A half-finished leather watch strap on a workbench beside a watch case, calipers, a steel rule and a pricking iron.
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A Leather Watch Strap

ByPeter Joeseph 'Briefcase Maker' Kalafatis

The smallest thing I’d ever put a saddle stitch into, and the one that sits against skin all day.

A watch strap is a belt for a wrist, cut to the millimetre and worn against sweat, cuffs and the edge of a desk from morning to night. I make briefcases. A briefcase is the opposite end of the trade: heavy bridle, big panels, holes punched by hand through layers that fight the awl. So I’ll state my bias up front, the way I always do. Everything that makes a strap good is a briefcase skill made small, and everything that makes it hard is that it’s small.

Video: Hand Sewn Leather Watch Strap Tutorial (Follow Along!), from Corter Leather on YouTube.

This is a project, start to finish, with a materials list. Steps from other makers carry their names, and the ones from my own bench say so.

Measure the watch before you cut anything

Two numbers decide the strap: the gap between the lugs, and the wrist.

Hands folding the skived end of a leather watch strap around a spring bar with a bone folder.

Start at the watch, not the hide. The lug width is the distance between the lugs at the top and bottom of the case, and Watch & Strap’s sizing page says 20mm is the most common, with 18, 22 and 24mm also common. Measure it yourself with calipers or look up the model. Don’t guess from a photo.

Then cut a hair under it. A member writing as Danne, in a leatherworker.net thread on watch straps, advised cutting a strap for a 20mm gap “slightly under 20mm to make room for edge paint.” In my view the same allowance makes sense for a burnished edge.

Length comes next, and it comes in two pieces. Delugs, a strap maker, lists its standard lengths as long and short ends of 105mm and 65mm for small, 115mm and 70mm for medium, and 125mm and 75mm for large, with wrist ranges for each. Their advice for a wrist between two sizes is to size up. Watch & Strap does it another way: measure the wrist, add the distance across the watch from lug to lug, and compare that total with the usable length of the two pieces.

Most of the holes go on the long piece, and they get punched last. Kevin Lee’s walkthrough in Primer leaves the buckle holes until after the strap is built and the wrist is measured again. That order costs you nothing. Punch early and a mistake costs you the strap.

Materials and tools on the bench

Thin leather, a sharp knife, small irons and fine thread. Everything else you probably own.

The list, kept short:

  • Vegetable-tanned or English bridle leather, split thin for the top layer
  • A thin lining leather, if you want a lined strap (calfskin is common)
  • Steel rule, calipers, and a sharp knife
  • A splitter or a skiving knife
  • Contact cement and a bone folder
  • Small pricking irons or stitching chisels, and a stitching awl
  • Two harness needles and fine waxed polyester thread
  • A stitching pony or clam
  • Edge beveler, wood slicker, gum tragacanth, glycerine soap, beeswax and fine sandpaper (or edge paint)
  • A single hole punch and a slot or oval punch for the buckle tongue
  • A buckle, two stainless steel spring bars, and a spring bar tool

The leather is the part people get wrong. Gear Patrol’s profile of a one-man strap shop follows Alex Gravelle of Velle Alexander in Saint Paul, Minnesota, building a strap with an upper of English bridle, “Produced by Wickett and Craig in Pennsylvania.” That’s the same American bridle I cut briefcases from, on my Leather Choices page. He lines it with a French calfskin made for watch strap linings, and glues a layer called Velodon between the two to keep the strap from stretching.

My opinion: the choice of leather matters less than the thickness you bring it down to. Thick bridle on a wrist is a dog collar.

Splitting the leather down to strap weight

Bridle comes off the bend built for a horse. A wrist needs a fraction of that.

Macro of a lined leather watch strap edge with small saddle stitches and a burnished edge.

Here’s the bench work I know. On straps I thin the leather on an old hand-crank splitter, then stitch two thinned pieces back together, so the strap has a good face on both sides instead of a grain side and a fuzzy flesh side. That’s how I build briefcase straps. On a watch strap the same idea holds at a smaller scale: a thin top layer of good grain, and a thin lining, glued face out.

Gravelle splits his top leather and lining to 0.5mm for the three-layer keepers, according to Gear Patrol. Half a millimetre. A splitter set that fine has to be sharp and set true before the strap leather goes anywhere near it.

No splitter? A skiving knife on a hard, smooth surface does the fold area, and you buy the strap leather thin to start with. Paul Anthony at Bespoke Unit, writing up a rustic Horween strap made by James of Threaded Leather Co, put the leather at about 3mm, unlined, left raw to darken with wear. That is a different strap: one layer, no lining, thicker and stiffer.

Cutting, folding and fitting the keepers

The fold around the spring bar is the joint. Get it flat or the whole strap lifts off the wrist.

Cut both pieces against a steel rule with a knife sharp enough to shave. Shape the tip of the long piece by tracing a coin or a template and taking it down in small straight cuts, the way Lee does, then sand it round.

Now the fold. The end of each piece wraps around the spring bar and glues back on itself, and that doubled leather is where a strap gets fat. Lee’s instruction is to skive the fold area down to roughly half the thickness of the strap, and he says why in plain words: “Skiving ensures that the folded edge still lies flat.” Put the contact cement on neatly, keep it off the underside, and leave the channel for the bar clear of glue. Fold it with a bone folder and dry-fit the spring bar before the cement grabs.

Keepers are where skiving gets hard. Mablung, in that same leatherworker.net thread, said end keepers are usually lap-skived gradually, then cemented and stitched, and that it takes real skiving skill. Bespoke Unit’s strap uses two keepers, one fixed at the buckle end and one floating. Gravelle’s are three layers, each split to that half millimetre.

Lee cuts the small oval for the buckle tongue ideally after folding, so it sits where the fold actually landed. A slot cut where the fold was supposed to go is a slot in the wrong place.

Stitching small with hands built for big stitches

Here my own argument turns on me.

A finished hand-stitched leather watch strap fitted to a steel watch, buckled and resting on a shirt cuff.

I’ve spent years telling people a hand saddle stitch is the strongest thing you can put in leather. On a strap the reasons hold. Jon Quinn of WatchGecko, in a piece on saddle stitching on watch straps, traces the stitch back to saddlery and says each stitch is formed with two needles and a single thread and locks on its own, so one failure doesn’t open the seam. Gear Patrol says Gravelle sews his straps by hand with the same stitch, each one secured on its own.

Now the harder part. My own page on The Art of Hand Stitching admits that hand stitching tends to have slightly bigger holes, because they’re punched by hand and sewn with hand needles. “The hand is limited to how small it can get, especially with thick bridle saddlery leather.” A briefcase can carry a bold stitch. A watch strap can’t. Big holes on a 20mm strap look like a horse blanket.

So the strap asks for other tools. Mablung recommended smaller-than-usual pricking irons or chisels, finer thread and needles, and a sharper awl. Danne warned that thin leather is hard to stitch with a consistent result. Both are right, and they pull against each other: thinner leather wants finer holes, finer holes want a lighter hand, and a lighter hand on thin leather wanders.

What carries you through is feel. The skill in stitching isn’t strength, it’s knowing through the needle when a strand has popped inside the layers, and that only comes the way a guitar player’s calluses come. You sit there until your fingers stop complaining. My opinion: keep the tension even from the first hole to the last, because on a strap this narrow one tight stitch shows.

Edges, holes and the spring bars

Finish the edge like a belt. Fit the bars like your watch depends on them, because it does.

Bevel the edges lightly. A heavy bevel on a strap this thin takes away half the edge. My post on beveling and creasing a leather strap covers the bench work at belt scale, and it shrinks down fine. Then choose: paint or burnish. Gravelle seals his with three coats of waterproof edge paint, per Gear Patrol. Lee burnishes in Primer, wetting the edge, rubbing it with glycerine soap, polishing, adding gum tragacanth and finishing with beeswax. I hand-burnish my briefcase edges because that’s the tradition I work in. On lined cases I use edge paint instead, because it also glues the layers, and in my view a lined strap is the same problem at a smaller size.

Punch the buckle holes now, with the strap on the wrist and the watch on it. Space them evenly and centre them on the width.

Then the spring bars, and they get more care than the leather. Matt Reudink’s aBlogtoWatch guide to choosing spring bars says to measure between the lugs and use the thickest bar that still fits the strap’s channel. If the bar moves back and forth or clicks once it’s in, it’s too small. He recommends 304L or 316L stainless, warns that cheap bars with springs that aren’t stainless can rust inside, and says a poor fit can mean catastrophic failure of the watch. A strap is leather. The bar is what keeps the watch off the pavement.

For keeping it alive afterwards, sweat, water and all, there’s a post here on how to care for a leather watch strap. And if you wonder who still wears a watch worth the trouble, there’s a piece here on why lawyers still wear watches nobody can see on Zoom.

When I started there were almost no good tutorials. I learned by trial and error, studying how finished bags were made and reading whatever books I could find. Anthony puts a strap like his at about forty-five minutes to an hour, depending on skill. Expect your first to run longer, with a fold that wants to lift and one stitch near the buckle that sits tighter than the rest.

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).

X-ACTO #1 Z-Series Precision Utility Knife: A precision craft knife for fine cutting. 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).

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).

DEEDYGO Genuine Bone Folder: A genuine bone folder for creasing and burnishing. See it on Amazon (affiliate link).

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Sources

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