How to Excavate Large Mortises

Question: I know you get thousands of questions everyday, but I thought I’d ask (being the noob woodworker i am).  I’m building my first workbench (been reading your blog, great stuff), and am a bit stumped on how to tackle the large mortise-and-tenon joints for the legs. 

I can’t use a normal pig sticker/mortise chisel for the job (as the largest one I have is 3/8″), so how do I do it? I don’t have a drill press, and I am trying to keep this strictly hand tools. Do I hand drill and pair out the edges?  If you could explain, I could get some sleep.

- Brian Simpson

Answer: For furniture work, you almost always excavate the mortise with a chisel alone when working by hand. However, workbench building is much more like timber framing than it is like cabinetry. So I find it best to excavate most of the waste with a drill. In your case, a 12″- or 14″-sweep brace and a large auger (whatever you can manage) will do the job.

Poke as many holes as you can in the mortise. Then bash out the waste with your mortise chisel. Pare the walls with a chisel to clean things up.

Cutting the tenon is no different than in furniture. However, you might select a rip-filed panel saw to cut the cheeks. Otherwise the work will be slow-going.

– Christopher Schwarz