On Wed, 31 Aug 2011 17:39:10 -0500, DougC
wrote:

For a project I can use either kevlar cord or thin steel cable.

The breaking strength for a given diameter (at least in the small sizes)
comes out very very close to each other: in one instance, .31" steel
cable was rated at 184 lbs, while .3125" kevlar cord was rated at 175 lbs.

Everywhere that sells the stuff usually gives the breaking strengths of
both, but not the working loads.

From other places online I gather that the typical rated working load
for steel cable is 20% of the breaking strength. Is this assumption
reasonable?

And what is the % for kevlar rope? The same, or higher or lower?

(-I know that there are other factors like kevlar's higher price, lower
abrasion resistance ect, but those aren't significant in this instance-)


Apparently the working load is an arbitrary percentage of the measured
breaking strength. see:

http://donsnotes.com/products/ropes.html
http://www.jamestowndistributors.com...+England+Ropes
http://www.phoenixrope.com/usage.html

See
http://www.tpub.com/content/MIL-SPEC...1145E00002.htm
for a sample Mil spec. Note only breaking strength specified.
Cheers,

John B.