Originally Posted by MT4Runner
You could always through-drill the speedrail fittings (once you get your setup dialed) and use PTO pins or through-bolts...or even just bolt/pin the corners and leave the intermediate crossbars mobile.
Drilling through the speed rails was on the list but then I saw several pictures of failed fittings where the cracks started at the point where they are drilled. Instead, I bent some corners on my buddies tubing bender and am going to slug and bolt the corners. This way I'll have diamond plate side rails and still be able to break it down to fit it into a plane. I figure I'll be about $600 in for a frame comparable to a $1,700 DRE or Eddyline that I can still break down. I bought the aluminum stock for the slugs on Amazon for something like $1/foot then just a couple of bucks more for stainless bolts and nylocks. The only drawback is that when you don't have machine shop accuracy for the holes when you drill them you just need to stamp or otherwise mark everything so you can get it back together without pulling your hair out.
You're right about the welded corners, see above. I went with 1.25 tubing so that I could use NRS Oar Towers instead of the DRE style, which I don't like. The tensile and yield strength of either 1.25 or 1.5 sch 40 6061 aluminum is so off the charts relative to all of the other failure points on a raft/frame combo that it doesn't realistically matter.
Inner and outer rails will be welded together and the bow and stern non-speed rail connections will be slugged and bolted if you can follow along with what I am saying. It ultimately becomes a hybrid. The slugged connections are for all intents and purposes like NRS fittings, the adjustable bay fittings are speed rail, and the diamond plate is welded providing the rigidity to the sides.
I figure that if I run into a situation where the frame fails then I have much bigger problems anyway.