Making Kitchen Knives – Part 15 – Tumble Time!

I was on and off working on this project in February. I have filled my tumbler with very fine sand (one that is used to fill in the spaces between concrete pavement bricks) and walnut shells and I polished the blades with increasing grit belts, then I stuck them into the tumbler for a day or two until I thought I can get the scratches all out after 12 hours evaluation.

It was still more time consuming than I would like to, mostly because many blades were ever so slightly bent, a problem that I really hope to solve with plate quenching in the future. On a bent blade, the concave part gets polished quickly, but the convex is a pain in the ass.

So I progressed slowly and at 150 grit I stopped, thinking that the fine sand can take the scratches out in time. It did, however, it took over a week in the tumbler, so next time I will go probably somewhere around 240 or perhaps even 320 grit before going to the tumbler. The blades did have a nice sand-blasted like look to them, so they were de-facto good to go functionally, but I thought they might be still improved by putting them in the tumbler some more. So I did, into a mixture of jeweler’s rouge (Fe2O3 powder) and crushed walnut shells. And I was right, they have now a very nice satin finish that I think is perfect for kitchen knives.

A mirror polish can be a bit sticky, so for kitchen knives, it is not the best option. I will see how sticky this polish is in a bit, but it looks good. Unfortunately, pictures do not give it justice, I won’t even try.

Time-wise, I have spent about 110 minutes per blade with this polishing process to achieve this result. So an improvement of 58%, but with a different look in the end.

Here is the blade line-up from worst to best:

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The first left blade has a slight crack on the edge. Not from the tumbler – that would be possible, but it did not happen – but from the one time where I forgot that the blades are drying on a rug and I took it to wipe my hands. All twelve fell to the floor and this one cracked near the edge and will have to be re-ground to a different shape – I do not know which yet. It was also one of the curly ones and that might have played a role too.

The second blade from the left would be perfectly OK if I did not mess it up. There is a place about 1/3 from the tip where I run accidentally not over the edge of the platen but over the corner. I nearly ground through the blade there, making an unseemly spot where it is paper-thin. I will probably prototype this to a much smaller blade, like a peeling knife. A lesson for the future.

The third and fourth are the remaining two of the curly-wavy blades. One will be re-shaped into a fish gutting/filleting knife for my uncle, one will remain an all-purpose kitchen knife, only with a slightly narrower blade than intended. It will be more similar to the knife I gave my mom and my brother.

The next five blades have a slight bend to the right side that I was unable to straighten out. They will be functional, but cutting straight will be a bit difficult, so not ideal for bigger things like cabbage, but still OK for carrots, leeks and onions, and sausages.

The last three are what I intended to achieve. 25% success rate – a disaster. But I am still learning, so hopefully next batch comes out better.

 

A Knife for my Brother

I did not manage to finish a knife for my brother’s 50 birthday last year, for I nearly hacked off my finger with a hatchet. So I am rectifying the issue this year.

This is the blade that was hardened when I was working on the rondel dagger. It is not a perfect blade, aesthetic-vise. I messed up the polish a few times and I had to eventually stop trying to correct it otherwise the knife would turn into a small razor. It is a good universal kitchen knife, very good cutter, I am just not happy with the surface finish. But it is either this or nothing and this year I want to give my brother a knife I know he wants. He is going to appreciate it even with the flaws.

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

I tried to make up for the flaws with the handle, so I have used a piece of partially rotten lilac branch that I have harvested last fall. It is just stunningly beautiful wood and this is probably the prettiest knife handle I have made so far. The wood is rock-hard with tiny pores (lilac is one of those woods that can take 1000 grit polish without dirtying) and would probably hold up well even without the boat lacquer coating. But it was partially rotten, so the outlying regions were not only discolored, but also softer, so I soaked it in boat lacquer to stabilize it. With the coating, it should be near indestructible.

The lilac-colored heartwood will probably age into dark brown over the years, but it might take a really long time since the branch was already several years dead when I cut it off.

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

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

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

A Hunting Knife – Auction for FTB Legal Defense Fund

You can still donate, the damage Richard Carrier has done with his petulance is not undone yet. I cannot afford to donate any meaningful cash right now since I have no income. But I can afford to donate a bit of time. So I am giving this knife in exchange for the highest donation. Details see further.

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

Technically it is a hunting & fishing knife since my first customer specifically requested it for angling, but you need not be a hunter for having a use for it. I am regularly using a knife like this when collecting mushrooms or just walking in the forest when it might come handy. It would also be useful as an all-purpose knife for camping. The false edge is sharp, but not cutting sharp. The blade is signed and numbered “2” in Glagolitic script.

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

I made a simple leather scabbard, this time symmetrical so the knife can be conveniently fastened on either left or right side since the preference of its future owner is unknown.

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

The handguard/bolster has a few dark spots. These are inclusions in the used material (see further).

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

The endcap is fastened over an ornate stainless steel washer into which is the end of the tang peened.

If you are interested, write your bid in comments or per e-mail to affinity (note, I might not be able to post your e-mailed bids in the comments next two days, there is a huge storm coming our way and I might experience blackout).

If you bid from outside of the European Single Market, please make sure that you are allowed to import such things and be prepared to pay for any import/customs fees, duties or other taxes as may be relevant in your region/country/state. I will pay for the postage.

The knife will be sent to you after submitting proof of the promised donation. If the highest bidder reneges on their promise, it will go to the next one in line. The start is 10$ (the cost of materials), the sky is the limit.

The auction will run for two weeks until February 23. 2019 and this post will be pinned to the top of the page until then.

More info below the fold.

[Read more…]

Making Kitchen Knives – Part 14 – Straightening Curls

Last time I was working on this project, I had some very bad results from quench. This week I have finally managed to test one idea of correcting the problem and maybe prevent it from ever happening again in the future. And I am glad to say that it did work. Not perfectly, but the new process is definitively worth to use instead of the old one.

Here is first the comparison of the three worst blades before and after. As you can see, there are still some curls in there, but they are noticeably less pronounced and one blade is almost completely straight. They will still come smaller than intended out of the polishing process, I will still have to remove some material from the edge until I get to the straight part, but I estimate it to be about 1/2-1/3 of what it was before. On the worst blade, the curls went about 10-15 mm from the edge towards the spine, whilst now it is about 3-5 mm. That is a significant improvement, and I think that had the blades been quenched from a straight form, they would never have curled in the first place.

As I alluded to previously, the process that I wanted to use for correcting the blades is called plate-quench. It cannot be used for simple carbon steels. Only so-called deep hardening steels can be thus quenched, and N690 is such steel, according to some articles I found on the internet. Nevertheless, it is better to not have the internet at all than to believe everything you can read on it – the manufacturer recommends oil quenching.

So I have tested the process first on one blade that I accidentally broke when correcting an ever so slight banana-bend. When the broken blade hardened properly – which I have confirmed not only by scratching with my gauges, but also by breaking off a tiny piece of it – I went on with the curly ones. On one of these, I confirmed the hardening too by breaking off a tiny piece of the tip, with the remaining two I was satisfied with the scratch test only.

For the plate-quench are used two flat plates from either alluminium or copper. These two metals have very high heat conductivity and thus can cool down some steels fast enough for them to turn into martensite. Luckily I got quite a few nice slabs of alluminium on hand. And because I wanted to make the process a bit faster (despite not making time-measurements this time), I have made a simple prototype quench-jig.

It consists of two identical pieces of alluminium with a small hinge, and locking pliers. The hot blade went out of the forge between the plates with the edge towards the hinge. Then it was firmly clamped by the pliers to hold it straight. When it stopped glowing near the tang – indicating a temperature well bellow 600 °C – I dunked the whole thing in a bucket of cold water just to be sure. And just as last time, because it costs nothing, I have put the blades into a freezer straightway for a few hours before tempering them. None of the three blades cracked.

Not an actual quench, staged photo – sometimes I miss having third hand greatly. © Charly, all rights reserved. Click for full

It worked reasonably well and quick. I will definitively improve it and build a proper jig when the weather is nicer and I do not freeze my nuts off in my workshop. I will add a more stable hinge(s) and maybe even screw one of the plates to the pliers.

Another advantage of this process is no burnt oil gunk on the blade, no flames and no stinking oil fumes.

Poor Man’s Belt Grinder – Mark 3

My belt grinder has served me well, and for a hobbyist, it would be probably good enough. But since I am inching my way towards knife making not being just a hobby, I needed some significant improvement on it. And an opportunity luckily arose.

One of the good things about my previous employer was that there was an internal process for employees to get obsolete materials and equipment either cheaply or completely cost-free. I have used this opportunity quite often and got a lot out of it – I am well stocked in graphite and alluminium, I got precise analytic scales completely for free, and one of the last things I have managed to get was a variable frequency drive.

I was not able to haggle this one down to zero, it was a bit pricey even though used, and I also had to pay a bit to a professional electrician to connect it for me. I could get a new one for a bit cheaper if I capped it at the 1,5 kW that my motor has (this one can handle 5,5 kW) and took the cheapest one there is, but it was still a good deal even if it was not exactly a bargain.

And it works like a charm, even when I am not able to use anything more than the manual mode yet. Finally, I have the ability to change the speed of the motor as I need it, I can even reverse the rotation. I have tested it already and it is exactly what I hoped for-  finally I can work wood without burning it and I can sharpen tools and have a bit more time before the edge starts overheating.

I hope it continues to work well – I have great plans for the future. Multiple grinding wheels, a polishing attachment and, maybe, even a lathe attachment. The belt grinder shall not rest!

My first Commission – Part 10 – Starting the Sheath

First I must say that my writing will continue to be very, very sparse for about two weeks (again). I think I finally found out what is wrong with my hands. I had a pain in my metacarpal bones and joints ever since I worked a bit too much in a too short time. Sometimes it almost went away, but then it came back with a vengeance whenever I did some work. The orthopedist has made an x-ray and has ruled out arthritis, and I have not visited a doctor since because it got multiple times better to the point I thought I am OK.

I think I know what is wrong – I think I have started to develop stress fractures. Those are not visible on x-ray until they develop in a full-blown fracture.

And whenever they almost healed, I did something to aggravate them again. There is only one cure for that – several weeks of no-strain. And due to the nature of the injury, that also means no-excessive writing on PC, no grinding knives, no cutting or splitting wood, etc. I have tried consistently this last week to do that and today and yesterday I was again almost pain-free. But I think I need to keep it up for at least two more weeks for the bones to recover completely. If that does not help, then I am going to the doctor again to try and find out what the hell it is.

What I could safely do was to coat the knife handle with boat lacquer. And this weekend I started, carefully, working on the sheath.

First I have cut the two slabs for the sides and then two strips for the belly and the back. To get the strips to conform with the blade geometry I did not cut them curved but I formed them from a wet leather strip. When it dries, it holds form nicely and it saves material.

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

The next step was to glue everything together with wood glue. In case you ever do this, beware. Wood glue on dry tanned leather works really, really fast. Not superglue-fast, but fast enough for you to want to be sure that when you press the parts together, they are in the correct position straight away. Wetting the leather beforehand might give me some time, but I did not want to do that because the clamps would leave impressions in it.

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

I have let it dry for a few minutes, then I took off the clamps and I inscribed a line with a knife-tip for stitching and cut the opening for a belt. In case you are wondering why there are round punched holes at the end of the cuts – those are there to avoid stress concentration and thus to prevent the leather from tearing further when used.

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

Now I leave it to completely dry until tomorrow evening. In the meantime, I am trying to figure out a way for making my maker’s mark on the leather. I could cut it, but that seems a bit inelegant.

My first Commission – Part 9 – Fitting, Signing, Assembling

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

The HDD magnet proved to be very useful when polishing the bolster/handguard. It proved to be strong enough to hold it when grinding on the belt grinder, but also when polishing with the angle grinder. I did not intend to use the magnet in this way, but now I will because it has proven itself to be extremely useful for holding these tiny things steady. Shame that other metals that I am going to use for these things – aluminium and brass – are not magnetic.

The next thing I have done after the bolster was fitted was to make the handle. That did not go too well as you may remember. The first piece of wood had cracks, on the second piece of wood I messed up the drilling and the third time was the charm. It is a nice piece of wood and looks great when the grip is fully shaped, but I do wish that I have managed to get the grain alignment a bit better. But grain alignment is not something that anyone else fusses about that much, so I should not fuss about it either. Here you can see the grip roughly cut and shaped on the belt sander.

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

After the grip was shaped, I have also glued to ti the end cap/pommel thingie and I have decided to sign the blade before assembly.  For that, I have tried a new thing, which unfortunately completely and utterly failed.

I have bought photosensitive lack that is used for etching PCB boards. The idea is, you spray-paint your metal surface, you print your design, you put your design on the surface and use UV light to quickly deteriorate the paint on illuminated areas. Then you wash out the deteriorated paint with a 1% solution of NaOH and voila – you can etch.

The paint did not deteriorate under UV lamp as advertised and the NaOH solution did not wash it out of the illuminated areas. I have followed every step of the instructions, multiple times, and it just did not work. So I tried to increase the NaOH solution concentration – and it washed off all of the paint. So until and unless someone shows this particular product to me to work, I am considering it an unfortunate waste of money.

I do not want to make my signatures too big, and I want to number the blades from now on, and the wax is not very conducive to tiny fine details. So I had to revert back to how I did things in the past, with slight improvements. I have covered the blade with plastic adhesive tape. But this time I have used double-sided tape on the parts where the signature and numbering were due to go, and then I glued to it one print of the now useless stencils for the failed photo etching. Then I cut out the letters with shaving razor and a pointy scalpel blade.

Because I did not want to damage this blade, I have first tested this new technique on the failed machete (that fail has proven quite useful, I have hardened piece of steel for experimenting).

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

Etching in a cup with solution works, but it takes a lot of space and a lot of solution to immerse the whole blade. So I have built myself a new thingie that allows me to perform etches with very little solution.

I took a piece of graphite and ground it flat to about 20x30x5 mm. On top, I glued a piece of wood and covered it all with excess epoxy glue to protect it against moisture. The next day I drilled a 6,5 mm hole into the wood down to the graphite. Lastly, I took a piece of 8 mm brass pipe, cut M8 thread in the hole and on the pipe, and I screwed the pipe into the hole so far that it has a solid connection with the graphite.

For the etching itself, I have simply put a piece of felt soaked in diluted FeCl3 solution on top of the design, between the blade and the new graphite electrode. Anode (+) on the tang, cathode (-) on the brass pipe and after five minutes the job was done. The etchings are clean and nice looking.

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

 

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

Just like last time, I have no pictures of the assembly. Imagine me slathering epoxy mixed with wood dust all over the tang, hammering the handle onto it and then peening the end of the tang whilst being in a constant state of panic that something goes wrong. Nothing went wrong, although I am not happy with how the peen turned out. But the customer did accept in advance that peened tangs can be a bit unseemly. Even unhardened stainless steel does not like to be peened and tends to crack around the edges. And I did not dare to try and weld soft steel stud at the end of the tang, this steel allegedly does not weld well. But maybe I will try something different for the second blade. This one is unfortunately stuck with this, although it might get a bit better with some more polishing.

 

So the knife is now more or less finished and functional. The last thing to do is to clean and polish the wood to about 300 grit and then impregnate it with boat lack.

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

My first Commission – Part 8 – Bugger

I thought I will finish shaping the handle today. Instead, I have to start all over again – the piece of cherrywood that I used had some deep cracks (they were not on the outside) that got too wide and too visible in addition to two unseemly knots. The knots themselves could be seen as a part of the wood, but the cracks kill it definitively.

I have just spent some 2 hours shaping a piece of firewood.

YouTube Video: Original Vs Reproduction – Which is better?

What I find the most interesting about his video is the realization that our modern perceptions of what is and is not beautiful are heavily skewed towards unreasonable and sometimes unachievable perfection. Sometimes perfection that you can only evaluate up so close, that you need a magnifying glass and calipers.

I blame the industrial revolution and mass-produced machined goods.

My first Commission – Part 7 – Sharp!

Hell isn’t forever after all. Today I have finished both blades and for the second one, I opted for a satin finish. Not because it is easier – it is not – but because I wanted to see the difference and decide what I like more for the future. Well, I am still undecided, but I can see the difference. And so can you, although it was not easy to think of a way to photograph this.

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

The satin finish was made by me not going to the finest buffing compound. Instead of that, I went for a fine abrasive pad right after the medium buffing compound and I dragged it along the blade a few (hundred) times. And I probably will do some more.

After the blades were finished, I have decided to sharpen them. I probably will sharpen blades before assembly for several reasons. Firstly I like making apple seed (convex) edges, that give the blade look as if it does not have a secondary bevel at all. For that, I might need to re-buff the blade a bit, and that can only be done before the handle gets in the way. Secondly, should I scratch the blade by accident during the sharpening, it is easier to re-polish it before assembly. So whilst I do not necessarily sharpen the knives to shaving sharp at this stage, I do sharpen them to some 90%.

This steel (N690) should not be sharpened at an angle steeper than 15°, steeper than that and the fine edge allegedly tends to break off. I have no reason to doubt this since the blades are hard as hell. This time I have a way to get a really nice and consistent angle – I could use my magnetic jig. So I did. The N690 is steel with so-called “secondary hardening”, so it is basically nearly impossible to overheat and destroy the edge during sharpening. Nevertheless, I took care to take my time and not overheat it, it does not pay to get into bad habits.

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

You may see that there is no platen behind the belt, so I am using a slack-belt setup here. That means the secondary bevel will be concave and the cutting edge itself will be sharpened in fact at an angle a bit higher than 15°, which is ideal for a hunting/camping knife of this type.  Convex grinds are very durable – the knife that I have made for my mother needs sharpening only about two-three times a year despite being used and abused daily.

Speaking of that, when I was at it I also sharpened all her kitchen knives. Those took just one-two very quick passes on the slackbelt and then a few passes on my stropping wheel (made according to Walter Sorrell’s video)

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

Your eyes do not deceive you, that grinder with the stropping wheel is back-to-front.  For stropping, the wheel must rotate in the direction of the edge, not against it, because it is softer than the blade and if you try stropping against the edge, the blade will bite into the fast-spinning wheel and dire consequences will follow. Having the grinder backward allows me to work on the upper side of the wheel, so should it grab the knife and throw it, it will hit the wall and not my leg or the concrete ground. I find it also a lot easier to strop the blades that way.

The stropping wheel gets the knives to scary-sharp in mere seconds. I am using the coarse stropping compound, in my opinion, it makes a better edge than the fine ones.

Now the blades are polished, nearly completely sharp and wrapped in masking tape. It took me three times more time than I think it should and about 30% more than I thought it will. But now the most time-consuming and nerve-wracking part is hopefully behind me and next steps will be free of trials and tribulations. Or at least with significantly shorter ones.

My first Commission – Part 6 – Halfway Through Hell

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This weekend I only could work for about 4 hours on this project, but I have finally managed to finish one blade.

I am not happy with it. Like, at all. I could have done a better job, and I have done a better job in the past. I just could not get into the thing at all. I kept making mistakes, and whilst to make a mistake on belt grinder takes a split of a second, correcting it can take hours. After 400 grit I went to hand-sanding. It is more strain on the fingers than the belt grinder, but a lot less space for a mess-up. And therefore I was, paradoxically, suddenly a lot faster. I might switch to hand sanding on the other blade sooner.

After 1000 grit I went for buffing wheels. Buffing a blade like this is not optimal and if I did not mess up the grind on belt grinder so often as I did, I would not go for it and I would polish it up to 7000 grit sandpaper. However buffing has one advantage, besides being fast – it hides and smoothens slight imperfections on the bevels by ever so slightly rounding up the ridges. Which is also the reason why I normally would not go for buffing for a blade like this.

This is the blade that goes to the customer. Next weekend I will hopefully finish the second one and then I can start on the accessories.

But after I am done with currently started projects, I will definitively make a batch of these. It is a complicated shape, and thus an excellent exercise.

 

My first Commission – Part 4 – Welcome to Knifemaker’s Hell

I really wish my first customer has chosen a knife with simpler geometry. For future projects of this kind, I will have to make some more attachments for my belt grinder, because it is woefully inadequate for the concave false edge. I messed that up several times already and quite a few times I got frightened that I will have to start all over again. Whether I manage to correct the slight flaws that are in there remains to be seen, my guess would be no. It will cut alright, but it won’t be perfect no matter what I do. Grrr.

This weekend I have spent with grinding as much time as I could – approx 4 hours each day. More is not possible, at least not for me. Grinding on belt grinder is for me very mentally tiring, because I have to concentrate a lot more than I had to when grinding manually. Because whilst grinding on the belt grinder is quicker, it is also possible to make mistakes quicker.

At this point, I should be finished with polishing, but I am unfortunately not even halfway through. Mainly I have myself to blame for this. If you remember, when writing about the kitchen knives I mentioned that after the first grind with the magnetic jig I went back to freehand in order to be able to alternate the angle of attack to get a flatter and more even grind. Well, I forgot to do that with these two knives and I ground them both up to 120 grit ceramic belt on the jig. The result was ever so slightly wavy grind that I had to correct now that the blades are hardened. So I had to start all over at 40 grit and work my way up, sweating profusely whenever my hand slipped slightly. But at least one thing is clear now – whatever misgivings I had about the blades being perhaps not hardened properly, I do not have them anymore. They are extremely hard and tough to grind, which is why it took me so long to get to 150 grit today, which is the point at which I had to call it quits.

Still a long way to go. © Charly, all rights reserved. Click for full size.

I estimate I will need about ten more hours overall, on and off the belt grinder, before I can call these two blades finished. That means at least one more weekend. At least. It also means more than double the time that I think it should have taken me. When I am done with this and with the kitchen knives, I will probably make a batch of these blades as an exercise, I must get the muscle memory and experience and know-how to do a proper job in a reasonable time, I cannot dick around with one blade for months on end anymore.

My first Commission – Part 3 – Quality Control

I took both blades to work and measured the hardness on the tang and near the spine. On one blade I have measured 52 HRC, which is actually good and is the value that I was aiming for this area. The second blade however only measured 47 which gave me a pause, because it just did not feel right (it is still perfectly OK value for the spine though). Scratching with an ordinary file has shown that both blades are softer at the spine than at the cutting edge, which is too desired and that it came out that way straight out of tempering means that I do not need to temper the spine extra with a propane torch, which was my original plan.

The “better” blade looks now like this.

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

You can see the scratches from further testing at home, where I have indeed established that both blades are approximately identical – both hardened through, but harder at the edge, both probably 52 HRC and more. So how came about the difference in measurement? I got an idea how that could happen and it turned out to be correct – the blade with lower measured value is ever so slightly bent, it is not visible with the bare eye, only when I put a straightedge alongside it and looked against the light. And I have measured it on the convex side, which means it was behaving a bit like a spring thus lowering the measured value. That is the reason why these measurements are supposed to be done on clean and flat-ground things with parallel surfaces.

And how did I establish, that both blades are nearly identical? With these.

Gages for estimating hardness. © Charly, all rights reserved. Click for full size.

I have made these miniature chisels in the winter and I measured them at work. I used nearly the same process as when McGyvering the precursors for these last year. Then it got put on hold until yesterday and today when I finally got to etching their HRC hardness onto the blades and inserting them in handles.

They are not perfect, for some reason the hardness can wary within one blade so the higher one does not always reliably scratch the lower one, but they do give me an estimate. For example, I have also tested the tempered blades for kitchen knives. One blade got scratched with the 53 gauge, but none got scratched with the 51. From the rest, none got scratched with the 57 gauge, and the 62 scratched all blades but three. And all gauges can scratch the unhardened tang.

That is a far better result than I expected – no blade seems to be under 52 HRC, which is the lowest limit I have set to myself for knives. I did not pull this value out of a hat – it is the lower tolerance limit used for combat knives in former Czechoslovak People’s Army, and I reckon if it is good enough for the army of a paranoid totalitarian state, it is good enough for me. And since 62 HRC is nearly the upper limit for the steel I used for these knives, it seems that despite still a bit improvised setup, I have indeed hardened some blades as well as it is possible.

Although there is no reason to really think one of the two blades is really worse than the other, still the blade where I measured 52 goes to the customer, and the blade where I measured 47 goes into auction here (provided I do not destroy one in due course).