In the world of woodworking, so much is "square" ... it's nice to make things that are round once in a while, and if you have a table saw, yes, even a table saw can make round blanks. The first time I ever heard of this, I thought ... that sounds dangerous, but then it was explained that to start off with, all you really do is make a buch of series of straight cuts until the wood is almost round, then finish up the last bit by just skimming the all those straight cuts ... a pretty simple concept really!!
Watching on Youtube: https://youtu.be/6TCFzoRVo1k
Like a lot of jigs, the circle making jig for the table saw can be made fully adjustable with all sorts of variable stops and clamps. The one that I elected to make is the simple version that might be for a one-time use, of for a limited number of round blanks. If you were going to make many, many, circel blanks, you might want to opt for a more complex version. For mine ... I started off with ...
... a basic sheet of cut-off plywood, about 18 inches square. I measured the distance from the edge of my mitre slot to the edge side of my table saw blade. This measurement, plus 1/4 inch, was then transferred to the underside of my square jig's base and was used to mark where the mitre blank would be attached.
The blank wants to be attaches slightly further away from the blade so that when the blank is flipped over, the edge of the jig base needs to be cut by the table saw blade so that it then fits flush with the blade.
After the jig has been flipped over and trimmed with the saw blade, the next thing is to use a square to mark a 90 degree line about the middle of the jig base, out from the blade. All this is for is a reference line in which to insert a finishing nail that will later become the pivot point of the circle jig.
Now it's time to prepare the blank to be cut. You need to start off with a square piece of wood, MDF or what ever it is you are cutting, mark diagonal lines from tip to tip to find the centre of the board and drill a small hole that the finishing nail will fit through and become the pivot point.
NOTE - If you are making a table top, and our material is thick enough, you will not have to drill a hole all the way through. Often a hole that is about 3/4 the depth of our blank material is quite suitable for the pivot point to rotate on.
After you done all the preliminaries, it's time to cut the blank material. Start off by cutting the corners, then cut the corners again, then cut all the corners again. At this point you will have a blank that is nearly round. The final step is to position the circle blank, just about the position of the blade where the top of the blade covers over the top of your circle blank. At this point you can turn your table saw on, move the circle jig up to that blade position and slowly rotate. The blade will ever so slighlty skim the edge of your wood and give you a perfectly round blank.
Copyright - Colin Knecht