(I think I was turned on to this by Shannon Rogers in the Hand Tool Workshop – and since then, it’s been a go to item in my kit.)
Its one of my favorite tools, because of it’s simplicity and general utility is a router plane. I have a pair of small ones that I use for close in work, hinge mortising and fine trim work. I have a pair of largers ones set up with optional fences and with different style blades. They excel as working on the bottom of flat surfaces that need trimmed parallel to a higher face.
Router planes, or “hags tooth”, it is a very simple tool.It comprises a cutting edge that is held in place below a flat sole. It’s held on the right and left sides, with the right and left hands, and generally used by holding one side in place, and rotating the other side. It can be used with the blade facing away from you or towards you. The blades usually can be turned 180 degrees, to have the cutting edge in front of the sole, allowing working all the way up to a stopping point.
I use these for joinery when I need to clean up a dado or rabet that I’ve blasted out with a chisel (or with an ATB tablesaw blade). It leaves the bottom of the dado nice a clean, allowing for a very good glue joint. I have also used them to clean up tenon cheeks, however when I do that I attach an auxillary base to the bootom of the rotuer plane to allow for spanning the wider gaps that tenon will create. Using another peice of stock, the same thickness as the stock the tenon is cut from, is required to ensure that I’m staying parrallel to the surface. I made one out of 1/2″ mdf, but would like to make another (when I have time) out of a clear substrate so I can more easily see what I’m doing.