How To Join Two Pieces of Wood At 45 Degrees

Virtually every project in a woodworking shop has joint work, whether making a table, a chair, a desk, a bird feeder, or a picture frame.

Every woodworker needs to be familiar with the various types of wood joints available for their project and have all of the tools and accessories needed to form the right one.  When you are joining two wood pieces together, you want that joining to last.

Usually, joint work for most of our projects will be 90-degree or flush; we want the corners to be square, or we want the surface to be flush.  Think something boxy (cabinet or desk) or flat (tabletop).

Sometimes, though, we find ourselves with an odd angle, perhaps a countertop or cabinet corner or an octagonal frame for a mirror or cropped photo. ( Why octagonal?  Eight sides, 8 x 22.5 = 90 degrees. )

That is the question for today – a corner that will be 45 degrees when assembled, meaning a couple of 22.5-degree cuts.

Let’s examine the types of joints available to choose from and then figure out the best one for the project and the best way to form it.

Types of Joints in Woodworking

While there are many forms of joinery, and different methods of attachment (glue, nails, dowels, biscuits, and more), we’ll mention only a handful to choose from:

  • Butt joints.  Simply stated, 2 pieces of wood joined by putting their ends together without any special shaping or cuts.  Glue would be a part of the joinery method, and you could choose nails or screws, dowel joints, biscuit joints, or pocket holes to hold the two pieces together.  With a 45-degree angle to create from our 2 pieces, this is not a good choice.
  • Edge joint.  Two pieces of wood joined edge to edge, as in planks joined to form a table top or desktop.  Glue would be part of the joinery method, and you could choose dowels, biscuits, or pocket holes to hold each piece to the next.  Again, we have a 45-degree angle to create from our 2 pieces, so this also is not a good choice.
  • Miter joint.  This is the typical method used to create the joints of a picture frame, for instance, and involves a miter saw and 45-degree cuts.  Two 45-degree angles form the square corner.  We’ve got a 45-degree angle to create, not cut, but a miter saw will still be a part of our project.  The cuts we’ll make with it will be 22.5-degree cuts since 22.5 x 2 = 45 degrees.  So, we’re part of the way there, at least with the power tool.
  • Pocket hole joint.  The angle is not conducive to a pocket hole joint.  Let’s just rule this one out.
  • Mortise and tenon.  Simply, no.

Well, we have a tool that will be part of the project, so that’s a start.   But we’ll have to come up with another method to join the two pieces of wood together at the 45-degree angle.

While we want every joint we form to be a strong joint or at least one that will be durable and last a long time, some joints don’t necessarily have to be that strong.  If they are not supporting any weight, we simply want them to be durable.  The corner of a cabinet or countertop, for instance, or a multi-sided picture frame simply needs to last.

The Miter Saw Cut

Miter Saw Gauge

We’ve determined that our miter saw will be a part of the project and will be used to create the two 22.5-degree cuts.  While 45-degree cuts are the usual ones we use the miter saw for, it is capable of making other cuts, too.  If your miter saw can make bevel cuts, too, that is another option.

The pieces you are cutting might have a bearing on which miter saw talent you use.  You may be able to make the cuts simply by setting the angle of the saw blade to a 22.5-degree angle.  

This is becoming a more common angle to cut in woodworking, as 45-degree corners have many applications – the octagonal picture frame mentioned earlier, where 8 pieces are jointed at 22.5 degrees each to form the frame; or, and here’s an unusual one, the component pieces joined to form an original segmented turnery piece before it is attached to the lathe.  

We happened to mention such a technique in a recent article on these pages.  If you’re interested, you will find the article here, along with an image of the turned piece assembled and finished.  Scroll down to see the beautiful piece.

Getting back to the miter cut, simply set the miter gauge to 22.5 degrees, and make the cuts.  

If the shape or size of the workpiece makes another method a better alternative, use the bevel-cut ability of the miter saw to make that cut. Simply set the bevel angle gauge to 22.5 degrees, or 67.5 degrees (do the math, turn the workpiece, and you have your 22.5-degree angle), and make the cut.

The Table Saw Cut

If you don’t have a miter saw or a miter box with a handsaw (old school) but have a table saw, no worries.  You can make the same cut on the table saw with a little bit of effort and a couple of accessories.

Cut your workpiece to size, needing only the 22.5 angle cut to be made.  Then, set the blade angle.  For this, rely upon a digital angle gauge instead of a protractor, as it will be more accurate and reliable.  A slightly off-cut will leave a gap when the two pieces are attached.

Use a vertical router sled attached to the table saw’s fence to guide the pieces through the blade.  It will need to be close to get a good cut, a quarter inch.  Be sure you are wearing all of your safety gear – goggles, face mask, gloves, and maybe even hearing protection gear.

This is something of a difficult cut, but if you approach it slowly and carefully and are skilled in the use of your table saw, it is a viable method of getting your 22.5-degree angles on your workpieces.

Assembly Of The 45-Degree Angle Joint

45-Degree Angle Joint

With the cut workpieces in hand, we turn now to the joinery.  While other woodworkers will have their own way of joining these pieces, we have a fairly straightforward method that we think you’ll find worth considering if you should need to form a 45-degree joint.

What You’ll Need To Form a 45-Degree Angle

Gather wood glue, clamp blocks, spring clamps or spring miter clamps, hot glue, v-nails or brads, a v-nailer, and a brad nailer.

It may sound like a lot, but then again, this is an unusual joint to be forming at a less than common angle.  Let’s make sure you’re familiar with some of those needs.

Clamp blocks are simply pieces of wood you’ve created for this particular purpose.  Their size will depend on the size of the workpieces you are joining.  They will be triangular in shape and cut at the same angle as the workpiece – 22.5-degrees.  Cut them at the same time as you cut the two pieces you are joining.

The rest of that clamp block will be the 90-degree angle of the piece the block was cut from.  This is important, as it will be the right angle for the spring clamps when the time comes to clamp up the joining.

Joining The Workpieces For A 45-Degree Angle

You will be attaching the clamp blocks to the workpieces at the end of their 22.5-degree cuts.  They will be serving only a temporary purpose, though, so you’ll be attaching them with only hot glue, not wood glue – a craftsperson’s glue from a glue gun.  Just a dab or two will be enough to hold it in place for its temporary task.

Glue the two workpiece ends and join them.  Grab your spring clamps, and attach one of them to the top of the clamp block; adjust the workpieces until they are aligned, and then attach the second spring clamp.  Let them sit until the glue dries and your 45-degree angle joint is formed.

An Alternative To Regular Spring Clamps

As an alternative to the spring clamp, you could use a spring miter clamp.  You’re more likely to have spring clamps in your workshop, though, and they are more than adequate for the task.  We wrote about spring clamps and spring miter clamps recently, also, and you’ll find that article here.

Securing a 45-Degree Angle Joint

You’re not quite done yet.  The clamp blocks will come off with a little tap from a hammer or mallet and a scrap piece of wood.  Put the scrap piece against the clamp block and give a little tap to dislodge it.  

There will be some residue of hot glue on each of the workpieces that you can remove carefully with a sharp chisel.  Light sanding will remove whatever little remains after that.

Depending on the purpose of the 45-degree angle joint (decorative or weight-bearing), you may want to secure the joint further with either a brad or two or a v-nail.  A filler of some sort can be used to fill the holes and then sanded down to create a smooth surface, either for staining or painting.

Clamp blocks may be new to you, or perhaps you are interested in creating your own that would be reusable and will not need to be hot-glued to a workpiece.  In that case, we found a video that will be very helpful and make the task of creating your workshop’s clamp blocks for all future projects where you have angles other than 90 degrees to form and clamp.

The math is pretty easy for creating a 45-degree angle, and the method and process for doing so, including the actual joining, is not technically difficult.  Don’t let the odd angles through you off or make you choose some other project.  In woodworking, there is always a way.

Leave a Comment