Tools for setting snap fasteners on a leather strap, a hand setter, snap anvil, mallet and punch, beside loose brass snap parts.
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Setting Snap Fasteners on a Leather Strap

ByPeter Joeseph 'Briefcase Maker' Kalafatis

Four pieces of brass, one hole, and no way to take it back.

Setting snap fasteners on a leather strap looks like the smallest job in the shop, a hole, a post, a cap and a few hits with a mallet, and that’s why it ruins so many good straps: nobody respects it until a post folds over sideways and the only fix is a cutoff wheel. Here is one ordinary task done in order. A strap end of thick vegetable-tanned leather gets a Line 24 snap so it can close around a ring or a handle. At every step there’s a way to wreck it, and most of them come from the same place.

Video: How To Set A 4 Piece Snap | Ohio Travel Bag Workshop, from Ohio Travel Bag on YouTube.

That video is the Ohio Travel Bag workshop, the one Weaver Leather Supply puts on its own snap page. My bias first. I’m a stitcher. On my Maker page I say I shape it, I stitch it, I finish it, and a snap is none of those things. So the steps below belong to the suppliers and to the makers on the leatherworker.net forum, and when it’s my judgment, it says so.

Step one: pick the snap for the leather

Size is a weight decision, not a looks decision.

Hands holding a snap setter upright over a brass post in a brown leather strap resting on an anvil.

Snaps come in lines, and the line number is the size. Art, writing on his leatherworker.net blog in 2015, lays them out: Line 24, also sold as Durable Dot, runs about 5/8 inch across; Line 20, the Baby Dot, about 1/2 inch; and Line 16, sold as glove or Segma snaps, about 3/8 inch, for light closures and thin straps. The four-part ring snaps, he says, come in short, medium and long posts.

Then the leather has to agree. Buckleguy’s listing for its Line 20 and Line 24 ring socket snaps gives a maximum material thickness for each one: the long-post Line 24 is rated for leather up to 16 ounces, about a quarter inch, the long-post Line 20 up to 12 ounces, and the short-post Line 20 up to 8 ounces.

What goes wrong here is a big snap on a thin strap. In a forum thread on Line 24 snap problems, a maker setting them on 3-ounce guitar-style straps found the male half sitting off center, and the member Chief31794 told him plainly that Line 24 is too large for 3-ounce leather and to look at glove or Segma snaps. A heavy snap on light leather is a wrench bolted to a shoelace.

My opinion: on a strap of real weight, a Line 24 earns its place. On anything thin, go down a line before you go down a grade of leather.

Step two: measure the stack and choose the post

Post length decides the job before the mallet comes out.

Every snap source says the same thing in different words. Art’s blog calls post length critical and puts it bluntly: if it’s wrong, “it will never be right.” Too long, he says, and you can file it back. Too short, and nothing saves it.

So measure the stack where the snap sits, not the leather in general. A strap end folded around a ring is two layers plus a glue line, maybe a lining, and it squashes. Buckleguy recommends that between 1 and 3 mm of post come through the material. The Weaver how-to, using 7.5-ounce leash leather, wants about 1 mm showing on each side, enough metal to roll over the socket. On the forum, the numbers cluster in the same place. Jordan, in the thread on how to set Line 24 snaps, likes the post sitting just proud of the leather, about a sixteenth of an inch. NVLeatherWorx, in a thread on optimal shaft length, wants at least 3/32 inch through before setting.

That same thread is a warning. Its starter set Line 24 snaps with posts of about 3/16 inch into lined 8 to 10 ounce leather, and the shaft ended up just inside the snap, with nothing to roll. Several snaps ruined. Another member, Studio-N, did the arithmetic: 10-ounce leather is 10/64 inch, add 2/64 for the ring and 8/64 for the roll, and you need about 20/64, or 5/16 inch, before any lining goes in.

Thick strap, short post? Thin the leather where the snap goes. Jordan countersinks around the post with a French skiver on heavier work. I split strap leather on an old hand-crank splitter for other reasons, and the earlier post on skiving and splitting covers how to take weight out without weakening the piece.

Step three: punch the hole

Tight to the post, square to the strap.

Macro view of a cleanly set brass snap beside one with a bent post in tan leather.

The Weaver page cuts the hole with a revolving punch and gives no diameter, so pick the tube that fits your post. Tree Reaper, in the Line 24 problems thread, says to keep the hole as small as you can and still fit the post. A loose hole lets the post lean before it’s even struck.

Mark the spot from the finished side, center it across the strap, and check it against the hole on the other piece before you punch either one. If the cap side and the stud side don’t line up, the snap will close with the strap twisted, and you will feel that twist every time it opens.

On a strap, the edges matter too. If the strap is getting beveled and creased, do that first, the way the post on beveling and creasing a leather strap lays it out, and then decide where the snap sits. A crease line running under a snap cap looks like an accident.

My opinion: punch a test hole in scrap of the same thickness first. Art gives that advice for the whole job, start to finish, and all it costs is a strip of offcut that was headed for the bin anyway.

Step four: set the cap side

Cap face down in the anvil, and tap.

Weaver’s steps: push the cap post up through the leather, fit the socket over it, check that the post shows a millimeter or so, set the domed cap into the anvil, and peen the post over the socket with the hand setter and mallet.

This is where posts fold. On the forum, the member waddy described the long cap post on Line 24 squashing to the side instead of rolling. In a thread on Line 20 and 24 posts bending, Mablung found that posts bend most when the leather lifts off the anvil’s plane as the setter takes the pressure, and put a block under the body of the strap near the snap to keep it flat. In another thread on setting snaps, CitizenKate stressed striking the post squarely, and Bob said the tool should be held straight. Elliot found the rough rings on some setters catch and crush the post, and polished them.

Then the swing. Chief31794 traced off-center snaps to “Beating them violently.” Tap lightly until the post seats. Art adds the other half of it: you can always set more, never less, so stop when the snap doesn’t spin. Set it too deep, he warns, and the ring pulls in on itself and weakens.

My opinion: the anvil, the setter and your wrist should make one straight line down through the post. Everything that bends a snap is something out of that line.

Step five: set the stud side and test it

Same rule, other half, then work it open and shut before anyone else does.

A finished chestnut leather strap fastened around a brass ring with a brass snap fastener.

Weaver’s stud side mirrors the cap: eyelet up through the leather with about a millimeter of post showing, stud over it, flat side of the anvil or a hard surface, setter over the post, and strike until the metal spreads and the parts lock.

Two failures show here. One is a snap that won’t close. TinkerTailor, in the shaft length thread, says a post that runs a little long can leave the snap not quite closing, and a few more hits usually fix it. The other is a snap that pulls apart under a light tug, which points back to a post too short to roll over properly. Art’s line covers both, and it stings: there’s no unsetting a bad snap except with a rotary tool.

On short runs, hand setting works. The makers who set hundreds of snaps keep pointing at presses. Mulesaw, in the post-bend thread, uses a small manual press because it presses absolutely straight. Randyc, in an older thread on problems with Line 24 snaps, never mastered hand setting and stopped having problems once he bought a press and dies.

Then open and close the strap. Again. Again. If it pops on a gentle pull or twists as it closes, cut it off now, while the strap is still yours.

Where a snap belongs, and where it doesn’t

The stitcher’s case against the snap has a hole in it.

Here’s my case. On a briefcase, the strap that carries weight and takes a yank on a train platform should not hang on a snap. My straps get hand-stitched buckles, no rivets, and the earlier post on why the strap-and-buckle closure lasted makes the longer argument. A buckle can be read at a glance. Pull it, and you see what holds.

Now the hole in it. I started making the Marcellino latch for lawyers who didn’t want a buckle. They wanted in and out of the case fast. That is the whole argument for a snap, made by the people I build for, and I answered it with hardware. So the honest version is narrower than the one I started with. My opinion: a snap is right where a closure gets opened all day and carries almost nothing, a keeper, a flap tab, a strap around a handle. It’s wrong anywhere the weight hangs.

Pick solid brass if you can. The post on solid brass hardware outlasting the leather gets at why the metal tends to outlive the strap it’s fixed to. The Buckleguy snaps listed above are solid brass.

None of that forgives a short post. Nothing does.

WUTA Rawhide Mallet: A rawhide-head mallet for striking chisels and punches. See it on Amazon (affiliate link).

Weaver Leather Supply Silent Poundo Board: A self-repairing poundo board for punching and stamping. See it on Amazon (affiliate link).

OWDEN 9 Pieces Leather Hollow Punch Set: A nine-piece hollow punch set for round holes. 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).

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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