Making a Curved Box Hinge
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The process of making a curved patchbox hinge has occasionally come up in discussions, both in classes and on the web, and in at least one printed source on rifle making you may have found the statement that a curved hinge will not function.

While it is true that many original makers did use hinges that were essentially straight, there are also old rifles where the hinge is curved to match the shape of the stock. After making my first rifle with a straight hinge I decided that curved hinges were more pleasing to my eye and I have been using them on my rifles since the late 1960s. I have also taught a few classes on mount making during the NMLRA Seminars at WKU and show students in those classes how to make and fit curved hinges.

While there is no substitute for hands-on, supervised training, I hope this web page will provide enough basic information to allow someone wanting to learn to make a box that matches the flow of their stock to get a good start on teaching themselves.


The steps involved are pretty much the same for any type of hinge that is made as part of the sheet metal finial and door rather than being soldered on. (Cast boxes are made by several very different processes.)

I have never mastered the process of making boxes out of the extremely thin sheet seen on some original rifles or casting my own sheet brass.  Although Wallace Gusler cast the sheet brass for the mounts in his Gunsmith of Williamsburg movie, it was a real challenge and he ended up casting sheet about an 1/8 inch thick and hammering it out thinner. I suspect that is why cast boxes are often fairly thick and have the hinges cast in and drilled for the pin.


I usually start with sheet brass that is either 16 gauge (.051”) or 14 gauge (.064”). (The thicker material is what I would generally use on earlier rifles.) Anneal the brass and rough out rectangles for the door and finial. I make them both a bit oversize and don’t bother with any layout until after the hinges are fit.

For the hinge pins I have used everything from coat hanger wire to drill rod. Now I prefer the spring steel wire sold as “music wire” in many hobby shops and the better hardware stores. Pick a wire that is as close in diameter to the thickness of the brass.

A lot of modern makers like to use some sort of jig or form to help bend the hinges but I have never seen the need for any tools other than a hammer and a vise for this step. While it is true that 18th-century sheet metal workers like tin and silversmiths used a lot of dies, I have never found any evidence that a gunsmith had a special tool for what to me is a very simple step.

Fold the annealed brass back on itself to begin forming the barrel of the hinge. The amount of overlap in not critical and as you will see in later pictures I have been in the habit of filing the lap inside the box door into a decorative shape. (I guess you’d call this a shop detail of the Colonial Williamsburg shop since many of the rifles made there have some form of this decoration.)

The hinge is formed around the pin and you need to make sure that the pin stays all the way out against the inside of the bend. See the three drawings below. Going from the second drawing to the third is accomplished by driving the outside of the hinge down into the correctly spaced gap between the jaws of a vise. That also thins the lapped over section a bit as it moves the pin so it aligns with the sheet of the door or finial. Depending on how much you have work hardened the brass, it may need to be annealed again during this to get a sharp corner where the exterior of the door or finial buts against the barrel.

Drawings 1, 2, & 3 showing major steps in forming the hinge around the pin.

Once the hinge is formed both halves are bent to match the curve of the stock. Anneal the brass again first. Depending on the style, period, and length of the door this curve can vary from slight to fairly pronounced. If the stock is a form where the wrist carries back into the butt, the curve may be asymmetrical with a sharper bend in the top toward the comb. To avoid dinging up the hinge barrel, I add this bend by hammering on the inside and driving the brass down into a curve cut in the end grain of a piece of wood. Hammer marks on interior surfaces are normal in period work.

Drawings four and five show the bent hinge of a finial. The curve of the door is simply matched to the finial by eyeball. Now you can pull the pins out of the door and finial.

Drawings 4 & 5 showing the finial hinge curved to match the stock (pin in gray) and the three female knuckles cut to receive the door (pin shown but not colored).

The reason a curved hinge works is shown in the fifth drawing. Waiting until after it is bent to cut the knuckles allows them to be cut perpendicular to the stock and parallel to each other. All the mating surfaces of the two halves of the hinge are in the same plane as the opening motion of the door. If the knuckles were cut before bending the hinge to fit the stock there would be gaps at the top and binding on the inside after the bend was added.

Most of the boxes I have made have two knuckles on the door but the number really doesn’t matter. I show three in drawings 6 & 7 and in the unfinished box below. The 7th drawing shows a tiny bit of relief cut at the bottom of each knuckle. These have two purposes; they free up the hinge to open wider, and they make fitting the door to the finial easier.

Drawings 6 & 7 -- pin not shown.

For an early rifle a short, wide door and a short finial could be required. On a wide door three knuckles are stronger than two.

This blank box was made while I was teaching a class at WKU and I have never had an occasion to use it.

I make the door knuckles first then scribe and inlet them into the finial working from the outside inward. As soon as the door is in enough for the pin holes to begin to line up, I file a long taper on the finial pin and drive it in to draw the door up tightly against the finial. Carpenters doing timber frame construction use a long steel pin for this same purpose of drawing joints together but I cannot recall the name they give the tool.

If it is fit well the hinge will barely move when first completely assembled but a little filing on the exterior and a couple of drops of oil will allow you to work it back and forth until it moves freely. I save the final dressing of the outside of the hinge until after it is inlet in the stock and everything is being filed down to match the wood and brass.


Below are some pictures of curved hinges:

This box was made about 1995 and I have kept it as a demo piece to use in the classroom. Obviously it has never been on a rifle. The finial is a very stylized version of a Valley of Virginia "spiral flower." When finished it would have been similar to this one valley_rifle.htm

This hinge is more curved toward the comb side because it was intended for a rifle with the cove of the wrist carried back into the butt.


This is the box on my current hunting rifle. 2002_rifle.htm