What psi (pounds per square inch) have to do with this?
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800 Psi is the rated strength of threads cut into epoxy resin for strength, as tested by WEST Systems and published in the articles I posted.
I don't mean to quibble. I think the observation that facts by themselves aren't always applicable or useful in understanding what's needed.
The cited published fact means little per se. I respect West Systems, use their stuff, trust them, etc., etc. HOWEVER:
- Is the cited psi capacity in tension, compression, or shear?
- Does it mean that you take the projected area in square inches of the threads perpendicular to the long axis of the screw in one direction and measure it against "withdrawal" with an imposed load of x pounds?
- How is the load applied? Slowly (like if you take the Superglue guy who is hanging from a helmet which has been attached to a square [inch] which he is gently hanging from) or like you snapped it with a sudden load?
- Is the load applied torsional or just axial?
- The factoid is only relative; and then maybe relevant or not (i.e. proportional with some safety factor)?
How some fitting gets loaded-up and what the substrate is has a lot to do with whether the materials fail. Examples: mortar and bricks. Work great in compression -- work for shit in tension -- work okay in shear. (if you allow me to generalize.)
Another example, more relevant: In the case of the dodger fitting let's talk about how the fitting is "challenged" and has to respond to forces. In the axis of the two screws that hold the fitting that the dodger is attached to things happen very differently if the load is limited to being in-line with the axis of the screws and the "hinge-pin" that fitting has with the dodger frame. Take the same fitting and bend the dodger framer from the side -- suddenly the "hinge-pin" ceases to just a point load and it becomes one where the frame of the dodger is acting to create a twisting, torsional element that is imparting very different forces. So an 100# load (for example) on the dodger isn't transferring 100# -- but the dodger frame becomes a lever that is twisting and bending the little screws in a very different way.
The "speed" (actually acceleration or deceleration) of the load on the fitting is material. Example, for illustrative purposes, you can take 200 pounds and slowly load up the fitting -- but take 200 pounds and slam it onto the fitting and it just is completely different. Force exerted (or received) is a function of load and acceleration (i.e. time, rate of change of speed, etc.)
If the loading is in a predictable directions and is not subject to dynamic changes, then deducing what is adequate is easier. (e.g., a picture frame hanger which is restraining a load very close to being only in shear will hold a __# item). But approximating what a person being thrown around by a pitching boat or tripping and catching themselves from falling forward, back, or sideways is a much different thing. ;^)))
A seemingly simple dodger which (for example purposes) is strapped back and tightened down and fully secured is a different assembly than one that has it front wind rolled-up, it side curtains not in, or it's retraining lines not taught and running aft to make the sides, front, and top function light a stretched membrane.
Anyway, I've OVER DISCUSSED THIS ISSUE WAYYY TOO MUCH. ;^))) I apologize. Hopefully JViss will have turned his thread alert off.