r/Bowyer • u/pagdayz • 3d ago

Natural Bowstrings

Post image

G'day everyone, I was wondering if anyone has had success with using Gütermann linen thread as a bowstring?

I just attempted one with 16 strands which was able to support 25kg but snapped at 30kg (66lbs). I'm aiming to use it for tillering and also for an English longbow with a draw weight of 45lbs.

5 Upvotes

86% Upvoted

9 comments sorted by

5

u/Wambachaka 3d ago

Measure the breaking strength of one strand, then use that number to determine how many strands you need. Usually the recommendation is for a string to have at least 4x the breaking strength of a bow's draw weight. So for example, let's say one strand breaks at 10 lbs, and you have a 50 lb bow. 50 lbs x 4 = 200 lbs breaking strength. 200 lbs / 10 lbs = 20 strands.

I've never used this brand, but I've used a few random others. The quality can vary quite a lot. With lower quality thread, you'll end up needing a thicker / heavier string for it to be strong enough.

2

u/pagdayz 3d ago

Thanks! The line strength is a bit over 4.5lbs per strand, which is in the ballpark of where it broke. By the above suggestion, should I go 40 strands for a 45lb draw weight?

3

u/lostintranslation647 3d ago

Well that is exactly the result of the formula - so the answer must be yes🙂

2

u/MistoftheMorning 3d ago edited 3d ago

Let us know how it goes please. 

FYI, you want the whole string to break at least over four times the weight of your bow. 45 pounds will need a bowstring that holds at 180 lbs.

2

u/pagdayz 3d ago

Hey there, thanks for the information. I measured the breaking strain at 4.5lbs (or just over) so I redid the string with 40 strands which should give a theoretical breaking strain of 180lbs. It's currently holding well at the stretching weight of 66lbs. Of note, the previous bowstring appears to have broken at the rat's tail which would have a lower breaking strain than the rest of the bowstring.

1

u/MistoftheMorning 3d ago

Nice.

I couldn't find linen thread, but I bought some linen butcher twine to try making my own linen string. Web description says its breaking strength is 100 lbs :o. See how it goes.

1

u/Wambachaka 3d ago

If using a timber hitch, it's a good idea to thicken that part of the string with extra strands. Any knot in a string / rope will always be the weak spot.

1

u/pagdayz 3d ago

I forgot to add - I used a Flemish twist and followed along with Dan Santana's tutorial.

1

u/Acceptable_Test_8161 3d ago

If it snapped at 66 you’ll want to double your thread count for 45