Laying out a finger joint requires precision. Here’s the manual approach for a table saw jig:

1. Choose Finger Width: Select a finger width that is appropriate for your stock thickness, typically between 1/4" and 1/2". The finger width must match the width of your cutting tool (dado blade or router bit).
2. Create an Index Pin: Your finger joint jig needs an index pin that is the exact same width as your finger width. This pin is used to space the cuts perfectly.
3. Make the First Cut: Make the first cut on the edge of your workpiece.
4. Use the Index Pin: Place the newly cut slot over the index pin on your jig. This positions the board for the next cut.
5. Continue Cutting: Make the next cut, move the new slot over the pin, and repeat the process across the width of the board.
6. Cut the Mating Piece: For the second board, the first cut is made with the board's edge offset from the initial starting position by one finger width, ensuring the two pieces will interlock.

• Finger Joint / Box Joint: A corner joint made up of interlocking, square-profiled fingers.
• Finger: The rectangular protrusions that form the joint.
• Slot/Socket: The space between the fingers where the mating fingers fit.
• Index Pin: A precisely sized guide pin on a finger joint jig used to space the cuts evenly.
• Dado Stack: A set of blades used on a table saw to cut a wide channel, ideal for making finger joints in a single pass per slot.

"A common frustration with finger joints is a fit that's too tight or too loose. This almost always comes down to the setup, not the calculation. Your dado blade might be labeled 1/4 inch, but it could be a few thousandths off. The best practice is to always make test cuts. Cut a joint in two pieces of scrap from your project material. If the fit is too tight, add a paper shim to the side of your jig's index pin. If it's too loose, you may need a slightly wider blade or a different setup. Dial in the fit on scrap before you ever touch your final workpieces." - Woodworking Journal Editor

Small Craft Box: You are making a box with sides that are 4" wide and 1/2" thick. You choose to use 1/4" fingers.
The calculator will determine the number of fingers and spacing, ensuring the joint starts and ends with a finger for a clean look. It will provide the exact number of cuts and the starting/ending adjustments needed.

Workshop Drawer: You are building a utility drawer from 3/4" plywood that is 8" wide. You opt for sturdy 1/2" fingers.
The calculator will lay out the joint, likely with 8 fingers, and provide the precise cut depth, which might be slightly more than 3/4" to ensure the joint sits flush.

• Mismatched Finger and Slot Size: The most common error, caused by an incorrectly sized index pin or dado blade setup.
• Inconsistent Pressure: Not holding the workpiece firmly against the jig and fence for every cut can lead to uneven finger spacing.
• Incorrect First Cut Setup: Failing to properly offset the first cut on the mating board will prevent the two pieces from fitting together.
• Bottoming Out: Cutting the finger depth too shallow will prevent the joint from closing fully. Cutting too deep can weaken the joint.

• Box Making: The quintessential joint for small to medium-sized boxes, from jewelry boxes to humidors.
• Drawer Construction: A strong and attractive alternative to dovetails for building drawer boxes.
• Small Case Construction: Ideal for building small cabinets, tool totes, and other case goods.
• Joining Boards Lengthwise: A different type of finger joint is used in manufacturing to join short boards into longer ones, creating a strong end-to-end glue joint.