Circle Cutter Jig for the Bandsaw - SUPER EASY!

I wanted to build the "Jupiter" table from Nick Offermans book "Good Clean Fun" and needed to find a way to make the circle top. I had never done this, so it was a little intimdating at first, but once I figured it out I couldn't believe that I havn't built this jig before!

This jig is super easy to build. There are tons of ways to upgrade the jig with adjustability or other features, but for this project, I wanted to keep things super simple. Lets dive into it!

Supplies

3/4" plywood (at least a 12" square is recommended)
3/4" wide material for a runner. (This should fit perfectly in the miter slot of your saw, with no play)
A small brad nail
glue
more brad nails for nailing in the runner and stop block

Step 1: Measure and Cut the Plywood Base

Depending on how much plywood you have available, try to make the base of your circle jig a little bit bigger than your bandsaw table. You can bias the base to the right side of the blade to give you more room for circles. The goal here is to take advantage of as much space as possible, depending on the size of your bandsaw table.

Place the plywood base on the bandsaw and mark where the runner and blade will be on the jig. These marks will come in handy later on.

Hint: If you are REALLY limited on materials, attach the runner (next step) so that the entire platform is left of the blade. This won't give zero clearance at the blade, and may increase tear out, but you will be able to cut a larger circle!

Step 2: Cutting the Runner / Miter Rail

Cut the miter rail from a thin piece of hardwood or plastic. The runner should be around 1/4" thick and 3/4" wide. Cut this rail a little bit wider than you need, and then slowly creep up on the exact dimension for a perfect fit. If you cut the rail too narrow (like I did!) try again. Any slop or looseness in this rail will affect the accuracy of your jig later on - this is worth getting right!

Step 3: Attaching the Runner and Stop Block

Glue and brad nail the runner to the bottom of your sled, using the marks you made earlier. (Because you did mark the miter slot and blade location....right???)

I like using super glue to hold the rail in place, and then some 3/4" brad nails to finish it off. I also prefer to leave my runners extra long, and then use a saw to trim them to length.

For the stop block, grab a chunk of scrap plywood and nail it to the BACK of the sled. This will stop the sled at the same location every time when inserting it into the blade of your saw.

Step 4: Cutting the Kerf

Carefully, with your bandsaw ON, place the runner of your jig into the miter slot and push the sled into the blade until the stop block contacts the saw table and then turn the saw OFF

Make a mark just behind the teeth of the blade. This will mark the apex of your circles.

Step 5: Marking the Center of the Circle

Use a combination square to run the blade tooth mark across the jig. This will be the line that you make any center points of the circles you want to cut on.

Measure from the kerf the RADIUS of the circle you want to cut. Drill a small hole that fits a brad nail at this point.

HINT: I suggest measuring and drilling a hole at least 1" larger than you actually want to end up with. Sometimes, the circle jig is slightly off, so this gives you a chance to make that last bit of adjustment before cutting to the final dimension.

Step 6: Cut a Brad Nail and Then Cut a Circle!

Cut the head off of a brad nail and insert it into the hole in your jig. Then, mark the center point on the material you want to cut a circle out of, and place this over the brad nail.

Finally, feed the whole assembly into your bandsaw blade and when the jig stops, begin rotating the material to cut a circle.

BAM! AWESOME CIRCLE CUTTING MADE EASY!

Step 7: BONUS! Sanding the Edges

Bonus tip! The bandsaw can leave a really rough edge around your beautiful circle. In order to clean these up, I simple clamped my belt sander to my work bench. This worked great and I didn't even have to buy a disc sander! #amievenawoodworker?

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12 Comments

bpark1000

Tip 2 years ago

You need to account for the "lead" of the saw (where the blade does not cut parallel to the saw table). Make test cuts in scrap. If the cut tends to spiral inward or outward, adjust the pivot point forward or backward to eliminate this tendency. Use a blade with a wide tooth-set. Do not use narrow-kerf blades!
Someday, bandsaw manufacturers will WAKE UP and make a bandsaw with a table that can rotate a few degrees to eliminate the hassle this causes!