Core, three-quarter view

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Core

A 255 mm full-tang fixed blade in Böhler N690 steel at 58 HRC, with a Forprene grip. Designed by us down to the tenth of a millimetre.

€249 Planned retail price

  • Böhler N690 stainless steel, hardened to 58 HRC
  • 5.0 mm stock, full flat grind to a 0.4 mm edge
  • Full tang, lightened from the inside
  • Forprene grip with diamond-lattice relief
  • APEX NEWTON engraved 1.0 mm deep on spine and tang
Overall length255.5 mm
Blade length126.9 mm
Blade stock5.0 mm
Hardness58 HRC
SteelBöhler N690
HandleForprene
Weight≈270 g

01 · Blade

Cut, machined, ground.
Beautiful even where you will never look.

The profile is laser-cut from 5.0 mm N690 plate, then machined to its final shape. A full flat grind runs from 11.2 mm below the spine all the way down to a 0.4 mm edge: thin behind the edge so it slices clean, full thickness at the spine so it takes a beating.

CAD side view of Core: assembled knife above, blade and tang without handle below
Assembled, and stripped to the steel. The tang is the same piece as the blade.
Profile
Drop point
Cutting length
126.9 mm
Stock
5.0 mm
Grind
Full flat, from 11.2 mm below spine
Edge thickness
0.4 mm
Blade height
32.5 mm
Spine
Flat, radiused edges, jimped
Process
Laser-cut, machined, ground
CAD isometric view showing APEX NEWTON engraved along the spine and the grind faces
Here: APEX NEWTON engraved along the spine.
Core tang with two lightening windows and APEX NEWTON engraving
And here: the tang, lightened from the inside and engraved where only the owner will ever see it.
Cross sections: handle stack of scales, liners and tang; blade section with flat grind to a 0.4 mm edge
Sections. Handle: 9.0 + 0.9 + 5.0 + 0.9 + 9.0 mm. Blade: flat grind to 0.4 mm.

02 · Steel

Böhler N690.
Austrian steel, chosen for one job.

N690 is poured by Böhler Edelstahl in Kapfenberg, Austria. It is a martensitic stainless chromium steel with high carbon, alloyed with cobalt, molybdenum and vanadium. Böhler rates it for knives and for food contact. We chose it because it does three things at once: holds an edge, shrugs off moisture, and survives hard use.

Composition, weight %

CCrMoCoVSiMn
1.0817.31.11.50.10.40.4

Böhler N690 datasheet. 17.3 % chromium makes it stainless; 1.08 % carbon makes it hard; cobalt strengthens the matrix.

Böhler property ratings

  • Wear resistanceVery high
  • Corrosion resistanceHigh
  • Toughness & ductilityGood
  • PolishabilityGood

Our heat treatment

Target hardness
58 HRC
Steel's range
up to 59–61 HRC
Hardening
1030–1080 °C
Tempering
100–200 °C

Bending and impact

Hardness and toughness pull against each other. N690 can be pushed past 60 HRC; we stop at 58. That one point buys toughness: under side load the edge is more likely to roll than chip, and the 5.0 mm spine takes batoning without drama. A rolled edge is straightened in a few strokes. A chipped one is gone.

Edge holding and sharpening

Carbon and chromium form hard carbides that resist wear, which is why Böhler rates wear resistance very high. At 58 HRC the steel still takes a fine edge and comes back on diamond or ceramic stones. You get an edge that lasts, without a steel you need a workshop to sharpen.

Corrosion

Above roughly 13 % chromium a steel is stainless; N690 carries 17.3 %. Blood, sap, sweat and rain do not turn into rust overnight. Molybdenum adds resistance to pitting. Rinse, dry, done.

03 · Handle

Forprene.
Rubber grip, engineering-plastic precision.

Forprene is a thermoplastic vulcanizate: cured EPDM rubber locked inside a polypropylene matrix. It feels like rubber in the hand and is moulded with the accuracy of a technical plastic. We chose it over G10 and micarta because those are hard laminates. Forprene gives a little under the fingers and keeps its grip when wet, cold or gloved.

Close-up of the Core handle: diamond-lattice relief, contour grooves, recessed hex screws and lanyard hole

Material class

Type
TPV (EPDM + PP)
Hardness scale
Shore A, firm grade
UV, ozone, weather
Excellent
Acids, bases, alcohols
Resistant
Detergents, solvents
Resistant
Fatigue, abrasion
Resistant
Thermal
Insulating

Material ratings from the Forprene supplier.

Geometry

Handle length
126.7 mm
Height
36.8 mm
Thickness
24.8 mm max
Scales
9.0 mm each
Surface
Diamond lattice + contour grooves
Front
Slanted stop for the index finger

Soft where it touches, hard where it counts

The steel tang runs through the full handle, so strength comes from the metal and grip comes from the Forprene. The slanted front gives your index finger the same stop every time. The lattice gives traction without the sandpaper feel of aggressive texturing. And because it insulates, it does not suck the heat out of a bare hand in winter the way metal does.

04 · Exploded view

Eight parts. Nothing hidden.

Two screws hold Core together. Every part is drawn and specified by us.

Exploded view of Core with numbered parts 1 to 8
  1. 1
    Blade and full tang

    One piece of Böhler N690, 5.0 mm thick, running the full length of the handle. Two lightening windows inside the tang, APEX NEWTON engraved 1.0 mm deep.

  2. 2 · 3
    Handle scales

    Forprene, 9.0 mm each. Diamond-lattice relief, contour grooves along the edges, counterbored so the screw heads sit below the surface.

  3. 4 · 5
    Liners

    0.9 mm plates between steel and grip. They separate steel from grip and draw a thin line around the handle.

  4. 6 · 7
    Screws

    Hex-socket, Ø8.4 mm heads on Ø4.9 mm shanks. Two screws hold the whole knife together, so it comes apart for deep cleaning.

  5. 8
    Lanyard tube

    Ø6.0 mm outside, Ø5.0 mm bore. Lined, so a cord never rubs on raw steel.

Dimension drawing: handle 126.7 mm, blade 126.9 mm, overall 255.5 mm, lanyard and screw hole positions
Overall 255.5 mm · weight ≈270 g (CAD estimate)