My Take on Wood Hinges

Alex Reid

Member
Messages
739
Location
Zushi, Japan
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
woodhinge1.1.jpg


Pic 1. Using two 3.2mm spacers to cut first index key slot
woodhinge1.jpg


Pic 2. With top and bottom index key slots cut
woodhinge2.jpg


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.
woodhinge3.jpg


Pic 4. Cutting the last finger joint on the first blank
woodhinge4.jpg


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.
 

Alex Reid

Member
Messages
739
Location
Zushi, Japan
Pic 5. Slotted blanks ready for round over
woodhinge5.jpg


4. I do the round over after I cut the slots as I am using a flush-cut bit with my hinge held in a vertical position in a round-over jig. This way there is no chipping on the sides as there would be if you ran the blank over a round-over bit in a horizontal position and you have more control over the profile of the round over. To make the jig use a piece of scrap about 30mm thick by app 50mm wide and long enough to hold the blank. Round over the left side edge of one end and cut a rabbet to depth the same as the thickness of the blank (Pic 6 ). Round over with flush-cut bit (Pic 7).

Pic 6. Round-over jig with rabbet cut and round over on corner
woodhinge6.jpg


Pic 7. Round over with flush-cut bit.
woodhinge7.jpg


5. Now we are ready for the last step; drilling the 2mm hole for the brass pin. A note to bear in mind here it is crucial that the hole is center top to bottom and side to side as the hinges or lid can bind or the lid will lift away from the box unevenly and be unsightly. Set-up your drill press and drill a couple of test holes to make sure. When you are confident all things are right, place the hinges in the together position with a spacer so they aren’t touching. (I used a piece of letter paper folded once. This is app 0.15mm) Pic 8.

Pic 8. Hinge ready for drilling a 2mm hole
woodhinge8.jpg


6. Once the hole is drilled put a pin through and check hinge action. Look at the space between the end-points and mating hinge. As you move the hinge does the space stay the same distance or can you see lift or binding? It should stay parallel. The hinge should open to just over 90 degrees. Finally if all things are right take the pin out and cut to size with a backer board to prevent chip-out on the corners. I cut the ones pictured in Pic. 5 to 20mm. Put the pin back in and file and sand till flush.
 

Alex Reid

Member
Messages
739
Location
Zushi, Japan
7. Now the hinge is ready for installation. For this we use a hinge-morticing jig (Pic 9). Again I use a quick and dirty, throwaway style jig, nothing fancy. What is important here is the guides are square all around and the correct distance apart. The distance between the two guides on the X and Y axis will be router base size minus router bit diameter plus width or length of hinge.

In my case
- 160mm – 3.2mm + 22.4mm = 179.2mm for the width
- 160mm – 3.2mm + 40mm = 196.8mm for the length

The underside of the jig has a cleat positioned with a distance from the cleat to the center of the mortice equal to the distance from the bottom of the box to the center of the hinge pin. In other words you want the hinge pin to be centered on the opening line between the box and the line.

Pic 9. Hinge morticing jig
woodhinge10.jpg


8. Clamp the lid to the box and position the mortice jig into place. (Here I have marked center on the jig and box. Now it is a simple matter of lining up the two and clamping the jig into place (Pic 10)).

Pic 10. Hinge morticing jig clamped in position with box and lid clamped together
woodhinge13.jpg


9. With a plunge router set to a depth half the thickness your hinge rout the mortices (Pic 11).

Pic 11. Hinge mortices cut
woodhinge14.jpg


10. Now there is the option to square the corners of the mortices or round off the hinges. I prefer to round off the hinge corners. I do this on a disk or spindle sander. I routed out the mortises with a 3.2mm straight bit so the corners have a 1/16 radius. Careful you don’t take too much off.

11. Check the fit and if everything is okay glue the hinges into place (Pic 12). I use Titebond PVA glue careful to avoid excess squeeze out and overflow into the fingers. Apply clamp and let glue dry.

Pic 12. Check the fit is tight, glue and clamp
woodhinge15.jpg


Finished
4.jpg


You can download this pdf file to print for use in your shop.
http://mokkou.jp/woodhinges/MakingWoodenHinges.pdf
 

Stuart Ablett

Member
Messages
15,918
Location
Tokyo Japan
Boy Alex, that sure is a lot of work, but man, are those hinges COOL!

You got some very innovative solutions to some problems, way to go, and thanks for the step by step tutorial! :clap:
 
Messages
2,369
I was thinking the same thing. A lot of work...

After seeing all that...and I hate to bring this up because it was a lot of work and a lot of set-ups...I think the hinges would look a bit better with some rounded over edges or at least a chamfer on them. They look good, but I think they just look unfinished without eased edges of some type.

Just my opinion. Of course with all the set-ups you did, I think a little rounding over would be a pretty easy thing to do. :)
 

Alex Reid

Member
Messages
739
Location
Zushi, Japan
Travis,

Thanks for the input. I also think a beveled edge would look good. I thought about doing it and would have done it if I squared out the mortices. In this case I ended up rounding the corners instead, which I also like.
 
Messages
2,369
Travis,

Thanks for the input. I also think a beveled edge would look good. I thought about doing it and would have done it if I squared out the mortices. In this case I ended up rounding the corners instead, which I also like.

Yeah I like that as well. Personally I have a like for chamfers. I like the crisp transition from 90 degree surfaces to 45 degree surfaces in between which of course is what a chamfer does. Round overs are nice too, but I prefer chamfers.

I never really noticed this small detail before until I worked on our last yacht. The boat owner liked chamfers and not round overs and after a year or so, I guess I ended up liking them too. When I have my druthers, chamfers take the nod. I sneak them in on other yachts now and then when I think I can get away with it :)
 

Bill Simpson

Member
Messages
1,758
Great piece of work and a cool presentation.

Not that you are not right, but came to my mind that I wonder if doing the round over before cutting the finger joint might facilitate use of a roundover bit and perhaps an easier/safer method. I may be wrong or out of touch with reality but that is my take.

Aside from my silly interjection, I was really interested in your approach, nice job and thanks for the presentation. :thumb:
 

Alex Reid

Member
Messages
739
Location
Zushi, Japan
Great piece of work and a cool presentation.

Not that you are not right, but came to my mind that I wonder if doing the round over before cutting the finger joint might facilitate use of a roundover bit and perhaps an easier/safer method. I may be wrong or out of touch with reality but that is my take.

Aside from my silly interjection, I was really interested in your approach, nice job and thanks for the presentation. :thumb:

No probs Bill. It can also be done with a roundover bit but you have to use a backer board to prevent chipping. With the jig I have used I think the flush-cut method is quite easy and safe.
 

Bill Simpson

Member
Messages
1,758
No probs Bill. It can also be done with a roundover bit but you have to use a backer board to prevent chipping. With the jig I have used I think the flush-cut method is quite easy and safe.

I was thinking a backer board would be necessary as well. Its just that I am not comfortable with out in the open trimming like you demonstrate... I feel safer when I have a fence to help (I guess it goes back to 1972 when I got my fingers caught up in a shaper.... Ouch!!! :eek: All came out well after stitches and aside from a few scars only my pride and courage suffers)

I do like the way you approached the hinges, Good job and Nice Demo. :thumb:
 

Wes Bischel

Member
Messages
896
Alex,
Thanks for the PDF. The hinges look great on your box. When I looked at the first jig, I thought it would also work well for small finger jointed boxes!

Thanks again for taking the time to put it all together.

Wes
 

Alex Reid

Member
Messages
739
Location
Zushi, Japan
Alex,
Thanks for the PDF. The hinges look great on your box. When I looked at the first jig, I thought it would also work well for small finger jointed boxes!

Thanks again for taking the time to put it all together.

Wes


Wes, I thought the same. In my latest keepsake box I made a small tray for inside and while I made miter joints for it I thought later that finger joints using this jig would have worked great. Next time eh...
 
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