Crossbows - Everything about Building, Modding, and Using your Crossbow Gear

Latest topics

» Medieval bowyer
by Dark Factor Today at 12:30 pm

» Medieval composite bows
by kenh Today at 10:55 am

» New crossbow builder
by wjbates1430 Yesterday at 2:10 pm

» Airsoft Crossbow-Finished at Last!
by JacobL Thu Oct 12, 2017 7:27 pm

» Powermaster Madness
by c sitas Wed Sep 27, 2017 8:41 am

» Powermaster
by c sitas Wed Sep 20, 2017 9:58 am

» Best wood for a novice?
by Geezer Sun Sep 17, 2017 9:21 am

» Adding a steel sear insert?
by Geezer Fri Sep 15, 2017 7:13 am

» Great Machines
by c sitas Sat Sep 09, 2017 5:39 pm

» Medieval Crossbow Bolts DIY Question
by Rumburak Thu Sep 07, 2017 12:17 pm

» Berkhamsted Castle and Glasgow Museum wooden prod crossbow
by Juniper Fri Aug 25, 2017 3:54 pm

» Beware of Alchem
by Archer46176 Mon Aug 21, 2017 3:33 pm

» How to measure and cut leather for prod
by Celtic Archer Sun Aug 20, 2017 5:56 pm

» Crossbow with built in lever?
by John Edgerton Thu Aug 17, 2017 12:38 pm

» Of Bows and Torsion Engines
by JacobL Mon Aug 14, 2017 12:03 pm

» Early Lever and pin Crossbow
by topfmine Mon Aug 14, 2017 8:56 am

» Crusader crossbow
by topfmine Mon Aug 14, 2017 8:53 am

» First Efforts
by rickraedeke Tue Aug 08, 2017 5:25 am

» aluminum prod
by Phil Abrahams Fri Aug 04, 2017 8:38 am

» First whitetail buck taken with medieval crossbow
by Phil Abrahams Fri Aug 04, 2017 3:38 am

» Airsoft Crossbow
by JacobL Wed Aug 02, 2017 9:11 pm

» Questions about steel prod specs
by JacobL Mon Jul 31, 2017 8:25 pm

» Faking a medieval composite crossbow prod.
by JacobL Mon Jul 31, 2017 8:13 pm

» Airsoft Bow
by JacobL Sun Jul 30, 2017 1:56 pm

» Hello All!
by JacobL Sun Jul 30, 2017 12:54 pm


    Crossbow string question

    Share

    mazawakhan
    Fresh Blood

    Doesn't mean
    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 14
    Join date : 2015-11-23

    Crossbow string question

    Post by mazawakhan on Wed Jan 27, 2016 10:54 am

    Im about to make a string for my new crossbow. I am going to make it out of hemp twine to keep it somewhat historically accurate. The twine has a 20 lb rating. What is the rule of thumb for making the string as far as strength goes? I think I remember it being 4x the pull weight of the bow. So that is this correct?
    avatar
    twedzel
    Fresh Blood

    Doesn't mean
    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 47
    Join date : 2014-01-08
    Age : 45
    Location : Vancouver Island BC

    Re: Crossbow string question

    Post by twedzel on Wed Jan 27, 2016 1:26 pm

    Before you start, don't assume the packaging is correct. Do a few break tests to get the actual strength of some single strands. Hemp twine is usually made of shorter fibers (poorer quality) than what was historically used. This can leave it prone to weak points. So you want to make sure you are on the conservative side for number of strands per draw weight. Standard recurves tend to go 4-5x draw weight and crossbows higher as they are subject to more forces as well as abrasion. A lot of guys are using 28-36 strands of Dacron (which is rated to about 50lbs) on their Excalibur bows. So you can see a large margin of safety is probably a good idea given the forces involved and the potential damage to the bow if it breaks. Also heavy strings on crossbows is less of a detriment to performance than it is on recurves.
    avatar
    kenh
    Crossbow Junkie

    I live here!


    Crossbow JunkieI live here!

    Posts : 734
    Join date : 2012-08-03
    Age : 69
    Location : Living Aboard a Sailboat in Fort Myers, FL

    Re: Crossbow string question

    Post by kenh on Wed Jan 27, 2016 2:35 pm

    Hemp twine is not going to work very well.  Too short of fibers, and far too many of your 20# strands to make a safe thickness string for any reasonable poundage bow. 

    Long strand flax (not linen) cord would be much more historically accurate, not very expensive online, and much stronger.

    mazawakhan
    Fresh Blood

    Doesn't mean
    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 14
    Join date : 2015-11-23

    Re: Crossbow string question

    Post by mazawakhan on Wed Jan 27, 2016 5:31 pm

    kenh wrote:Hemp twine is not going to work very well.  Too short of fibers, and far too many of your 20# strands to make a safe thickness string for any reasonable poundage bow. 

    Long strand flax (not linen) cord would be much more historically accurate, not very expensive online, and much stronger.
    Thanks for the input! Can you point me to a place that sells this stuff?
    avatar
    kenh
    Crossbow Junkie

    I live here!


    Crossbow JunkieI live here!

    Posts : 734
    Join date : 2012-08-03
    Age : 69
    Location : Living Aboard a Sailboat in Fort Myers, FL

    Re: Crossbow string question

    Post by kenh on Wed Jan 27, 2016 8:57 pm

    Craft Shops - sewing & needle work type crafts.  Some hobby shops.  Ebay -- search on flax cord or flax string.  Or just google "flax cord" and see how many thousands of places sell it...
    avatar
    OrienM
    Workshop Savvy

    Did you see my tool collection?


    Workshop SavvyDid you see my tool collection?

    Posts : 134
    Join date : 2014-08-01
    Age : 41
    Location : New Mexico, USA

    Re: Crossbow string question

    Post by OrienM on Thu Jan 28, 2016 7:07 am

    I made my string from hemp (cheap cord from walmart)...I'd agree it's weaker than some other natural fibers, but  it can be done if the string is made thick enough. Mine is fully 3/8" thick, with heavily reinforced loops...I quickly broke several lesser strings before I got this one to work.

    So, it can work, but using good quality flax will give you a better chance of success. Given the time it takes to make up a decent string (for me, about four hours...), it makes a lot of sense to use the best materials for the job.
    avatar
    Xamllew
    Tinkerer

    If there is a will, there is a way.


    TinkererIf there is a will, there  is a way.

    Posts : 72
    Join date : 2015-06-13
    Age : 25
    Location : Florida

    Re: Crossbow string question

    Post by Xamllew on Fri Jan 29, 2016 12:23 am

    Hemp gets pretty fuzzy but it certainly will work for bows under about 200lb draws. I've been using a fairly thick 3/8" flemish twist hemp string served with dacron for several months of regular use, the added thickness might rob a tiny bit of performance but I prefer the natural look of it over dacron.

    mazawakhan
    Fresh Blood

    Doesn't mean
    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 14
    Join date : 2015-11-23

    Re: Crossbow string question

    Post by mazawakhan on Fri Jan 29, 2016 10:53 am

    Thanks for the replies! I had some B50 laying around and made an initial string yesterday on my homebrewed jig. I will try and make a hemp string this week sometime. My crossbow pulls just under 200.

    Sponsored content

    Re: Crossbow string question

    Post by Sponsored content


      Current date/time is Wed Oct 18, 2017 4:07 pm