Circle Cutting Jig

20 Minutes
Easy
If you have ever tried to cut out a circle, you will know how hard it is, whether using a jigsaw or router, it never seemed to be a perfect circle when you have finished.
The easy way to resolve this problem is to make a circle cutting jig, there are all sorts of fancy jigs out there, that slide, adjust in some way, and look the business, but you don't need them.
All you need is a piece of scrap, I used 1/2" plywood, how wide depends on your router, I used my trim router for this, which is not very big, so I only needed a narrow piece.
Fix your router to the board, putting a drill bit in the collett, and plunge the router, this mark will be the centre of the hole for your router bit. Remove the router, then measure along a center line from that mark, in whatever increments you wish to use. I started at 6" and then at 1" intervals.
Using a 1" forstner bit, I cut the hole for my router bit, then drilled holes at each of the increment marks using a 5/32" bit, you can use any bit, but make a note of the size, I wrote it on the board, because you will need the bit again. Having done this re-attach the router.
Take the board you intend to cut, find the centre of the circle, and drill a hole using the bit you used previously for the increments. place the jig in place with the drill bit acting as a center pin, and using a 1/4" straight bit, take several passes around the circle, so as not to labour the bit. Once you know you are nearly through, turn the board over, and cut from the other side, in this way you will have no tear-out.
You end up with the perfect circle!
PhilCo
Want more details about this and other DIY projects? Check out my blog post!
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