Saturday, January 18, 2014

Twine Numbering--They are not Uniform!

As I begin collecting more rigorous data for an up-coming article, I begin testing samples from different manufacturers. I begin searching the net for published data, and I learn a few things that you might already know, and that I knew but just can't get used to:
  • Different company's use different numbering conventions. Robline uses the diameter in millimeters times 10. The others pull numbers out of the air.
  • Strength data is seldom published. The few data points I've found seem accurate, but mostly thread manufactures expect you to guess. Just pitiful.
For polyester twine, some average values:

Robline #4     0.4mm        10 pounds
Robline #6     0.6mm         21 pounds
Robline #8      0.8mm         50 mounds
Robline #10    1.0 mm         90 pounds
Robline #15   1.5 mm        180 pounds

If it is important to you...
  • Make a loop with a fishermans bend or other strong knot.
  • Wrap the line around a broom stick such that the knot is 1 1/4 wraps around from the start. Add another 1 1/4 wraps. In this way, the knot will not break.
  • Hang 2-4 passes over a pull up bar and stand on a bathroom scale. Read how light you are when it snaps, subtract, and divide by the passes.
Then you'll know.

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