Circular Logic - "let Curly Neal shows you the way..." I needed to cut a round window in in wood for my current project. My originial attempt with a jigsaw was good but not good enough, tolerances were tight and it just wasn't cutting it (ha-ha). I needed to insure a nice round cut. So I decided to get jiggy with it... Got out a crappy piece of extruded acrylic I had lying around the shop that I got at home depot a long time ago. Put the router at one end and squared it up. Then I took my carbite scribe and traced the base shape onto the acrylic. Then I used the square to draw a centerline up the acrylic. At the other end away from the router base location, I measured two inches on each side and then drew lines to the outside edges of the base footprint. Then proceeded to cut the perimeter out with a jigsaw... Then I put the acrylic back on the base and found the mounting hole locations and marked them with a marker. Then drilled and counter sunk the holes on the drill press. They need to be counter sunk or you could scratch the work surface when using the jig. Once I was sure the holes in the jig matched up with the holes on the router base, I found the center of the routerbit and marked it with a marker and made a pilot hole for my hole saw and then cut a hole with my hole saw. This will be so the router bit can get to the work material. I used an 80mm hole saw but any size that allows your largest bit through will suffice. Now it's time to test it out. I find the center of my circle location and mark it with an "x" and then line up my centerline on my jig with it. Then I line up the router bit with the outside edge of my circle. I'm cutting a 10" window so this mark is 5" away from my previous centermark "x". Now I have the jig on the work material where it needs to be to work. I then mark on the jig where the pivot location needs to be and also write a note to myself for future reference (5" outside edge using 3/4" bit). It's importanted to note which bit you used because later on, if you use a smaller/larger bit, it will change your dimensions of the cut. Then I drill a hole on the mark with a drill. I drill a large enough hole so a screw can go through fairly tightly. The jig needs to rotate around this screw so it needs give but not to loose that it has any play in it. In other words, you should be able to move the jig but not jiggle it around. In this particular case, you can see the previous hole I made. You need to mount your work material on another piece of scrap because you need to cut through your workpiece or when you complete the circle, the material that you are screwed into will come loose and you run the risk of the bit moving out and cutting into the outer edge of your circle (I learned this the hard way). I put a scrap piece of the same material in the center as a spacer. The screw goes through the jig, center piece, scrap wood below, and into my workbench surface. I also wrapped the two pieces of wood together with tape and clamped the whole thing down so it didn't wander when I worked. Then it's just a matter of turning the router on plunge a little and run it around the material. Here it is after one lap. You need to take several passes getting a litte deeper with each lap... After more passes.. Out comes the ring that used to be my previous attempt at the window with the jigsaw... And the result. You can see in the wood underneath where I cut into it a little, and why you need to have it there. The new window is perfect. good luck.
Why can't you just use a big honkin hole saw? j/k... Good idea, much cheaper and more custom than buying a hole-jig...
i like that idea...but why not just buy the 15 dollar metal kit...i saw one in ACE hardware theother week
Yeah a ten-inch hole saw is almost impossible to find. (ive got one) hehe the only problem is finding the hole cutting blade thingys (technical name?) on ebay.
I'm surprised by the lack of enthusiasm here, so let be the first to say a big well done eddie! Of course the beauty of the jig is that it will allow you to cut whatever size circle you like, negating the need for various sized holesaws, and you could even make a real whopper for cutting round table tops. edit - how about making an ellipse jig?!
That's also useful for making sub rings for fiberglassed speaker enclosures. I'm sure there are some auto audiophiles in the house.
Yes, Nice job Eddie, I have used the same kind of jig that came with the router attachment for my Dremel, and it works well too. BTW, wouldn't this belong in Guides section? just a thought.
Nice work Eddie, you must be a fan of Norm's Ellipse jig coming up! Ingenuity is not limited to modders. A beautiful home made ellipse jig http://www.cheiron.tzo.com/woconews/projects.asp?ID=31&Name=Gaylord+Mann and plans to make your own http://www.popularwoodworking.com/features/fea.asp?id=1260
Erm, just wondering eddie, what's that rather large Bit-tech template you have at the back there? Have I missed something?
Re: Re: cutting circles with a router - tutorial oops... that wasn't supposed to be in the pic... I already had to scrap one of my tutorial pics because it had something in the shot that wasn't supposed to be there. Consider this an unofficial preview then... that's it, gonna have to make one of these eliptical jigs now... that's just too cool and versitile. for the record, that's not a template, that's a logo cut out of 2mm aluminum and was my first attempt, scrap now, gonna make another.
AH! Feel free to delete my last post if you want to keep a secret! And if you get stuck with that logo, don't forget, I'm only 2000 miles away! edit - actually I may be able to offer you some advice here, you know you can use slot-drills in your router don't you? I hear "home depot" is good for this, so you may want to look for some single flute, high helix slot drills for that aluminium. Make sure you pick up some cutting oil too.
