Some Knives Again – Part 1

I finally got time to work on knives again and finished some of the second overabladeance blades and two of the first one.

First a set made from an apple branch fork. I have left some of the woodborer’s lacework visible, most of which was just below the bark. Deeper holes and cracks were filled with brown-dyed epoxy.

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The stand and the handles are made from one piece of wood and the grain on the handles is a continuation (plus-minus a few mm) of the grain in the bloc. I added some solder weight to the bottom of the bloc so it is heavier and more stable because I did not want o disturb the shape by adding legs. I aimed for a more flowing and organic look and two straight metal legs would distract from that. I also have tacked on a few anti-friction pads.

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It was not easy to make the slits for the blades so they are a bit rough around the edges but that is OK and in line with the design. When I was deciding how to close the back of the slits, the nearly invisible seamless gluing of flat boards that I do for straight bloc designs was not an option so instead of trying to hide it, I opted for a bold contrast. I glued in a black-locust strip and I have left enough space for a dark-brown epoxy strip around the edges too.

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The bigger knife has some chatoyancy in the handle, something that I did not expect. But I did not make the wood too shiny – I only sealed it with one epoxy dip and I did not seal it for a second time like I do for shinier surfaces – I have just buffed and waxed the set. Thus all the wood has a somewhat satin look to it and the handles are nicely grippy.

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The bigger blade has a minor etching defect near the handle that I thought would be hidden under the scale but It is not, unfortunately, because I made a slight mistake in the glue-up. Also, the blade is slightly thicker and heavier than is typical for this type of my knives, it has a somewhat “choppy” feel to it. All in all, it is a mixed bag as usual, I am not proud of the work I did, but I do not hate it either.

Sometime during this week, the set will be available in the shoppe. There also are slightly more pictures on Instagram.

Sciencing Sharpness – Part 5 – My Sharpening Kit

I have found a blunt-ish knife, one that I use in the cellar to open wooden briquette packages. It was not exactly blunt but it was slightly blunt and I have run it over a quartz stone to make it blunt. It is a knife from high-quality stainless steel but it has been sharpened so much that it has lost about 30% of its width. I have tested with it my traveling sharpening kit. I have done completely freehand sharpening, holding the stone in my left hand and knife in the right hand, no angle measuring, not even angle estimating, just putting the blade to the stone in a way that “feels right” and going on from there like I used to before I got the machinery to be precise. I tried to look up on the internet the grits of the stones that I use but it ain’t easy because one of them is a no-name generic grey carborundum whetstone and as you will see, it does not appear like I found the right ones. I have also used all of the orange thread that I have reinforced with PVA glue and from now on I will use the nylon thread since I have already bought it.

Here is the picture that’s worth a thousand words:

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And here are less than a thousand words explaining what’s in the picture:

It is a bit strange that the fine grey layer of the cheap whetstone does not perform much better than the coarse layer and even performs worse than the beige layer on the colored stone which should have slightly coarser grit. There are several possible explanations or a combination thereof – I got the grey stone grits wrong, I done did do a bad job with this layer, or the fact that this stone uses a weak binder and sheds grains very easily plays a role, or I messed up the measurements. Nevertheless, the knife was capable of cutting freely hanging printing paper at this point, although not very easily, and it did bite into a fingernail.

Anyhoo, the second stone is much harder and I actually know the exact grits from the manufacturer. And once I got to the red layer with “just” 500 grit, the knife was shaving-sharp. The leather strops might have burnished the edge a bit but there is no statistically significant difference anymore from the 500 grit stone. It looks like there might be one, a very minor one if I had performed more measurements or had a more precise method.

I would say that it is pretty convincing for my argument that a two-layer whetstone and a strop are all that is needed to get and keep knives sharp.

It also appears like 500 grit stone is sufficient to maintain a knife edge shaving sharp without any further ado. But I would say that shaving hair with the stropped knife feels slightly “smoother” on the arm than with one that went just over the stone and I feel inclined to trust my skin sensors (they are much more sensitive than the kitchen scale after all) on this issue so I’m not convinced that the strop is completely useless. Measuring as fine differences as these might be is not a task that can be done with a rigged-up kitchen scale.

Sciencing Sharpness – Part 4 – Failing to Improve the Measurements

My mother was ordering some things from an online drugstore and I jokingly said if she could order me a nylon thread too. And surprisingly, the shop did carry a 0.25 mm nylon thread. It arrived today. I have immediately run an experiment to evaluate if it delivers better results than my old, PVA glue-impregnated thread. And sadly, it does not.

I made 25 measurements with both threads with a razor and then with the testing knife sharpened at 10°. And the results are interesting, but not good.

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The nylon thread performed statistically significantly better for the razor – the values were less spread out. But when it came to the knife they were both about the same, with no statistical significance whatsoever. And there were outliers in both sets. A disappointment, really. A lower spread would allow me in the future to get useful results with fewer measurements per each test, this way I am somewhat stuck with making at least ten measurements.

At least all four sets had normal distribution which means that averaging multiple measurements should give precise-ish results.

I think that the biggest problem is the scale’s lack of a Hold function and the frequency at which it renews the display. Well, it is still useful and the thread did not cost too much. And it is easier to span.

Sciencing Sharpness – Part 3 – Angle vs. Sharpness

It is not good for my ego to have the predictions mostly correct again, but this time there were things that surprised me a bit.

I have included a sharpening angle of 10° which I never use in praxis because it is not recommended for the N690 steel due to reduced edge retention at that angle (tendency to chipping), but that would not be a problem in this test and it is a data point of knowledge in case I make some carbon-steel sushi knives or razors in the future.

Now the boxplot:

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So I got the prediction about how the cutting force will rise mostly correct. Mostly, not completely.

ANOVA test has found no significant difference between the first four angles but I am sure there would be one if I had performed more measurements and/or refined the testing method. The Lookandsee test does indicate a slow rise in cutting force from around 25 gf to around 50 gf.

The jump at 30° is a bit more sudden than I expected. I suspect that it is a fluke. And then the rise at 40-45° was a lot less than I expected.  It seems that the 90° cutting edge is still significantly better than no cutting edge, which would be somewhere around 3-4 times worse with a cutting force of around 1000 gf. I did not expect that. The best-fit function is quadratic. This is less drastic than the predicted exponential growth, although still significantly faster than simple linear growth.

So in conclusion, it does appear that my opinion that whilst there is a difference at angles 10-25°, it is not big enough to matter for casual knife users is substantiated. The angle 30° performed slightly worse than I expected, and the angle 45° performed significantly better than I expected.

I am going to think about all this some more and then I decide how to proceed from now on.

Sciencing Sharpness – Part 2 – Grit vs Sharpness

Notwithstanding dangerousbeans’s comment at the last article, I did find in my steel offcuts pile a blade that broke after it was nearly completely finished, with etched logo and all. That means learning about the sharpening properties of exactly the steel that I use in exactly the state it is in a finished product. In different steel, the results might come out a bit differently, which means I am mightily glad that I could do my tests on this – an absolutely ideal testing specimen.

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I have sharpened the blade stub at a 15° angle which is the angle at which I usually sharpen kitchen knives, and always those that I make from N690 steel. (When tasked with sharpening store-bought knives from unknown steel I occasionally sharpen them at 20°, especially if it is clear from the state of the knives that the customer is not particularly careful about their use.)

I established the bevel with 120 grit and then I progressed from 180 and 240 grit Zirkorund and then Trizact belts (in the evaluation translated into grit equivalents) from A 65 all the way to Trizact A6. I only differed from my usual sharpening procedure in one way – I used fresh belts, instead of old ones. Normally for sharpening, I am using old belts because sharpening is extremely rough on the belt and destroys it very quickly.

The measuring method is wildly imprecise – the testing thread is not homogenous, the angle at which I put the blade on it is not always precise, I do not always hit the center, I am not pushing with constant speed, the kitchen scales do not renew the measured value with sufficient frequency and probably several other variables. I have experience with such measurements from my previous job though and there are ways to get relatively reliable, reproducible, and usable results even so. One of those ways is to make lots of measurements – that is why I took 12 measurements, discarding two of the most egregious outliers and making the evaluation with the remaining 10. There are mathematical methods for discarding outliers but for my personal purposes, the Lookandsee method suffices. (Thirty or fifty measurements would be better, but I am not going for exact values for individual grits, I am going for a comparative assessment between those grits. Anyway, not going to write a boring lesson about measuring).

Here is the boxplot of those ten measurements per each grit:

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And it looks like my prediction from yesterday was bang-on. Which is satisfying to my ego, but also boring in a way. It would be much more exciting if it were different.

What you see here is the cutting force going rapidly down from ~270 g at 180 grit to ~ 75 at 400 grit. At this point, the blade is capable of cutting freely hanging paper. Then it falls some more to ~40g  at 800 grit and more or less stays there till the end (the knife is shaving-sharp at these stages). The slight increase at 1200 is a fluke that would most probably go away if I have made more measurements and/or invested time and resources in refining the method. I made ANOVA test and there is no statistically significant difference between the last three fine grits.

So in conclusion, sharpening knives beyond 1000 grit indeed appears to have very little practical value. At 800 grit the blade is already shaving-sharp and polishing the edge further only costs more time without noticeably improving its cutting capabilities. With more precise measuring method there might be a difference, but it would be very, very tiny. I think that I can replace the last two belts with a leather belt infused with stropping compound and get the same result. And since time is money, I will do exactly that.

Sciencing Sharpness – Part 1 – Predictions

I hope to use my new sharpmeter to get some knowledge about, well, sharpness. And since I am going to be playing at science whilst doing so, I have decided that I will write down the predictions for my tests. The tests will not be blind, because I will be doing both the sharpening and testing and there will still be some subjectivity to these tests, but nothing is perfect. I am doing these tests to gain some knowledge and I will share that knowledge for free but there will inevitably be bias.

The first test that I intend to perform is the influence of grit on edge sharpness. I think that after establishing the bevel with 180 grit the cutting force will go down significantly with the next steps, but it stops changing significantly above 400 grit. My reasoning for this is the fact that it is possible to get a knife shaving-sharp with ca 320 grit stone and at 320-400 grit usually the wire edge/burr falls off. I think that I have mentioned in the past in comments somewhere – either in Marcus’s place or here – that going above 1000 grit in sharpening makes little sense function-wise, although I cannot find the comment now. I will go up all the way to trizact A6 belt (the equivalent of 2000-2500 grit) in the experiment.

The second test that I intend to take is the influence of the sharpening angle. There was a heated debate between me and Marcus on this issue a while back -click-  and I really want to test it (caveat from the first paragraph applies doubly). I expect the force needed to cut the thread to rise exponentially, i.e. slowly from 10-25°, then some more for 30° and even more for 40° and again even more for 45°. I won’t test sharpening angles steeper than 45° because it makes no sense IMO since a 45° sharpening angle means a 90° edge. I know from praxis that knives sharpened at 15°, 20°, and 25° can be shaving-sharp. I do not know much about the 30° angle, since that is extreme and I only sharpen hatchets and axes at that angle and I never even tried to get those to shaving-sharp. They do cut paper though.

So, sometime this week I shall heat the workshop again, sharpen some steel offcuts (probably pieces of old hacksaws) and go measuring.


It is freezing here and I still do not have the slightest inclination to do something useful. But I need to heat the workshop occasionally to prevent it from completely freezing. Not that it would be super bad, except that maybe ice forming in the cooling receptacle near the grinder could damage it. Anyhoo, yesterday was a workshop heating day. I could not do anything super useful – it took me hours to raise the temperature to a bearable level and soon after I stopped feeding the stove, the temperature got down quickly again. But I could use the time to do something small and simple so I have made a device for measuring knife sharpness (I did not invent the concept, I saw the principle somewhere on the interwebs sometime ago).

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It is simple and consists of two main parts. One part is a board with four legs and a 35 mm hole in the middle. A tiny table that can be put over my kitchen scales.

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The second part is a small wooden cylinder with a cutout and two screws on each side of it.

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I can span a thin thread between the two screws and when the cylinder is put on the scale through the hole in the middle of the tiny table, I can cut the thread safely for me, the scale, and the furniture.

The main downside is that my kitchen scale does not have a “Hold” or “Max” function so the measured values are not super precise. Another problem is the used thread – a very thin fishing line would be probably better since this one has a tendency to get damaged during spanning. Or perhaps a very thin copper wire – I might try to extract some strands from leftovers from speaker or ethernet cables. But when being very careful with spanning the thread and doing the cut slowly and carefully, the setup gives useable results and I did learn some things.

Here is a boxplot of 10 measurements with the three cutting implements in the photos – a fresh razor blade, a paper-cutting-but-not-shaving-sharp sharp knife, and a blunt table knife (I used the non-serrated part which is about 1 mm thick),

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The razor had an average cutting force of ~6 g, the sharp-ish knife ~60 g, and the blunt knife ~ 1000 g. The less sharp the blade the bigger the spread but even with sometimes ridiculous outliers, there is a definitive and statistically significant difference between these three and it does give me some information and opens future opportunities. I would like for example to examine the relationship between sharpness and sharpening angle, to get some hard data to back up my opinion that anything between 10-30° works just fine. My prediction is that the relationship is not linear and as the angle gets steeper, the cutting ability gets exponentially worse.

I did learn one thing – my “Not a Masterpiece” was sharpened at a 20° angle and the only knife that actually scares me – the bigger knife from the two-knife applewood set – was sharpened at 15°, yet both measured within the same range as the razor. Although the applewood knife completely failed to register on the scale one time, thus my suspicion that it is the sharpest knife I made so far might be true.

Of course this only tests edge geometry, not blade geometry. I could use a similar setup to test the influence of blade geometry on cutting force too, but I do not have a reliable medium to do so yet. All things that I have thought of so far are either expensive (cork, rubber, silicone) or have highly inconsistent properties (fruit & veggies). But maybe I will think of something to test blade gomtry too.

An Experimentental Knife Set

A friend gave me in the spring some cherry wood from a tree that died and dried standing up in their garden. That means the wood has many cracks, some fungus damage, and discolorations. And she asked for a kitchen knife for herself as her primary cooking knife. The type of blade that she requested would be more of a fish-gutting knife for me, but she has her own cutting style and I am not a knife snob to sneer at someone’s cutting technique. If one is not cutting their fingers off, the main thing is that they get the ingredients down to size and to each their own I say.

I got to work but I got distracted several times. Firstly, when I was cutting the steel, I got a small offcut that just lent itself to be made into a small peeling knife matching the one ordered. Secondly, when I was selecting the wood for the handles, I found one piece that was big enough for both handles and a bloc. And thirdly, when I was pondering making legs for the bloc I got an idea to try to make a foldable leg, so I tested it. Having a lot of problems to deal with makes me extremely prone to such distractions. It is a bad habit.

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© Charly, all rights reserved. Click for full size

The knives have very simple rectangular handles that are nevertheless comfortable to hold. The blades are N690 steel,  without ricasso, tumbled. The numbering on the smaller knife is a bit unreadable, but such is life. Bolsters and end caps are from buffalo horn. I made them thin because she expressed a wish for the wood to be the dominant design feature.

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© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

The wood grain and cracks in the handles match that in the bloc. This is exactly why I have used this particular piece of wood, it had just the right size for this. The wood has fairly small pores and is not overly decomposed so trying to infuse it with resin would be an exercise in futility, thus I only coated it with three layers of resin, sanded it with 800 grit, and then I buffed it with home-made silica-based buffing compound.

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© Charly, all rights reserved. Click for full size

The foldable leg is bent from an old knitting needle. The holes in the sides of the bloc are offset so the leg has two stable-ish positions. It is just a gimmick that won’t probably see much use but it would make packing the knives for travel easier if one were inclined or in need of to take their cooking knives with them on travels. But mainly I wanted to try to make it.

If she accepts these, I will actually only charge for the bigger knife since that is all that was agreed upon. The small knife and the bloc she will get together with her husband as a belated wedding gift.

Another Overabladeance

I was spending way too little time actually making knives this year since I spend two-three days a week carting my parents to and from various doctor appointments. And when finishing this batch, my new tumbling receptacles did not work with this particular type of blades and I had to modify them significantly. However, I do have now thirteen finished blades, eleven tumbled from N690, and two from spring steel, mirror-polished with hamon.

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Four kitchen knife sets three three-piece and one two-piece. You might notice that this time I went for blades without ricasso. The reasons are several but the main one is that such blades are significantly easier to make. Really significantly easier. They turned out well and I must say there is something satisfying about getting two chef-knife blades so flat that they stick together when wet. They are probably flat to within a few hundredths of a mm.

The two-piece set in the lower left corner is actually a half-commission. A friend of mine has ordered the bigger blade and I have decided to make the smaller one from an offcut to accompany it. I will also make a bloc as a belated wedding gift. To be fair, I could not give them a proper wedding gift on time since they kept the wedding secret, so it is not that I was inconsiderate, just ignorant.

From now on, I will for several months only dress blades. I still did not finish all of last year’s Overabladeance. The two Puuko I made still have no sheaths. I only started to make these blades because of the commissioned machete in the summer and the commissioned kitchen knife from my friend – I needed a sufficient amount of blades to fill the tumbler and not waste the forge heat. For both things, ten blades is a minimum. So actually I might make some blades again – if I get a commission.

A Commision With a Point

I hope the customer will accept this, I am not completely happy with the result. An acquaintance of mine has given me some deer antlers for crafting and she also commissioned a knife made out of one of them. The antlers are from her father, who is a gamekeeper and she wants to have something to remember him by. She requested a small letter opener with a stand that can also work as a paperweight. Lenticular grind and not fully sharpened edges. Oak wood for the stand because her office has oaken furniture.

From the manufacturing point of view, there were not very many interesting things – I ground and polished the blade and blackened it with oak bark, then I fixed it to half of the antler with the burr at the pommel end. Because the antler is old, scratched, and irregular – as antlers are – I have hammered the pakfong pommel into an irregular shape. I also hammered the bolster and I only wire-brushed and polished them over the hammer marks. A bit interesting was the making of the stand.

To weigh it down, I chiseled holes in the bigger piece of wood before gluing it together and I poured molten solder into it.

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I learned this technique from my maternal grandfather. I have never met him – he died long before my parents even met – but he made for my grandmother a top for winding the thread on bobbins and the top has been weighed this way on its circumference. Molten solder cools in wood quite quickly and it does not char the wood on the edges all that much, especially if it is hard and dense wood. I was itching to try this out for years.

The pakfong throat on the stand for the blade was a bit difficult to make and there I had to use a creative solution to make it hopefully solid enough so it does not become undone in a breeze. I did not want to rely only on epoxy, so I soldered two pieces of copper wire onto the pakfong piece, and I glued those into tight-fitting holes. This way it should hopefully withstand even some mild abuse like falling on the ground.

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© Charly, all rights reserved. Click for full size

The full finished set weighs about 860 g, I have possibly overdone the weighing a bit. The stand is slightly decorated with pokerwork and the underside is covered with brown natural felt so it does not click when put on a table. The finish is tung oil and beeswax, which are more pleasant to the touch than lacquer or epoxy.

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© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

Crafting Perk Unlocked – Hamon

When making the commissioned machete in the summer, I had enuff steel left for one additional blade and two more blanks lying around made from the same steel, thus I decided to try my hand at making a blade with hamon again. So far, I have succeeded only once, with a “mystery” stainless steel, and I had to cheat by carbonitriding it for several hours at ca 500°C. The 54SiCr6 is 0,5% carbon steel, which is not ideal for hamon. 1-1,5% carbon would be better. But I decided to try it nevertheless because if I fail, I can (usually) always harden the whole thing.

Well, I did fail in multiple ways – from three quenched blades, one had to be tossed completely, one I damaged because of unforeseen circumstances, and one turned out OK. This is better than my previous attempts and I think I have a working process now for making blades with hamon. Here is how I did it.

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First the used materials – three blade blanks ground with 40 grit. I went for three different geometries to see what happens. A sample size of 1 per geometry is of course not very indicative of anything, but it is better than nothing. On the left is a bottle of liquid glass, a water solution of sodium silicate, a chemical that is sold cheaply in CZ and is used to waterproof cement, make cement go harden faster, and as a binder for heat-resistant cement. Then there is a receptacle with perlite, which I have bought in huge amounts for use both in my gardening and knife-making endeavors. And the last ingredient is fine-sieved dirt from my garden taken from deep below the topsoil – I have a heap of this too from the building of my sewage cleaning facility.

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The first step was to cover the blades with a thin layer of just the liquid glass mixed with some clay and sprinkle some more clay on top of that to soak up excess liquid glass and prevent cracking of the layer when drying it with a heat gun (a torch and charcoal fire work both too as I found out later).

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Here you see the various phases of the second step, which consisted of adding several layers of perlite. For this, I have used the mixture of liquid glass and dirt again, but I have sprinkled it with perlite. The liquid glass serves as a binder, the clay as a filler to prevent cracking, and the perlite as an insulator. I dried the added layer with a heat gun again and I continued to add these layers until I had about 1 cm thick insulating layer on each blade. To finish it off I have added one more layer of liquid glass and dirt only to make a hard shell that holds it all together.

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Initially, I went for three different hamon lines, but unfortunately, this did not work out. After I quenched the machete and one of these blades (I forgot which one) without problems, I had trouble reaching the required temperature again because the coals got smaller and the blown air did not reach under the uppermost layer anymore. So first quench was unsuccessful on two blades, I had to cover them again and try to quench them again. This time I was using the charcoal fire to quickly dry the successive layers and it worked well. Next time I am preparing blades for hardening this way, I will probably combine it with BBQ dinner, combining pleasant and useful.

As I already mentioned, two of these unfortunately failed.

The first fail was the blade with a fuller – it cracked near the ricasso. That is always a risk with hardening steel and it is higher with this method it happens even to masters of this craft because the blades must be quenched in water which is more stressful than oil. So while I am not happy about having to toss the blade, I do not beat myself over the head over it either.

The second fail is the drop-point blade. And I am beating myself over the head about it because this is completely my screw-up. I have read books, internet articles and watched videos about how blades with hamon are made, but I do not remember anyone ever mentioning that a peculiar thing can happen when the hamon line is parallel with the edge – the steel has developed lengthwise stripes that when polished, look under certain light conditions and from certain angles like lengthwise scratches made with low-grit sandpaper. I have ground the blade very thin trying to grind these phantom scratches out, I messed up the grind completely at the end near the ricasso and I had to remove the ricasso and shorten the blade to “save it”.

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Here you can see it finished. It is still a blade suitable for small outdoor/hunting skinner knife. Maybe. I will think about it and maybe try to make a suitable handle for it. But I do not like blades without ricasso, not only for aesthetic reasons but also because that way the tang actually really is way too thin for comfort near the handle. But I have finished polishing it because I needed to find out the best finishing method on it before finishing the only successful blade. Btw. it still has those phantom scratches near the tang where the hamon is close to the cutting edge. They drive me crazy.

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The best polishing process was pretty standard although very laborious. From 320 grit up I have inserted hand-polishing after each belt-grinder step, removing the angled belt-grinder scratches with lengthwise ones. This leads to very smooth and very flat surfaces and crisp lines and ridges. From 2500 grit upwards it was only hand polishing and only lengthwise. Here you can see the result at 5000 grit, which is the phase at which I left the workshop and went indoors. I have tried buffing the failed blade with buffing wheels and commercial buffing compound but this has led to an interesting effect – the hamon went completely invisible although it could be brought out by etching with oak bark for an hour or two. So for this blade, I have forgone the buffing altogether and went to 7000 grit sandpaper with walnut oil (it is runnier than other edible oils, and does not stink like WD40). 7000 grit is the finest abrasive paper that I can easily buy but it still did not bring out the hamon very well. I could just about see it but it was still nearly impossible to make a photograph of. I etched it with oak bark, but I did not like how it looks so I removed the oak patina again with 7000 grit and I tried another buffing method, one that I have used in my rondel dagger project – very fine hematite.

I put some paper towel cuts in a receptacle with finely ground and sieved hematite dust and shook it a bit so some dust gets caught in the paper towels. Then I dusted the paper towels off to remove the coarser particles that still might be there. I smeared some dubbin on the blades and I tried buffing them manually with these hematite-primed paper towels with lengthwise strokes, using the spine of the blade as a guide. And that has resulted in a nice mirror-polished hardened edge and slightly foggy yet still mirror-polished soft spine, making the hamon really pop out. That way it was not only easily visible but I was also finally able to make a picture.

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Hamon is the white line between the darker hardened edge and the lighter soft back.

I am not planning on making very many of these but it is nice to have the knowledge and skill how to do it. I think this blade is deserving of nice fittings so after I etch the logo and serial number, I will start seriously thinking about what kind of handle and sheath to make for it. I am done making blades for a few months however, I still did not dress all of those from last year’s overabladeance and I have eleven kitchen-knife blades in the tumbler now. Unfortunately, I have longer pauses between knife-making days than I like.

Sciencey Thoats About Tangs

Teh almighty YuTub algorithm has recommended this video to me:

Why military gear isn’t always a good idea…

And whilst I do agree with the title and the overall message of the video, I do have some objections to it. It is not an issue that can be distilled down to a universally true video quip.

First the agreements:

Military gear that is issued to grunts en masse needs to be essentially consumable. The grunts will lose it, steal it and/or destroy it with gross abuse and negligence on a regular basis. I read about conscripts in the Austrian army in WWI breaking their bayonets by opening cans. Stealing was a problem even in former Czechoslovakia, with the UTON  even though that was not issued to every grunt but mainly to paratroopers. The knives disappeared regularly as the soldiers reported them “lost during exercise” even though they had to subsequently pay for them and everyone knew they took them home. Those knives are good, but they are not as excellent as some people think they are “military grade” is definitively not always a synonym for “high quality”.

Now the disagreements:

A good bushcraft knife needs not to have a full tang to be reliable. It is more complicated than that – rattail tangs were and are used in even swords and machetes to this very day and they are not useless. Puuko is a survival knife with hundreds of years long tradition for example. The above-mentioned UTON also has rattail tang, and one that does not go all the way through the handle at that, and still it is a knife that can withstand serious abuse. I have put some of my knives with similarly thin tangs through their paces, both full-length and half-length hidden tang and they withstood serious abuse just OK (although I was only using them as knives, see further). Hidden tang alone is not an issue, the overall construction and heat treatment are.

My biggest beef is with the presented “knife gets stuck and you try to wiggle it out”. Sorry, but if your knife gets stuck in something hard right up to the hilt, then you are probably an idiot for using the knife wrong. A knife is not, and should not be used as a pry bar. But let us say one were to use a knife for making firewood splinters from a log by batoning. That is a legitimate use for a bushcraft knife and it can get stuck that way. It happened to me with my working knife and I had to use serious force to get it out. However, if you try to “wiggle it out” by holding it solidly against the ground and pushing at the handle sideways, you are definitively an idiot for trying to remove it in the least effective and most dangerous way imaginable. Simply put, abuse like that shown in the video does not represent even remotely reasonable and appropriate use of a knife, not even a bushcraft knife that should be sturdy.

Another thing I would like to address is the handle material. It is shown to be natural leather rings and apparently, not overly compressed and not glued together or hardened. That is a problem because it is a soft material that can easily be compressed and give way for the tang to bend. A wooden handle – like on European medieval swords and daggers – significantly improves the resistance of the tang against bending. If the rings were glued together and hardened by hot wax or boiling or epoxy, it would improve the durability and resistance of the handle significantly too.

The thickness of the tang and the blade at the weakest point plays a far greater role than the width. The force needed to bend/break a flat profile rises linearly with width but exponentially with thickness. If you double the width of the tang, you double the force to bend/break it. But if you double the thickness of the tang, the force needed to bend/break it can rise approx ten times (I do not know exactly how much, the calculations are complicated and I cannot pretend to understand them). So a knife with a thickness of 3 mm and full width (~15 mm) tang will be about as strong as a knife with a thickness of 4 mm and 6 mm wide hidden tang.

A role also plays the heat treatment of the tang. A fully hardened tang will be stronger and more resistant to bending and will spring back when bent. But when bent beyond the plastic deformation, it will be more prone to permanent damage and/or catastrophic failure when straightened again as shown in the video. Unhardened tang – that is used throughout history for swords from Europe across Asia all the way to Japan I might add – is easier to bend but can subsequently be straightened again.

And lastly – anything will break if used wrongly or excessively abused. A knife is not bad because it cannot be used as a pry bar and a pry bar is not bad because you cannot cut cutlets with it. When I made the custom machete, I tested it by hitting a brick with it – but I still advised the customer not to do that.

Not a Masterpiece Sheathed

I have realized that I did not show this on Affinity, only on Instagram. With all that is going on, I haven’t done any actual work in my workshop for weeks now, but this one was finished months ago. In the end, I have decided to make a simple, unadorned sheath for my Not a Masterpiece knife. I decided to do that because I felt in the end that an overly decorated sheath would needlessly distract from the beautiful woodgrain in the handle. The striker and ferrocerium rod have simple stainless steel handles. The bronze caught patina, which was to be expected. It does require some maintenance to remain shiny.

© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

The full set is for sale in the Knife Shoppe.