We visit Wellington workshop of knifemaker Shea Stackhouse and follow him making of a Damascus Steel puukka knife
A CUTLER DEMONSTRATES THE PROCESS OF MAKING A DAMASCUS KNIFE
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.
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 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.
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
Charring the handle