DIY Geometric Shelf Angled Cuts on Miter Saw

See 2 easy ways to cut the proper angle for hexagon and triangle shelves. And see how to accurately measure to ensure your shelf is the right size when finished.

See it All

Below you will find:

• Tools list
• Video tutorial
• Step-by-step written tutorial with snapshots

Video Tutorial

See 2 ways to make the 30 degree cuts, including:

• a miter cut on a saw that doesn’t tilt
• or with a bevel cut, which I also think is easier and safer

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How to Make Geometric Shelf Angled Cuts on Miter Saw

Written Tutorial

Get details with screenshots of the build as shown in the video above.

Geometric Shelf Angles

Both triangle and hexagon shelves can be made with a 30 degree cut on your miter saw.

That’s because it’s all about how you mate the boards.

The interior hexagon angle is 120 degrees and is made when combining two butt-end boards at 30 degree angles.

The triangle has 60 degree interior angles and is made when combining 30 degree angles butt to face.

Two Ways to Set Miter Saw

There are 2 ways to setup your miter saw for 30 degree cuts.

A miter cut set to 30 degrees works on any saw.

And a bevel cut only works on a compound saw that can tilt. This is my preferred way and I’ll show you why in a moment.

Miter Cut

Step-by-step instruction on how to make the 30 degree miter cuts.

The first way I’ll show you is to simply set your saw to cut a 30 degree miter angle.

The back guide of your saw is a straight line, which is 180 degrees.

Because the blade of your saw is 90 degrees in reference to the back guide, when you set the saw to the 30 mark, you’re actually changing the angle from 90 on one side to 60 degrees. And that makes the angle on the other side 120 degrees.

I used a digital square to ensure the angle was dead on 120 degrees.

And I just find it easier to place the digital square on the more open side to ensure my blade is perfectly aligned, as precision matters with these cuts.

Limitations with Miter Cut

While this type of cut works, there are some limitations and safety issues with doing miter cuts this way for these shelves.

First, you’re limited in the width of the board you can use, as it has to be stood on end, and the top of it has to be below the bottom of your blade when it is raised.

That doesn’t make for as stable a setup as laying the board flat.

Second, there are limited clamping opportunities to hold the board to the back fence of the saw. And clamps are needed as you don’t want to put your hands that close to the blade while cutting.

The only place I found to clamp was very near to the saw itself, which is not ideal, but it can work.

Make Miter Cuts

Make your first cut on the end of the board, to miter it to 30 degrees.

Then flip the board away from you.

Measure and mark the outside dimension of your shelf.

Move the board into place.

As you can see in the video, my cut length is so short that I had to clamp on the intake side and can’t use a stop block. That’s inconvenient and can lead to inconsistency too.

Then make your next miter cut.

That will give you a trapezoid with 30 degree miters slanted toward the center on each end, as shown below.

Flip the board away from you.

Measure for the inside of your shelf dimension, or move the board to your stop block, if you found a way to use that.

And make your next cut.

Bevel Cuts

Step-by-step instructions on how to make the bevel cuts.

This is my preferred way to make these cuts, and here’s why:

• you are not as limited on board width
• it’s safer to lay the board flat
• you have normal clamping opportunities for safety too

Set the Bevel

Set your saw to 0 degrees so that it is parallel to your fence.

Tilt it to the 30 degree mark on your bevel gauge.

That will actually be 60 degrees because your saw is actually 90 degrees to the table surface and 90 – 30 = 60.

A magnetic, digital angle finder is the best way to ensure your angle is spot on and even the good ones are only about $20.

Make the Bevel Cut

Cut off the end of your board for the first bevel.

Then flip your board away from you.

Measure and mark for the outside length of your shelf.

Move the board into position.

Carefully check that you are on the line.

If you have a stop block, clamp it on now. This makes it so easy to get exact length cuts every time, no matter which way the board is flipped.

And this is another big reason I like doing bevel cuts over miter cuts.

Make your cut.

That will give you a trapazoid with 30 degree miters on each end, as shown below.

Flip the board away from you.

Either measure for the inside dimension of your shelf, or move it down to your stop block.

Make your next cut.

Having a stop block will radically help you avoid mistakes with measuring, as you would have to alternate measuring the inside and outside dimensions of your shelf each time you flip the board, or be super careful to always measure either the long or short side each time.

That’s it!

Now you’re ready to join your 30 degree angle cut boards and make some decorative shelves.