There are many ways how to cut a circle in wood. You can use a jigsaw, a trim router a hole saw or even a table saw. The easiest way to cut out a rough circle shape is to use the tool freehand. But if you want to cut a precise circle the best way is to use a tool in combination with a woodworking jig.
To cut an accurate circle with a jigsaw you can use a jigsaw circle jig. To cut a circle with a table saw you can use an adjustable table saw circle jig. These methods work but sometimes they can be quite tedious. One of the most important things when cutting with a jigsaw is to use the right jigsaw blade and quite often you end up with skewed edges. Using a table saw will ensure precise perpendicular edges but cutting a circle on a table saw is cumbersome and it’s not exactly the safest method.
Using a trim router is the best way how to cut a precise circle in wood. In combination with a router circle cutting jig, you will achieve the desired results. I have already built a router jig for cutting circles. It is a great jig, unfortunately, the only disadvantage is that after several turns with the router the cable gets tangled. It’s not a big deal, but it’s not comfortable. However, this is not the case with cordless trim routers.
This time I made a circle jig with an upgrade. The router attached to the jig is not fixed to the circle base with screws but adjustable bearings. This allows the router to rotate freely on the base. The router always remains in the same position and there is no need to worry about the cable anymore.
The router circle cutting jig is designed for cutting smaller circles (from 1cm to 31 cm in diameter) and can be used both with cord and cordless trim routers. Also, any type of hand router can be used, since the router is not fixed to the base but gripped by adjustable bearings.
I built the circle jig in a few hours. The material is easily available. For the base, I used birch plywood and MDF.
This is an easy project for beginning woodworkers and one of the must-have jigs for a trim router. If you want to cut precise circles in wood, then this jig will help you with that. Besides, the material doesn’t cost much and you will see how often you will use it.
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Table of Contents
- The Material you will need
- General Questions
- What router bit to use to cut a circle?
- How to make a Router Circle Cutting Jig (with Bearings)
- Step 1: Build the Base
- Step 2: Make Bearing Mounts
- Step 3: Make an Adjustable Slider
- Step 4: Make a Test Circle Cut
- Step 5: Add a Self-adhesive Scale Ruler
- Router Circle Jig Video
- How to Cut a Circle with a Router Circle Cutting Jig
*Safety is your responsibility. Make sure you know what you’re doing and take all necessary safety precautions while working with power tools. Safety comes first!
Always be cautious and careful when using any power tool.
Material needed to make a Router Circle Jig
Material – Birch Plywood, MDF
Router circle jig – base plate
Plywood – 35cm x 12cm x 0,65cm
MDF – 21cm x 5cm x 0,6cm
Router circle jig – adjustable slider
Strip – 11,5cm x 1,5cm x 0,65cm
Other:
6mm, 4mm Drill Bit, Forstner bit – 20mm
M6 Bolts, M6 Washers, M6 nuts
M6 Wing nut, Bearings
Wood screws, Wood Glue, Epoxy
Sandpaper, Double-sided tape
Adhesive metric scale
Aluminum flat bar, 4mm brass bar
Tools:
Circular Saw
Hand Drill
Trim Router – (Dewalt D26203)
Chisel
What router bit to use to cut a circle?
1. Straight bit
A double flute straight router bit is one of the basic router bits that can be used to cut a circle in wood. To cut a circle, turn the router slowly and gradually trim the individual layers of the material. That will prevent the bit from getting burned and the resulting cut will be clean. If used correctly, you can achieve great results with this bit.
When routing the blade of a straight bit is in less constant contact with the material since the bit tends to chop straight into the stock instead of slicing off the material. The blade of the bit touches the material along its entire edge, which is why it is necessary to take less of a cut and don’t feed as fast to prevent the bit from breaking.
Also, pay attention to the router’s rpm and the speed and depth of the cut to prevent the bit from burning, and possibly breaking. Chips and sand are not easily pulled up from the cut and it’s good practice to continuously clean the cut while using a straight bit.
2. Spiral bit
A spiral upcut/down cut router bit is the best router bit to cut circles in wood. The shape of the bit ensures more constant contact with the material. The blade of the bit touches the material only in several places along its length which reduces the chance of the bit being destroyed or burned.
The spiral shape of the bit provides a nice chip clearance and pulls up the chips and the dust from the cut more easily. Spiral router bits are the most expensive than straight bits, but typically they perform better and they ensure better results.
Let’s start building!
The circle jig is made of birch plywood and MDF. I use a thinner (6mm) plywood board to use as much of the bit length as possible.
Different types of hand routers can be attached to the jig. The router is not directly fixed to the cutting base but secured with bearings. Mounting and dismounting a router is very quick and there are no delays in setting the jig up.
The other benefit is that the bearings secure the router in place but the router can freely rotate on the spot. That allows to easily cut circles preventing the cable of the router from getting in the cut path or getting tangled up.
Router Circle Jig parameters:
- Cut circles from 1cm to 31cm in diameter
- Easy and quick setup
- Scale ruler for precise setting of the circle diameter
To build the saw guide you will need a circular saw, a trim router, and a hand drill.
NOTE: The circle jig will work with router bits of different sizes but you will get the best results if used with one specific bit size. I am using a 6mm router bit.
How to make a Router Circle Cutting Jig (with Bearings)
Step 1: Build the Base
Measure and cut pieces for the circle base – plywood piece (35cm x 12cm x 0,65cm), MDF piece (MDF – 21cm x 5cm x 0,6cm). Together they create a t-slot for the adjustable runner that sets the diameter of the circle.
To cut all the parts I was mainly using a circular saw with a circular saw straight edge guide and a circular saw track, though a jigsaw would work as well.
1. Cut a slot in the plywood piece
Cut a slot along the centerline of the plywood base piece (1,5cm x 26,5cm). Use a jigsaw with a jigsaw guide or a router with a dado guide to cut a precise and clean slot.
2. Cut a slot in the MFD piece
Cut a slot along the centerline of the MDF base piece (0,6cm x 19cm). Also, trim off a few layers of the material on one side of the MDF piece for the scale ruler – 1/2mm is enough. The width of the slot is equal to the width of the scale ruler.
Glue both pieces together and secure them with screws.
NOTE: It is important that both slots are aligned. Draw lines on the pieces and use them as guides.
Step 2: Make Bearing Mounts
The position of the mounts can differ depending on the router. I am building this circle jig primarily for a Dewalt D26203 Trim Router. The circle base plate delivered with the Dewalt router has a diameter of 11,5cm.
You can either drill the holes specifically for your router base or if having multiple routers, you can make a universal circle base plate that can be used with each of the routes and would fit the circle jig.
Drill 3 6mm holes in the base. Carve a hexagon around the holes for the nuts (Insert an M6 bolt in the hole, outline the bolt’s head and use a chisel to carve out a hexagon). After insertion, the nuts must be completely flush with the surface.
Use epoxy to fix the nuts permanently in the holes.
NOTE: To drill the holes for the nuts it is possible to use a Forstner bit as well. Though I wouldn’t recommend it. The 6mm plywood board is not thick enough and you can go easily through it.
Attach the bearings to the base and adjust them as necessary so they fit tightly around the circular base plate. (The bearings have an inner diameter of 8mm so they can be easily adjusted if used together with a 6mm bolt).
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Step 3: Make an Adjustable Slider
Cut a plywood strip (11,5cm x 1,5cm x 0,65cm) and drill in 3 holes along the centerline. The inner hole has a diameter of 6mm the outer holes 4mm.
1. Inner hole – tightens and fixes the slider in position (either with a wing nut or a wood knob)
Carve a hexagon around the center hole and insert an M6 bolt in. Use epoxy.
2. Outer holes – one serves as a pivot point, the other as a readout of values on the scale ruler.
First, insert a brass pin in the hole closer to the router bit and let 4mm stick out – this pin serves as the pivot point (remember the pin points down into the cut material). Mount the slider in the slot and secure it with a wing nut.
After mounting the slider add the scale value reader.
Step 4: Make a Test Circle Cut
Make a test circle cut before attaching the scale ruler. Cutting a circle will serve as a reference for the placement of the ruler.
Mount the router on the circle cutting jig and set a circle diameter to 10cm (I am counting with the outer edge of the router bit). Cut a circle and measure how much you differ from the set value.
Step 5: Add a Self-adhesive Scale Ruler
Once finished with the test cuts, keep the settings and tape a scale ruler to the base of the circle jig.
This is what the finished router circle cutting jig looks like. You may not be using it daily but it is definitely one of the top 5 woodworking jigs for a router. Surely pays off to have one in the shop.
DIY Router Circle Cutting Jig Video
If you want to see and learn step by step how to make a circle cutter and cut a perfect circle with a router, watch the video below.
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How to Setup and Use a Router Circle Jig with Bearings
Provided steps below describe how to set up and how use a Router Circle Jig. Take all safety precautions.
How to Cut a Circle with a Router Circle Cutting Jig
- Mount the router on the circle jig between the bearings and secure it with screws
- Insert a router a bit
- Set the circle diameter by adjusting the slider and the pivoting point
- Drill a hole in the stock for the circle jig
- Place the pivoting point of the circle jig in the drilled hole
- Cut the circle
