I want to tidy up the bottom edge of a wooden door threshold.
I've never used a router but I thought it would be the perfect tool for this, running the router along the top edge of the door sill and cutting away rotten timber along the bottom edge. Sounds simple, I just have to buy the appropriate router bit. But after some fruitless searching I am at a loss to find the bit I need. I guess I need a slot cutter bit (to cut away the underside of the sill) with a shank mounted bearing (to run along the top edge of the sill).
I found template edge trim bits that look a bit like that (but the bearings are are all flush with the cutting edge) but was surprised that nothing off-the-shelf seems to be made (I could add a bearing and collar to the shank of a cutter bit but this does not seem to be recommended). All the guided cutter bits use an end bearing. I could use a guide fixed to the back edge of the step I suppose.
Is that the best solution or is a router the wrong tool for the job (there is no space for a circular saw etc though a multi-tool cutter could do it).