Of course the first thing you need is logs. A good source may be someone who has a portable sawmill in your area. Contact woodmizer sawmills to get a list of owners near you.
If you have your own trees, have someone saw them for you.
Step 1: Dovetail Jig
The easiest and fastest way to notch the logs is with a jig
My site has plans to build your own if you want : http://logdovetailjig.com . By building your own, you can have a custom set of jigs that will work for your particular log dimensions and end up with the gap between the logs that you want.
Our example cabin for this instructable is 11'-8" x 16' using logs that are 7" thick x 9" high. The gap will be 2.5 inches. Yours could be other sizes. The plans are custom designed for whatever dimensions are specified.
After you decide on the cabin dimensions, add 4 inches to each and use those numbers to cut the logs to length.
So the logs for this example would be cut 12' and 16'-4".
The jigs shown are for half dovetail notches and take about 2-3 hours to make.
Step 2: Attach the First Jig
Lay the log on a side and mark a line down the center using a chalkline. The jig also has a centerline marked on it with holes cut out that make it easy to align the jig with the log.
The jig attaches to the INSIDE face of the log. (The face of the log that will be on the inside of the cabin. This is facing upward in the photo)
Leave about 2 inches between the end of the log and the jig end piece. Attach it to the log with 3 sheetrock screws.
You will measure from the perpendicular edge of the jig as shown in the photo.
We said the log we were cutting was for the wall that is 11'-"8 inches log.
Calculate the interior dimensions of the cabin:
This is the outside dimension minus 2 times the log thickness.
So for our cabin, the short wall interior measurement is 11'-8" minus 6 inches minus 6 inches.
That equals 10'-8".
Align the other jig to the centline of the log and so that the perpendicular edge is at 10'-8":
Attach it with screws
Step 4: Chainsaw Blocks
The jig plans have instructions for making and attaching the saw spacers to the chainsaw bar.
They are needed to allow the saw to run along the jig without cutting into it.
Step 5: Saw the Notches
Roll the log over and saw the notches using the jig to guide the saw. After making the two cuts for one notch, remove the scrap piece of wood and make a second pass. This will make the saw cut very smooth for a good fit.
It takes about 4 minutes to complete notching on one log.
See a video on youtube:
Step 6: Stacking the Logs
Stack the logs!
Step 7: Chinking the Logs
I used permachink which is a synthetic log chinking product. "Log jam" is similar.
Install foam backer rod in the joints. Apply the chinking. Moisten with a spray bottle and smooth with a small trowel or modified putty knife.