Make a Dado Jig for Router

Make a dado jig for router that will help you make accurate and precise dadoes, grooves, and rabbets.

I’ve been wanting to build this dado jig for router for some time and I really regret not building it sooner. I recommend everyone to make it as soon as you get your router. 

A router dado guide is a multi-purpose workshop jig that can be used to cut dadoes, grooves, or rabbets. It is suitable for making dado joints, or rabbet joints and it can be used as a mortising jig as well. It is easily adjustable, cheap to build, and great to use. 

The overall dimensions are 70 x 20cm, which gives you roughly 50 cm to cut dadoes depending on the size of your router base. Mine is designed for a DeWalt router but it can be built for any router.

This is a beginner-friendly project requiring basic tools. Check out the jigs I used to build it. (see at the end of this article).

RELATED: Also, check out these other Router Jigs or this Wooden Knob Jig you could use to build the star knobs in this project. If you are interested in how to make dado without power tools check this article – make a dado without a router.

DIY Router Dado Jig Video

If you want to see how it is done, watch the video below for a step-by-step guide on how to make an exact width router dado jig.

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Table of Contents

  1. Material you will need
  2. General Questions
    1. How difficult it is to build?
    2. What is the difference between a dado and a groove?
    3. What is the difference between a dado and a rabbet?
    4. Which router dado bit should I use?
  3. Making the Router Jig Base Unit
    1. Attaching the First Guide Rail
    2. Attaching the Second Guide Rail
  4. Assembling the Router Dado Jig
    1. Fixing Both Base Pieces Together
    2. Making Wooden Knobs
  5. How to Cut a Dado with a Router

*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.

What you'll need to make the Router Dado Jig

Router Jig:
2x MDF desk (70 x 9,5 x 0,5 cm)
-> start with one MDF desk (70 x 20 x 0,5 cm)
4x Spruce wood (9,3 x 2,8 x 0,5 cm)
2x Spruce wood (22 x 2,8 x 0,5 cm)
2x Aluminum L Angles (64 x 1,4 x 1,15 cm)
10x Wood Screws – 1,5 x 0,95 mm
10x Washers – for screws above
Dado Router bit – ø6mm Straight Router Bit

Other:
2x M6 Bolts – 3,5 cm
Double-sided “carpet” tape
Wood Glue
Forstner bit – 10mm, 15mm
M6 T-nuts
Hole saw – 3,8mm
Sand Paper / Sanding Wheel

How difficult it is to build and what do I need?

This is quite a simple project for beginners and one of the must-have woodworking jigs for a router. It is not difficult to build it, the project is straightforward and you can build the complete dado jig in a day.

Apart from the listed material you will need a router and potentially a jigsaw or any other power tool to make the cuts.

What is the difference between a dado and a groove?

The difference between a dado and a groove is in the orientation of how the cut is made. A dado is cut across the grain while a groove is cut with the grain. There is no other difference. Both cuts are often referred to as Slots.

What is the difference between a dado and a rabbet?

The difference between a dado and a rabbet is that a rabbet misses one of the sides. A dado runs across the grain and serves for a dado joint, a rabbet for a rabbet joint. By comparing both types of joints we find that a dado joint is stronger than a rabbet joint since it has a support on each side.

Which router dado bit should I use?

To cut both dadoes and grooves you can use a straight bit – double flute straight router bit. You will get good results for the majority of materials.

You can also use a more specialized dado cutting bit like a spiral (upcut/downcut) bit. Using a spiral bit will result in cleaner cuts since there is a more constant contact when routing and there is a small point of contact between the bit and the cut piece (instead of hitting the piece all at once as with a straight bit).
Additionally, an upcut bit will pull the chips up and out of the router dado cut and generally will give good chip clearance.

Unfortunately, the price of a spiral bit tends to be higher than the price of a straight bit.

Let's Start

The dado jig consists of 2 main parts:

  • Base unit – made out of MDF. The thinner the better (still hard enough) so that a sufficient remaining length of the router bit can be used.
  • Guide rails – made out of aluminum. Serve as a guiding fence for the router. 

All router bases have different sizes. Take into account the size of your router base so it fits perfectly for your jig.

Make the Router Jig Base Unit

I started off by cutting the MDF desk for the base. The base is 70 cm long and 20 cm wide. That takes into account the width of the router base, 2 guide rails, extra material for clamping, and a bit of extra material for cuttings. The base will be cut into two pieces in a later step.

Why I decided to go with MDF as the base piece is because it is straight and the router slides nicely on it. The thickness is 0,5 cm, which is sufficient to drill the guiding rails to it, and at the same time, it does not take much from the length of the router bit. But a plywood desk would do just fine.

At this point the cut doesn’t have to be perfect, it will be flushed later on.

Router Dado Jig - cutting the main base piece

Attach the First Guide Rail

Cut the 2 aluminum L angles.
They are shorter than the length of the base unit.

There will be a wood stripe on each side of the angle which serves as a stopper for the router and attaches both base pieces together.

Router Dado Jig - measuring and cutting aluminum guide rails
Router Dado Jig - Cutting aluminum guide rails

Drill a 4mm hole in the guide rail every 10 cm.

Use double-sided tape to first attach the guide rail to the base and then fix it with screws and washers. 

I left around 2,5 cm (+ the guide rail) from the edge that will be used for clamping.

Router Dado Jig - drilling holes in guide rails
Router Dado Jig - Attaching guide rails to router jig base piece
Router Dado Jig - Attaching guide rails to router jig base piece
Router Dado Jig - Attaching guide rails to router jig base piece

IMPORTANT: When using this router jig you always need to use the same size router bit. That is how the jig is designed.
That does not mean that you would be limited to making dadoes of that specific width only. If you wanted to use a different router bit you would need to build a separate router jig specifically for that one. 

I am using a ø6mm bit. I am very often making smaller cuts and a 6mm router bit does well.

Place the router on the base unit against the guide rail and cut across. That will set the exact distance between the guide rail and the router bit, making it zero clearance.

Router Dado Jig - Setting the right width between the guide rail and the router bit

There is a good chance the router bit is not centered. So once you make the cut, mark the base piece with the corresponding side of the router so you know which side of the router matches which part of the jig. 

Check the setup every time before using the jig. I am matching the front side of my router with the letter A. 

Router Dado Jig - Aligning the router front with the router base piece

Attach the Second Guide Rail

Repeat the same process for the second piece of the base. 

  1. Attach the aluminum L angle, leaving space for clamping
  2. Cut the wood excess using the other side of the router than used for the first piece
Router Dado Jig - Attaching guide rails to router jig base piece
Dado Jig For Router - Cutting wood excess from the other router base piece

At this moment you have 2 base pieces of the router dado jig. 

Dado Jig For Router - Front and back router base piece of the router dado jig

This is the width of one of the jig base pieces which is relevant to my router.

Dado Jig For Router - measuring the width of the router jig base piece

Assembling the Router Dado Jig

Fixing Both Base Pieces Together

First I am going to make 2 side fences for each side of the jig.

The fences will hold the 2 base pieces together using wooden knobs, also allowing to set the desired width of the groove.

Cut 4 wood pieces that match the width of each of the base pieces.

Glue the first 2 ones (as they are) to the base piece that will be closer to you when using the jig.

Dado Jig For Router - Cutting router jig stoppers
Dado Jig For Router - Attaching stoppers to the ends of the router jig

Drill a 10mm hole using a Forstner bit to sink the bolt’s head. Drill a ø6mm hole in the center of the other two for an M6 bolt.

Dado Jig For Router - Attaching stoppers to the ends of the router jig
Dado Jig For Router - Attaching stoppers to the ends of the router jig

Use a chisel to make a hexagon for the bolt’s head or hammer the bolt in and use epoxy to fix it in place. It is desirable that the head be flush with the wood piece. 

Dado Jig For Router - Inserting a bolt in one of the router jig end stoppers
Dado Jig For Router - Bolts inserted in a wood piece

Now glue the wood pieces on the second base piece with the bolts sticking up.

Dado Jig For Router - Attaching a stopper with a bolt on the router jig base piece

To hold the two router base pieces together and to set the width of the dado/groove as needed I am using a longer wood piece with a routed slot at one end. 

This way you will be able to set the dado width accordingly and lock the position of both base pieces.

My slot is 6 cm long and 8mm wide which allows me to make dado cuts up to 6 cm in width.

Cut the slot however you like. I already used this half-built dado jig to route the slot. I am using only one side of the jig at the moment (the other one serves as a base and leveler – as seen in the pic below. Since I am using a 6mm router bit I needed to rotate the wood piece one time for an 8mm slot). If you want to use the jig at this moment take a look at these tips first.

Nevertheless, a router table, a hand drill, or a coping saw will work as well.

TIP: If you’re going to use this router dado jig to cut the slot, tape the wood piece down using double-sided tape and clamp the dado jig to a workbench. All will be tight and fixed in place.

Dado Jig For Router - Attaching both router jig base pieces together
Adjustable Router Jig - cutting a slot with a dado jig
Dado Jig For Router - Fixing router base pieces together
Dado Jig For Router - A finished router dado jig for making dadoes, grooves and rabbets.

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Making Wooden Knobs

And now the star knobs that I am using to secure the base pieces in position.

Some time ago I built a Star Knob Jig that can be used to make wooden knobs – check out the post here – How to make Star Knobs with a Kob Jig. If you have a drill press the jig allows you to easily and repetitively make wooden knobs.

I didn’t use the knob jig this time though and I made the wooden knobs using just a hand drill.

To make a knob first mark its circumference. I used a 38mm saw hole for that.
Drill 10mm holes every 60 degrees. That will make a six-pointed star knob.

Drill a 6mm hole in the center for the bolt and a 20mm hole with a Forstner bit just enough deep for the T-nut to be flush with the knob.

Then cut out the knob with a saw hole.

Dado Jig For Router - Making a six star wooden knob
Dado Jig For Router - Making a six star wooden knob

To smooth the edges I mounted the knobs on a drill press and sanded them using a sanding wheel. 

Dado Jig For Router - Sanding wooden knobs

Finally, insert the T-nuts in the knobs.

Dado Jig For Router - A six star wooden knob

Mount the knobs and it is done!

This is how the finished router dado/groove jig looks like. Now it is ready to use. 

Router Jig - Adjusting the dado jig base pieces
Router Jig - A completed router dado jig ready for use

How To Cut a Dado with a Router

There are multiple ways how to use this router jig.

1. Cut Dadoes / Grooves – use the material to set the exact width of the dado/groove by inserting it between the jig base pieces and locking it down.

Then run the router along the guide rails and cut the dado. This will create an exact width router dado cut for the material you used as a reference. Perfect for making dado joints.

2. Cut Rabbets – Use only one base piece of the dado jig to cut rabbets. Draw a line on the piece you want to cut place the edge of the jig along the drawn line, clamp it down and make the cut.

3. Cut Mortises – Set the width between the base pieces as necessary and cut mortises. It is not as convenient as a jig designed specifically for cutting mortises, but it will do the job.

TIPS:
In whatever way you use this jig you might want to consider the following tips.

  • If used to cut small pieces use double-sided tape to fix the piece in place and avoid it from moving around.
  • Clamp down both the jig and the piece you’re cutting to a workbench while using the jig.
  • Level the jig as necessary around the piece you’re cutting so it stays straight and balanced when used.
Adjustable Router Jig - setting the width for the dado
Router Jig - cutting a dado with a router jig
Router Jig - making a dado joint with a router dado jig
Router Jig - making a dado with a dado jig
Router Jig - Router dado joint
Adjustable Router Jig - exact width dado

I love this router jig. This was a fairly easy project and it was really fun to build it. There are so many things you can do with it. It is easily adjustable, you can cut dadoes, grooves, rabbets, and even mortises. 

I have been using this jig for a few years now (as shown in my videos) and it is one of the best router jigs you can have in your workshop. So if you have a router or planning on getting one, you definitely need to add this jig to your gear.

One thing you could consider as a disadvantage is that this jig is built with/for one router bit only. If you would like to use a different size router bit you would need to use a separate jig. 

Also by using this jig I found out it would be really great to add extra adjustable stoppers that could be placed anywhere along the length of the jig. That would be perfect to make stopped dados and more accurate mortises. I’ll share a link to this build once ready.

Are you ready to build a dado jig? Let’s do it! 

HAPPY BUILDING!

RELATED: Also, check out these other Router Jigs and make a nice addition to your workshop.

  1. A router circle cutting jig for cutting perfect circles
  2. An adjustable router template guide to accurately and precisely cut specific shapes in the stock.

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An Adjustable Router Dado Guide Jig for cutting exact width dados and grooves and making dado joints.

I hope the information shared in this blog post inspired and now you are adding this router jig to your next builds. 😉

If you have any questions on the jig I might have missed in the post let me know in the comment section below.

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