Posted by Graham Knight on October 10, 2003 at 10:25:55:
In Reply to: Glue Strength Test Results posted by Mark Jones on October 10, 2003 at 09:37:31:
That has always been my experience when using epoxy for any purpose, the glue joint is always stronger than the wood, regardless of the wood used.
Even in the case of poorly made joints which I have been guilty of on occasion, the joint was always stronger.
: In the course of building Bo-Jest, I've regularly performed strength tests on each batch of epoxy mixed. Early on I went from volume mixing to mixing by weight using a gram scale; chemists involved in developing epoxies for use mix by weight, so I'm told. My tests are limited to simple separation (pry) and torsional forces, and are not measured scientifically by ft/lb but by result. All tests were performed upon plane-milled Douglas-Fir, "Poxyshield" glue as supplied from Glen-L was used with "Slow" type hardner.
: In all cases penetration was sufficient to cause complete fiber separation to at least a depth of 1/4" into the respective 1" sample pieces. Prying both by leverage and impact resulted in separation both parallel and perpendicular to the joint axis, but never did the glue separate from the wood. That is to say, the wood was always rent from itself, never the glue line.
: In regard to saturation depth, comparison of my solid wood joints to that of APA plywood gluelines seemed to be identical.
: I'm pleased with the results.
: - Mark