Mitre joints look very nice on a picture frame but they are weak for large frames. Of course there are splines that can be used but they are not as strong as a mitered corner bridle joint. So this technique is very useful for big frames but it can also be used for smaller ones.

A mitered corner bridle joint is very similar to an open mortise and tenon joint with the difference that the shoulders of each piece is mitered.

So in this instructable I will show you the way to apply this technique on a simple picture frame.

We will need:

Wood
Planer or hand plane
Jointer
Band saw
Radial arm saw or table saw
Wood glue
Stapler (optional)
Paint (any kind you like)
Router
1 cm rabbet router bit

This is a video showing the whole process step by step:

Step 1: Milling the Wood

First of all you have to mill your pieces to the size you want. I wanted my frame to be 50 x 40 cm so I had to cut 2 pieces 50,5 cm and 2 more pieces 40,5 cm. Its a good idea to make your frame 0,5 cm wider and 0,5 cm taller and after you finish it you will be able to clean all the sides with your plane and still be the size you wanted it.

The thickness of my pieces was 2 cm. It can be less than that but I wanted my pieces to be beveled.

Step 2: Cutting the Slots

Take the two vertical pieces of your frame and make a slot on each end. The depth of the slot must be equal to the width of your workpiece. For example the width of my workpieces was 7 cm so I had to make the slots 7 cm deep. The width of the slot must be one third of the thickness of your workpiece. Once you have cut all the four slots you must set your miter gauge at 45° and make the cut.

Step 3: Tenons

You can get the best results if you use your table saw and a miter gauge. I do not have a table saw so I had to make a jig for my band saw. It is the one you can see on the first two pictures above. You just cut a tenon having your workpiece clamped on a jig that holds the workpiece at 45°. Of course the jig that I have used can be used only on the band saw because it is really dangerous to use it on the table saw.

Step 4: Making the 45° Cuts

If you have used your table saw this step can be ignored. If you have used the bandsaw technique then keep reading. In this step I had to cut the shoulders of the two pieces once they could not be cut on the bandsaw. At least not cleanly. For this I used my radial arm saw. Once you finish this step your workpieces should look like this.

Step 5: Routing for the Glass

At this point you have to make the rabbets for the glass. Simply use a rabbet bit on your router and make a 1 x 0.5 cm rabbet on each piece.

Step 6: Bevel (Optional)

I wanted each piece of my frame to have a bevel. I had to make a simple jig with some scraps of melamine and use it on my bandsaw to make the bevels.

Step 7: Assembling the Frame

Add some wood glue on the tenons and assemble the frame. Use some clamps to apply some pressure while the glue dries. You can also add some staples on the back side of the frame.

Step 8: Finishing

Once the glue sets you can finish your frame. sand all around the frame and apply the finish you want. I applied two coats of primer and two more coats of a water based paint.

Step 9: Final Steps

Add the glass and the picture. Then you can add a piece of 4mm plywood behind the picture .Use some staples to secure the plywood in place. Screw a picture hanger behind the frame and you are ready to go! Have fun and be safe.

Introduction: Mitre Bridle Joint for Picture Frames