We visit Welling­ton work­shop of knife­maker Shea Stack­house and fol­low him mak­ing of a Damascus Steel puukka knife


The Shed - - Contents - By Jude Wood­side Pho­to­graphs: Jude Wood­side

Shea Stack­house looks too young to be a cut­ler at only 25, yet he has been mak­ing knives since he was 16. Having been taught jew­ellery and black­smithing ear­lier in his var­ied ca­reer, both of th­ese skills have con­trib­uted to his cur­rent prac­tice. He works from a small but rel­a­tively spa­cious work­shop in Wainuiomat­a, where he not only pro­duces some ex­em­plary knives made with his own Damascus steel but also runs week­end day cour­ses in his work­shop teach­ing knife mak­ing, Damascus steel mak­ing, and even black­smithing.

The beauty of a small knife

Shea owns a very nice power ham­mer that dom­i­nates the work­shop; it is more than 100 years old. He made his forges — a small one for knife mak­ing, and a larger one for Damascus steel and black­smith work. He also made many of his own tools, in­clud­ing ham­mers. The ad­van­tage of owning a power ham­mer is the abil­ity to make tools eas­ily.

Shea makes a va­ri­ety of knife styles, es­pe­cially chef knives, but his favourite knife pro­file is a small util­ity knife, a tra­di­tional Fin­nish de­sign known as a puukko. Of all the many elab­o­rate knives that get made in his work­shop, he finds the most ap­pre­ci­ated are cook­ing, util­ity, and small hunt­ing knives.

Hunters don’t usu­ally carry large Rambo-type knives in New Zealand — you are un­likely to en­counter a bear in the woods, but a knife to skin a beast is of value.

The beauty of a small knife like this, apart from its util­ity, is that it doesn’t re­quire much metal to make. The one shown fin­ished here page 22 was made from a small bil­let sawn from a larger piece of home-made Damascus.

Let’s make a puukko knife

When the bil­let is hot enough, turn­ing a bright or­ange-red, Shea be­gins to work it on the power ham­mer. The power ham­mer isn’t strictly nec­es­sary for this sort of knife but it does make short work of stretch­ing the steel out. After sev­eral heat­ings and pound­ings from the power ham­mer he turns to the anvil to shape and fash­ion the knife blade out­line.

On this oc­ca­sion he is able to use a newly minted ham­mer that he has only just fin­ished mak­ing for him­self. Shea likes to film his work and there is a video of him mak­ing this ham­mer on his YouTube chan­nel, Stack­house Knives.

With the ham­mer on the anvil he is able to form the shape of the blade. He fo­cuses on de­vel­op­ing the tip — though not mak­ing it too sharp, as that would cause the tip to over­heat — and gen­er­ally forms the out­line of the knife. As the steel is ham­mered it tends to bend in one di­rec­tion and the knife­maker can use this ten­dency to ‘draw out’ the steel into the pro­file he wants.

With the blade nearly formed he turns again to the power ham­mer to draw out the tang. This type of knife tra­di­tion­ally has a long, ta­pered rat-tail tang, usu­ally at­tached to the pom­mel by tap­ping the end of the tang and screw­ing a through bolt to it, or peen­ing it in the pom­mel.

Descal­ing as you go

He works on the tang on the anvil too, be­ing care­ful not to flat­ten the blade ma­te­rial too much close to the shoul­ders. “I like to keep a bit of meat around the shoul­der,” he says. This is po­ten­tially the weak­est part of the blade, where it is at­tached at the handle, and leav­ing more steel here con­trib­utes to the strength of the blade. It’s im­por­tant to reg­u­larly clean the scale from the knife as you progress — the last thing you want is to ham­mer the scale into the knife metal. It is very dif­fi­cult to re­move later. It re­quires reg­u­lar brush­ing with a wire brush.

Once the knife is shaped to the right pro­por­tions it can be put back into the now-cool­ing fur­nace to al­low it to ‘soak’ and re­lieve any stresses that the per­sis­tent beat­ing may have in­duced — in other words, al­low­ing the metal to re­lax or, in tech­ni­cal jar­gon, ‘nor­mal­ize’. Nor­mal­iz­ing the steel re­sults in a more fine-grained ho­mo­ge­neous struc­ture that is eas­ier to

He also made many of his own tools, in­clud­ing ham­mers

work and less likely to crack or warp. It is al­lowed to cool in air so that it re­mains an­nealed and soft for the ini­tial grind process.

The shape of the bevels and the shoul­ders is drawn on the piece di­rectly with marker pen and the first grind is started. Shea likes to de­fine the shoul­ders and rough out the bevel ar­eas, be­gin­ning to grind the blade to shape. He does most of the pre­lim­i­nary work on a large lin­isher us­ing a new 60-grit ce­ramic belt. With the scale largely re­moved he marks out the shoul­ders with a straight edge and scriber and files them to the line.

Hard­en­ing the blade

At this point, with the out­line of the knife formed, it can be hard­ened. It is only the blade it­self that needs to be hard­ened so the tang does not need to be placed in the forge. When the metal reaches its crit­i­cal tem­per­a­ture — a bright or­ange-red — it can be quenched. Shea prefers to use soya oil for quench­ing, but almost any oil will do. How­ever he cau­tions against us­ing used en­gine oils be­cause of the im­pu­ri­ties and their ten­dency to catch fire.

Austenitic steel

Steel has a crys­talline struc­ture and un­der­goes sev­eral changes when it is heated and cooled. Car­bon steels have an ‘austenitic’ tem­per­a­ture, the point at which they are no longer mag­netic. Stain­less steel is austenitic at room tem­per­a­ture so it is non-mag­netic, but other steels — in­clud­ing tool steels — re­quire be­ing heated to their crit­i­cal tem­per­a­ture, which is usu­ally be­tween 1050°C and 1090°C.

When austenitic steel is quenched the struc­ture changes to ‘marten­site’, a very rigid crys­talline struc­ture that is also very hard. How­ever, be­ing very hard it is also brit­tle, so the steel must be tem­pered to al­low the marten­site to al­ter slightly so that it be­comes less brit­tle. It’s im­por­tant

This is po­ten­tially the weak­est part of the blade, where it is at­tached at the handle

that the steel be al­lowed to cool to room tem­per­a­ture first be­fore the tem­per­ing is car­ried out; how­ever, tem­per­ing should be done within an hour of quench­ing. Shea dries off the oil and be­gins tem­per­ing almost im­me­di­ately.

Tem­per­ing for the knife’s use

To tem­per the blade it must be heated to a straw yel­low colour — usu­ally about 220˚C — with a di­rected flame like a propane torch, al­though it’s pos­si­ble to do this in a do­mes­tic oven. It can be dif­fi­cult to see the change in colour in bright light, so it’s best to do this in a shaded place. Here it is pos­si­ble to see the colour in the pic­ture. The ac­tual tem­per­a­ture of the tem­per­ing varies be­tween 220°C and 350°C depend­ing on the us­age of the knife.

For ex­am­ple, a knife used for camp­ing, that will need to with­stand a good deal of rough han­dling with­out break­ing should be tem­pered at the higher tem­per­a­ture — a blue colour, es­pe­cially along the spine. A knife in­tended for the kitchen, which is re­quired to main­tain its edge, re­quires a cooler tem­per.

Shea is aim­ing to get a straw colour on the sharp end of the blade and a light blue colour along the spine. This will keep the blade edge hard and the spine slightly softer to ab­sorb im­pact.

Fi­nal grinds and pol­ish

Now comes the more fo­cused grind­ing, run­ning through a range of grits on the smaller belt lin­isher. Shea starts with 40- and goes to 120-, 180-, and 240grit belts, suc­ces­sively pol­ish­ing out the scratches from the pre­vi­ous belt. Given that the blade is now hard­ened it takes a while to do this and it pays to per­se­vere. The blade must, of course, be reg­u­larly

It’s im­por­tant that the steel be al­lowed to cool to room tem­per­a­ture first

cooled to en­sure that over­heat­ing doesn’t dam­age the tem­per.

The fi­nal part of the prepa­ra­tion is hand-sand­ing the blade to achieve a high pol­ish with 320 and 400 grits. He clamps the blade to a piece of hard­wood and, us­ing wa­ter as a lu­bri­cant, works down the blade at right an­gles to the belt grind­ing marks to re­move the last traces of the 240 belt.

Etch­ing out the Damascus pat­tern

With the blade pol­ished it only re­mains to etch the steel to bring out the Damascus pat­tern. Nor­mally Shea prefers a lighter acid like cit­ric, but in the in­ter­ests of time, here he re­sorts to hy­drochlo­ric. After only 20 min­utes the pat­tern is clear on the blade. The acid must then be neu­tral­ized in a bak­ing­soda so­lu­tion im­me­di­ately and the knife washed and dried.

The handle

The bol­ster is 6mm brass; the blade is laid out on the brass ma­te­rial and the width of the tang at the shoul­ders marked off di­rectly on the brass. The open­ing is scribed onto the brass piece and it is cen­tre-punched at ei­ther end for 3mm holes to be bored within the open­ing. 

This stage can in­volve a lot of drilling and te­dious work with files to get the open­ing right. But Shea leans on his jew­ellery ex­pe­ri­ence and uses a jew­eller’s saw to cut the open­ing so that it re­quires only a mod­icum of clean up with files. The fine jew­eller’s saw can be threaded through the holes and cuts the soft brass with ease.

The bol­ster is fit­ted after some trial and er­ror. It is im­por­tant that the fit is tight around the shoul­ders for aes­thetic rea­sons and to pre­vent dirt and wa­ter en­ter­ing here. Fur­ther dec­o­ra­tion is pro­vided on the handle by a piece of coloured plas­tic shim; this too has to be cut and fit­ted. The handle is jar­rah. This knife, as men­tioned pre­vi­ously, is in­serted in a hole through the handle and held in place with epoxy, and the end is ei­ther tapped and screwed or peened in place over the pom­mel.

The pom­mel is also a piece of brass but it re­quires only a hole bored to take the tail of the tang and not a slot. Shea drills a slight coun­ter­sink at the hole to ac­com­mo­date the spread steel of the peened tang. First he squares the ends of the handle with a large rasp, again this is a crit­i­cal step to en­sure a tight fit against the bol­sters.

He marks the lo­ca­tion of the tang on the side of the handle stock, and also marks the open­ing and the end of the through bore. The larger end is drilled out first and the other end bored out with a smaller di­am­e­ter drill. Once the hole is cut and the tang fits Shea tapes over one end and fills the hole with quick-set­ting epoxy. He has found an epoxy that is both re­li­able and un­af­fected by heat or move­ment, having tested a few. With the blade in a vice the handle is fit­ted over the tang and the pom­mel and its as­so­ci­ated plas­tic shim is at­tached.

Fi­nal fin­ish­ing

When the epoxy has set he peens the end of the tang to hold the pom­mel in place and se­cure the handle. Now it only re­mains to shape the handle and pol­ish the lot. Again the lin­isher is called into ser­vice to shape the handle and the brass bol­sters. A ce­ramic belt makes short work of the shap­ing. When he is satisfied with the shape of the handle he fin­ishes the shap­ing by hand with a file.

Shea likes the look of a charred handle. He uses his blow­torch for the process. The char­ring can help to harden the handle but he is mainly do­ing it for ef­fect, plus the light char­ring con­trib­utes to a bet­ter grip. It’s im­por­tant to keep the flame mov­ing and not let the torch burn too deeply into the handle stock. A pol­ish of the handle with some oil and the knife is done.

Shea Stack­house has a web­site — stack­house­knives.co.nz — where he dis­plays a gallery of his work and that of his wife, Lena, who makes jew­ellery. He also has a Face­book page and a YouTube chan­nel, Stack­house Knives, with sev­eral videos of him at work.

The bil­let of Damascus steel that Shea forged

The power ham­mer saves time when draw­ing out the hot steel

The heated bil­let ready to be worked

Draw­ing out the tang

The anvil and ham­mer are still nec­es­sary to get the shape right

Above: Re­heat­ing the knife blankBe­low: The knife tak­ing shape from the ham­mer

The knife blank with the bevels and shoul­ders marked out

Rough grind­ing the blade and shap­ing the pro­file and the bevel

Grind­ing the shoul­ders to shape

Cleaning up the shoul­ders for a sharp edge. This pays off later when the bol­ster is fit­ted

Far left: Etch­ing in acidLeft: Cut­ting out the slot to fit the tangBe­low: Mark­ing the po­si­tion of the tang for the first bol­ster

Clock­wise from top left: Grind­ing the first of a suc­ces­sion of grinds; the blade after suc­ces­sive grinds up to 240 grit; the etched blade show­ing the Damascus pat­tern

Mark­ing the tang on the handle

Peen­ing the tang

Shea likes to fin­ish off by fil­ing by hand

Rough-shap­ing the handle

Brush­ing off the loose char

Fin­ished knife

Char­ring the handle

Newspapers in English

Newspapers from Australia

© PressReader. All rights reserved.