The side rails are 54.25" long, 3.5" wide, and have 20 degree angles at both ends. The dados for the treads are 3/8" deep and are also cut at 20 degrees and are 10.5" on center starting from the top (the highest step is at the bottom and is about 11.75" from the floor). The top of the side rails have a relief cut that is .75" x 1.5" to allow the ladder to extend under the top bunk far enough for some "L" brackets to fasten the ladder to the underside. The treads are 3.5" wide, and the overall width is 12". I eased all the edges with a 3/8" round-over bit.
I assembled it with brads and glue. I also got some no-skid drawer liner from the dollar store and hot glued strips under the feet and in the notch between the ladder and bunk to protect the floor and trim.
We take ours down to put the slide in. You could change the angle so the ladder would be a bit more steep, but allow the slide to close without removing. The down side is it may make it a little harder to climb down, especially during the night. You could also tweak the tread spacing to make each step exactly the same spacing as the first.
I can put together a Sketchup drawing with dimensions if anyone is interested.
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