What size steel for a boning knife?

A boning knife is narrow, and its height at the heel is what sets the bar. The preset is a 6 in blade, 1 in tall at the heel, with a 3/32 in (0.094 in) spine and a 5 in full tang. Add 1/8 in for clean-up and you need 1 1/8 in, which rounds up to 1 1/4 in. With the spine, that makes it 1 1/4 × 3/32 in flat bar. The matching KraftyDesign blank (the "Draw this blank" link) is narrow, with a long curve up to a point near the spine for working around bone. At 3/32 in, this is a stiff boning knife. America's Test Kitchen (ATK) tested knives sold as flexible and preferred a moderate amount of flex, with spines about 1.25 mm (about 0.05 in) thick. It found blades with spines around 2 mm more rigid, and 3/32 in is about 2.4 mm. Thickness decides how far a blade flexes, not hardness. If you want more flex, grind it thinner. The calculator starts on 1084, and AEB-L and MagnaCut give the same 1 1/4 × 3/32 in bar. 14C28N is sold in metric thicknesses, so the calculator flags 3/32 in as uncommon for it. Check what your supplier stocks.

The calculator starts on stock removal for this one. Stock removal takes the whole 11 in profile plus clean-up: about 11 1/4 in of bar per blade. That is about 6 oz of bar for a blade that finishes around 4 oz. A 12 in bar gives one blade and a 48 in bar gives four. The 24 and 36 in bars give two and three, all at the same cost per blade. Forging the bevels and the point stretches the blade, so about 8 1/2 in of the same bar (about 5 oz) is enough. The blade finishes near 3 oz. An 18 in bar gives two and a 36 in bar gives four, both at the lowest cost per blade. A 48 in bar gives five. If you start thicker and forge down, set "Forged thickness" to "One size up". That starts you at 1 1/4 × 1/8 in, and it only applies in forged mode. The calculator won't forge AEB-L, CPM-154, 14C28N, MagnaCut or A2. Pick any of them and it works out the bar as stock removal, even with Forged selected.

What a boning knife is for

A boning knife is for taking meat off the bone. ATK calls it a butcher's tool with a thin, narrow blade made to work its way between joints. In its testing, cooks boned chicken breasts and trimmed silver skin and fat from a beef tenderloin. They also took the bone out of a cooked pork shoulder. Friedr. Dick, a German maker of butcher's knives, adds skinning meat and poultry and cutting through tendons. Wikipedia gives the usual length as 5 to 6 1/2 in. Most of the knives ATK tested had about 6 in of usable blade. ATK says that length lets a boning knife carve out both small bones and bigger ones, like the bone in a pork shoulder. Its top pick, half an inch shorter, was a little short for the big shoulder bone. Boning knives get used on game too. One BladeForums poster made two 5 in boning knives and used them on a deer. Afterward, the poster found 5 in too short a lot of the time and thought 6 in would be ideal.

How stiff it should be depends on the meat, and people disagree about it. ATK's testers liked a moderate amount of flex. Thicker, more rigid blades couldn't hug the breastbone of a chicken or the bone in a pork shoulder quite as closely. In a BladeForums thread on making a boning knife, one reply wants a thicker spine to stand up to twisting in joints. A poster who says they worked in a butcher shop for many years disagrees. That poster says butchers never use a boning knife for twisting and that it needs to be thin and flexible. The blade is narrow for tight work. A poster in another thread who bones turkeys says it has to "turn very short corners as you follow the bone". The blade can be straight or curved like a scimitar. ATK slightly preferred a fairly straight blade, because the point was easier to direct. Friedr. Dick says the curved version is more in demand now because it slides along the bone more easily. The preset's blank is the curved kind. Japan has its own boning knives. Korin, a Japanese knife shop in New York, describes the honesuki as a poultry boning knife that can be used in place of a Western one.

These stories come without sources, so read them as lore rather than history. Friedr. Dick says boning was already in demand in all ancient cultures, done with sharpened horn or a specially shaped stone. It says the knife was first used only to take out bones, and that skinning and removing tendons came later. It gives no source for any of this. Several knife sellers and blogs say the hankotsu, another Japanese boning knife, is traditionally used on hanging carcasses. Two of them add that it is held in a reverse grip, and one says edge down. None of them cites a source either. Korin describes the hankotsu as a strong, sturdy knife for cutting meat away from the bone, not for cutting through bones.

Stock for a boning knife

One BladeForums poster made two 5 in boning knives from 0.070 in 1084 and found them a little too flexible. The poster suggests starting around 0.090 in and tapering the spine to about 0.060 in, but not so thin at the tip that it breaks off in the meat or on a bone. That puts 3/32 in bar about right as a starting thickness, if you taper the spine toward the tip.

Widths assume blade height + 1/8 in rounded up to stock; thickness is the finished spine rounded up. Change the inputs above for your own pattern.

Steels that suit it

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