Kitchen Knives Set – Part 1: Thoughts and Design

So, this is my next big-ish project, I have decided to make a basic set of kitchen knives – three knives and honing steel. I am not entirely sure about how useful honing steel is with knives from N690, but I have used it on my mother’s knives and it seems to work. It does not appear to hurt. If this small set works out OK, I will make more in the future and perhaps add some specialized knives along the way, but this basic set is meant for casual cooks like myself (and indeed most of my friends), who do not need a special blade for every task and will be probably very content with one knife for 90% of work.

And because this time I am preparing perhaps for more future projects, I have made templates in photoshop, printed them out, and laminated them in transparent foil for future use.

© Charly, all rights reserved. Click for full size.

© Charly, all rights reserved. Click for full size.

The grid is metric, with the smallest scale being 1 mm.

The “meat” knife is a de-facto universal knife, one that I expect to take care of that 90% of work. Medium-sized blade with a round tip, ergonomic handle for firm grip, suitable for slicing protein as well as fine-dicing herbs and vegetables. And for remaining tasks, there is a small peeling knife with a sharp tip for piercing and a relatively straight blade for scratching-peeling, and a big chef knife for tackling difficult cabbage and for those occasions when cutting a lot of big-ish vegetables or huge chunks of whatever is necessary.

The chef knife has holes along the blade edge, which should help with reducing the sticking of whatever is being cut to the blade. It is easier to make than hollow grind or S-grind and it does work too. The handle is ergonomic as well but it is formed with a focus on two main uses of such a big blade. The thicker butt with a hook end prevents the knife from flying out of the hand when chopping, and the thin front with a lot of space for fingers allows for a choked-up grip with the index finger and thumb on the blade for fine slicing and dicing with a rocking motion.

All these designs should work as expected since they are based on knives that I have already made in the past. Of these, the least tested is the chef knife, but I still do not expect any trouble. I won’t follow the designs exactly, they are just approximations and I expect to tune them up a bit during the work. Any thoughts and remarks on the designs are welcome, as well as any suggestions for further additions to the set ( I am thinking about fish-knife and cheese-knife).

However, I will definitively introduce one new and relatively original feature right now. One that I have not seen used by another knifemaker (which does not mean nobody does it, I just did not see it done). As you can see, there are four-five holes for pins in each tang, which might seem a bit excessive and dorky-looking. That is because I need more pins – two will be wooden and two will be metallic. And they will not be visible. That is, the knives are designed as full-width tang, but the pins won’t appear on the outside of the handles. I have tested this idea on one broken blade and it seems to work perfectly OK for a kitchen knife that won’t get hit with a mallet or hammer too much. Or at all, as things should be.

So stay tuned for the following articles with a full write-up of my manufacturing process for this project. I am decently far already given that I only could work three days this week. And because a video was requested, I am filming (almost) all work as well. But I make no promises there – a future video is, at this time, uncertain and might or might not happen.

Whinge, Knives, Whinge

It took me four months to finish the batch of knives that I started in July. I have documented every hour that I have worked on knives, and the results are not good. I have only managed to work about 20 hours a week. Plus some hours that I have not counted, like when I was making new tools, repairing or improving them, etc.

Please allow me to whine a bit about the causes of that.

I either have chronic fatigue or I am a chronic hypochondriac. I am reluctant to go to a physician right now, partly because of the ongoing pandemic and partly because of last year when after several months of pain, I never got a conclusive diagnosis – and the pain only subsided after a course of steroids that I got for a really bad but unrelated virus (possibly flu) that snuck up on me right before Covid hit Europe. So I am not all too optimistic about our GP being able to help me with this.

I have been more or less tired ever since that possible flu. You remember that short walk in the forest in August when I brought home two full shopping bags of ‘shrooms? It took me three days to get over that, and one of those days my legs hurt so much I was barely able to go to the loo. After just several hours of hand-sanding knife handles my back and hands hurt for two days. Etc. etc. ad nauseam. Add to that the necessity to spend time carting my parents to/from doctors, stacking firewood to the cellar, caring for my trees, and the result is that I do a lot less work than I want to.

I have never seen the point of exercise because my body never reacted to it the way other people’s bodies seem to. I did get stronger, but only in relation to my starting point. In high school, when I could exercise under professional supervision free of charge, after months of work I was barely getting just below the level where my schoolmates have started. This year is that – only worse. I am not going exactly downhill, but just barely. Plus my hands started to hurt again two weeks ago. With the sun gone, I have at least looked at what safe dose of Vitamin D I can take in supplements and I am taking that because it seems to help a bit.

Whining over. I hope it gets better. At least it is not getting worse.

The last knives I have finished are four universal kitchen knives from a batch of five blades. One of those blades was not suitably hardened after all- near the tang was about 2 cm soft part. I do not need to toss it, but I do need to try and quench it again with the next project.

These are a bit heavier and thicker (3mm) than my previous knives of this type because they are made from what was left over from the slabs for chef knives. I have also changed the geometry of the handle a bit – instead of a rounded rectangular profile it has a rounded trapezoid profile. They are also about 2-4 mm thinner overall and 5 mm thinner and shorter at the front to better allow a choked-up grip with thumb and index finger on the blade. And they are pointy this time.

One knife has the handle from apricot wood and I have tried tubular pins filled with the same wood. I think it looks good and I will use that idea in the future again.

© Charly, all rights reserved. Click for full size.

© Charly, all rights reserved. Click for full size.

Two knives have the handles from pickled black locust. It is perfidious wood, in the future, I have to be more careful – the scales were probably not fully dried when I ground them to final size and they shrunk on me a tiny bit when I was finishing the surface with resin. So the tang does exceed the handles a tiny bit. That can happen due to a bad shaping job too, but that was not this case – they were perfectly flush originally, I swear. Lesson learned I have to put this wood in the oven for an hour or so before glue-up and grinding the outline. Now I can forget the lesson before finishing the next batch.

© 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.

And last was fitted with padauk wood that I have again got for free with steel shipment. A prime example that there really is no need to use tropical woods, it does not look that much better than the black locust.

© Charly, all rights reserved. Click for full size.

© Charly, all rights reserved. Click for full size.

Knives are a bugger to shoot, I will have to build myself some better lighting system. Either the blade is over-exposed, or the handle is under-exposed, or the colors are off, or all three.

If you are interested in knife making, on Sunday I will start a detailed series about my next knife-making project. Not because I am qualified, but because I want to.

Brass Chisel

I made a new tool. I do not know whether someone else is already using it in a knife-making context, I would not be surprised if it were so. But I never heard anyone talk about it – a small chisel made from brass. I think it is a very good addition to my toolbox, well worth the ten minutes or so that I have spent making it. The inspiration were tools that I was using in my previous job to clean burnt plastic off of various testing devices.

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This may sound like a joke tool, akin to the inflatable dartboard, chocolate kettle, or ceramic rivets, but it is not. But why would anyone make a chisel out of a soft material like brass, that will not hold an edge?

I am glad you asked.

When making knives with the use of epoxy glues and resin, an inevitable problem arises – epoxy stuck to places it should not be stuck to. I am always doing my best to clean any rogue epoxy from the bolster/blade boundary etc before it hardens with a towel soaked in denatured alcohol, but the epoxy tends to flow and bleed over during curing too, plus there is often some contamination on the blade where I fail to spot it in time. That needs to be scraped off, very carefully, without damaging the blade surface.

With my last batch of knives, I have used with great success a square piece of brass, so for the last few pieces, I ground it roughly into a chisel shape and fixed it to a handle. And it works great, exactly as it is supposed to work.

There are several reasons for using brass and not other materials like alluminium or mild steel:

  1. Brass is harder than epoxy, resin or wood, but softer than even unhardened steel. So it can be used to scrape the glue off steel not only on the blade but also on the tang, without damaging the polished surfaces.
  2. Unlike alluminium, Brass does not come with a hard-oxide layer from the shop, neither does it form one over time. It forms a patina, but that patina is not hard enough to scratch steel. Alluminium does scratch steel, partly due to the oxide layer, partly due to galling. Ditto mild steel.
  3. Brass is one of several so-called non-galling alloys, but alluminium is a strongly galling metal. That means that brass does not lead to wear and tear when it slides on a steel surface, whereas alluminium will tend to contaminate, even if not necessarily scratch (if you remove the oxide layer beforehand thoroughly), steel on contact.

And thats all, folks. If you need to scrape glue off of polished surfaces, a brass chisel might be just the tool for you.

 

My Little (Stitching) Pony

Since sewing leather sheaths whilst holding them between one’s knees is a huge pain in all kinds of regions, I have decided to bite the bullet and build myself a small stitching pony. It is very simple, but, as usual, it took me way more time to make than it should have. Here it is for you to admire.

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It is made from reclaimed firewood, so I have spent a lot of time sanding of splinters.  The “H” formed base is for stability, but the two planks are only fixed with one screw each and tightened only with a winged nut. That way I can loosen them, and fold them so the pony can be put out of the way and leaned against a wall when not in use, together with other useless junk I posess, like painter’s easel.

You can also see that I have bought a suitcase for my leatherworking tools. It is already full to the brim and I have barely begun :(.

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Jaws are covered with leather, here it is not fully trimmed yet. You can admire the high precisisn’t with which I am usually assembling these tools.

The right jaw is fixed, the left jaw swivels on a hinge. They are tightened via one long screw with a winged nut. The screw is deliberately very loose, so it cannot be overtightened.

© Charly, all rights reserved. Click for full size.

A piece of wedge-shaped hardwood with slits slides on two screws and under the winged nut, allowing for a sort of easy quick-tighten and -release tool.

It works as it should. Like all tools, it gets some getting used to, but it does make the leather stitching several orders of magnitude easier. I have tested it today and I was definitively a lot quicker. And my back hurt less.

Expect some leatherwork in future too. Hopefully.

Card Weaving

kestrel is graciously sharing her woven artwork with us, and she’s taken the time to teach us about how this type of weaving is done. I’m sure you’ll agree that it’s fascinating.

 

Card weaving (or tablet weaving as it’s also called) is a very ancient craft going back quite a ways. A very wonderful find was the Oseberg ship with two women buried in it. Among the many textiles found, there was also a loom with the warp still attached to the weaving cards. However historians believe card weaving is much older than this 9th century find. Card weaving was a technique people used to create very strong and sturdy as well as ornamental bands. Some of the very ornamental bands seen in religious textiles were created this way. 

 

Although I used to weave quite a lot, for whatever reason, I had never tried card weaving. I’d had to give up weaving (there was no room for my very large loom and I had to sell it) but recently I decided I wanted to weave again. My big loom was gone, but you don’t need much to do card weaving. 

©kestrel, all rights reserved

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Punch and Die (and Fun)

I do not have the genius of Leonard da Quirm, but I do share one trait with him – I get easily distracted and sometimes spend several days trying to shave off a few minutes of some task or save a few bucks. Sometimes the effort definitively pays off – as in the case of my belt grinder or my forge burner, sometimes it is a success but with a question mark whether it was worth it – like the unbender (now I know it was worth it, btw, I have used it several times already and it is time-saver), and sometimes it is a bit of a flop, as when building a vacuum pump. If I had a definitive fail, I do not remember it, and so I allowed myself to get distracted again these last two days.

I have a problem with making metal bolsters, handguards, end-caps, and pommels. As in, it is difficult to get material thick enough to make them pretty, and even if it were not difficult, the result would be overtly heavy and thus would put the knife balance totally out of whack. The proper way to make bolsters and end caps is to make them hollow, and there are techniques for that. One of them is forging – as I did in the rondel dagger project. But that is labor-intensive, has poor reproducibility, and requires special tools anyway. Or I could buy prefabricates and adjust my design(s) to fit what is already on the market. Screw that!

So I have decided to make some new tools, and test them. The inspiration was a technique of minting coins before the invention of fly screw-press, which I have seen as a child in some black and white movie which has shown the making of Prague groschen at Kutná Hora. I remember nothing else about the movie except the part where they strike a punch on a silver blank with a hammer and thus make a coin. I think there was some drama and history in there too…

First I have made a die out of 5 mm high-carbon tooling steel. It consists simply of two holes – one for the bolster and one for the end-cap  (I have chosen my small hunting knife as a pilot project because I think the design will be improved a lot by it and because I do plan to make more of these knives in the future). Second I have ground two punches out of square stock of high carbon tooling steel that I have scrounged at my previous job. Grinding the forms with angle grinder was not easy, but it was not insurmountably difficult either. I had actually a lot more trouble with welding onto it the 15 mm round stock for holding the punch in place and for striking – my welding sucks, bigly. And because at least the first strike needs to be real mighty, I have built a small wooden stand to hold the punch in place for that.

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With the assembly on the concrete floor, as you see it in the photo, I have given it a mighty whack with my puny Mjolnir. And I rejoiced because it was a success. To protect the floor from damage I have put it on a steel plate for subsequent tries and I went and punched four sets for the four blades that I have currently in making, three out of brass and one out of pakfong.

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The pakfong was a bit thicker than the brass so it gave me some grief, thus the surface is not so smooth on the end-cap – I had to whack it several times and it wandered off the die and I struck it without noticing it. But that should not be a problem, there is enough material in there to polish these dents out.

It took me mere minutes to punch all these, and after a long time, I was really, really happy for a bit. There are a few details to iron out – like making a better stand for the punch, making it so I can put it safely on my anvil, figuring out the ideal amount of overhang and so forth – but it functions as it is and it is a massive saving in time already. Whether the knives will really look better remains to be seen, but I am confident they will. Further, this opens a lot of new possibilities for knife designs for me.

I Probably Won’t Do This Again…

After a month of work, I am finally at a phase where I have something to show for it. The kitchen knives are in the tumbler for the second day now, tomorrow I shall check if they are ready or not. But it need not hurry, I have enough to work with – eight fully polished blades.

© Charly, all rights reserved. Click for full size.

Today I have etched the logos and numbers on these because it is easier to do on a naked blade than on a finished knife. Now I can finally work on finishing at least some of these into final products while the kitchen knives tumble.

Working in bulk does save significant time and even resources, but 18 blades in one go was a bit too much. I am going to reduce the batches to 8-12 in size. That way it should keep its savings, but the polishing hell will not be that long. Polishing is extremely onerous and unrewarding work because one keeps doing the same thing day after day, working through the row of belts with very slow progress. With one knife, it is one-two days of a boring slog. With eighteen knives, it was three weeks – and one of them got broke and nine only to 120 grit before going into the tumbler, if not for that, it would be even longer.

These are not perfect, some of them have serious problems regarding symmetry, although only in one case it is visible with the naked eye. On all of them is it visible with calipers. I am starting to doubt that I will ever do a good job, but there are some signs of progress. One of those signs has, unfortunately, a bit of a negative consequence on these blades, all 17 of them – they are a bit thicker than I expected (a few tenths of a mm). That is because I have gotten a bit better at working on the belt grinder and thus I did not grind away as much material as I used to by having to correct mistakes

Mind you, they all will cut perfectly fine even so, and some of them already do despite not being sharpened yet. But a thinner blade will always cut better. On the other hand, these should be extremely sturdy and should be able to withstand even some serious abuse, and that is a plus for a hunting knife. We will see if there will be people willing to pay for these without bashing me over the head afterward.

Now to think about how to dress-up these blades and the accompanying sheaths. I think I have quite a few more weeks of work ahead of me, but now it should be creative work, and therefore much more fun.

Well, It Sucks, But…

My goal in mcgyvering a vacuum pump was to remain under 100,-€ – which I did – and get better results than I have achieved with my shop-vac setup – which I did too. Still, I do not know whether to be disappointed or satisfied.

I wanted to utilize things that I already have, which includes several water pumps that are used to water bonsai trees and vegetable beds in summer and pumping water out of the cellar in the winter and some spare piping from house renovations. So I had to buy only the things for making the vacuum pump itself – in combination with a water pump, the best option seemed to be something based on the venturi principle.

So I went and bought these parts:

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The parts were connected to each other more or less in the order as they are laid out on the picture. The black plastic hose connector was fitted into the brass one to lower its inner diameter. The brass hose connector right next to the right side of the chrome T junction is the inlet nozzle – I have glued an old tip from a silicone sealant tube (not depicted) in it to get the position and size of the nozzle correct. Into the upper brass hose connector was glued the white plastic 6 mm hose connector for the air suction.

So water comes in the T-junction from the right, gets squeezed through a nozzle which sprays into a slightly bigger opening in the outlet left, behind which is again a big pipe. The spray drags with it the air surrounding the nozzle and that way achieves suction through the top of the T-junction.

I am not able to write-up complete how-to, but this is the final product up and running in a vat of water.

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The bubbles show it is working. When I connected the suction tube directly to a new vacuum manometer, I got a suction of whopping 0,6 bar, which did really impress me. Unfortunately, I do not get anywhere near that when I connect everything to the jar. After a few minutes, it stabilizes at this.

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0.22-0.25 bar is still a bit more than what the shop-vac could achieve (which was 0.2). So it is usable and it is a definitive improvement because unlike the shop-vac it can run non-stop with zero risks of overheating anything, and it also makes nearly no noise, so a win there too. But when it achieves this, it still bubbles, so it still draws air. And when I close both ball-valves on the lid (one ball-valve is for pressure release, one for the suction), I start losing pressure in the jar really quickly. That tells me that the jar is not properly sealed and this here is not the maximum this setup can achieve, but an equilibrium between the pump and the improper sealing.

I had to make a new lid from five layers of plywood for this, with two ball-valves and the manometer, so there was a lot of potential for failure. But I did use water/airtight plastic sealant for everything and I went over all connections once more, yet I still cannot identify the leak(s). If it was a pressurized container, I might find the leaks with help of soapy water looking for bubbles, but I do not know how to check vacuum tightness.

So this is where I am now and this is where I leave this be for a few days at least. It has occupied me for three days already, time to go back to making knives.

This Was Not Supposed to Happen – Quality Control and Salvage

The last batch of knives did come out of quench straight-ish, but the tangs were a bit crooked on some blades. No biggie, he said. Those are not hardened, he said. Will be corrected in a jiffy, he said. And then he broke a blade in half because he was an idiot.

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Still, I do not think the blade should have broken like this, it is tempered and I did not exert too much force. But maybe I did. Unfortunately, the tangs did partially harden on some blades, which is a major headache because I have to heat them up significantly in order to straighten them now. As my hardening experiment has shown, with this steel all that is supposed to be soft must not be heated above the 1050°C at any point in the process. Which, admittedly, I did not know for sure at the time of quenching these blades.

So what to do with this? I have spent nearly eighteen years being involved in quality control in one way or another, and I must say it is a great way to make enemies at all levels. Customers hate you for the crap your colleagues have produced, your colleagues hate you because you point out to them that they have produced crap and the management hates you because you cost them money (both when things go well as well when things go awry) without generating any profit whatsoever. And everybody expects you to tell them how they should solve the problems you found – despite that part being actually their job, with yours only being the pointing out of the problems.

Now I am my own quality control so at least now it really is my job to solve the occurring problems. For example, apart from this broken blade, one blade seemed to be softer near the tang. I have decided to continue work on it anyway and I established later on that it was only slight decarburization and the steel is sufficiently hard deeper under the surface. So far so good. But is there anything that can be done with this broken blade? Well, I surmised that yes, and I have decided to try some new things whilst doing it.

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The broken-off tip was long enough for me to grind small (9 cm) blade out of it with enough steel left for a short hidden tang. I have simply cut it with an angle grinder to the desired shape and then thinned, formed, and polished the blade on the belt grinder. The notches on the tang are there to allow for the epoxy to grab onto.

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I have made the handle from a piece of apple-root from a dead tree given to me by my neighbor. The bolster is from a coconut shell. The wood was partially rotten, so I have decided to try my hand at a new thing – stabilizing the wood with epoxy resin. And to utilize my resources meaningfully on this experiment, I went and cut some more wood, even more rotten, from a willow trunk that lay in the garden for years. It is full of holes, wood dust (AKA grub poop), fungal discolorations and it is extremely porous, it even crumbles in parts.

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I do not have a compressor or a proper vacuum pump, and I was unwilling to spend any money on them at this stage, the resin itself was pricey enough. So I tried my best with things I already have at hand and I came up with this.

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These are two huge thick-walled glass jars for canned fruit, with removable snap-on covers. They should withstand vacuum reasonably well. I have replaced the glass-covers with ones made from particleboard, with the joint and snap-on latch made from fencing wire around some screws.

The jar on the left has a ball-valve in the middle, with 6 mm tubing attached to it. The jar on the right has two 35 mm holes and one 6 mm hole in the middle. To the middle hole is attached the thin tube from the left jar, shop-vac is connected to one of the big holes and a swiveling cover is over the second hole.

I have given the knife with handle suspended in resin in the left jar. When the shop-vac was running with the ball-valve open and the big hole covered, it sucked air reasonably well out of both jars. But shop-vac cannot run with blocked intake for too long, thus the ball valve and the covered hole – after half a minute I could close the valve (keeping the low pressure for a few moments more), opened the big hole and left the shop-vac cool with flowing air for a minute or two. Then I have repeated this process as many times as it took until no bubbles were rising from the resin.

To get an estimate, I weighed the knife before and after, and it has gained about 20 g of weight (65 to 85 g), which seems reasonable, the wood was not extremely rotten, only slightly so. I have also weighed one of the willow pieces and the weight gain there was much more extreme – from ca 20g to 120 g. I have not cut the wood to see how deep the resin has penetrated, but it definitively penetrated deep enough to work on pre-formed handles, even if not on squared wood.

So this has confirmed that I can do this with the equipment I already have and that investing in some better equipment is thus warranted. Still, I am hesitant about spending 100,-€ or more on a vacuum pump, I hope I can mc-gyver something a lot cheaper. On Wednesday I am going shopping for parts. If I succeed, I will let you know.

Oh, and here is the finished knife.

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Overall length 20 cm, blade length 9 cm at the spine, 3,5 cm wide, satin finish (trizact A100). The handle was polished to 1200 grit and buffed with beeswax.

I have given the knife to my neighbor because she has refused payment for the dead tree and I think she should get something for such beautiful wood. She did not object this time and I hope it will serve her well.

Different Hardening Methods for N690 – Experiment

When I was hardening the blades two days ago, I have tossed in there six cut-offs as well and I have used different methods to quench them. After that I had still one piece left so I have heated that up to the 1050 °C and let it cool in the forge. Then I performed some tests and the results are very interesting.

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These are the samples and methods used (marked by the number of notches on the edge):

0 – left to cool in the forge
1 – untreated
2 – left to cool in the air
3 – quenched between Al plates only
4 – oil
5 – water
6 – AL plates + water + Freezer fro 2 hours

None of the samples were subsequently tempered, so they should be at peak hardness.

With the sample size just 1 piece per method I cannot of course perform too many tests. The idea was to polish the samples – which I did. And already during the polishing, I have noticed that all samples seem to be hardened, except #1.

The next step was supposed to be to etch the surface and look at the structure under a microscope. Well, that did not work at all, and the reasons are a mystery to me. Just as it happened with the knives last time, it happened again here – the electrochemical method worked on some samples perfectly, but completely failed on others. I was unable to solve the problem. Another thing was that my microscope apparently does not have big enough magnification to see a difference between the original steel and the quenched one. I could re-build it and improve it about ten times, but I am still not sure if that would be enough and I do not want to get sidetracked to that now, it would be probably more than one day of work and I have already spent two days having fun instead of working.

So I did what I could with samples of this geometry. First trying to scratch them with my hardness measuring gages .

The sample # 1 could be scratched by the lowest 38 HRC gage, which was to be expected.

All samples except # 1 could not be scratched by the 62 HRC gage, so they are at hardness 62 HRC or more. Which is something I did not expect, especially not of # 0, which was left to cool in the forge – and that took definitively several hours. I was expecting this sample to be harder than the new steel, but not hard enough for a knife – but it evidently is more than enough hard for a knife, hardness 62 is in fact quite excessive.

Secondly, I have tried scratching the samples against each other, and the results became even more interesting. All samples could scratch # 1, as expected. But none could scratch #4 and #4 did scratch all, whilst the remaining five could not scratch each other, so they are all of the same hardness.

Thirdly I have put the sharpest angle of the triangle approx 10 mm into a vise and break it off. #1 has bent easily, as expected, all others have snapped off.

What can I deduce from this? Several things.

  1. Sample #4 was hardened with the method recommended by the manufacturer and did come out as the hardest of them all, possibly somewhere around 63-65 HRC, which is as hard as steel can get. It could be a fluke (remember – sample size 1), but it could be the reason why this method of hardening is recommended. It is not surprising.
  2. From a practical standpoint, the method of quenching seems to be quite inconsequential nevertheless. The oil quenched sample would be brought down a few points in heat treatment anyway and for practical purposes, anything above 51 HRC will be usable with just a bit more edge maintenance, anything above 55 HRC will have reasonable edge retention and above 57 HRC we are in the realm of no reason to complain whatsoever. In this light, the difference between the recommended oil quench and all the other methods seems to be so small as to be trivial and only interesting from a nerd standpoint.
  3. The freezer step does not seem to have done anything for this one piece, but this does not rule it out from use on larger pieces that could not be so thoroughly and consistently heated in my setup. Did not do any harm either.
  4. Although tempering was not tested, this experiment does indicate that it is just not possible to really destroy the edge on this steel by overheating it during grinding/polishing since even cooling it from the 1050°C to room temperature over the course of several hours hardened it very nearly as well as the recommended oil quenching. I will not test tempering temperatures with regard to this specifically since there are graphs to be found on the internet that show already that the hardness of N690 does not get below 56 HRC up to 900°C.
  5. If I want to peen the end of the tang, or do any other work with it, I must be careful to not heat it above the critical temperature at any point in the process. Because once heated above certain threshold, this steel hardens, I cannot prevent it and I probably cannot anneal it again.

It would be interesting to see what is the exact influence on toughness/strength once tempered. I could not find it, so I will have to test it myself. But for that, I will need another sample geometry. So maybe next time.

All in all, the N690 seems to be pretty remarkable steel. It does not have the label (and price tag, otherwise I could not use it) of “super steel”, but it is no wimp either and apparently is not very fussy about the heat treatment, apart from the requirement to heat it above 1050°C.

Quenching Jig

I hope you are not bored with my writing about knife making yet. It is not that I do not care about other things, but knife making is where most of my focus is right now. And this week I had barely the strength to do anything else at all.

I have started a new batch of blades, 18 pieces altogether – 4 small hunting knives, 4 badger knives, 5 chef knives (prototyping new design), and 5 universal kitchen knives. So this whole week I was drilling, cutting, and grinding steel every day. I have progressed reasonably fast, despite being also slow. Because I simply cannot handle more than 6 hours net a day at the grinder, and I have to make a substantial pause every two hours. My hands are doing reasonably OK and I have been pain-free for a few months by now (despite never having a diagnosis about what was wrong last year), but even so, the vibrations are a strain on the fingers. And after two hours not only the glasses start getting foggy – the mind does so as well and thus the risk of injury increases.

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Today was a big finale of that busy week and all knives went into quench and tempering. This time I have decided to use quenching foil on all blades, despite bad experience on some blades the last time. I have decided to do so because the protective coating that I have concocted did work well but also was a real pain in the ass to remove afterward. And that did cost me a lot of time and I destroyed two belts before I figured it out. But I have tried plate quench with on this steel with moderate success), and I have hoped, really, really hoped, that doing plate quench on newly ground and straight blanks will lead to straight blades without having to scrub off a hard crust.

And following the maxim of Scrooge McDuck “Work smarter, not harder”, I have done my best to make the plate quench easy and reliable – I have built myself a jig. The construction is very simple and it did only take me a few hours.  I have used the locking pliers and aluminum plates from last time, but I have connected it all into one piece that can be easily used in one hand. So instead of one hinge in the middle of the plates, I have added two hinges on the sides. Then I have drilled holes in the fixed jaw of the pliers (and re-ground it a bit) so I can screw one of the plates to it with two M4 screws. The movable jaw is not fixed to the second plate, but it does fit into a groove cut in it and it was also re-ground for a better fit at the angle where most blades will be gripped.

© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

The idea was that I will hold this jig in my left hand, with my right hand I pull a blade out of the forge, insert it between the plates (still in the foil), lock the pliers and dunk the whole thing into a bucket of water. And it worked well! None of the knives came out of the quench with a perm or as a banana-imitation, none have cracked either, at least I did not notice it yet. All but one blade quenched properly (and that one I have re-quenched OK the second time) with hardness above 55 HRC, most even over 62.

© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

Hardening all these blades took me only 15-16 minutes per blade, so even with all that foil wrapping, I was well within a reasonable time. There was only one small problem towards the end – my new burner worked really well and I have reached and held 1.050-1.080°C without problem with four blades in the forge, but after a few hours, it started to struggle. I thought at first that I am running out of propane, but that was not the case. As it turns out, the propane bottle got too cold (just 10°C) after that long continuous decompression, and the gas was evaporating less. I am not sure yet how to solve that problem for the future.

Now the blades are in the second tempering cycle (each cycle two hours at circa 180°C) and they did not seem to develop any bends or curls in the oven either. So far, so good, let us hope it stays that way since I am going to try some new techniques with this project again.

 

Project Badgermascus – Part 12 – The Final Badgering

The knife is finished, although not sharpened, and here are the final pictures. I am going to make more knives of this design because I think it is a good knife for forest walks, especially mushroom hunts. And I am naming the design “Badger”.

© Charly, all rights reserved. Click for full size.

The overall length in the sheath is 205 mm. The sheath is from vegetable-tanned leather, carved (badger paw print, frame edge), stamped (leather weave, edge trimmings) and dyed, thoroughly infused with beeswax, oiled with olive oil on the inside and buffed with dubbin outside.

© Charly, all rights reserved. Click for full size.

The sheath has a metal belt clip. This allows the knife to be worn not only on the belt but also clipped onto/into the pocket or boot. The pommel sticks out of the sheath far enough for a comfortable grip with index finger and thumb when pulling the knife out. The knife clicks into the hardened leather firmly enough to not fall out of it with its own weight, but can still be pulled out comfortably.

Stitching is made with a two-needle saddle stitch with artificial sinew. The end knots are melted together and hidden.

© Charly, all rights reserved. Click for full size.

Brass fittings have a black patina with clear brass badger paw-prints over the pins. Scales are from naturally aged cow bone, slightly larger than the tang and wider than the brass fittings. The right scale is adorned with scrimshaw engraving of a badger head – this is a new skill that I had to learn but kept secret since I had no guarantee it will work out. I think it did work out OK. I may add a bit more pigment once this hardens, but maybe not, I like it the way it is. The badger is colored black with coal dust, the patterns, and the frame, with ochre (rust).

© Charly, all rights reserved. Click for full size.

Handle length 100 mm, drop-point style blade 87 mm length, 3 mm thick at the ricasso. Point of balance just behind the first two pins in the handle scales, also between the index finger and middle finger. It feels a bit handle-heavy but nimble. The steel has dark-grey patina from an oak bark extract.

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The left side of the handle is unadorned except a few scratch grids around the pins. The left side of the blade has significantly different steel pattern due to how the san-mai was hammered at the Badger Forge.

© Charly, all rights reserved. Click for full size.

Back of the tang has a row-of-crumpled-leaves fileworks, the belly has a simple triangle pattern.

Overall, I am satisfied with my work here. There are things that I am critical of, there are things that I definitively might have done better – it is not a masterpiece yet, but I think I am getting there. I have learned a lot again and many of the things that took me several days this time should be just a day or even less the next time (the leatherwork for example).

Project Badgermascus – Part 11 – Stitch This!

The day before yesterday I had to make the leatherwork all anew, because I spilled some glue on the forefront of the sheath and it has proven to be irreparable damage, it completely ruined the leather. So I have made a new piece, this being, therefore, the fifth attempt. And when I was at it, I have improved my tools to make a better job.

© Charly, all rights reserved. Click for full size.

I have re-filed the basket-weave stamp to make it crisper and bite more deeply. That has allowed me to better feel the position of the stamp when moving it along the edge and positioning it in the next point on the pattern grid. I have also used a straight edge and I scribbled a faint line for each row before stamping along it.

To get the dye better into the tips of the claw marks I have needed a very fine brush, so I had to make one. And since I do not have any weasel hair, I have used a few strands from a goose feather. It has worked perfectly.

This is my first attempt at a sheath with a metal belt clip. I have first riveted the belt clip to a piece of leather and then glued/stitched that piece of leather onto the sheath. Only then have I glued and stitched the rest of the sheath together. This avoids any contact between the knife and the metal of the clip and secures the clip very firmly in place.

For making the holes I have used 2 mm drill bit in my drill press since I found that to be by far the most convenient method. For stitching, I have used saddle stitch, and I hope I have used it correctly. I had trouble finding a comprehensive tutorial on how it is done.

BTW, holding the work between my knees is really uncomfortable, I will have to make myself a proper tool for this. So many tools that I still need… Anyway, back to the stitching.

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Saddle stitching is made with two needles and here you can see how I do it. First I am pulling the right needle through the hole all the way to the end (top). Then I put the left needle in the hole whilst wrapping the thread from the right needle around it in a loop (middle). When carefully pulling the left needle through the hole (taking care to not stitch through the thread already inside) it creates a knot that gets tightened inside the hole when both threads are pulled to the limit (low). This kind of stitching is very strong and it does not unravel even when the thread is worn/cut/breaks in one spot.

© Charly, all rights reserved. Click for full size.

The almost last step in making the sheath was wet forming. I have put the whole sheath into lukewarm water and let it soak in there as long as bubbles were coming out of it. When it was all soft and pliable, I have wrapped the knife in food wrapping foil, put it in the sheath and formed it around it simply by finger pressure until it had a shape that I wanted. I have used clamps too, but only for a few minutes around the edge, I did not leave in clamps until it was fully dried, it was not necessary. In fact, to let it dry I have simply hung it on a window handle as you can see in the picture.

Today was the final day of this project. I did make some minor mistakes when making the sheath, so I had to glue a little wedge of leather inside with five-minute epoxy, but that is simply a lesson learned for the future and not something to worry about aesthetically or functionally. I must simply remember next time to make the blade portion shorter (and slimmer) and the handle portion longer. But it was working just fine, the knife holds in it strong enough to not fall out, but it can still be pulled out with just two fingers by the pommel. So I have infused it with beeswax and dubbin*, so it is hard almost like plastic, but still with a pleasantly natural and organic feel to it. That made it a lot darker and I applied some black patina too to make it look a bit aged, to fit the knife.

So, after a month of procrastination interspersed with bouts of hectic work and attempts at learning new skills, at least one piece of steel out of three has made it into a final product. I am going to try and make some nice pictures and tomorrow I will post them.

  • The dubbin that I have made almost two years ago and which I stored at room temperature the whole time did not go rancid or moldy or bad in any noticeable way, and the leather on the products I used it on did not degrade in that time either.