I have been writing out the process I went through in building an Oldwolf Workshop version of a Medieval Hutch Chest. If you are coming in on the middle of the saga you can catch up on where we've been by clicking on the link HERE.
Here I am using a whole article to explain just how I fit and set the till for the chest. A till is at least the verbiage I use for the small segregated area on one side of the chest's interior. Its a nice place to store more delicate or smaller items.
I had the choices of using a 1/4" straight bit in the router to plow out these grooves, but honestly, in those situations I feel like I have less control than I'd like. So I stayed with the hand tools on this one, besides any excuse to use my router plane. I carefully measured, and remeasured, and remeasured again to set out where I wanted the dado's cut using a carpenter's square to set the angle at a good 90 degrees and making sure there was space for the lid to lay down flat with the larger chest lid closed. I then shortened the dado on what would be the upright panel by another 3/8ths inch so I could cut a haunch in the panel to help hide the dado. With a 1/4" drill bit I bored the ends of the cut to a 1/4" deep.