It seems to me that routers (in conjunction with homemade jigs) are an excellent tool for making almost any mortises we need. Clearly faster and more precise than chisels or chain mortisers. A deep mortise can be hollowed out by fashioning a steel sleeve and recycled shank together (mig welded and trued) so as to cut e.g. 6, or 7 inches deep. This sounds too easy and economical. Am I missing something?
