Chestnut bridle leather briefcase panel on a punching board with a stitching chisel and maul, ready for punching stitch holes.
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Punching Stitch Holes in Thick Bridle Leather

ByPeter Joeseph 'Briefcase Maker' Kalafatis

The stitch gets the credit. The hole does the work.

A saddle stitch can never run straighter than the holes under it. On thick English bridle leather those holes are the hardest part of the seam to get right, because the leather is dense, waxed and stubborn, and it shoves back against every tool you drive into it. I punch my stitching holes by hand, so each one is a small decision made with a mallet, and a briefcase panel carries hundreds of them.

Video: Punching Stitching Holes to Chestnut English Bridle Leather Briefcase Panel, from Marcellino NY Briefcase Maker on YouTube.

The video on my channel is one of those panels, in chestnut bridle. The steps run in order, and when a step belongs to a toolmaker, that company gets the credit. My bias first. I sew by hand for a living, so I rate the hole higher than most people do. Keep that in your pocket while you read.

The hole is the unit of the work

Count the holes, not the stitches.

Hands holding a diamond stitching chisel vertical on a marked stitch line in thick bridle leather before the mallet strike.

People look at a hand-stitched seam and see thread. I see punctures. A row of them, evenly spaced, square to the edge, the same depth from the first to the last, with the thread doing nothing more than filling them in. If one hole sits a hair off the line, the stitch through it leans. If one is torn wider than its neighbours, the thread rides loose in it and the seam has a soft spot you can find with a thumbnail.

On my Maker page I put it this way: “The side nobody sees is where a weak stitch gets found out.” That back side gets settled at the punch, long before anyone threads a needle. Drive a chisel in at a slight tilt and you get a clean row on top and a drunk one underneath. Nobody notices until the seam is done.

Then everybody who turns the bag over notices.

Bridle makes all of this harder. My Leather Choices page describes English bridle as traditionally “very waxy, thick, heavy, and stiff,” and Hermann Oak’s version comes in around 8 to 12 ounces, heavier still once a lining goes on. Every one of those qualities fights the punch. The wax grabs the prongs on the way out, and that grip is exactly what tempts a tired wrist to twist the tool free. Thickness gives a tilted chisel more room to wander before it breaks out the far side. Stiffness means the leather won’t forgive a bad hole by closing up around the thread. Put three layers of the thickest bridle together, gusset, body and pocket, and the punch is only the first fight. The needle is the second, and my fingers lose that one.

So treat the hole as the unit. A seam is built from holes the way a wall is built from bricks, and one cracked brick doesn’t get hidden by the two good ones beside it.

Choosing the tool that makes the hole

Four tools, four different holes.

There are four common ways to make a stitching hole. Each one leaves its own shape behind, and the thread has to live with that shape for as long as the bag does.

A diamond stitching chisel cuts an angled, diamond-shaped slot all the way through. Weaver Leather Supply’s guide to picking a stitching chisel says diamond chisels make angled holes for a traditional saddle-stitch look, and lists flat-prong chisels for straight, rectangular holes and French-style chisels with fine rounded prongs for handbags and briefcases.

A pricking iron only marks. According to the Wikipedia entry on the pricking iron, it leaves dimples a fixed distance apart, and each one gets pierced with an awl before sewing. Two operations per hole instead of one. That is slower, and it hands the angle over to the awl and to whatever hand is holding it.

A round-hole punch takes material out. The Maze Leather article on the differences between leather stitching tools says round punches take more time but give “much more even holes than the diamond punch,” and pairs them with thicker thread around 1 to 1.2 mm. The same writer puts their practical limit at about 4 to 6 ounces of leather, which rules them out for most briefcase bridle before the argument starts.

A lacing chisel makes a flat slit meant for lace. Maze Leather notes that regular thread can push that thin cut out of shape and pucker the line.

For thick bridle, the real choice comes down to two. The diamond chisel goes through in one strike. The pricking iron with an awl gives more control and costs more time at the bench, hole after hole, panel after panel. The Weaver page also says to match the prong count to the line: one or two prongs for corners and tight curves, four to six for straight runs.

Weaver’s guide says thin leather calls for finer chisels and heavier leather for larger prongs. My opinion: take that at its word. Buy the chisel for the leather you actually cut, not the one that looks good lined up in a set.

Marking the line and setting up the bench

Three steps before the mallet comes out.

Macro view of evenly spaced diamond stitch holes on the back side of a thick bridle leather panel.

Most bad holes are bad before they’re punched. I learned that the slow way, by trial and error, and I nearly quit more than once. One of those errors went across the room. Setup is the dull part, and it’s where the seam gets won.

  1. Mark the stitch line. Tandy Leather’s article on punching sewing holes says to use a wing divider, stitching groover or ruler to mark “a consistent distance from the edge.” Weaver’s hand-stitching tools page separates the two main tools: the wing divider scribes a guide line, while the groover cuts a channel the thread sits down into, which cuts snagging and also gives the chisel prongs a track to follow.
  2. Pick the spacing. Weaver’s chisel guide gives a chart tied to the job: 3 mm (9 stitches per inch) for wallets and watch straps, 4 mm for general work, 5 mm for medium-weight bags, and 6 mm (5 per inch) for saddles and belts. Those are their numbers, not a law. Choose one and hold it for the whole piece.
  3. Set the surface. Tandy calls for a cutting mat or similar pad under the work. Weaver describes its rubber Silent Poundo Board as something that keeps punches from dulling and chipping and takes some of the noise and vibration out of the strike. A steel or stone slab straight under a chisel is a quick way to ruin the points.

One more decision belongs here: punch two layers together, or each on its own. In a leatherworker.net thread on sewing thick leather, the member Tugadude advises that some leathers are thick and stiff enough that both layers should be punched before gluing. Stack two pieces of bridle and the total may be more than a chisel can cross straight. Then the back row wanders. The back row is the one I judge a seam by. On thick work I punch every hole and line it up before a needle comes near the leather, because thick bridle won’t stitch any other way. You can’t find the next hole by feel halfway through a panel.

Driving the chisel through bridle

Upright, rock it out, step one prong back.

This is the part on the video. The steps below are the toolmakers’ method, written as instructions.

  1. Seat the prongs on the line. Weaver says to align the prongs on the guide line and hold the chisel “straight up and down to avoid uneven holes.” Tandy says the same thing in degrees: 90 to the surface.
  2. Strike with a non-metal mallet or maul. Tandy’s word is firmly. In my view a timid strike on thick bridle is worse than a hard one, because a second blow has to find the same slots again, and it rarely finds all of them.
  3. Rock it out, do not twist it. Weaver warns that twisting the chisel on the way out widens the holes and weakens the seam, and says to rock it gently back and forth instead. Wax-heavy bridle grips the prongs hard. Your forearm will want to wrench, and it has to be told no.
  4. Walk the line. Set the first prong of the chisel into the last hole you made, then strike again. Tandy describes it as overlapping each new set a little with the last. Nothing else keeps a long panel true.
  5. Check the back. Tandy’s closing advice is to make sure every hole goes cleanly through and to clear out debris with a needle. Turn the panel over after the first few sets, not after the last one, when it’s too late to do anything but swear.

On a corner, change tools. A one- or two-prong chisel lets the line bend without stretching the gaps. Around a curve I go one step at a time, one strike, look, move, strike. It’s slow. So is picking out a seam.

My opinion, for what a diagram can’t show: treat every strike as its own. Full-grain leather is a natural material and it varies across the hide, so the blow that seated the last set may be wrong for the next one. The mallet has to listen as much as it hits.

Bigger holes, and why that is not a defect

The hand has limits. Work inside them.

Finished hand saddle-stitched seam on a chestnut bridle leather briefcase with straight, evenly spaced stitch holes.

Here is where my own case runs into a wall, and I’d rather walk into it in front of you than pretend it isn’t there.

Everything above pushes toward holes that are small, tight and straight. Then I go and say the opposite on my own page. On the art of hand stitching I wrote that hand stitching tends to have slightly bigger holes, because they are punched by hand and sewn with hand needles, and that the hand is limited in how small it can get, especially in thick bridle saddlery leather. A machine can sew a finer seam than I can. That is a fact, not an apology. It is also a strange thing for a hand stitcher to put on his own website.

Both things hold. Small holes are better, right up to the point where the tool, the thread and the leather stop agreeing with each other. In the leatherworker.net thread, the member Martyn puts it in working terms: awl, needle and thread have to be balanced, and if you need pliers to drag the needle through, the hole is too small for what you’re pushing into it. Force a fine chisel into heavy bridle and you get a hole that is neat on top and torn on the bottom.

Now the part that stings. I wax my needles and pull them through the thickest work with pliers. By Martyn’s rule, my holes there are too small. I’ve argued with that rule, usually with the pliers in my hand, and I haven’t won yet.

The Maze Leather article makes a related point about diamond chisels. They tend to leave the back of each hole a little frayed, with a smaller opening underneath. That’s the honest cost of a one-strike tool in thick leather.

So the target isn’t the smallest hole you can make. It’s the smallest hole the leather will take cleanly on both faces, filled snug by the thread, with no gap at the edges. Bigger than a machine’s, yes. Sloppier, no.

My opinion: the back of a seam tells you more than the front. A slightly larger hole, square and clean on both sides, beats a tiny one that staggers out the far side like it took the wrong exit.

What goes wrong

Most failures are a tilt, a twist or a blunt point.

The same handful of mistakes turn up across every one of these sources, and none of them show until the thread is in.

  • The tilted chisel. A few degrees off vertical on thick leather puts the back row off the line. In the leatherworker.net thread, Tugadude traces wandering back-side holes to an awl that isn’t held upright, and the same logic holds for a chisel.
  • The twisted exit. Weaver lists twisting on removal as a common error because it opens the hole. Bridle wax makes it tempting.
  • The wrong chisel for the weight. Weaver names a chisel that doesn’t match the leather thickness as a common error.
  • Blunt points. Martyn’s line in the thread is that if you think your awl is sharp, it probably isn’t sharp enough, and he notes that blunt tools make leather deform, drag and wrinkle.
  • Skipping alignment. Weaver says it plainly: uneven stitching follows.
  • Punching on a hard surface. Poundo boards and cutting mats exist for a reason. Steel under the prongs dulls them, and dull prongs tear.

None of these is dramatic. A seam goes bad one hole at a time, quietly, and the bag it belongs to carries a full load every working day. The stitch will take the blame. It was the hole.

If you’re still building a basic set of tools, the earlier post on this site about a complete leather craft tool kit lists the groovers, awls and punches that come in one, and it’s a fair place to start before buying chisels one at a time.

Weaver Leather Supply Silent Poundo Board, 12 x 12 inch: A rubber punch board that takes the shock of a mallet and keeps the chisel teeth from dulling against a hard surface. See it on Amazon (affiliate link).

Weaver Leather Supply Diamond Leather Stitching Chisel Set: A set of 4 mm diamond stitching chisels for punching saddle-stitch holes. See it on Amazon (affiliate link).

WUTA Wing Divider: An adjustable stainless steel wing divider for marking a stitch line. See it on Amazon (affiliate link).

Leather Carving Hammer Mallet: A nylon-headed mallet with a wooden handle for striking chisels. See it on Amazon (affiliate link).

Fiskars 18 x 24 Inch Self-Healing Cutting Mat: A self-healing cutting mat, 18 by 24 inches. See it on Amazon (affiliate link).

John James Saddlers Harness Blunt Point Needles: A set of blunt-point harness needles, five sizes with five needles of each. See it on Amazon (affiliate link).

Mandala Crafts 150D 0.8mm Black Flat Waxed Thread: A flat waxed polyester thread, 0.8 mm, in black, for hand sewing leather. See it on Amazon (affiliate link).

As an Amazon Associate I earn from qualifying purchases. A commission may be earned if you buy through this link, at no extra cost to you.

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