Originally Posted by Echo 78
Can anyone steer me in the right direction?
First, for stainless fasteners, call Parker Merrick in Florida at 800-432-3700 or 954-761-1677. Tell them that Whitney referred you, might get preferential pricing. Expect to buy boxes of 25-100 pcs.
Now for the complicated part.
Riveted and bolted (screwed) joints are intended to perform in exactly the same manner; the fastener pulls the joined parts together with enough tension that the joined parts cannot move, and sprung tension in the fastener keeps the joint from developing play and wearing loose.
Blind/POP rivets* typically use compression in the joined materials to provide this tension. In soft materials, if the area under the head or under the bulbed shaft is too small this tension won't last long, and loosening and leaks
will follow. They are an ideal fastener for initial assembly, but don't have an infinite lifespan.
Bolted joints typically use the fastener as a sprung element, but that isn't practical in the case of thin fiberglass/wood structures, so the bolted assembly is once again the spring. When I through-bolt as we're discussing, I will typically use neoprene-bonded sealing washers on the outside, with either truss head or countersunk oval head** screws, metric fender washers to fit, and nylon-insert lock nuts. The neo-bonded washers are slightly conical, and between that and the rubber layer there's a pretty strong spring force. The metric fender washers are thicker than US standard, and don't sink into fiberglass or wood easily.
Bolted joints tend to hold up longer, seal better, can be retightened, and can be maintained. Riveted joints are quicker and a little less expensive, but don't last as long.
Complicated enough? :-)
*If you're going to use blind rivets, seek out "closed-end", which won't need to have the mandrel hole sealed to avoid leakage.
**Neo-bonded washers are a metal roofing or metal building fastener, if your local supplier has no idea what they are. If you want a larger washer and a very clean look, use oval head screws with a neo-bonded washer that the screw head sits down into. This won't be the "correct" size, but between head fill and gasket compression it works very well.
Next we can do bonded joints!!