How to Easily Cut Perfect Circles Using a Router and a DIY Circle Guide
Creating precise and clean circles in woodworking projects can be challenging with traditional tools. However, using a router equipped with a custom-made circle cutting jig offers a highly accurate and efficient solution. This method allows you to craft circles of various sizes without the need for specialized or expensive equipment. Whether you’re making decorative trays, cake plates, or other round wooden pieces, this technique provides professional-looking results with minimal effort.
While you can purchase commercial circle jigs, making your own from scrap materials is quick, cost-effective, and highly customizable. Plus, it’s a satisfying project that enhances your woodworking skills. In this guide, you’ll learn how to construct a durable and reliable router circle guide from basic materials, ensuring your future projects have perfectly round edges every time.
Tools and Materials Needed
Tools:
- Electric router (preferably with a straight bit)
- Saw (preferably a table saw or hand saw)
- Drill with bits of various sizes
- Measuring tape or ruler
- Screwdriver
Materials:
- 1/4 inch MDF or plywood sheet
- 5mm shelf pin or similar pivot pin
Step-by-Step Construction of the Circle Cutting Jig
Step 1: Prepare the Base Board
Begin by cutting a piece of 1/4 inch MDF or plywood to your desired size. The length should match the width of your router’s base plate, and it should be at least 1-2 inches longer than the radius of the largest circle you intend to cut, plus the width of your router’s base. This flexibility allows you to create larger circles without limitations. For added stability and durability, consider using a sturdy 1x board if your router bit length permits.
Step 2: Create the Router Mounting Platform
Remove the router’s base plate by unscrewing it carefully with a screwdriver—avoid using impact drivers to prevent stripping the screws. Position the router’s base plate on one edge of your prepared MDF. Mark the screw holes and the center hole onto the MDF using a pencil. Use a drill with an appropriate-sized bit—preferably a Forstner bit—for the center hole, ensuring it is large enough for your straight bit to pass through comfortably. Drill countersunk holes at the screw locations to allow the screw heads to sit flush or below the surface, preventing scratches on your workpieces.
Step 3: Mark and Drill Pivot Points
Identify and mark the center of your router’s base plate on the MDF. This point will serve as the main reference for your pivot. Measure and mark where you want your pivot points to be, corresponding to the radius of the circles you wish to cut. Remember to account for the radius of your router bit; for example, if your bit is 1/4 inch in diameter, add 1/8 inch to your measurements for precise cuts.
Drill a 3/16 inch hole at each pivot point, fitting a 5mm shelf pin snugly. These pins will serve as pivot points during cutting. If you plan to make multiple circles of different sizes, add additional pivot points by repeating this process at varying distances from the center mark. To cut circles that are close in size, offset the pivot points slightly from the center line to avoid structural weakening of the jig.
Step 4: Attach the Jig to the Router
Securely fix your DIY circle guide onto your router’s base using the original screws, ensuring they are fully countersunk to prevent scratching. Insert a straight router bit—preferably 1/4 inch—into the router and set the depth shallow for initial passes, reducing tear-out and providing better control. Slide the router’s sleeve back so the bit just clears the jig, leaving around 1/16 inch of clearance. Run a shallow pass to verify the setup before making full-depth cuts.
Step 5: Cutting Out Your Perfect Circle
Mark the center of the wood piece you wish to cut and drill a small 3/16 inch hole at this point. Insert your shelf pin into this hole and place the router’s pivot pin into the corresponding pivot hole on your jig. Turn on the router and carefully move it around in a circular motion, keeping the pivot pin firmly in place. Gradually deepen the cut with successive passes—about 1/18 inch per pass—until the entire circle is cut through. During final passes, move the cut-off section away from your work surface to prevent accidental damage.
After completing the cut, sand the edges lightly to remove any roughness. The result will be a perfectly round, smooth-edged circle ready for finishing or assembly. With this DIY router circle guide, you can produce consistent, professional-quality circles tailored to your project needs. Have fun experimenting and creating beautiful round woodworking pieces with confidence!