KBBS Archive 50,000

Dynel?

Posted By: Pete Rudie
Date: Thursday, 26 July 2001, at 2:40 p.m.

In Response To: Re: Sam, what is your opinion? (Tony)

I recall a thread on this topic that was interesting until degenerating into a flame war. If stiffness is resistance to deformation and strength is ability to absorb loads without breaking, it seems logical that increased stiffness does not necessarily equal increased strength, for the reason stated below. We come back to the problem that wood has tremendous strength along the grain, but very low strength across the grain. That is, the force necessary to separate adjacent wood fibers is much less than that required to lengthen or shorten them, and that in a nutshell is the paddle shaft problem.

Perhaps one solution is not to use glass as reinforcement, which has good strength but is brittle, but rather dynel or one of the other polyesters or aramids, which allow some elongation before breaking? I seem to recall that dynel has about 5% elongation at break, vs. less than 1% for glass. Can't remember the source, so am happy to stand corrected if wrong. But the JR Sweet catalog carries dynel tube for this application, see below (scroll down to Dynel Sleeve & Cord).

: As I remember, Sam Mcfadden's experiment has proved that encasting wood in
: fiberglass does not increase the utimate breaking strength, but rather
: lower it.
: The theory is once a minor break starts, the localized stress is unable to
: redistribute to other area, thereby, concentrated in one single spot.
: Result in the utimate failure of the entire unit. If component (either
: wood or fiberglass) is designed to be able to handle the stess single
: handly by overbuilding, then, why do we need the other?
: Sam, what is your opinion?

JR Sweet - dynel tube for paddle shafts

Messages In This Thread

Paddle Rehab *Pic*
Chip Sandresky -- Wednesday, 25 July 2001, at 7:22 p.m.

Sand aggressively
Paul G. Jacobson -- Thursday, 26 July 2001, at 2:43 a.m.

Penetrating epoxy *Pic*
Pete Rudie -- Thursday, 26 July 2001, at 1:03 p.m.

posting proceedure?
Elliott -- Thursday, 26 July 2001, at 1:43 p.m.

Re: posting proceedure?
Pete Rudie -- Thursday, 26 July 2001, at 2:19 p.m.

Re: posting proceedure? *Pic*
Elliott -- Friday, 27 July 2001, at 8:12 a.m.

BEAUTIFUL!!! *NM*
John Monfoe -- Saturday, 28 July 2001, at 4:58 a.m.

Re: The Celtic knot....
Shawn Baker -- Thursday, 26 July 2001, at 5:43 p.m.

Re: The Celtic knot....
Pete Rudie -- Thursday, 26 July 2001, at 6:36 p.m.

oof
Nick Schade - Guillemot Kayaks -- Friday, 27 July 2001, at 9:10 a.m.

Re: Sam, what is your opinion?
Tony -- Thursday, 26 July 2001, at 1:36 p.m.

Dynel?
Pete Rudie -- Thursday, 26 July 2001, at 2:40 p.m.

Re: Dynel?
Sam McFadden -- Thursday, 26 July 2001, at 3:25 p.m.

Re: Sam, what is your opinion?
Sam McFadden -- Thursday, 26 July 2001, at 3:07 p.m.

why d'ya think that is, Sam?
Les Nightingill -- Thursday, 26 July 2001, at 4:41 p.m.

explanation
Sam McFadden -- Thursday, 26 July 2001, at 7:06 p.m.

That helps a lot, thanks Sam *NM*
Les Nightingill -- Thursday, 26 July 2001, at 9:45 p.m.

Re: Sam, what is your opinion?
JimC -- Thursday, 26 July 2001, at 5:15 p.m.

Re: I'll just have to make another
Chip Sandresky -- Thursday, 26 July 2001, at 7:34 p.m.

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