Worked a little more on the handle assembly this week, it's going to feel good to complete it and give the toolchest its form. I noticed that in Tom Fidgen's original design, the vertical handle posts were notched into the bottom runner but when he taught his class at Dictum they took the approach of bridal jointing in a bottom stretcher. I emailed Tom about this and graciously, as always, he got back to me with a detailed explanation. The original design had a weak point and had snapped where it was screwed into the bottom runner. The stretcher approach ties in the entire handle assembly into one piece, thus balancing any forces and load exerted.
I wasn't happy with the flatness of the stopped dado area, I had attempted to level it using an iwasaki file but the surface was still much too uneven. When I held it against the toolchest I could see a lot of light, perhaps more than glue could overcome. I decided to lap it against some 220 sand paper which did the trick nicely. No more fiddling, aside from the handle and bridal mortises, the vertical handle posts are pretty much complete.
Notching the upper handle runners.
Slowly but surely progress is being made.