Wood Frame Pack

I would NOT cut into the spars at all. Doing so makes for lots of weakness. Bad idea.
I had a similar problem when making pack frames out of aluminium arrow tubing (same as tent poles really). So I made fittings to hold the joint together.

This is the sprung frame by itself.

This is one of the joints. Couldn’t you do something vaguely like this with your wood frame?

Cheers

In regards to the notches versus mortis and tenon, I wonder if you really need either?  Could you just put them on top of each other, use wood glue and then wrap something around it for strength?

Sailors have been lashing spars together since mankind first learned to harness the wind to move a water vessel. Not only are such lashings durable and reliable, but they have some inherent give so that stresses are absorbed by (small) movements of the joint rather than being transferred to the spar(s).  With a little experimentation, I bet that give could be exploited to produce a more comfortable carry.

A square lashing (http://www.animatedknots.com/lashsquare) is commonly used to bind spars at right angles. A diagonal lashing (http://www.animatedknots.com/lashdiagonal) is used for braces. You can double up a structural member using a sheer lashing (http://www.animatedknots.com/lashshear).

Using modern spectra cordage for the lashing would minimize bulk and maximize strength and durability. Finish the wooden parts in marine spar varnish and you would have a beautiful, flexible and durable pack frame.

And while it might not look like fine furniture…it would be totally unique and oh-so cool. And what would be more awesome than the juxtaposition of such a frame with modern packbag, belt and shoulder straps hung off it?

Fiber Fix is just a woven composite of fiberglass and some other fibers that are pre-treated with an epoxy that reacts with moisture. I’ve wondered if it had carbon fiber in it, but inquiries to the company went unanswered.

It works pretty well, and is moderately priced, however if you bought fiberglass cloth and epoxy in bulk, it would save you a lot of money over Fiber Fix.  Even buying bulk kevlar/carbon fiber composite cloth would probably be cheaper in the long run.

Whatever epoxy resin that is on the woven composite, cures pretty fast though.  A little too fast (and even with just atmospheric moisture).  Before wrapping my carbon fiber/7075 Al frame with some Fiber Fix at joint areas, i had cut up some of the “tape” so it wouldn’t all cure at the same time and i could use it on more than one area.  Some of the last used stuff, did not bond very well because it was already curing by the time i got to those other pieces.

Overall, i would still recommend it. Just use it fast.