(Originally From This Post)
Materials and tools used
- 3.2mm straight router bit
- 1/8” round-over router bit
- Flush-cut straight bit (with bearing on bottom)
- Finger-joint jig
- Round-over jig
- 2mm brad-point drill bit
- 75mm x 22.4mm x 6mm ebony blank
- scrap plywood for mortising jig
- 3.2mm spacer x 2
- 2mm diameter brass rod (material is optional – I prefer brass for this)
In this tutorial for making and installing wooden hinges I use ebony blanks cut and milled to a specific size related to the size of my cutting bit. I use a 3.2mm (1/8”) cutting bit mounted in my router table. The width of the blank will therefore be 3.2 multiplied by the number of fingers and slots. I want a hinge that has 4 fingers/3 slots and the mate will have 3 fingers/4 slots. So the width of my hinge will be 3.2x7=22.4. (You can also make them a little wider and cut to size on the table saw after slotting the finger joints). The length of the blanks will be any length desired but should be around 75mm (3”) for ease of clamping and cutting on the finger joint jig. The thickness of the blank will be 6mm or if you are working in inches 1/4” will work well. (Here also you can use a thicker blank and re-saw later for a production run).
1. Make a finger joint jig like the one pictured in Pic 0. I use a quick and dirty jig so the face is a throw away piece for this use only, screwed on from the back. The faceplate height is cut to the same height as my blanks (this is important). Place two spacers between the fence and faceplate and rout a slot through the face (Pic 1). Flip the faceplate end-for-end and do the same (Pic 2). Remove the spacers, move the faceplate against the router fence and cut another slot only on the bottom this time. Screw the faceplate onto the jig. Place a 3.2mm key in the first and second slot (Pic 2). Depth of cut should be about 0.1 mm over thickness of blank.
Pic 0. Quick and dirty finger joint jig
Pic 1. Using two 3.2mm spacers to cut first index key slot
Pic 2. With top and bottom index key slots cut
The blanks and the faceplate are cut to the same length for ease of cutting and stability. Because the blanks are long and narrow stability is an issue. Of course a clamp does hold the blank in place but having the extra key slot makes the job a lot easier, a little less fumbled and more accurate.
2. Place a blank in position (Pic 3) and begin cutting the joints. Flip the blank end-to-end and cut right to left until last slot is cut (Pic 4).
Pic 3. With blank in first position.
Pic 4. Cutting the last finger joint on the first blank
3. As in step 2 cut the slots for the matching hinge. Start the first cut with a 3.2mm spacer between the key index and the blank, flip end-to-end and continue cutting right to left until the last slot is cut. Note: it is at this point you will see how much you have to trim the width to size if the blanks were over-size to begin.