Does anybody know if there is a 1 3/4" or 1 7/8" auger bit on the market for use in a 1/2" drill for boring 2" mortises? Milwaukee only makes them up to 1 1/2". Their 1 3/4" "self-feed" bit is more of a saw-tooth type bit, and doesn't clear chips from the bottom of a 4" mortise.

I had the same problem and could find only a couple of very expensive suppliers (over $100 per bit). I ended up using the inexpensive sawtooth Forstner type bits sold by Woodcraft. In spite of warnings in various books on timber framing, I was able to drill with a 1-7/8" bit within the 2" mortise marks, even where knots were present. My drill is a Milwaukee 1007-1. I made a simple fixture, a 2" hole in a 1' piece of 2x4 planed to a thickness that causes the bit to bottom out at 4-1/16" (about 1-3/16" on the 2x4). If you need to drill deeper, you could use thinner stock.

I forgot to mention - you do need to make 2 passes with this bit. Drill 2" deep, clear the chips, and then finish the hole. jekbear

The 1 1/2" auger bit I got about a year ago cost me $75 so a bigger bit costing around a $100 sounds probably right. When I got my antique boring machine and bits, one of them is a 2" bit. I use this to bore out a 2" mortise. Mortises should be deeper than the length of the tenon to 'allow' for shrinkage of the timber that has the mortise in it. So clean 'bottoms' shouldn't be a big concern, cleaning out with a chisel usually does the trick. Mortises should be at least 1/8" to 1/4" deeper than length of tenon, maybe even more. Good luck, Jim.