Hi Carl,

Are you talking about mortises or peg holes? If you are talking about mortises, I'd agree with Brad on a boring machine or chain mortiser. However, you can use just a drill without a guide. You could freehand it with a magic marker line on your bit for depth reference. If you go that way most likely, you are going to have a significant amount of chisel work and slick work to get the mortises right.

It really depends on how you want to work. If you are looking for speed and precision the chain mortiser is the way to go; precision the boring machine; and if you just want to work with small economy and no time constraints you could just drill them and then hand tool. Brad mentions that the boring machine is as fast as the chain mortiser. I have only used a boring machine once (so I might not be as fast) but cutting circles instead of rectangles is just going to take longer, due to the chiseling of crescents and corners in the mortise.

As far as the pegholes, you can purchase the "timber framing portable drill guides". Again, it is up to you to balance the price of these puppies against how much you will use the tool. They are great for precision and speed. Also using the right auger bits will allow the drilling of pegholes to stop before blow-out because the screw at the end of the bit will lose purchase before blowing-out the other side. It seems that all the drill guides are in metric. Does anyone know of drill guides for standard bits?

As an aside, I would recommend always drilling the pegholes before the mortises. If you don't there is chance of your bit falling of the axis you want when it freely (no wood to cut) passes through the mortise.