I needed some holes for the Roubo legs to slot into. These are through tenons so it is important that the workbench top is close to flat and has square edges otherwise the lay out lines for the mortises on the top and bottom will not match. I had put a lot of effort in squaring each piece of the top before the glue-up so it only took 5 minutes with a jack plane to get rid of the glue squeeze-out and any uneven parts of the surface.
I simply placed the legs on the upside down bench-top to figure out by eye where they should be located. They ended up being 13 inches from what will be the bench end after it is trimmed to size. I hope this will allow for an end vise if I ever choose to install one: I think a Wonder Dog will do the job, though, given that a lot of people don’t use their end vise all that much. The simpler the better.
Marking the mortise lines was a case of tracing around the leg tenons and then transferring the lines to the top of the bench. I made sure to score the lines with a knife, and then a chisel, so that the subsequent boring/chiseling did not damage the wood beyond the mortise.
So the tenon’s mortise waste was then drilled and chiseled out. The dovetail’s mortise was sawn and chiseled – a much faster operation. The final dry fitting took a few hours to complete because it is difficult to figure out where any tight spots were (each leg assembly has two tenons, two mortises and many shoulder segments to investigate). Eventually an acceptable fit was managed.