I got the drum sander mounted on the platform last night. It has captive nuts in its base for mounting, and a pencil was sacrificed to mark their locations.
The sander in the stowed position. This shows the back bracing piece. Because the platform rotation will be limited to 180 deg, the shorter tool (planer) will be rotated on this back side so I can maximize the height of that lateral support. Part of this exercise is to see how much room there is to extend that piece upwards. With the planer head raised higher than I'll normally need, I found that I can raise that back edge about 1.5" more and I can change the shape of the back piece to create built-in gussets where it meets the sides.
Here you can see how the knob on the drum sander dictates the height of the shelf. I probably have about a 5/8" or 3/4" gap there.
And because the drum sander is more heavily weighted towards its right side (the motor), this is the equilibrium point with the heavier planer on the bottom. I could shift the planer, but that would cause its handle to protrude out of the side. I could shift the sander about 1-3/8" to move its motor towards the center, but I'm not sure that will help much. It's not ideal, but even with the tools unbalanced, it's easier to rotate with both tools installed than with only one.
