The 100 x 30 pieces were duly ripped into two 50 x 30 and then glued back together (bookmatched) as 50 x 60s. This has the effect of reversing the grain, so any tendency to warp will be largely cancelled out.
It also produces some nice grain effects, hope you can see it here :
Also made the top and bottom members of the two sides, cut the tenons : shoulders on the TS with a crosscut sled, sides on the TS with a vertical tenon jig - see below (this was done before they were shaped of course, I just forgot to take the photos !)
They were then shaped with the obligatory G&G cloud lifts : rough cut on the bandsaw, then smoothed out by hand with files, glass paper, spokeshave etc.
Then I cut the matching mortices (12mm, 35mm deep) using the router in a router box to give me a bit more stability.
Managed to make one front and one back corner post OK (have been known to make two identical !)
and did a quick dry assembly.
Next step will be to rout or TS a slot for the side panel. I will also add a bracing cross member in the middle, but it will be on the inside edge, hidden behind the panel and will also serve as a shelf support for the middle shelf which will be fixed to brace the middle of the cabinet.