I’m having problems with my workbench, specifically the bench top part. My tabletop portion had a lot of variation in heights of the 2×4’s that I used, resulting in a very heterogeneous surface on one face after the glue up. I’m trying to plane it down to a smooth, homogeneous block, but I’m afraid I will end up not making it square and true. Any tips on this? Any straight edge recommendations to measure the flatness? Hand plane recommendations? I currently have a 5, 4 and 7 Stanley planes.
You could use a router and a flattening setup/sled (lots of videos online to help you through that process) if you have access to one. Paul has videos on flattening large boards with hand tools and a bench top can be flattened the same way. Shop made winding sticks and a shop made straight edge can be produced pretty simply for the work. You can just use some aluminum angle material (make sure you sight it for straightness) from a building supply house as makeshift winding sticks if necessary. Even the sole edge of the #7 can be used as a straight edge to some degree. It is easy enough to camber the blade on the #5 and move the frog back to open the mouth (I would use the #5 for rough work and set the #4 up for smoothing) and use it for heavy stock removal, essentially a #5 scrub plane. Watch any of the many videos available, take your time and build your skills as you build your bench. Keep in mind that you can revisit the final smoothness of the working surface after the bench is assembled if need be. Have fun.