3D Convex Edge
Edge typesIllustrations are navigation markers, not technical evidence. They do not establish exact geometry, material identity, finish or coating identity and properties, adjustment settings, coating colour, hair classification, tooth pattern or removal rate, mechanism, fit, diagnosis, origin, performance, or result.
Description
The 3D convex edge uses multi-radius grinding for the smoothest possible cut. Learn how this premium edge type reduces friction and improves slide cutting.
3D Convex Edge
Quick look
- Hybrid stroke: Layered convex radii keep the cut stable from heel to tip, even on long blades.1
- Power plus glide: Delivers convex smoothness with enough bite to drive through dense sections.1,2
- Premium build: Found on high-end sword and hybrid blades designed for mixed salon and barber work.1
Why stylists pick it
3D convex grinds introduce multiple arcs along the blade, so the edge maintains contact as you transition from the heel’s power zone to the tip’s detailing point.1 That geometry feels luxurious on slide passes yet keeps enough structure to plow through coarse hair when you switch to blunt work.1,2
Technique map
- Long blunt passes on coarse sections where a single shear must cut and detail.1
- Slide transitions mid-cut without grabbing the hair or losing stability.1
- Barber/salon hybrid services that mix scissor-over-comb with soft, dry finishing.1,2
Usage notes
- Maintain light, even pressure along the stroke; the multi-radius grind does the stabilising for you.1
- Drop tension slightly compared with a bevel so the layered arc can glide.2
- Rotate to a maintenance shear for rough prep to preserve the premium edge for polish work.1
Maintenance
- Partner with sharpeners experienced in multi-radius edges-flattening the layers removes the 3D benefit.1
- Clean and oil after each client to protect the polished faces common on this grade of shear.1
- Store in a rigid case; the longer blades that use 3D grinds amplify damage from knocks.1
Brands & products
Kamisori catalogues the multi-radius geometry across its Sword line, Kaos, Emerald, and Diablo II. Juntetsu applies a 3D-angled sword blade to its Premium Cobalt line, and Mizutani markets a Kengata sword-blade edge that sits in adjacent territory without strictly being multi-radius.
Sources
- Scissor Hub - Kamisori Sword Professional Haircutting Scissors
- Dark Stag - Convex vs. Bevelled vs. Serrated
Context and comparison
The 3D convex edge is distinguished from standard convex (hamaguri-ba) by a secondary grind on the back face of the blade: instead of the standard flat or slightly hollow back, the 3D version curves outward on both faces, creating a biconvex cross-section. The practical result is reduced friction throughout the stroke — neither the cutting face nor the back face generates the drag that a flat-backed hamaguri-ba creates when riding against the opposing edge. Most 3D convex shears appear at the premium end of ATS-314 and cobalt-alloy catalogues, where the additional hand finishing required to achieve the geometry is built into the price.
See Also
Frequently Asked Questions
3 answers you can open one at a timeWhat does the "3D" mean in 3D convex, and how does it differ from standard convex?
A standard convex edge uses a single radius — one continuous curve from the blade face to the cutting edge. A 3D convex applies different radii at different points along the blade length, so the curve is tighter near the heel (where more cutting force is applied) and progressively shallower toward the tip (where detailing requires a finer, more precise edge). The geometry maintains consistent blade-to-hair contact throughout the full stroke, rather than allowing the edge to lose contact mid-blade as the angle changes. The term “3D” refers to the geometry varying in three directions — along the blade, across the blade face, and in the depth of the grind — rather than simply having a single curved cross-section.
Which brands use 3D convex edges and on what scissors?
Kamisori catalogues multi-radius 3D geometry across its Sword, Kaos, Emerald, and Diablo II models. Juntetsu applies a 3D-angled sword blade to its Premium Cobalt line. Mizutani uses a related approach called a Kengata sword-blade edge on some models, though the geometry differs from the strict 3D-convex definition. The edge type appears primarily on hybrid salon-barber scissors where a single pair needs to handle both blunt perimeter cutting and fine detailing work in the same session.
Can a 3D convex edge be resharpened, and what should I tell my sharpener?
Yes, but the sharpener needs to know the edge has multiple radii. Standard convex sharpening assumes a uniform curve and applies the same pressure and angle along the full blade. On a 3D convex, that approach collapses the geometry into a single radius, removing the variable-curve design. Tell your sharpener specifically that the scissor has a multi-radius or 3D convex grind and ask whether they have experience maintaining that geometry. A capable sharpener will work the blade in sections, adjusting angle and pressure to match the intended radius at each point rather than running a uniform pass from heel to tip.
Comments & questions
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