tenon joint

More details would probably be helpful. Are these round mortises/tenons? Rectangular? Do the logs have a flat face on which to register a drill press attachment, for example? Or are you going totally rustic here?

If rustic is the answer, then a round tenon cutter on a good drill combined with an auger bit to cut the mortises is probably your best bet.

-- Anything worth doing is worth redoing several times.

You can cut mortises in many different ways. A drill bit in a drill press would work. It would
take a steady hand to do it with a hand held drill. Without the drill press it would be hard
to keep the mortise wall straight.

Another way is to use a router. A plunge router with a fence works well. You could also
do them completely with a chisel. Getting good results would require some practice. A mortising
machine is the easiest way that I know. But it requires that you have one! I have used one
but don’t own one.

Tom

I’ve cut mortises with a hand held drill and drill bit successfully.
While it’s nice to have a drill press, you can successfully keep holes in line by using a doweling jig.
As mentioned, you will have to either 1) square the ends of the mortises with a chisel if your tenons are square, or 2) round over the shoulders of the tenon to match the round mortises.

A doweling jig costs under $50, and you can use it for other joinery.

-- Gerry

Gerry you are right. People some time use a brace to drill the holes too. I guess it just
takes some practice.

Does the doweling jig just center the holes or does it help keep the holes straight?

Tom

http://i615.photobucket.com/albums/tt240/lcurrent/th_IMG_0118.jpg

http://i615.photobucket.com/albums/tt240/lcurrent/th_P1010008.jpg

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http://i615.photobucket.com/albums/tt240/lcurrent/th_P1010008.jpg

Last photo LCJIG much much easier Larry

-- lcurrent ( It's not a mistake till you run out of wood )