Designing Hinges in Hardened Leather

When building cases and boxes in leather, I often find myself debating what mechanism to use to attach a lid. Most often, that’s a simple flap, or perhaps strap hinges, as in the box pouch on my oxblood quiver. With my new “X1 leather hardening technique”, though, I wondered if the new material could support a stronger, more durable mechanism more similar to hinges we’re familiar with.

The internet doesn’t make much mention of leather being used as a hinge, especially outside of the common application seen above. One YouTuber built a design similar to one I tried, though it seems he made no attempt to harden the hinge and approached the project more as a humorous curiosity than as a genuine crafting technique. In all, only a few methods were attempted, and it didn’t take long to come up with something new for the tool kit. I think that until now, leather simply wasn’t rigid or durable enough to be considered for this style of mechanism. With the X1 method, novel applications can be developed that were previously unrealistic.

A design was needed that created a hinge with an acceptable range of motion, durability, bulk, and ease of construction. A balance was needed between a robust enough mechanism that could hold up to daily use that was still slim and unobtrusive. The idea was to make something more elegant than current options.

The first design used two strips of heavy vegetable-tanned cowhide to make each hinge. Hinge knuckles were cut, and the hinge sides cemented together.

The sides were stitched or riveted together, the leather hardened, and a hole drilled for a brass rod as a hinge pin. I’d hoped the hardened leather would be rigid enough to retain the pin under normal use. Unfortunately, I quickly found after constructing this design that the hinge would need a little more reinforcement to be usable.

Next was a hinge style similar to those more commonly found on doors. Construction was straightforward. Slots to create hinge knuckles were cut on each hinge piece.

These pieces were then hardened…

And clamped to shape.

Once cooled, a wooden pin was carved from poplar, the hinge sides aligned, pin inserted, and the hinge mounted.

This hinge style is very strong and I think could even be used to hang cabinet doors or in other common applications. This hinge could be built into heavy-duty leather items; I’d likely fold the far end of the hinge back under the lid/flap, and stitch in place. The trade-off for strength and durability is, of course, bulk.

Next I wanted to try something on the other end of the spectrum- as minimal and lightweight as possible. A single-thickness of leather was cut for the hinge.

Knuckles were cut, the pieces hardened, and a pin hole drilled through the knuckles of both pieces.

This was definitely the easiest hinge to assemble, and actually worked quite well. Given that the hinge wasn’t weakened by a split right along the hinge pin, the hardened leather had plenty of strength to hold up to abuse. I used a scrap of wire for a pin in this sample, and was unable to pull the hinge pieces apart.

The last hinge design attempted struck a balance between the two previous methods, seeking to be both strong and slim. This method was also definitely the most work to assemble.

This hinge was again built with two sides to each hinge piece. Strips of leather were cut, and a groove cut on the inside of each hinge side.

These grooves were then widened with a bone folder to accept the brass rod being used as a hinge pin.

To avoid the weakness of the first hinge, this one will be reinforced with stitching to prevent the pin ripping out. A stitch groove was cut, stitch holes marked, and edges beveled.

This profile shows the hinge geometry being created. On the bottom is the hinge pin channel; on top, the stitch groove, just barely ahead of the pin, and a beveled edge.

The two halves of the hinge are cemented together, making sure to keep the pin grooves aligned.

Hinge knuckles are cut, stitched, pin inserted, and knuckles trimmed to allow for free movement. My trimming here was sloppy, and it took some time to refine the technique for a better fit.

I left the pin in the hinge during hardening, and clamped flat to cool.

Once cool, the pin ends were trimmed and mushroomed, and the hinge mounted. I adjusted the screw positions once to stop them colliding and increase range of motion.

This hinge design worked very well and is also extremely strong. Since it uses two layers of leather instead of one, it’s slightly more bulky and considerably more work than the second method, and would be a great middle of the road option.

A few notes I took while making hinges- leather has the particular advantage in this case of being normally flexible; I found it’s a good idea when drilling pin holes to do this before hardening, which allows maneuvering the drill bit into tight spots that would be otherwise impossible to access with rigid material.

I found that Barge cement completely fails during the X1 hardening process- it’s very important than any hardened areas are stitched to ensure a solid seam instead of relying on cement.

Trimming hinge knuckles and notches is a little tricky. I found the best approach to be cutting them to match up tightly, then hardening, and going back in afterwards with an exacto-knife blade and shaving just enough material to allow the pieces to move freely, while minimizing gaps.

When first attempting to move two freshly hinged and hardened pieces, it might help to gently warm them first with a heat gun to loosen the grip of the leather on the hinge pin slightly.

Click here for a photo-journal of the build process for a hardened eyeglass case using one of the hinge designs.

Thanks for reading, and please reach out if you use any of these methods in your work. Thank you!

Jason Timmermans