question about Dacron?

[muntries]

I just want to ask a couple of quick question regarding making a flemish string. The suppliers are selling Dacron B50 at 1/4lb and 1lb. I'm assuming this is individual strand strength and relates to the number of strands per bundle, am I correct? I'm planning to have a go at making them after I found this great build along http://poorfolkbows.com/flemish1.htm.

Second question, how do I find out how many strands for a 40lb bow for either of the two B50's the 1/4lb &/or 1lb? Or am I completely missing the point?

Simon

[matt61]

Hi Muntries
Those weights they quoting are the weight of the roll of string.A quarterpound roll will make quite a few strings, especially if you buy two colours for making flemish strings. Off the top of my head a strand of B50 has a breaking strength of about fifty pound.For a 40lb bow, 12 or 14 strands would do the job.
Cheers
Matt

[muntries]

Thanks Matt,

Good job I didn't go off my own instincts there otherwise I would have been making a string thick enough for ships rigging

Cheers

Simon

[Stickbow Hunter]

Good job I didn't go off my own instincts there otherwise I would have been making a string thick enough for ships rigging

Yep.

Matt's pointed you in the right direction.

Jeff

[Bill]

Please forgive me if I'm incorrect, but my 1/4 pound spool of dacron has only five pound breaking strain thread on it and that is why I make my strings with twelve strands for a 50# bow I use 12 strands x 5# = 60# the extra strands for safety, but if each strand has a breaking strain of fifty pound then all for the better..........Bill

[Stickbow Hunter]

Yeah Bill B50 is approx 50lb breaking strain hence the name. If it was only 5lb breaking strain your string would break. Some of the newer materials like Dyna Flight 97 are around 125lb breaking strain.

On the inside of the label that came with your Dacron it should suggest how many strands for what poundage bow.

Jeff

[GrahameA]

Afternoon All.

It is a little hard to find actual values for the breaking strain of various fibres used in bow strings however, there are some numbers of the web if you want to search for them.

Adding to Jeff's comment

Regarding B50 -

Breaking Strengths are no longer published by BCY because discrepancies occur, due to different test methods. BCY can provide minimum breaking strength information upon request, but as a general guide, B500 Dacron has a 45lbs break strength. It should be noted that all modern materials far exceed the strength required to perform satisfactorily as a bowstring material.http://www.abbeyarchery.com.au/p/BCBD50 ... +blue.html http://www.bcyfibers.com/technical_shee ... -17-08.pdf

Brownell string material - http://www.brownellarchery.com/products.htm

New string materials

Commercial string materials have developed from B50 to
Kevlar and then Fast Flight. We are now in the next
generation of string materials with stronger, better
shooting products such as BCY Dyna 8125 and Brownell
D75. Both these materials offer superior performance in
comparison with regualar FastFlight. For a non-stretch,
non-creep compound string material you now have a choice
in several blended string materials such as BCY 450 Plus
and Brownell Ultra Cam, the new standard in
compound string materials.

String material comparison chart
Material Breaking Strength (single strand) Diameter
Brownell B50 50 pounds 0.018
Brownell Traditional 54 pounds 0.019
Brownell FastFlight 95 pounds 0.018
BCY Dyna 8125 120 pounds 0.018
Brownell D75 130 pounds 0.016
Brownell S4 160 pounds 0.023
BCY 450 Plus 155 pounds 0.021
Brownell Ultra Cam 125 pounds 0.012

http://www.jvd.nl/catalog/pag68-71.pdf

A small read concerning materials - http://www.texasarchery.org/Documents/A ... 1rt100.pdf

[Bill]

Well there you go, many thanks, Jeff and GrahamA another new day and I've learnt another new thing.
I always thought that each strand of the Dacron B50 was only 5lb, but there you go I was wrong and now am the better for it.

[muntries]

so does having more threads in a bundle actually affect performance ie arrow speed?

[muntries]

Bill, better than thinking they were only 1/4lb

[wal]

Jeffros sticky at the top of this page is great, and this link explains a good round string as opposed to a cable.

http://www.rmsgear.com/tutorial_string_2bundle.htm


Cheers

[GrahameA]

Morning.

so does having more threads in a bundle actually affect performance ie arrow speed?

Going back to first principles.

For given thread diameter and mass per unit length.

1) The more threads you have in a string the heavier the string will be. Thus you are accelerating a total heavier mass and the string will contain a greater proportion of energy. i.e the Arrow will leave the bow art a lower velocity.

2) The more threads in a string the larger the diameter of the string thus the more drag thus more energy used in accelerating the string. End result the arrow will leave the bow at a lower velocity.

So more strands than req'd give you a double hit in slowing down your arrow.

[muntries]

Thanks for the info Steve, then with my weight bow I'll probably stick with 12 strands. I'll post my creation/monstrosity when I get the string and finish it

[Brumbies Country]

Morning.

so does having more threads in a bundle actually affect performance ie arrow speed?

Going back to first principles.

For given thread diameter and mass per unit length.

1) The more threads you have in a string the heavier the string will be. Thus you are accelerating a total heavier mass and the string will contain a greater proportion of energy. i.e the Arrow will leave the bow art a lower velocity.

2) The more threads in a string the larger the diameter of the string thus the more drag thus more energy used in accelerating the string. End result the arrow will leave the bow at a lower velocity.

So more strands than req'd give you a double hit in slowing down your arrow.

It's a good point Grahame. The Historical bow division (ABA) stipulates Dacron and being a relatively small bloke and not therefore being able to use heavy poundages I've looked at this a bit. For my around 45 lb self-bows 10 strand dacron strings work out fine. While we are on Dacron I talked to Daryl Reeks recently. He shot his World IFAA longbow records with dacron, has shot with dacron for years, recently switched to FF, but he reckoned he didn't lose much re performance using dacron.

Simon

Simon