I'm building a Roubo bench with a 4 inch maple top. The top has to have 4 mortises cut that are 2-1/2x5x2 deep. They are huge. I started with an electric router, bushing and template until I ran out of bit at 1 inch. That was easy and accurate. Then I went to drilling and chopping. I must be doing something wrong, or it's just the nature of this beast. It's taken me all evening just to chop out the other inch of just one. Any recommendations?