mine and by the looks of it your crossbow may be longer then mine.
    Thanks Ben
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    Geezer
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    Re: taking off from where others left off

    Post by Geezer on Wed Dec 05, 2012 6:53 am

    Hokay.... you're finishing old Jayhawk kits... Here's the straight-skinny. The original steel bowstrings will prove inadequate for their task... they're heavy and slow, they'll stretch in a few weeks and then won't stay on the prod. You need to cut the slotted prod down to elongated spuds, file down the edges, and fit a new fiber-string. Artificial sinew or Dacron B-50 will work nicely.
    Second, Jayhawk prods have a hole drilled thru the center... that's the weakest pointin the stock. The mounting bolt thru that hole will work loose regularly, and eventually the prod will break through the hole in the center. It's a light bow, you're not liable to get hurt, but eventually the prod will fail there.
    The simple drop-hook release should serve tolerably well for light bow, but it will tend to wear the string-serving heavily, and may mis-fire. Building a string-snubber over the lock, to keep the string from hopping over the hooks on release, will improve performance. Changing out the steel string for just about anything else, will help more. Still, you're gonna have fun. Enjoy the adventure. Geezer.

    panne
    Fresh Blood

    Doesn't mean
    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 46
    Join date : 2012-10-21
    Location : abbeville, la

    Re: taking off from where others left off

    Post by panne on Wed Dec 05, 2012 7:44 am

    i just kept the steel strings for examples of what not to do. the string i'm using is some 10# mil spec polyethelene. same material as b50, just had to use more strands. i served it with artificial sinew. i polished off the corners of the string nock, but had wondered if i could cut them into pin nocks. i also polished the rails and trigger hooks.

    i didn't have too much choice on this one when it came to the bolt through the center, but think i will add some type of block over the front to reduce the flex over the hole when i figure out how i want to add a stirrup. the block would also hide the ugly bolt sticking out and if and when it does break hopefully keep it from hurting anyone. the bolt is anchored into a crossways hardwood dowel so the threads weren't pulling with the grain. hopefully it would reduce the amount it can loosen.

    this one will probably end up being a semi functional wall hanger. if i build another one using the extra prod, i plan on ditching the bolt through and mounting it inside the tiller and wedging it between some steel plates. i'd also ditch the stock trigger since one of the tillers i have already has a notch lock installed.

    i'm using these for practice builds, so that i can get a better idea of what to do when i get the parts to build one with a steel or fiberglass prod in the 100-125# range.

    i also have this idea for modifying the trigger to a roller nut style. i'm thinking if i cut the lugs off along the sides and move the pivot point it may work well for the sear on a roller nut.

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