It’s been more than four months since I started this project, but it’s finally done! The bunk beds came out awesome and the girls love them. In this post I’ll give a summary of the steps to build the beds, and then show some photos of the completed bunk.
Welding the Frame
The aluminum frame came together relatively quickly, at-least compared to my wood-box test project. Compared to the wood box, the frame of the bunk had a similar number of welds, except with much larger pieces of aluminum .. which was much more satisfying.
One thing I did learn relatively quickly, was that warping was much more pronounced with my longer pieces of aluminum … a bend of a few degrees causes a lot more deflection over the course of a 6-foot tube than a 6-inch one. The warping is supposedly from over-heating the aluminum … I tried to do faster shorter welds, but I still ended up with some warping.
I designed the aluminum frame to have a lot of vertical strength, but very little self-supporting side-to-side strength. The strength there would come from attachment points on the floor, wall, and ceiling.
My design called for the bottom bunk to be made out of wood, as I wanted it fully enclosed and with laminate to match the existing furniture in the camper.
Welding the Top-Bunk Sheet Metal
I chose to weld a very thin (0.04″ thick) piece of aluminum sheet metal onto the frame of the top bunk rather than using heavier plywood. Having never welded thin sheet metal before, I was in for a few surprises.
The first challenge was that the thin metal warped incredibly fast. I started with the sheet metal clamped perfectly aligned on-top of the frame, and started welding it down around the perimeter starting on one end and moving toward the other. By the time I got to the far end, the sheet metal there had migrated about half an inch to one side.
I had some extra metal to spare, so I was able to just weld it down anyways and then cut off the excess hanging over the frame. However, the bigger problem was that the “bubbles” had formed in what used to be a flat surface, such that when pressed the aluminum would pop downward (and then back up when released). When this happened, a loud BANG echoed through the thin aluminum sheet.
If the bed made huge banging noises every time our oldest re-positioned up top, that definitely wasn’t going to work.
To try to compensate for this, I tried spot-welding the underside of the aluminum sheet to the frame. The trouble here was that as soon as the sheet aluminum started heating up, it would immediately warp away from the frame.
My first two attempts at welding it in place left large half-inch gaps between the frame and the sheet metal, with a blob of filler in between (which meant big lumps on the top surface). Ugh!
It was sad seeing what was formerly a pristine shiny and flat piece of metal getting so pocked up with bad welds and so wavy from the heat warping. I finally decided I wasn’t going to be able to make this pretty, so I resorted to making long “arch” welds that I slowly built up. When I heated the sheet aluminum to start the arch, the metal would predictably warp away from the frame … but by waiting for it to cool, I could then connect the arch to the frame quickly before the sheet aluminum had too much time to run away from me.
It was messy. It looked ugly. But it worked– no more popping on the top bunk! The surface of the top bunk is definitely not flat anymore .. however, with a mattress on-top that doesn’t really matter. The only bummer is it meant that the bunk wouldn’t make a very good table when moved down to the lower position .. which was supposed to be one of the features. However, as it turned out .. lowering the top bunk is difficult enough that I’m pretty sure we would have never used that feature anyways.
Scribing the Walls
I had never scribed something before.. in fact, I didn’t really know what the word meant, aside from that it was something that I needed to do to make a rectangular piece of wood match the curved walls of our Airstream.
However, a few Youtube videos later and I had built myself a home-made scribe tool (which consisted of a piece of wood with a level strapped to it and a hole for a pencil).
In order for the board to be tall enough for the high part of the ceiling, it could only fit right in the middle of the trailer before it was scribed. Therefore, my scribe tool had to be quite long, which made it more difficult to use.
I ended up tracing the curve of the wall in two passes– first with a long scribe tool, and then after cutting a “rough draft” of the curve, I brought the wood closer to the wall and used a shorter scribe tool to make a more accurate final trace.
One of the walls was to have a shoe cubby in it, so I also used my router to cut out a cubby hole. This particular piece of plywood had a stunning image of a bear (two eyes and a nose) formed from the knots.
The existing walls in the Airstream had a rubber edging where they butted against the aluminum, and I wanted to match that. I had a hard time finding the edging (or even what it was called), but finally found the product at Out of Doors Mart.
Oh man, laminating. I’ve spent a lot of time laminating on this project, and gone through a lot of glue. If I had realized how much glue I was going to use, I would have bought it by the gallon instead of continuing to buy the small containers (of which I probably went through a dozen).
I called Airstream so that I could find out the laminate they used in our 2018 Airstream Sport so I could match it perfectly. Here’s the two laminates (which I ordered through Home Depot):
- Solid white laminate for counter-tops: Wilsonart Linen (the “standard matte finish” that I ordered has a little bit of texture to it, where as the factory installed laminate is completely smooth– but it’s really not noticeable)
- White wood-grain laminate for cabinets/sides: Wilsonart White Cypress
I talked about it previously in “Building out the kitchen of our Sprinter van” — but the basic process is to paint wood glue onto the wood and back side of the laminate, let it dry, and then iron the laminate on. Works great, takes forever.
I knew one of the challenges of using aluminum and wood together would be figuring out how to connect the two materials. Everywhere that I wanted wood and aluminum to connect, I needed some kind of bracket that I could put a screw through.
Below are samples of a few of those brackets:
Bung Holes (seriously)
Yet another word that I didn’t know existed. When you have thin sheet metal (or in my case, thin tubular metal) and you want to tap a threaded hole for a screw, what do you do? Apparently, you weld in a “bung”!
Yes, I had to drill bung holes. I know it’s immature, but I just couldn’t get enough of talking about my bung holes.
The purpose of the threaded bung holes was to bolt the top-bunk it place while still having it be removable, as well as the side railings and ladder.
Before I started drilling huge holes in my aluminum frame, I used some scrap to do a test run. Below is a view showing the solid aluminum bung welded inside a hollow square tube with a bolt screwed into it:
Step 1: Drill a big (3/4″) hole
Step 2: Cut a 1″ long piece of solid round 3/4″ diameter aluminum and stick it in the hole
Step 3: Weld the bung in place
Step 4: Grind the welds flush
Step 5: Drill a hole in the bung
Step 6: Tap the hole
I don’t have a photo of the taping step .. but it simply involved turning a tap (a rod with sharp tooth-like threads) with a pair of vice grips.
All in all I had 30 of these bungs to put in place .. so as you can imagine, this step was tedious!
The Ladder and Railings
Another tedious step was welding all the slats in the railings. In retrospect, I wish I had added one more rung to the ladder… but with practice the girls have gotten better at climbing it.
Moving the Light Switch
There was a light switch positioned on the aluminum wall of the Airstream such that after completion of the bunk bed it would be inside the lower bunk. This would be pretty inconvenient, and most likely very annoying (as a 4-year-old would have exclusive control over our lighting).
I decided to move the switch to the new wooden wall on the side of the bunk.
I removed the switch from the aluminum wall, then cut a hole in the wood wall and inserted the switch there. The wires inside the Airstream wall were plenty long enough to pull out of the wall and reach the new location.
I made a little aluminum “patch” to cover the large hole left in the Airstream wall, and screwed that in place.
Ahh, the drawer. I was almost done, and it was down to finishing touches. The drawer was one of my last big challenges. I had had some practice making dovetail drawer boxes from working on the van kitchen so that part was a bit easier this time around.
One thing that made this drawer install particularly challenging was that I had some error in my measurements when installed the bed frame such that the frame resembled a parallelagram with the front shifted about a half an inch over relative to the back. I had to cut some pretty large angled shims to get everything lined up OK.
The final part of the project was a small desk with a cabinet for clothes underneath. Just like in the van flip-up table I decided to use the SOSS brand hidden hinges that embed within the plywood .. which meant I was once again grabbing my trusty router to mortise holes for the hinges.
And of-course lots more laminating. I used a simple magnetic cabinet latch to keep the table top from bouncing around when we’re on the road.
Below the desk is a slot for our laptops– something we never could find a good home for previously.
Slide-out Standing Table
Underneath the top bunk platform is a slide-out standing height table. This is where Sarah and I can eat our breakfast on a rainy or cold morning.
Cubby Hole & Kids Table
When the dinette used to be in the Airstream we kept two IKEA DRONA boxes under the dinette table. So when I designed the bunk bed, I left exactly enough room to fit those two boxes.
The other feature of the cubby is that the top slides out to form a kids table.
On the underside of the table I used two spring-loaded latches to keep the table from sliding out while the kids are using it.
Underneath the table is also a swing down leg:
It took a lot of research to find good curtain tracks … I finally found some I liked on curtain-tracks.com:
I drilled holes in the aluminum track and screwed it directly into the Airstream ceiling for the top-bunk. For the bottom bunk I welded the track in place.
A Test Trip
Before the bunk bed was completely done (but done enough to sleep on), we took a test trip for a few nights to try it out.
One issue that we noticed right away was that the legs of sleeping little ones could slide through the rail and get stuck .. so we later added bumper pillows.
And that’s it! Here are a few more photos of the completed results.
You can read part I, II and III of this series of posts here: