Cutting a circle of wood freehand is usually difficult, although the tests I have done so far with this jigsaw table were quite satisfactory. Anyway, the best option is to make a woodworking jig to cut the circles in wood, an easy to make circle jig such as this one that I make in this blog post.
So, we are going to see how I make a woodworking jig to cut circles, and how I use the jig to cut wooden circles.
To make this simple guide to carpentry, I will take advantage of the miter cut carriage that I had manufactured (and that is the same as the base of the wooden squaring cart that I had also made), and that as some of you already know, it did not give me the expected result. It is nothing more than a piece of marquetry sheet metal, with a pair of slats underneath that fit into the sides of the jigsaw table, and which slides facing the cutting blade.
To cut the circles I will need to have some space to the right, so as the base of this jig is too small I will screw a piece of a pine board that I have in the workshop.
I screwed it flush with the front of the jig base, and shifted to the right as far as possible, but making sure that if necessary I can still hold it in the left using a clamp.
Now I take the cart back to the saw, and turn it on to cut a groove in the wood. Whenever you use this guide, the saw blade will enter this slot.
And the radius of the circles to be cut will be perpendicular to this slot. So, I draw a couple of lines perpendicularly to the slot.
And on these perpendicular lines I am going to mark the radii that I consider necessary. As I say, on these lines I mark the radii. On one line I mark even numbers (even centimeters) and on another I want to mark odd numbers (odd centimeters).
And using a fine drill bit, I drill guide holes in all the marks. I drilled them using a hand drill, but it would be more precise to drill them with the drill press. And if at any time I need to make a circle whose radius does not coincide with any of the marks I made, I just have to draw another line perpendicular to the slot, I mark the necessary radius and I drill the corresponding guide hole.
I can use a nail as a pivot point or pivot pin, but I think that a nail would deform the guide holes and they would get loosen if I cut many circles with the same radius. So I prefer to use a screw, but I had to file half the length of the threads of the screw.
So I can screw it into the corresponding hole and it will be tight every time I have to use it.
Now the trick of this guide to cut circles is to put the guide on the saw so that the line with the radius that I am going to cut, and which is perfectly perpendicular to the slot, is right on the teeth of the blade. of the jigsaw. When the circle cutting guide is in position I have to put a sergeant behind it to act as a stop. So I know that when I go to cut the circle, the fence will go to its correct position marked by the stopper.
To cut the circle, I have to cut a square of wood that is slightly larger than the circle that I want cut, and I drill a guide hole in the center.
And now I fit that center hole on the screw that will work as a pivot pin, and that I already screwed in the position that corresponds to the radius of the circle that I want to cut. I have to make sure that the surface of the workpiece is perfectly in contact with the surface of the jig, and I must be careful in case the tip of the pivot pin protrudes from the top of the workpiece, lest I nail it in my hand when I press the wooden workpiece.
And now I can start cutting the circle. I turn on the jigsaw, I put the circle cutting jig on the jigsaw table top, and I start cutting the wood straight, not allowing it to spin. So I'm going to cut straight until I bump against the clamp that I had put as a stop.
And now keeping the fence against the stop I start to turn the wood as I cut it. You have to cut little by little, but it is easy and you just have to be careful at the end of the cut, lest the saw gets into the inside of the wooden circle and it gets damaged. It is best to let it come to the end smoothly and not try to go back and forth to improve the finish of the cut. It is preferable to remove the circle and sand with the disc sander the small imperfection that may remain.