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Wood Hinges and Hasp

A gentleman in Washington contacted me and got a pattern from me to build some wood locks.

Then he contacted me and wanted to know if I could design and build some wood hinges and hasps for 2 chests he is building. He sent me an article on how to build wood hinges.  The article covered making wood hinges for small boxes.

I used scaling to help to decide how to scale up the hinge size from the smaller to the larger box. I went with 3/4" thick wood, 3/8" wide teeth, and 3/4" tooth depth. I was able to add 3/8" wide teeth to my existing jig for cutting box joints.

I then made a Google Sketchup of the chest, wood hinges, and hasp.

Here is the basic hinge design:

The original design intent was to make the hinge 3 inches long.  If you do this, then neither of the 2 hinge pieces has 2 male pins on the outside. If you add 1 tooth width, to 3-3/8", then the bottom piece shown above has the desired 2 male pins on the outside.

Getting the finished length of the hinge is tricky. You would think that if you want the hinge to be 8" long, then each of the two pieces should be 4" long..........incorrect!!  Because of the 3/4" overlap, if you cut each piece to 4" length, you will end up with 8 - 3/4 = 7-1/4" long. I made this mistake, so the hinges shown here are 7-1/4" long.

Here is a back view of the chest showing the 2 hinges:

 The hinges are 5" from the ends.

Hasp Design

The hasp has to work with a large wooden lock, like the 1856 Railroad Lock (shown in another of my web pages under wood locks).

I was pretty sure that I could bend 3/16" diameter brass rod, and I had some in stock left-over from whirli-gig projects.

Here is a Sketchup of the hasp design I came up with:

When you design a hinged hasp like this, the groove in the outer piece needs to extend lower than just the bottom of the brass rod. This extra groove length is needed for the arc the hasp has to swing through. This arc also creates the need for the 2 lead-in chamfers shown above.

 

And here is a front view of the chest with hasp and the 1856 railroad lock:

Trial Run

I decided to make 2 hinges as a trial run. I ran into a couple of things building the 2 trial hinges.

The pattern noted above says to avoid round-over router bit (because of tear-out), and made a template for a straight cutter with roller bearing to follow. This works fine on the pattern hinge, because it is only 7/8" tall. All of the straight cutters with roller bearing are only a maximum of 1 inch of cutting length. The hinges and hasp for the bigger 18hx33Lx16deep box would be 3 to 4 inches wide. On the trial box, I tried rounding over the hinge using a very long 1" sanding drum on the drill press.  This worked, but the radius on the hinges was inconsistent in size since I was doing it manually.

I decided to make the hinges wider than they needed to be, then saw them down to size. I sawed the blank, then did use a 3/8" diameter round-over carbide router bit. Then I use the box teeth jig on the table saw. This method worked much better for the bigger box.

A regular 1/8" drill bit only drills about 2 inches deep, and the hinges/hasp are 3 to 4 inches wide.  I put the hinged pair into my big drill press vise, then drilled from each end.  Then I took a 12" long 1/8" dia bit and drilled from 1 end, through the hinge. This was a bad plan, because I ended up with 2 holes on the end the long drill bit exited. I refined my technique to not drill through from 1 end, and stop short with the 12" long bit. Also drill from both ends. This worked much better.

I also followed the patter advice of putting a piece of paper between the hinges when you drill the guide pin. Because my hinges are so much bigger, I used a piece of cereal box cardboard versus notebook paper.

Another thing I noted was that 1/2 of the hinge pair should have male ends on both ends of the hinge width. This makes a much more pleasing appearance. For example, the hasp has 6 male teeth on the piece with male teeth on each side of the hinge. This means the mating piece has 5 teeth.

Jig to Bend 3/16" Dia Brass Rod for Hasp

 

 

 

 I made the initial bend using a c-clamp, then used the bar clamp to draw the curved end against the wood jig. Then did the final bend by clamping up the vise.

 Table Saw Set-Up to Cut Teeth

 

 You also need the 3/8" wide spacer block start cut 1 of the pair of hinges. It took the 2 outside dado blades plus 1 center blade to make the 3/8" wide cuts.

I made a YouTube animation that shows the teeth cutting process:

 

 

Drilling Pin Holes in Hinges

 I put each piece of the hinge pair in my big vise, then drilled as deep as a standard 1/8" diameter bit will drill. I put 2 pieces of cereal box cardboard as spacers before I starting the drilling processes.

Then I used my super-long drill bit to re-drill from each side, being careful to not drill all the way through. If you drill all the way through, you run the risk of creating a 2nd hole in the outlet side.  I learned this the hard way on the trial run I did.  Using the revised technique, the hinges turned out fine.

 

 Verifying the Hasp Design with an 1856 wood Railroad Lock

To verify the hasp design would be ok, I tried out the hasp with an extra 1856 railroad lock that I have. The design turned out to be fine.

 

 

 All Parts Rough Cut

 Here is a photo of the 4 hinges and 2 hasps rough cut.  The 2 hasps are done except finish sanding. The 4 hinges need the following work:

-table saw to desired width

- drill 1/8" pin holes

-cut 1/8" brass rod to length

-verify hinges work ok, file/sand as needed for good fit

-finish sand to 220 grit

 Finished Hasps

 Here are photos of the finished hasps. They still need final 220 grit sanding.

 

 

 

 

Finished Project

 And here are the finished 2 hasps and 4 hinges ready to ship out.

 

 

 

 

Lessons Learned on this Project:

1. don't drill all the way through on 1/8" brass, come from both ends, but not through.

2. use cardboard spacers when drilling 1/8" pin hole.

3. It takes a lot of trial & error on the table saw to get the teeth spacing just right. 

Although I had never made wood hinges before, they turned out to be very similar to making wood boxes with tooth joints. The same type of table saw set-up is used to make the teeth. Hopefully these hinges will be a nice additional touch to the chest project.

 

 

 

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