Paradise ponders, rectangular redwood edition... Well, now that I've finished snowplowing for the day, I managed to get some time in on the steps project. I made 3 more passes through the planer on each of the 8 4x4s that I started with. That's 24 passes today (half filling my dust collection barrel!), and now the redwood 4x4s are distinctly rectangular in cross-section – but the corner radius milling has been completely removed.
The first photo shows the 8 former 4x4s; the next two show the micrometer measurement of the thickness and width, respectively. So ... the 4x4s are now dimensional lumber, 2.8225" x 3.3530". :) The thicknesses are all the same to within my ability to measure, though that will change as the pieces dry out. The widths vary considerably, though: from 3.2733" to 3.4504". Note that all of them are under the 3.5" that they're supposed to be. I'm not sure if that's the mill cheating us a teensy bit, or (more likely, I think) shrinkage from the wood drying out.
One of the challenges of building out of solid wood is dealing with shrinkage. This project is much less critical than, say, a tabletop. I will be using dowels to keep the centerline of the pieces stable, and then good glue joints to attempt to keep edges from shifting. I'm using good quality glue that resists shear forces, but even so, if the differential shrinkage between two adjacent pieces is too high, they will slip and form a little ridge. The only way I know of to guarantee that that won't happen is to glue up all the pieces and then dry them in a kiln for at least a few days. The few days I've got, but the kiln I do not. :) I'll be letting them dry in my heated barn for 4 or 5 days before I sand them down. Hopefully the majority of any differential shrinkage will have occurred by then..