Stitch groover and edge creaser side by side on a workbench next to a strip of vegetable-tanned leather.
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Groovers or Creasers

ByPeter Joeseph 'Briefcase Maker' Kalafatis

One tool takes leather away. The other pushes it down. That difference decides everything after.

A stitch groover and a creaser hang next to each other on most leather benches, and from across a room they look like the same tool twice: a wooden handle, a steel tip, a guide that rides the edge. They are opposites. A groover cuts a thin strip of leather out of the grain so the thread can sit below the surface. A creaser cuts nothing; it presses a line into damp leather and leaves every fiber where it was. Which one you buy first depends on what you’re sewing, how thick it is, and how much you trust a blade near the face of good leather.

Video: Creasing brown bridle leather edges for my cross body case, from Marcellino NY Briefcase Maker on YouTube.

What each tool does to the grain

A channel is a hole you made on purpose. A crease is a dent.

Hand cutting a stitch groove along the edge of vegetable-tanned leather with an adjustable groover.

Weaver Leather Supply’s guide on how to use a stitch groover describes the job plainly. The groover cuts a shallow channel so stitches sit a little below the surface, which protects the thread from abrasion and keeps the stitch line straight. The fence sets the distance from the edge, about an eighth to three-sixteenths of an inch on most work, and the cut should be “Deep enough to seat the thread” without weakening the leather. Light passes. A sharp blade. Weaver says a dull one tears fibers instead of cutting them, and it names chrome-tanned leather as a common mistake, since it won’t hold a clean channel the way firm veg-tan does.

A creaser works by pressure. Abbey England’s listing for a 1.5mm fixed crease describes it as pressing a surface impression rather than cutting a groove, used as a decorative border and as a guide for stitching on belts, bags and straps. On damp vegetable-tanned leather the pressed line darkens and polishes, which is why so many finished straps carry one along each edge.

On Leatherworker.net’s “Groove v. Crease” thread, a retired holster maker who posts as Lobo sums up the difference in a phrase: creasing leaves the leather strongest by “removing no material.” That is the creaser’s whole sales pitch. Nothing leaves the strap.

The groover’s pitch is just as short. Thread that sits down in a channel, below everything that rubs past it on a desk or a car seat or a coat sleeve, doesn’t get scraped. Thread on top does.

The argument against cutting a groove

Anything that cuts the grain opens a place for a tear to start.

The grain is the tight, tough skin of the hide. Below it the fiber opens up and gets looser. Cutting a channel into the grain takes away part of the strongest layer you have, and on thin leather that part is not small.

That’s the worry on a long-running Leatherworker.net thread asking whether stitching groovers weaken the seam. One member, CitizenKate, put it flatly: “Anything that breaks the grain side of the leather, will weaken it.” Another relayed that saddlemaker Bob Beard didn’t gouge a stitch groove at all, but pressed the line with a modeling tool so the grain stayed whole. A later thread, To groove or not, reports Nigel Armitage arguing the same thing, and adding that a channel boxes the stitch in so it can’t lie at its natural angle.

Leather weight matters more than anything in this argument. In the “Groove v. Crease” thread, a maker who grooves both sides of heavy holster leather switches to a creaser on thinner stock, to leave enough leather under the thread. A groove that takes a sliver off thick bridle takes a real bite out of a thin lining.

I’ll tell you my bias before I judge it. I come at this from the stitching side. I hand saddle-stitch everything and gave up sewing machines some time ago, and every hole on thick work gets punched and lined up before a needle goes in. A hand-punched hole is a little bigger than a machine’s, and holes weaken leather too. One member of that 2017 thread made the point that stitch holes already weaken leather before any groover touches it. That’s true, and it’s an argument for keeping every other cut to a minimum.

The argument for it

Thread that rubs is thread that breaks.

Macro of a cut stitch groove beside a pressed crease line on bridle leather, showing groover vs creaser.

The best case for the groover comes from saddlemakers, whose stitching gets ground against by legs, horses and dirt all day. D.A. Kabatoff, a saddlemaker in British Columbia, wrote in the seam thread that he grooves most of his stitching for protection and that “on heavy leathers there doesn’t seem to be any reason not to groove.” He added that creasing gives less protection than a groove. Another member, Don101, said grooving has kept his holsters together.

Weaver’s guide puts the groover on the things that get flexed, rubbed and handled: belts, wallets, holsters, sheaths, bags and saddlery. In the 2017 thread, an English saddle-making instructor who posts as gmace99 said he grooves where wear is worst, a saddle flap where the rider’s leg rubs, and he also prefers a single crease or screw crease to dividers, because, in his words, “I would never use dividers to mark leather because they can scratch.”

That last quote tells you how close the two camps are. Even the man who grooves is creasing too, and nobody serious in those threads, not the holster makers and not the saddlers, claims one tool does everything. Read them long enough and the fight turns out to be about which seam, not which tool.

Buying a groover

Check the fence, the blade, and whether you can get another blade.

Most groovers sold for stitch lines are adjustable, with a guide that rides the edge and a small blade that cuts behind it. Ranges vary widely. Tandy’s Craftool Adjustable Groover adjusts from a sixteenth of an inch to three-quarters, and Tandy sells replacement blades for it. The Craftool Pro Stitching Groover cuts a groove listed at an eighth of an inch wide, adjusts out to well over an inch, and comes with a spoon tip for creasing and borders. Weaver’s own stitch groover adjusts up to an inch and a half from the edge.

Buy for the work you do. Briefcase panels and straps want a stitch line close to the edge, so a long reach matters less than a fence that locks and stays locked. A guide that creeps a hair while you pull will walk the line off true down the length of a panel, and you won’t see it until the stitching is in.

Blade first, though. A groover lives or dies on a blade sharp enough to cut on a light pull. A dull one drags and tears, and the tear is in the grain on the face of the work. Find out before you buy whether the maker sells blades and whether they’ll still sell them in a few years. A cheap groover with no spare blades is a tool you will throw away.

Then practice on scrap of the same leather you’ll sew. Groove depth looks shallow until the needles go through, and then it looks too deep.

Buying a creaser

Fixed or adjustable, heated or cold, sharp or rounded.

Finished bridle leather case with creased, burnished edges and a saddle-stitched bottom seam.

Creasers come in two main shapes. A fixed edge creaser has a slotted tip set at one width from the edge, like the Abbey crease at 1.5mm, and you buy one per width you need. An adjustable or screw crease has a thumbscrew or wing nut that sets the gap. The Ingenium museum in Canada holds a saddler’s shoulder vein creaser from the first half of the last century with exactly that, a wing nut for width, made for lines along the edge of large straps. The Waterperry Museum in England catalogs a saddler’s shoulder screw crease with a grooved plate at the end of a curved rod, pressed into the leather with the weight of the shoulder.

Both museum records say the old tools were heated. The Ingenium entry warns the creaser has to keep moving, since holding it still can scorch the leather. On Leatherworker.net’s hot creasing thread, the advice comes down to testing on scrap, since the right heat changes with the leather, its thickness and its finish. One member warns that veg-tan “will certainly burn if too hot.” The pressed line on hot work comes out darker and glassier than a cold crease. If you buy a creaser to heat, buy one with a handle long enough to keep your fingers off the steel.

Look hard at the tip. On an older thread about edge creasers, the poster found his thinnest one “just too thin and tends to cut the leather.” A creaser should be rounded and polished. If it has an edge, it is a bad groover.

The video above is me creasing the edges of brown bridle on a cross-body case. A creased line next to a hand-burnished edge is the traditional finish I keep, and it gets laid out the way I lay out everything else, with a ruler and my eye.

Which one goes on the bench first

The creaser. Then the groover, for the seam that will be dragged.

For thick vegetable-tanned leather and bridle, I’d buy the creaser first, and I’d buy a good one, because I’d rather have one creaser I trust than three I fight with. It marks the stitch line, finishes the edge, and takes nothing out of the grain, and it works on thin leather where a groove would cost too much. A creaser also fails quieter. A crease pressed slightly off is a dent in the wrong place. A groove cut off line is a missing strip of grain in the face of the work for good.

That’s my case, and here’s where it gives out. Picture the bottom seam of a briefcase, the one that gets set down on train platforms, garage floors, concrete steps outside a courthouse. Every time the case lands, that thread takes the scrape. A crease sets the line lower by a hair. A groove sets it lower by a whole channel, and down there the concrete has to chew through leather before it reaches the thread. Kabatoff’s argument was never about looks; it was about thread lasting on the parts that get dragged, and the bottom of a case is a saddle flap that lives on the ground.

So the honest answer is that a bench building bags ends up with both. The creaser does most of the work and all of the edges. The groover waits for the one seam where protecting the thread is worth taking a sliver of grain to do it, and the choice of which seam that is matters more than which tool you bought first.

Both tools sit under Tools and Leather, and the stitching that follows them sits under Basic Techniques.

Jmuiiu 7-in-1 Adjustable Leather Groover: An adjustable stitching groover for cutting a channel along the stitch line. See it on Amazon (affiliate link).

UOOU 4 Pcs Leather Edge Creaser: A set of four edge creasers in 1.0 to 2.5 mm widths. 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).

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).

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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