Using a jigsaw to cut a wooden disc freehand can be tricky. And despite I always get good results cutting with my jigsaw table, it is also tricky to cut a wooden disc freehand with this homemade tool. So, the best option is to make a circle cutting jig. E.g. one jig as simple as the one I will make in this post. Then, let’s see how to make a circle cutting jig and how to use it to cut a wooden disc.
To make this simple woodworking jig I will use a simple sled. This is just a piece of marquetry with two guiding strips under it. One guiding strip to each side of the jigsaw-table top.
But to cut the wooden discs I’ll need more room to the right. So, because the piece of marquetry is small, I will screw a pine board to it.
The pine board and the marquetry are flush in the back edge. And I put the pine board as much as I can to the right. But in such a way that I still can clamp it to the left of the jigsaw-table top. I won’t clamp it. I just want to make sure I don’t have too much weight to the right. And I also need a nice surface all around the jigsaw blade.
Now I turn the jigsaw on, and I cut the slot in the pine board. So now, every time I use this circle cutting jig, the jigsaw blade will enter in that slot.
And the radius of any wooden disc I will cut will be perpendicular to that slot. So, I draw a couple of lines that are perpendicular to the slot. One line at some centimetres from the other.
And I will mark some radius on those lines. In one line I mark even numbers (even centimetres). And in the other line I mark odd numbers (odd centimetres).
Now I use a thin drill bit to drill a guide hole in each mark. I drill them freehand, but it would be better to drill them in the drill press.
In the case I might need a different radius, I can draw another perpendicular line and I would mark and drill the radius in that line.
I could use a nail as a pivot pin, but with time it would deform the guide holes. And eventually the nail would enter loose in the holes. So I prefer to use one screw. But first I file the thread in the part that will protrude the jig. Because I don’t want it to screw the wooden disc I cut.
Like this I can screw the pivot pin in the circle cutting jig, and it will be tight every time.
Now, the trick in this circle cutting jig, is to move it forwards, until we align the line with the pivot pin and the teeth of the blade. Once it is in the right position, I put a clamp against the edge of the jig. Like this the clamp will work as a stop block.
To make a wooden disc, first I cut a wooden square. It must be big enough to make the disc. And I drill a guide hole in the centre.
Now I fit the pivot pin in the guide hole. Before this I had screwed the pivot pin in the hole that matches the radius of the disc I want to cut.
I must make sure the workpiece surface is flat against the jig surface. And I must also check if the pivot pin protrudes the workpiece top surface, because in that case I could injure my hands.
And I can already cut the wooden disc. I turn the jigsaw table on, I put the jig on the jigsaw table top, and I push it to make a straight cut, making sure the workpiece don’t turn, until the circle cutting jig bumps into the clamp.
And now I must keep the circle cutting jig against the clamp while I turn the workpiece to cut in circle. I must go slowly, but it is very easy to cut a wooden circle using this woodworking jig.
But I must be careful when I finish cutting the disc, because the blade could cut towards the inside of the disc. It wouldn’t make a big cut, but that could ruin the disc.
So when I reach the end of the cut I must go very slowly and let the blade cut all the wood. It is not a good idea to go back and forward trying to make a better cut. It is better to sand any imperfection with the disc sander.