Primitive Archer

Main Discussion Area => Around the Campfire => Topic started by: globalmark on August 19, 2018, 03:52:53 am

Title: How to set a crossbow prod - angle and depth Help needed
Post by: globalmark on August 19, 2018, 03:52:53 am

Hi

Just wondering does anyone know how to set a cross bow Prod - is there a way of doing this - in regard to depth and angle -
Basically I made a complete crossbow But broke my homemade bamboo prod while on the tiller - so Bought a 27" tawainese one 160lb that several people seem to use . I have googled heaps and found they have 3-3.5" brace and 11-12" max draw length ..

i made a modern style solid stock and will mount the prod in a square hole and then maybe a bolt from the front or a wedge covered in a metal plate .

Most people set prods in at 6˚ but i can find no information on how deep should it be in the stock and exact angle - is there a way to work this out ?
Thanks Mark

Title: Re: How to set a crossbow prod - angle and depth Help needed
Post by: Pat B on August 19, 2018, 06:49:32 am

Maybe Del will chime in. He's made a few xbows.

Title: Re: How to set a crossbow prod - angle and depth Help needed
Post by: Del the cat on August 19, 2018, 07:52:47 am

I try to set 'em up so that when you look along the string at brace the string is in a straight line, not bending up onto the track from the tips.
Lots of ways to achieve this. Tilt the prod or make it with the limbs sweeping up a tad.
https://bowyersdiary.blogspot.com/2011/10/crossbow-workout.html
Alternatively set up the angle by drawing a straight line from about half way along the track to the top edge of the prod and maount the prod at right angles to that.
It's all a bit of a compromise.
Del

Title: Re: How to set a crossbow prod - angle and depth Help needed
Post by: globalmark on August 19, 2018, 08:05:29 am

Hi Del

Thanks for the reply - so basically a good gauge is half way along the track to top of the prod ? not sure i follow exactly as i didn't cut any hole yet for the prod - as mentioned my prod will be in the middle of the stock not stuck on the end - so not sure how to do that unless i just use half the draw length stick the prod on the end temporally and do that ??
so there is no set angle ?
how about depth of the prod - exact middle of stock or closer to the top ? i would have thought closer to top but need enough wood for strength But is there a correct method or is it all just guessing ?

Thanks Mark

Title: Re: How to set a crossbow prod - angle and depth Help needed
Post by: Del the cat on August 19, 2018, 08:15:43 am

Mount the prod as high as you can without fouling the fletchings... that's why most medieval/primitive crossbows only used 2 fletch! :)
Sounds like you have the right idea.
Del

Title: Re: How to set a crossbow prod - angle and depth Help needed
Post by: globalmark on August 19, 2018, 10:53:40 am

Hi Del

Thanks for that Info - Just had a go at Laying it all out - come up with almost exactly what you have drawn there - seems to be approx 6˚ anyway and i also put just below the fletching slot so bit less then half way down the stock .
will attach pics what do you think -
also any recommendations on the fixing method - I was thinking make that slot larger and wedges held in by cover plates both side or a longer threaded Bolt/rod from the front - the prod came with steel plate and 2 rubber small stickers ??

Stock is currently very long as thats the length of timber I was going to cut to length after fitted the Prod _ how much sticking out the front is a good idea ??

Thanks Mark

Title: Re: How to set a crossbow prod - angle and depth Help needed
Post by: Del the cat on August 19, 2018, 11:21:25 am

There's loads of ways to fix it.
Your two ideas are both sound, don't worry too much about the angle as you can adjust it by putting in a thin wedge anyway.
I quite like the clamp bolt screwed in from front idea, but I've not used it myself.
I think rubber (or leather) facing on the prod where it is clamped is always a good idea, it helps to avoid any sharp edges which would concentrate the stress.
Del

Title: Re: How to set a crossbow prod - angle and depth Help needed
Post by: globalmark on August 19, 2018, 12:30:52 pm

Hi Del

Thanks for that - when get around to doing that i will try and post a pic or something hopefully during this week
 - thanks again Mark

Title: Re: How to set a crossbow prod - angle and depth Help needed
Post by: globalmark on August 24, 2018, 12:53:23 pm

Hi
To anyone interested pretty much finished today - little bit of polish , change few nuts more decorative ones, fine tune few bits  but shoots great in garage anyway  -
Thanks all for help everyone
So here are few pics - any questions happy to let you know . Also have more pics of parts if anyone interested - need to get to a field and test distance yet .
Finished with sanding sealer then few coats Danish oil , bees wax on top - Home made string with 28 strands of B50 and used Long bow serving thread - then wrapped Middle serving with thick linen thread and covered all in bees wax, Stainless steel plates (hiding prod hole and shoulder rest),Fold up Aluminium foot stirup, Arrow holder -Bit old bandsaw blade .
Home made Bolts/arrows - IPE , Oak , Maple and one bit shop dowel approx 9.5mm dia , turkey feathers , arrow tip glued on
Might need a sight eventually
Mark