As an example, I built a quad folding bunk bed that hangs off the ribs and the chair rail. It supports four full size adults simultaneously. We're talking probably 1500 lbs if you count the framework, mattresses, and people.
The ribs are really strong.
I have a recipe for you to follow. What you will do is install at least two rivnuts in the bus rib, on either side. Then, a piece of flat bar with the end bent out will be bolted to the rib. A hole drilled through the end of the flat bar will support a carabiner, then you'll attach the hammock to that.
Get this particular rivet set from harborfreight, because it's inexpensive and seems to last particularly well:
3-in-1 Riveter Kit
Order this bag of rivnuts from amazon. You want the 1/4-20 rivnuts.
uxcell 100Pcs Zinc Plated Carbon Steel Rivet Nut Rivnut Insert Nutsert 1/4-20: Amazon.com: Industrial & Scientific
You'll need a 25/64" drill bit for the rivnut. (sorta special)
A 1/4" drill bit for making a pilot holes and mounting your bolt holes.
2x carabiners for hanging the hammock.
Step bits to drill the carabiner holes.
Tool wax to keep your drills sharp.
Stuff from the hardware store:
Some 1/4-20 bolts. Try to get grade 5 or better fasteners.
Some lock washers and washers for the bolts.
A piece of flat bar, cold or hot rolled, doesn't matter. Dimensions should be 1/8" thick by minimum 1" wide. Personally I'd go 1.5" wide.
With a hack saw and a fresh blade, cut your flat bar into two lengths, 12 " long. Sparingly use some of that tool wax on your blade, you'll be amazed how well it works. (try just wiping a finger tip of it on the middle of the blade)
Each time you drill a hole in steel, dab a little swab of drill wax onto the tip of the drill bit. Your bits will last a lot longer and you'll save money.
All holes drilled should be in the center length of the bar. Don't go on one edge.
Using the pointiest step bit, drill one hole on the end of each bar, about 1.5" from one end. Drill it just big enough so you can clip the caribener onto the end of the bar.
Using your 1/4" drill, you'll want to drill three holes for your nutserts. At the opposite end of your carabiner hole, mark a point about 1 inch inward from the bar end, and another at 3, and another at 5 inches.
Do the same for the other flat bar.
Take each piece of flat bar and bend a little past the middle, probably about 30 degrees or so. You can bend it on the edge of the sidewalk or a rock, or a 2x4 or something. Just press the corner of whatever you're bending on against the bar.
What you want to end up with a small radius, so your three pilot holes still lay flat on the bar, and the carabiner hole has enough clearance to hang free when the thing is bolted to the wall.
Find the rib on the bus (look for the rivets) and make sure you're not drilling where there's a wire running up the rib for the running lights on the outside.
Lay bar against the skin (and where the rib lies beneath) and use a sharpie pen to mark through your pilot holes.
Now, use your 1/4" drill to drill three pilot holes you just marked.
Do this for both brackets.
Now drill out your pilot holes to 25/64" with the bigger drill bit.
Before you go mounting your nutserts, I'd suggest practicing first. Using a piece of extra bar stock, drill a pilot and a full size hole, and attempt to insert the nutsert and set it.
Go watch this video, then come back. I'll wait right here.
Ok, now that you can do the rivnut install, go ahead and set the three rivnuts on each side of the hanging points. You'll have a strong handshake afterwards.
I'd suggest painting your brackets because they will rust eventually, and if you're feeling up to it, try rounding the sharp corners with a file or even just a hack saw. Smooth is the way to go, because you're making furniture.
Finally, bolt the brackets with the caribiner hole hanging downward. Against the bar, lay the flat washer, then the lock washer, then the nut through it. Tighten into the rivnut hole. Don't over tighten, it should be snug and not feeling like you're going to rip it out of the wall.
Clip caribiners to brackets, and hammock to caribiners. I'd say this solution would be good for about 300 lbs or so.
Originally Posted by LtBattleBadger
I don't have access to the sides as I don't have the inner skin off. I don't possess the skills, tools, or knowledge to take off all those rivets and properly reattach the skin.