So I made a jig for my jig saw. I had the Kreg square-cut jig in mind when I made it. I used a couple of scrap pieces of wood. I don’t have a jointer or a plane, so I used the sides that looked the most straight. I’m guessing they were milled at least on one edge, since I got the wood from Home Depot. I checked these edges for square with my combo square and they looked pretty good. I used glue and clamped the two pieces together then used my nail gun to nail them together once I had them square with each other.
Now I can just line up the bottom piece with my line and I’m ready to go.
My first test was on a piece of 2×6. It didn’t take long for me to find out there were problems. It started off fine, then it veered to the left of the line a little, towards the jig. I stopped and thought that maybe I didn’t clamp it well enough, but it was clamped tight. I started again from the beginning to try to correct it and get a straight line, but it went left again and just kept going.
It was at this point I realized that it was veering because the blade was bending. I stopped and removed the jig saw and grabbed blade to see if it was loose.
It was at this point I realized that the blade gets really hot. Lesson learned.
So I thought maybe a 2×6 was too thick and that if the blade twists or I am not right up against the jig, it just can’t correct itself and keeps going off course. I switched to a 1×6 and tried again. It was a lot better, but there was still a tiny bit of travel to the left. The blade does look a little twisted when it’s installed, so it could be that. The lines are still a lot straighter than I would be able to achieve by eye. I’m thinking if I go really slow it might help keep it straight.
The picture below shows the results. The board on the left is the 2×6. You can see how much it veered because the blade was bending. The board on the right is the 1×6 and it looks pretty good. I should at least be able to get some pretty straight lines when I next practice some more Greene & Greene finger joints.
-- Chris, http://www.youtube.com/CMRwoodworks , Proverbs 16:9