Thursday, March 5, 2020

Bunkbed Ladder

A friend of my wife got a used bunk bed for her son, but it didn't come with a ladder. My assistance was offered, and a new project came across my bench.
I met with her and we decided on a few of the design choices for the project. I planned to make it out of cedar to match the existing bed material, and we decided to put the ladder against the far wall of the bedroom (center in the picture below). Other than that, I had freedom to do whatever I wanted.

I came up with a rough plan and rough measurements, then sketched it out for a sanity check. 15-degrees seemed to be a standard ladder angle, so I went with that.

The first step in the construction was to rip the stringers to width on the table saw. My shop is a disaster of a mess right now, but I was able to angle the saw so the full length of the wood would not hit into anything after cutting it.

I then rough cut the stair treads to length on the miter saw. The "plan" was to get two treads per piece. I intended to only need four treads, but I cut enough for six just in case.

Even though I went through over a dozen pieces of cedar at Lowe's, they were all cupped in some way. You can see how cupped they are, looking at the light between the wood and the top of the table saw.

The tool to fix this is a thickness planer. I ran all of the tread blanks through in one orientation to flatten the tops, then flipped them and ran them through until they were flat in the other direction. I settled on about 3/4" final thickness.

And here's the result of the thickness planing. I cut them to final width on the table saw, getting six treads, and final length back at the miter saw.

The next setup was a little hokey. I needed to cut the appropriate angle on the top of the stringer pieces to get the 15-degree ladder angle. This is the janky setup I came up with. I supported the far end on my bench vise, and clamped the workpieces both together and onto the saw securely. This is probably not the best way to have done this, but it worked pretty well. 

 Next was to lay out for the treads. Both stringers were mirror images of each other, and that made the layout a lot easier to figure out. To give the treads more strength, I used a special blade in the table saw called a dado blade. It plows out a trench in the wood in one pass, giving the tread something to fit into.

This is the dado blade setup. It took several practice cuts on a scrap of wood to get the right thickness. The dado set comes with a variety of shims and spacers to get any possible dado width up to about 3/4". I don't have an insert plate to use with my dado set yet, so I used blue painter's tape to try to reduce tear out of the wood.

This is the result of cutting with the dado set. You can see now how it will go together. The treads will fit into the dados on either stringer. They'll be glued and screwed into place.

You can see that they treads over hang on the front, and this is on purpose. The next step was to round all of the hard edges over, and the tool for that is a router table.

I don't have a router table, so I threw one together in a few minutes. It's mounted in my bench vise. I made an adjustable fence for the router table, but the round over bit I used had a guide bearing. The bearing meant that once I adjusted the bit for height, all I had to do was run the workpiece up against the bearing and it would cut consistently. The fence wasn't necessary for this project, but I plan to use this temporary router table for other projects and wanted the fence for them down the road.

I drilled clearance holes in the stringers so the screws were countersunk below the surface of the wood. I then glued and screwed the treads into place. Since the ladder was going to sit on a carpeted floor, I left the stringers long so that I could cut them to the appropriate length in place when I installed the ladder.

So I made this jig to let me do it accurately. The angle of the thinner strip of wood matches the angle of the ladder. On installation day, I simply measured the length accurately in place, clamped this jig onto the stringer, and cut it to length with a circular saw using the jig as a guide.

In the shop, I used a plug cutting bit in the drill press to make custom tapered cedar plugs. I glued these plugs into the clearance holes in the stringers, thereby hiding the screws. I didn't go for a perfect wood grain match, I like the look of the slightly different plug colors. Another design choice would have been to use a contrasting color for the plugs. I wanted the ladder to look as though it came with the bed, and the bed was only made from cedar. So I used cedar plugs. Though cedar can be used unfinished, I put on a couple of coats of wipe-on polyurethane to provide a minimal wear protection. The rest of the bed was unfinished, and you couldn't tell that I applied any finish when I was done.

This is the ladder installed. I cut it to length on location using the jig and a handheld circular saw. The treads are 12" apart, perfect for her son to grow into.

I used knockdown hardware, meaning that the ladder is removable in the event that they move or decide to sell the bed. This screw was drilled in, and it has a cross thread that allows for a screw to come in perpendicularly to it from behind the bed frame rail. The second screw pulls the ladder in close to the bed when tightened.

This is an example of the type of knockdown hardware that I used. The brass piece is what you see in the image above, and the bolt is what is coming from the back of the bed frame rail to hold the ladder in place.

I cut and shortened the upper bed rail. It was safer to have her son not have to climb up and over the side rail, then down onto the ladder. I reused hardware that came with the bed to secure this piece.

Since the only attachment point on the ladder was at the top, if it were kicked from the bottom, it could break pretty easily. So I cut and installed a support piece that anchors it about 2/3 of the way down from the top. This kept the ladder very secure from kicking at the bottom.

And this is what it looks like when people appreciate your work. Since she was a friend, I refused any form of payment. I had a lot of fun with this project, and I'm glad that her son has a cool new bunk bed. But she insisted, and she made me a delicious meal. Homemade chicken parm with pasta and garlic bread. I had a great time and I got a free dinner!

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