Knapped Steel Tutorial

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Knapped Steel Blade Tutorial, posted on The Carving Path Forum, September 19, 2007

The information contained herein originally appeared on www.thecarvingpath.net or www.thecarvingpath.com

forums. This compilation is copyrighted by TheCarvingPath.net, and each separate posting and/or image is

copyrighted by the original poster. This information may be freely distributed for the purposes of learning these

or similar techniques, but may not be sold or otherwise distributed for financial gain in any manner. Many of theprocedures or techniques described herein are dangerous, employ toxic or otherwise hazardous substances, or

may produce toxic or hazardous substances in the process of employment, such as dust or other evolved products.

This information is not intended for use by beginners or those uninformed about the proper use of the equip-

ment, materials or substances described. For heavens sake, do be sensible and safe when using these or similar

techniques. If you arent absolutely certain you are capable of using this information safely, then ask questions

or seek help and guidance by those who are.

Ive finally managed to get around to making another knapped steel blade, and Ive documented the

process I use. First, however, when youre trying to synthesize the features of something in your art, its

very important to understand the appearance of that which youre trying to imitate.

Along that vein, I dug up two examples of knapped stone blades, and also marked out the flake scar shapes

and patterns. One example is of a pressure flaked blade, and the other is of a percussion knapped blade.

Both of these stone blades are by Dr. J. P. Higgins, a friend of mine and expert knapper.

The first example is of a pressure flaked blade, this one in black obsidian (volcanic glass). Pressure flak-

ing is performed by using a hand held tool with a small point and literally pushing a flake off of the stone

with hand force only. Pressure flakes tend to be much smaller than percussion flakes, and appear to belonger (actually only more narrow and more shallow). This example is an oblique technique, and the

flake scars run across the blade at an angle. Parallel flakes run across the blade at 90 degrees. Knappers

normally try to make flakes from one side meet up with an opposing flake on the other side.


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The above is an example of percussion knapping, this blade in a heat-treated jasper. Percussion knap-

ping removes flakes by using a small but dense object to strike flakes from the stone. Percussion flakes are

larger, wider and deeper than pressure flakes. I usually simulate percussion flakes in my steel blade work

- simply because I like the looks better.

Heres my blade blank, along with a kozuka-like handle in copper (see Ford Hallams kozuka making

tutorial on The Carving Path Forum - http://www.thecarvingpath.net/forum/index.php?showtopic=950&h

l=kozuka). This will be a small, narrow blade so the blade blank is from 1/8 of an inch thick 1080 carbonsteel. For larger blades I normally use 3/16 to 1/4 inch thick carbon steel. I previously designed the blade

length and shape, and Ive rubber-cemented a paper copy onto the steel blank for use as a reference during

grinding and shaping. The blade steel has not been hardened or tempered at this point, the blade portion

is 5 3/4 inches long, 8 3/4 inches overall (not including the handle).


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If you examine any knapped stone tool, youll find that it is shaped like a lens in cross section. Here Im

using an angle grinder to grind that rough shape into the blade blank. Ive clamped the blade into a vise:

NOTE: THIS IS A HAZARDOUS OPERATION WITH THE BLADE STICKING OUT LIKE

THIS. PLEASE USE CAUTION WHILE WORKING WITH IT, AND REMOVE IT FROM THE

VISE ANY TIME YOU ARE GOING TO LEAVE IT UNATTENDED!

Also, with a thin blade like this, you should only grind the portion of the blade nearest to the vise - the

grinder will set up vibrations in the blade if grinding too far from the vise. This can damage the blade and

possibly you as well. When you need to grind farther out on the blade, reposition the blade in the vise.

Cross section of the blade blank should look something like this to start with.


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Here is another option for holding the blade for hand filing. I use a standard woodworking clamp fastened

in a bench vise to hold the blade horizontally.

Once again, this is a hazardous position, MAKE CERTAIN ALL THE CHILDREN HAVE BEENRUN OUT OF THE SHOP - THIS IS RIGHT AT EYE LEVEL FOR LITTLE PEOPLE!

Youll only want to work on the portion closest to the clamp because of vibration - this isnt as much of a

problem on larger, thicker blades, but was definitely a problem with such a long, thin blade as this.

Heres the blade in the handle, with a rough lens shaped cross-section ground and filed in.


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Heres a closer look - note Ive left the center of the blade at the original material thickness - well be

needing that thickness shortly.

Here Im marking in the centerline of the edge portion of the blade. This will provide a reference for how

deep well be grinding in the flake scars, so we can keep the edge reasonably straight and centered. I first

darken in the edge with a Sharpie permanent felt tip marker (dark colors only). Then, I select a diamond

burr size that is nearest to half the blade blank thickness (other types of grinding/sanding burrs will work

as well). I lay the blade blank on a flat surface and then draw the burr along the edge. This will scrapeaway part of the Sharpie marker color, leaving a bright mark. Flipping the blade end-for-end I repeat this,

leaving two closely spaced parallel bright lines. The center of the edge is halfway between these two

marks. Repeat for the other side. This is a quick and dirty method of center marking the edge, and works

surprisingly well.


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These are the tools I use for grinding in the flake scars, a Foredom flexible shaft grinder and small drum

sanders with medium grit sanding sleeves. I have three sizes, ranging from 1/2 inch diameter up to one

inch diameter. I keep a coffee can of water to cool down the blade as I grind. I hand hold the blade againstthe carving station you see the handpiece lying on. I can grind about two flake scars before the blade is

too hot to hold.

NOTE: DUST MASK AND EYE PROTECTION ARE REQUIRED FOR THESE GRINDING OP-

ERATIONS! YOUR EYES WILL BE VERY CLOSE TO HIGH-SPEED GRINDING, AND LOTS

OF VERY FINE SILICA DUST COMES FROM THE SANDING SLEEVE!

Ill be using the middle sized one (3/4 inch diameter) for this narrow blade, since it will most closely

simulate a short, smallish flake scar. A single sleeve was enough to do this 6 inch long blade by reversing

the sleeve halfway through the grinding. I find I use the far end of the sanding drum the most, leaving the

closest end pretty much untouched, so reversing the sleeve will make it last longer. I also leave the sleeve

a little long on the drum, so I wont hit the metal end of the sanding drum on the blade during grinding.

The sleeve will also bend at the end slightly, allowing detail grinds using just the end portion.Ill also use the very smallest sanding drum when I do the last inch at the tip of the blade where the small-

est flake scars will be.


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Ive drawn in (using the Sharpie permanent felt tip marker) the first few flake scars. I always start at the

base of the blade and work towards the tip. Since the base of the blade is where the blade will meet either

the handle or a blade guard, it is the most critical area in terms of fit and function. I grind in that area first

while Im fresh and alert.

Heres the first flake scar ground in. Im paying special attention to the base of the blades edge, where

the blade guard will touch. I want the edge to come to a point there without a flat spot that will look bad


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when the blade is installed in the handle. As I grind in the flake scar, I rock the grinder up and down and

move it along some of the length of the sanding drum so the scar is actually curved along the lens shaped

cross-section.

Starting to grind a flake scar (start at the edge, then rock the handle upward cutting in farther towards the

center).

Finishing grinding a flake scar in the center of the blade. Repeat as necessary.

Heres the second flake scar ground in (on the far side of the blade). Ive marked in the edges of the scars

with red to show how they overlap in the center of the blade.


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Heres the third flake scar. You can really see the lens-shaped curvature in the third scar in the enlarge-

ment. Also note Ive left the intersecting edges of the scars high. Dont forget to turn the blade over anddo the same for the other side. I try to keep both sides of the blade fairly even as I work the flake scars.

Theres a lot of adjusting as I go along, keeping the sharp edge fairly centered. I want a little undulation

in the edge for visual interest, but not too much!

Heres something to avoid as you work along. As Ive worked both sides of the blade, Ive left little flat


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spots along the edge of the blade (see the red arrows at the top and bottom enlargements). I want the flake

scars on both sides of the blade to meet in the center forming the sharp edge, but without these flat spots.

Ill correct this by grinding both meeting scars a little more at the edges, forming a small dip in the edge

when viewed from the top or bottom of the blade.

Heres a view of the same points from above in the finished blade - note how the edge curves in between

two sharp points. By a little more grinding, I created the curve and eliminated the flat spots so the higher

boundaries between two adjacent flake scars meet as points at the edge.

Here you can see where I removed the flat spots with the extra grinding. However, I dont want two ad-

jacent flake scars on one face to meet perfectly with two others from the other face of the blade. Notice

How Ive offset them slightly. Too much perfection doesnt look right in a blade of this style.


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Here Ive completed 5 rows of flakes, on both faces of the blade. Notice how the flake scars from one side

of the blade generally meet up with a matching flake from the other side, but Ive introduced enough

offsets to make the scar pattern more random and interesting.

At long last, heres the blade with all the flake scars rough-ground in. Ive done a little quality control and

checked to make sure there are no flat spots left along the sharp edge, in between adjacent flake scars, or

in the center. Now is the time to fix any problems.


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There are still some grinding marks left in the flake scars at this point left by the sanding grit. Ill go back

and use a Cratex grinding wheel (this one is fine grit, I think - its brown, whatever that means) to remove

most of those sanding marks. Now be careful here - youve worked hard to keep the edges crisp looking,

dont polish them off now. Im not looking for a bright and shiny finish here, just something to remove

all those little parallel sanding marks. This is supposed to have a little bit of a rustic look to it, so dont go

too crazy making it all perfect.

Here is the finished blade after heat treating and before descaling, slight polishing and bluing. Since this

is such a long and thin blade, I tempered it at 450 degrees F (232 C) so it isnt quite as hard (and thereforebrittle) as my normal blades (I usually temper simple carbon steel at 425 degrees F - 218 C). Im not go-

ing to go into the ins and outs of heat treating. Lots to say about that subject, and there are more in depth

discussions available on www.thecarvingpath.net or http://forums.dfoggknives.com.


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Heres the finsihed blade after a slight polishing with buffing compound, followed by a little gun blue(Birchwood Casey Super Blue). Ive added the kozuka-like handle (copper) and a fossil ivory guard and

butt cap, just because I thought it needed something. Now all that is left is to add some carved embellish-

ment to the handle and then patinate the copper.

Here are a few other examples of knapped style blades, just for reference. Hope this tutorial has been

enjoyable and of use to you.

Documents

Knapped Steel Tutorial