What size steel for a tanto?

A tanto has a straight spine that runs right out to the point, and its height at the ricasso is what sets the bar. The preset is a 4 1/2 in blade, 1.1 in tall at the ricasso, with a 5/32 in (0.156 in) spine and a 4 1/2 in full tang. Add 1/8 in for clean-up and you need 1.23 in, which rounds up to 1 1/4 in. With the spine, that makes it 1 1/4 × 5/32 in flat bar. The matching KraftyDesign blank (the "Draw this blank" link) has a straight spine running to the point. The edge is two fairly straight runs that meet at a sharp angle near the point. Blade HQ calls that corner the secondary point, and the short front run the secondary edge.

In metric, 5/32 in is about 4 mm. One BladeForums poster shows an American-style tanto in 4 mm 80CrV2. A 7 in O1 tanto in another poster's work-in-progress thread came from 0.200 in stock. At the small end, GP Knives, a knife retailer, lists a 3 1/2 in CPM-154 tanto at 0.14 in and a 2 in CPM-154 tanto neck knife at 0.11 in. The calculator starts on 1084.

The calculator starts on stock removal for this one. Stock removal takes the whole 9 in profile plus clean-up: about 9 1/4 in of bar per blade. That is about 8 oz of bar for a blade that finishes around 5 1/2 oz. A 12 or 18 in bar gives one blade, a 24 in bar gives two and a 36 in bar gives three. A 48 in bar gives five at the lowest cost per blade.

Forging the bevels and the point stretches the blade, so about 8 in of the same bar (about 7 oz) is enough. The blade finishes near 5 oz. A 12 in bar gives one, 18 in gives two, 24 in gives three and 36 in gives four. A 48 in bar gives six, and the 24 and 48 in bars tie for the lowest cost per blade. If you start thicker and forge down, set "Forged thickness" to "One size up". That starts you one thickness up, and it only applies in forged mode. Some smiths start much thicker: one BladeForums poster shows an 8 in 1095 tanto forged from 5/16 in stock or heavier. 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.

However you make it, the hard part is the line where the two bevels meet. In a BladeForums thread on grinding a tanto, one poster passes on advice to grind the main bevel first, then grind the tip bevel to meet it. Too much pressure near that line will wash out the crisp facet. One reply suggests practicing on a few kiridashi first, because the tip grind is the tricky part.

What a tanto is for

The American tanto is a utility and tactical knife, and most of what is said for it is about the point. Gear Patrol says the shape is strong, which makes it good for puncturing and piercing. Its everyday examples are opening plastic clamshell packaging and adding a hole to a leather belt. Knife Informer adds that the chisel-like point of the American version is good for scraping. Blade HQ describes the shape as two points, one at the front of the blade and another just before the tip. It calls the tanto popular on tactical and hard-working knives. Not everyone agrees about the piercing. In a BladeForums thread comparing the tanto with the drop point, one poster explains that the secondary grind puts a lot of metal up front. The same poster says more metal at the tip gives more strength but less penetration. By that view, the tanto gives up some piercing for a tip that is harder to break. It gives up belly too. Knife Informer says tantos have little belly, so they are poor at slicing or skinning game, and Gear Patrol notes that some people find the shape clumsy for slicing. On the short front edge, Knife Informer likes a flat grind because it adds strength.

Tantō (短刀) is Japanese for "short sword". Nihonto.com, a Japanese sword reference site, defines a tanto as a Japanese sword of less than one shaku, about 30.3 cm (just under 12 in). It says tanto existed as early as the Heian period, and that most early ones were made for practical use. The Heian period ran from 794 to 1185. The site also says hira-zukuri was the standard shape before the Muromachi period, which it dates from 1392 to 1572. The Japanese Sword Index describes hira-zukuri as flat sided, with no ridge line (shinogi). One BladeForums poster points out that most Japanese tantos had a curved point, not the abrupt American one. Spyderco, which makes knives to Bob Lum's designs, says the late Lum combined a traditional Japanese tanto with the reinforced tip of a katana. On a katana, the yokote is the line where the body of the blade meets the tip section (kissaki). The BladeForums grinding thread uses the same word for the line between a tanto's two bevels. A magazine article on Everand says Lum began making custom knives based on the tanto in the mid 1970s, and that Cold Steel took them into the mainstream with production knives. Gear Patrol credits Cold Steel with putting the sharp angle into the belly in the early 1980s. An Athlon Outdoors article says Cold Steel's founder, Lynn Thompson, is given much of the credit for the "Americanized" tanto. A Japanese-style tanto is a different knife to make. In a BladeForums thread on a traditional-style tanto, one poster says most first tantos are far too thick, and calls W2 a good tanto steel.

The rest is unconfirmed, so treat it as forum talk and marketing rather than settled history. Who designed the American tanto is still argued over. Spyderco calls Lum the first knifemaker to put a katana's reinforced tip on a tanto. In a BladeForums history thread, one poster says Lum told them that Lynn Thompson bought one of Lum's customs at a California show and used it as the model for Cold Steel's first tanto. Another poster in the same thread compared a Spyderco Lum tanto with a Cold Steel Master Tanto and found them not very alike. A third quotes the knife writer Ken Warner, who praised Lum's "oriental fighting knife" in the Knives '82 annual and showed Cold Steel's newly announced Tanto in Knives '83. Another remembers Thompson saying on a DVD that he invented the tanto point. The armor-piercing story is just as loose. Gorilla Surplus, a retailer, says Cold Steel marketed its American tanto as an armor piercer, and Knife Informer says tantos were designed mainly for piercing, especially through armor. One BladeForums poster criticizes Thompson's claims that tantos were armor-piercing battlefield weapons. Nihonto.com, for its part, says most early tanto were made for practical use.

Stock for a tanto

In a BladeForums thread on steel for a tanto, one poster suggests at least 3/16 in, or better 1/4 in, for a first tanto. That leaves plenty of room to grind, and a thicker blade may warp a little less. The same poster suggests 1075, 1080 or 1084 over 1095 for a first one, because they are a little more forgiving to heat treat and quench.

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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