How to Make a Picture Frame: Miter, Rabbet, and Assembly

Making a picture frame is a straightforward project that combines two fundamental joinery operations: the miter joint and the rabbet. The miter gives the frame its clean, seamless corners; the rabbet creates a recess to hold the glass, mat, and backing. This guide covers both, along with the assembly and finishing steps. The most common mistake is assuming that a perfectly cut 45-degree angle will automatically close tightly—it will not, unless the stock is square and the cut is precise. This page explains why and how to recover.

Cutting the Miters

The miter is a 45-degree angle cut on the end of each frame piece. When two miters meet, they form a 90-degree corner. The key to a tight miter is that the two pieces must be exactly the same length and the angles must be exactly 45 degrees. Any deviation—even half a degree—will show as a gap on one side of the joint.

Use a miter saw for accuracy, or a table saw with a miter gauge. Set the blade to 45 degrees and make a test cut on scrap. Check the angle with a protractor or a combination square. If the angle is off, adjust the saw and test again. It is better to spend time on test cuts than to ruin good stock.

When cutting the four pieces, remember that the length of each piece is the outside dimension of the frame minus twice the width of the stock. For example, for a frame that is 12 inches (30 cm) wide with 2-inch (5 cm) wide stock, the long pieces are 8 inches (20 cm) long. Cut all pieces with the same face against the fence to keep the angles consistent.

Cutting the Rabbet

The rabbet is a recess cut along the inside back edge of the frame. It holds the glass, mat, and backing. The rabbet depth should be about 1/4 inch (6 mm), and the width about 3/8 inch (10 mm). You can cut it with a router and a rabbeting bit, or with a table saw and a dado stack. If using a router, set the bit depth and use a bearing guide. If using a table saw, set the fence and blade height, and make multiple passes.

Cut the rabbet on the inside edge of each piece, but not all the way through the ends—stop short of the miter by about 1/8 inch (3 mm) to avoid breaking through the corner. Clean up the corners with a chisel. The rabbet should be smooth and flat, as it will be visible from the front if the frame is shallow.

Why Miters Do Not Close

A common frustration is that even with perfectly cut 45-degree angles, the miter does not close tightly. The cause is usually that the stock is not square—that is, the sides of the board are not at 90 degrees to the face. When you cut a miter on a board that is not square, the angle is correct in one plane but off in another, resulting in a gap. Check your stock with a square before cutting. If it is not square, plane or joint the edges first.

Another cause is that the saw blade is not square to the table. Even if the miter gauge is set to 45 degrees, if the blade is tilted, the cut will be off. Check the blade with a square and adjust if necessary.

If a miter does not close, the fix is to recut the piece, not to force it with glue. Forcing will only create a weak joint. If the gap is small, you can sometimes shim it with a thin piece of veneer, but this is a patch, not a solution.

Assembly and Gluing

Before gluing, dry-fit the frame to check the fit. All four miters should close without gaps. If they do, you are ready to glue. Apply wood glue to the miter faces—not too much, just a thin, even coat. Join the pieces and use a strap clamp or band clamp to pull the joints tight. Check for square by measuring the diagonals; they should be equal. If not, adjust the clamp until they are.

Wipe off excess glue with a damp cloth. Let the glue dry for at least an hour, or as recommended by the glue manufacturer. Do not rush this step; a joint that is not fully cured can shift.

Reinforcing the Joints

Miters are inherently weak because the joint relies on glue surface that is end grain to end grain. To make the frame durable, add mechanical reinforcement. The simplest method is to drive finish nails through the miters after the glue is dry. Drill pilot holes to avoid splitting, and countersink the nails. Fill the holes with wood filler.

A stronger method is to add splines. Cut a slot across the miter with a table saw or a router, and glue in a thin piece of veneer or wood. The spline adds long-grain to long-grain glue surface, making the joint much stronger. This is a good option for frames that will hold heavy items.

Finishing and Installation

Sand the frame smooth, starting with 120 grit and progressing to 220. Pay attention to the corners; sand them gently to avoid rounding over the sharp edges. Apply your chosen finish—oil, varnish, or paint. Follow the manufacturer’s instructions for application and drying times.

To install the glass and backing, cut them to fit the rabbet. The glass should be slightly smaller than the rabbet to allow for expansion. Place the glass in the rabbet, then the mat (if using), then the backing. Secure with small nails or offset clips. Attach hanging hardware, such as D-rings and wire, to the back of the frame. Position the hardware so the frame hangs level.

Common Mistakes and How to Avoid Them

The most common mistake is not checking the squareness of the stock before cutting. This leads to miters that do not close, and the frame is weak. Always check and correct the stock before cutting. Another mistake is cutting the rabbet too deep, which can weaken the frame or break through the front. Test the depth on scrap first.

A third mistake is rushing the glue-up. If the frame is not clamped properly, it can twist or become out of square. Take your time and check the diagonals. Finally, do not skip the reinforcement. A miter joint that is not reinforced will eventually open, especially if the frame is subject to changes in humidity.

Frequently Asked Questions

Q: What is the best wood for a picture frame?

A: Hardwoods like poplar, oak, or walnut are good choices. They are stable and take finishes well. Softwoods like pine are cheaper but can dent easily. Use the same wood for all four pieces to ensure consistent color and grain.

Q: Can I make a picture frame without a router?

A: Yes, you can cut the rabbet with a table saw using a dado stack, or with a chisel and mallet. A router is convenient but not essential. The key is to make a clean, even recess.

Q: How do I fix a miter that has a small gap?

A: If the gap is very small (less than 1/32 inch), you can fill it with wood filler or glue mixed with sawdust. For larger gaps, recut the piece. Do not try to clamp the gap shut, as this will stress the joint.

Q: What is the best way to hang a picture frame?

A: Use D-rings and picture wire. Attach the D-rings to the back of the frame, about a third of the way down from the top. Thread the wire through the D-rings and twist it securely. Use a wall hook rated for the weight of the frame.

Q: Do I need to use glass in a picture frame?

A: Glass protects the artwork from dust and damage. It is recommended for most frames. For a frame with a deep rabbet, you can also use acrylic, which is lighter and safer. Choose glass that is cut to fit the rabbet exactly.