Fitting a Lock to a Case Without Misalignment
The lock is the one part of a briefcase where a mistake the width of a pencil line costs you the whole front panel.
Fitting a lock to a leather case is a job of small, permanent moves. You mark, you cut a hole through the face of the leather, you push pins through it and spread them, and none of that comes back out clean. I do the delicate steps alone, lock alignment above all, with nobody else at the bench, because a small error there doesn’t mean a touch-up. It means cutting a new front panel. What follows is the job in order, step by step, with the way each step goes wrong when you rush it.
Video: How To Fit A Leather Briefcase Lock (Professional Use Only), from Leathercraft Masterclass- Online Video Courses on YouTube.
Choosing the lock before you cut anything
A lock you have not held in your hand has no business on the bench.
The scenario starts at the parts drawer. You have a front panel cut and the gusset not yet sewn. There’s a flap with a strap or hasp to carry the top half of the lock, and a case lock in its box. My page on High-End Locks says the locks I use come from traditional lockmakers in England or Italy, made with brass parts, unlike the zinc pot metal locks on most bags today. It describes the English tube key lock as installed with solid steel pins, and the round clock-style combination locks the same way, with the rectangular ones held by permanent screws. Abbey England’s hardware range says its lock and case fittings are cast at its foundry in Walsall.
My opinion: the Italian-made locks are the best I’ve seen, solid brass with palladium plating, where nickel and zinc are the cheaper roads. That’s taste and experience, not a lab test.
Here is what goes wrong at this step. You trust the box. Before anything touches the leather, take the lock apart and close it a dozen times in your hand. Learn where the pins sit, how far the case of the lock stands proud of its plate, how deep the hasp drops into the body before it catches. The tube lock on my page works like this: “The round button pushes down as you insert the top latch into the bottom, or pull it out to release.” If you can’t see that motion in your head with your eyes shut, you can’t place it on a panel.
Count the fasteners, too. Locks that once came with pins don’t always come with them now, a point one maker made in a 2017 leatherworker.net thread on brass locks and escutcheon pins.
Finding center and marking the pin holes
Measure from the edges the eye will judge, not from the edges that are easy to reach.
Find center on the panel first. Emmaline Bags, in a guide to installing turn locks and flip locks, folds the body piece in half to find its center line, then measures down to the height wanted and marks it. A stiff bridle panel won’t fold without leaving a crease you’ll see for years, so lay a steel rule across it instead, measure in from both side edges and mark where they meet. Do it twice. If the two readings disagree, the panel is out of square, and that has to be settled before any lock goes on it.
Then set the lock plate on the mark and check it square with a ruler from the edges, the way Emmaline’s guide checks a flip lock’s back plate so it doesn’t sit crooked. Use the edge the customer will see as the reference: the top of the panel, the line of the flap when it’s closed. A lock that is perfectly square to a panel that isn’t will still look crooked on a desk.
Now mark the pin holes. A member writing as jling, in a leatherworker.net thread on attaching a round brass lock to a briefcase, warned that the mounting holes sit very close to the lock box, and that they should be marked on the leather before the opening for the box is cut. Weaver Leather Supply’s guide to setting a turn lock marks its rivet holes with a leather awl through the base of the lock and has you practice on scrap first.
What goes wrong here is the order. Cut the opening first and the marks go with the waste. Then you are guessing pin positions off a hole, and a hole cut by hand is never quite where the drawing put it.
Cutting the opening and punching for the pins
Cut it small. You can always take more out. You can never put it back.
The opening for the lock body is the cut that scares people, and it should. Emmaline’s guide says to start with a small slit and trim in small steps, and lists holes cut too large among the usual mistakes. On a fabric bag a big hole means a loose lock. On a bridle panel it means a gap around the box that shows the raw fiber of the cut, right in the middle of the case, where every eye lands.
Cut inside the line. Fit the lock, trim, and fit it again. A knife that is not sharp enough to shave will push and tear on thick bridle instead of cutting, and the corners of a square opening are where it happens first. Keep the blade upright, so the walls of the opening are square to the face of the leather, or the box will sit tilted no matter how true the marks were.
Punch the pin holes with the smallest punch that lets the pin pass. jling found that escutcheon pins got little grip from the leather itself and that the backing plate did most of the holding. A loose hole doesn’t fix that. It makes it worse.
Before you go further, dry-fit everything. Emmaline’s guide does it with both plates and the flap between them before any glue goes near the work, and on a case the dry fit should include the hasp on the flap, closed onto the body, with the case standing as it will stand in use.
Backing the lock and setting the pins
The leather holds the lock in place. The plate and the pins hold it on.
Every lock needs something behind it. In that same thread on round brass locks, AndersenLeather said the stitching around a lock holds the backing leather, not the lock, and that a backing layer is needed because the lock box stands out from the panel and its edges are sharp. Another member, MY63, described an old English case with the lock riveted through and a piece of leather glued over the backing plate inside, no stitching showing.
Most installs go loose at the pins. jling found that peening a pin over thin leather pushed the pins back out, so the lock sat proud of the face, and that peening close to the mechanism was awkward enough to need a wood block drilled out to clear the latch. MY63’s answer was to hold the head of each rivet firmly against the face of the lock with a rivet set or a cupped rod while peening the back, with a ball-peen hammer: “Wood or leather will deform and make for a loose fit.” Small washers behind the rivets, he said, give the peened end more to grip.
The pins themselves matter. In the escutcheon pin thread, a member named gary said the brass-plated steel pins he had bought were “very hard to burr over,” and that solid brass rivets did a better job. A pin that fights the hammer gets hit harder, and the hard blows are the ones that bruise the face of the panel around the lock.
My opinion: for a case that will carry real weight, I’d rather have a rivet-installed lock than one that relies on prongs or glue. Rivets go through and get closed on the far side. Nothing else holds the same way when a heavy file pulls on the flap every morning.
The closing test
Close it full, close it empty, and close it standing up.
A lock that is fitted but has not been tested isn’t finished. jling, back in the round brass lock thread, cut notches for the latch bar to clear and still had trouble closing the case after assembly. Later the same maker found the lock hard to snap shut on an empty single-gusset case. AndersenLeather agreed that it was hard to close when empty and said it is the stiffness of the front panel that matters most, more than the number of gussets.
So test the way the case will be used. Close it with nothing inside, then with a full load of files. Close it standing upright on the bench, because in my experience locks work best with the case upright. Test it lying flat as well. A hasp that drops in clean one way is no proof it will the other.
What goes wrong at this step is giving up on it. A lock that needs a shove to catch on the first day will need a harder one in a year, after the leather settles and softens around it. If it binds, find out where before you blame the lock. Look for a bright scuff on the brass, because that mark shows you exactly where the two halves are meeting wrong.
This is also the step where a buckle starts to look good. A strap and buckle forgives a lot, a point made in Why the Strap-and-Buckle Closure Outlasted Every Alternative, and solid brass, as another post here argues, will outlast the leather around it. A brass lock fitted badly outlasts the leather too. It just takes the leather with it.
Why I stopped fitting the center lock
All of the above is true. I don’t do it on new cases anymore.
Here’s the turn, and it’s mine. My page on The Maker says it straight: “I no longer build briefcases with the center brass lock or the leather lining.” Both take more time than I can give. A man who writes a step-by-step guide to fitting a lock and then tells you he has stopped fitting them owes you the reason, so here it is, and it’s my opinion, not a rule. The lock is the one part of the case where hand work buys you nothing and costs you everything if it slips. The stitching can carry the marks of the hand. A lock is a machined thing set into a hand-made thing, and it has to be perfect, every time, in a material that moves.
I’ve said before that the only thing that makes me cry in this trade is a ruined briefcase. The lock is where that happens fastest. One hole too big, one pin peened off true, and days of cutting and stitching are scrap.
So I put my hours where the hand earns them. The closure I built for lawyers who wanted quick access without a buckle, the Marcellino Latch, was one answer to that. In my view a well-fitted center lock is still one of the best-looking things on a briefcase, and I’m not telling you to skip it. I’m telling you what it costs. Measure twice, cut small, peen with the head held hard, close it standing up, and do it alone, with the door shut and nobody talking.
Solid Brass Escutcheon Pins, 1/2" Long: A pack of solid brass escutcheon pins. See it on Amazon (affiliate link).
General Tools Scratch Awl with Hardwood Handle: A scratch awl with a hardwood handle. See it on Amazon (affiliate link).
IRWIN Carpenter Square, Steel, 8-Inch by 12-Inch: A steel carpenter square, 8 by 12 inches, for checking right angles. See it on Amazon (affiliate link).
12-Inch Stainless Steel Metal Ruler with Non-Slip Cork Backing: A 12-inch stainless steel ruler with a non-slip cork back. See it on Amazon (affiliate link).
Barge All Purpose Cement, Quart: A quart of solvent-based contact cement. See it on Amazon (affiliate link).
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Sources
- Marcellino NY, High-End Locks: https://marcellinony.com/high-end-locks/
- Marcellino NY, The Maker: https://marcellinony.com/the-maker/
- Marcellino NY, The Original Marcellino Latch: https://marcellinony.com/marcellino-latch/
- Leatherworker.net, How To Attach A Round Brass Lock To A Briefcase (2015 to 2016): https://leatherworker.net/forum/topic/63533-how-to-attach-a-round-brass-lock-to-a-briefcase
- Leatherworker.net, Brass lock and escutcheon pins (2017): https://leatherworker.net/forum/topic/78489-brass-lock-and-escutcheons-pins
- Emmaline Bags, How to Install Purse Turn Locks and Flip Locks in Bags and Purses: https://emmalinebags.com/blogs/the-studio-guide/how-to-install-purse-turn-locks-and-flips-locks-in-bags-and-purses
- Weaver Leather Supply, How To Set A Turn Lock (2022): https://www.weaverleathersupply.com/blogs/leathercrafting/how-to-set-a-turn-lock
- Abbey England, Abbey Hardware: https://abbeyengland.com/abbey-hardware
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