Slavic Saturday

I was actually thinking whether this would be better suited here or in the “Behind the Iron Curtain” series and I decided for putting it here.

Former Czechoslovak Socialist Republic has had a great tradition of stop-motion capture movies and one of its pinnacles was a series of short stories for children that was so succesful that it runs until today. The series started the same year I was born, and one of my favourite episodes “Tapety” (Wallpapers) is just three years younger. The series was originally named “A je to!” (It’s done!) and was aired in the evenings as a bed-time story for children.

You can enjoy this series no matter your native language since there are exactly zero words spoken. If you spend bing watching multiple episodes, feel free to blame me.

How Hard is Hard Enough?

This is about steel and blades OK? Just to be clear upfront.

In my article Knifesharpenophobia I have mused a bit about how being all anal retentive about the hardness of a blade is not all that necessary. Now I wish to revisit that heme a bit, after my hardening attempt of a blade did not go as well as I would wish to.

If you remember when I was trying to harden the rondel dagger I was also hardening a kitchen knife blade and I was pretty sure that this particular blade is properly hardened. So I took it to work and measured the hardness on the tang (the knife is not finished yet), where it is hardened, but probably not as well as the blade. And the gage showed HRC 54. From technical standpoint, difference between 50 HRC and 54 HRC is not trivial (HRC is not a linear scale) and that knife is thus indeed properly hardened. What was the difference in the work process? For that knife then I have used the gas forge only for heat-soak, the final heating to 1050°C  before quench was made with charcoal, which allows for more even heating. HRC 54 is still not full potential of this steel, but if the tang has it, the blade has probably more.

But this whole thing got me thinking again – is that even relevant? Do I really need to be afraid to give that knife to a fried as a gift because the hardness of the blade is “just” HRC 50? Am I being unnecessarily obsessive about an inconsequential detail (again)?

So I tried to look at what is the actual hardness of historical blades. I did not spend too much time with it, but the article Sword Blade Hardness: A look at the current research is an eye opener and a good read. To be clear, it is about swords, not kitchen knives, but it still clearly shows one thing – the crappiest knife that I have ever made is vastly superior to most knives that were used throughout history before the invention of blast furnace. Not because of my superior skill, but because I have access to superior steel. Furthermore, HRC 50 is not actually bad at all and someone who takes a good care of the knife would probably not even notice any downside when cutting. And it has an upside too – a blade in this hardness range needs to be sharpened more often, but stropping and sharpening should be reasonably easy and quick and the knife will not break easily when you drop it on the floor by accident.

It is not the best that could be, but it is good enough.

Making Kitchen Knives – Part 5 – Grinding, Polishing, Buffing

I was expecting this to be the most time-consuming part and so far I was not surprised – it was. You have seen my collection of abrasive belts during my Rondel Dagger series. Because the protective coating has proved itself to be way too persistent, I had to start with the coarsest Zircon belt all over again – that is what I meant when saying that I could have spared myself the trouble I have spent with finer belts before hardening. I wanted to give this blade the best surface finish that I can achieve purely by using machinery, so I went thoroughly through all belts, not switching to a higher one unless all scratches from the previous one were removed. Although towards the end of the line with last two Trizact belts I was not too fussy about this, because those leave so fine scratches that whilst they are barely visible, but they will always be somewhat visible unless I go with hand polishing afterwards – and that I did not want to.

So when finished with the finest Trizact belt I went straight to the finest buffing compound and gave the blade a few passes on the buffing wheel.

An important note – this is a knife without secondary bevel, with so-called “convex grind”. That means that during the polishing process the blade is also sharpened to very nearly final stage. Therefore towards the end it becomes a bit dangerous to handle it, because it can actually become completely sharp in places. I do not know what process other knifemakers use for achieving this grind, I am doing it with the slackbelt/hardbelt setup on my belt grander, that way I can do it in one go during polishing. The knife will need some sharpening when finished, but not too much. I like this grind because in my experience it cuts best and also looks best – but your mileage might vary and there is no accounting for personal taste.

speaking of taste – one of my friends when I have shown him my mother’s knife thought that I have made the tip round either due to laziness or because I botched it and making a round tip is easier. If you have such thoughts, forget them. Making a round tip is not easier than making it pointy-stabby. And the round tip is entirely intentional. This time around I actually consulted with my mother what she prefers for this knife design and I discussed with her the work in progress when it still had a point, and we agreed that to us this knife looks better with a round tip. Further, there is no point in having a point on an all-purpose kitchen knife like this, since needing a sharp point is actually a rare occurrence (the only one that I remember from the top of my head is gutting fish and poultry, and even there an actual point is used only briefly).

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

Enough rambling  Here you can see the blade before buffing to get a measure of how well the knife is polished after only Trizact belt grinding – after buffing it reflects a lot more.

That picture shows also that the grind is acceptably flat. The fact that the edges of the mirror on the wall are straight-ish and that my face is still recognizable despite being reflected back through a mirror 1,5 meter away is a good sign that the grind is flat.

However that comes at a non-trivial price. The whole grinding and polishing process took me 4:20 or 260 minutes. Buffing was mere 10 minutes from that. As I become more experienced this time will probably go down significantly, but some of that part of learning curve I have already done, so I do not think it will be too drastic. In order to shave-off a really significant amount of time here, I think I would have to either use completely different process (I have an idea there, but it will need a lot of MacGyvering), or be content with a less-than-mirror finish. So in next step I will experiment with different finishes and decide which is the best compromise between time spent versus looks. The problem with polishing is, that whilst it has zero negative impact on the function, it has 100% positive impact on the looks of the thing and negative on the price. And people are buying with their eyes but deciding with their wallets. Talk about contradictory requirements…

Making Kitchen Knives – Part 4 – Heat Treatment

This is when things did go a bit pear-shaped, although I learned that only today. You have seen my “equipment” before, but not in detail. Now you can see it in detail. An IR thermometer on the left, small insulated chamber with gas burner in the middle, a can of sunflower oil, and of course gloves and pliers.

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

With a blade this thin I have to somehow prevent carbon loss, because I cannot simply ground away a few tenths of a mm afterwards. There would be barely any blade left if I did that. So, as you can see on the last picture in previous post in the series, I tried to coat it with an experimental solution to prevent said carbon loss as an alternative to the rather expensive stainless steel foil. It worked and did not work at the same time and the knife is now in a stage when it will be crap no matter what I do. I am going to finish it anyway, just to get the measure of time, but this step was a definitive flop. Which I did not expect, because I heat-treated two knives from this steel without problems.

 

Firstly the gas burner has trouble reaching the necessary temperature of 1.050°C that this steel requires. It can reach them with success (the blade that I have given to my mother was hardened this way), but it takes a long time and it is difficult to heat up the blade evenly. I thought that I have reached the right temperature and quenched the blade OK, which was confirmed by subsequent scratch test with my impromptu gauges. However, as it turned out, the scratch test only passed because the protective coating has made a thin but hard layer on the surface that was bugger all to remove.

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

I hoped it would dissolve in hot water – that was the intention – but it did not. It was extremely difficult to clean off in the following step and after I measured the hardness on polished blade (properly – I found out we have HRC measurement at work), it had only about 50-51 HRC. That is weaksauce for a kitchen knife, although it would be OK for a machete. The blade is hardened, just not to its fullest potential. It will cut fine, but it will require more maintenance, so I will probably keep this knife for myself and not give it to anyone. Bugger.

In addition to above mentioned quality problems, this whole step took me more than 1 hour, and I am not counting the 1 hour in baking oven at 150°C, because that does not require my personal presence and thus does not de-facto cut into manufacturing time (and I can load the baking oven with 10 knives at once should the need arise).

At this moment, I do not see any way how to reduce that time. Making more knives at once might help a bit, but for that I would need to set-up heating with charcoal. If I do that, I  estimate that I could harden about 5-6 knives in one go, but that one go would take probably about 3-4 hours of constant work. So a saving of 15 minutes, or 25% time per blade could perhaps be reached on this step, but it is questionable.

A heat treating oven would of course completely change this whole equation, but that would be a big investment – they start at 3.000,-€. Should I ever have to produce knives for sale, a heat treating oven would be a definitive must, or I would have to simply send knives for heat-treatment. Right now I will try to do the heat treatment again by myself, and the next batch of knives will be split 50/50. One half hardened with the use of stainless steel foil, one half with modified coating, and I will either set-up a bigger gas burner, or use charcoal.

This step is put in the “high hanging fruit” basket. There is potential for significant time-saving here, but it is very difficult to reach with my current equipment.

Making Kitchen Knives – Part 3 – Basic Grind

This is the part where work on more blades in parallel is no more possible, but I have tested an improvement that I have hoped for to both save time and increase precision. Grinding symmetrically free hand a blade mere 1,8 mm thick would not be easy. My previous knife of this type was made from 2,5  mm steel and I messed up the grind. I have spent more time correcting my messed up grind than I liked to and in the end I had to opt for a blade without a clear transition between the blade and a ricasso.

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

I wanted to do better this time, so I have built an experimental jig. As you can see on the picture, it is a simple 30×50 mm block of hardwood (a leftover from building the belt grinder). Two screws hold the knife on the smaller side, and three screws are right on the edge opposite the knife. Those three screws pop out a bit out of the wood and by how much they pop out is how big an angle I have between the blade and the platen on the belt grinder.

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

I did not make a picture on the belt grinder, but you can see on the right the jig with a blade put against a machinist’s square. The advantage of this setup is that if I want, for example, ~0,3 mm thick edge before hardening and with the blade being ground all the way to the back, I know that I have to set the jig so that there is ~0,70 mm between the square and the back of the blade. Which is exactly what I have done, only without measuring, only eyeballing the gap and deciding “yup, that is what I want”.

The jig is set up so that I can screw the blade in two mirroring positions, but I did not bother too much with precision, because I did not know yet whether it will work or not.

It worked, but the imprecision was abit of a problem, as well as the way the blade is fixed. Two main problems occurred:

  1. The tip of the blade lay on the supporting table. That proved to be a problem, because it got snatched by the belt and dragged into the gap between the belt and the table. It messed up the grind in split of a second and I have spent no trivial ammount of time correcting it.
  2. Changing the blade on the jig took way too much time, even with accu-screwdriver. Part of the problem was the imprecision, because I had to monkey with it each and every time to get it right.

So a more precise jig that allows fro quicker change is required, and it also should hold the blade at least a few mm above the supporting table for better control. As a proof of concept it worked, it did indeed improve precision, but there is potential

During the grind I have made one time-wasting mistake, but I did not know at the time it is such. After I have established the grind with ceramic belts which go up to 120 grit, I continued to 240 grit on Zircon-carbide belts. As it turned out,  I could have spared myself those zircon belts alltogether, but more about that next time.

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

I forgot to make a picture of the ground blade, but here you can see it as it went into the next step in the process. You can see that I have managed nice clean line all the way to the back of the blade, which I was previously not able to do free hand.

The time spent with this was about 1:15, or 75 minutes. From that time I have spent approximately 10-15 minutes monkeying around with fixing the blade on the jig, and another 5-15 minutes changing belts on the grinder. I also wasted some time correcting messed up grinds. I think that a better jig and above all not going above the ceramic belts should cut this time in maybe a half, but probably not more – it is fidly work and probably the biggest factor is experience. I remember Walter Sorrels saying in one of his videos that he manages this in 10 minutes, but only because he has been doing it for years.

Right now I am putting it into the “low hanging” fruit basket, because I think I can easily get a significant 15-20 min improvement through better jig and not going too fine with the belts. The rest is, unfortunately, entirely dependent on how fast I will scale the learning curve.

Making Kitchen Knives – Part 2 – Draw, Drill, Cut

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Each bar I have is big enough for two knives, but I cannot simply halve them – there is nearly 10 cm overlap towards the tips. That way I get longer knives whilst wasting less material. I have made a new paper template and here you can see how I laid it on the bar. To draw the outline I covered the whole bar in blue color using very thick (1 cm) marker. A much cheaper and more readily available option to machinist’s blue. You can also see that  I have lost my drawing needle somewhere in the 10 square meters of my shop so I have made a new one from an old shuttle bobbin. I hope I won’t lose it too.

When doing this I have wanted to test an idea how to improve my process already, so I have made another template which allowed me to mark not only the two holes for pins, but also a hole at the center of the finger groove. Unfortunately I did not make a picture of that.

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

But here you can perhaps see why the third hole. After marking the hole positions with a center punch, I proceeded to the drill. But instead of a normal drill bit, I have spanned in it a step drill which allows me to drill holes from 4 to 22 mm. So I drilled 6 mm holes for pins and an 18 mm hole where the finger groove is. That way I do not need to mess around with some improvised way to grind a nice tight radius that I need. This is a big time and hassle saving in itself.

This is also first significant change in design to the prototype that I have given to my mother. She did not exactly complain, but she commented that a deeper finger groove would be more comfortable. So I am making the groove deeper and therefore the handle inevitably skinnier in this part.

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

I have marked and drilled both halves, then I cut the bar diagonally with an angle grinder. Using an angle grinder I have also cut excess metal on both knives since I live by the rule – if you can cut it, do not grind it.  After that I have tried another time-saving measure that I have thought up in my idle time – I have connected both knives with screws through the pin holes. With that I proceeded to the belt grinder to grind the outline of the blades.

It worked very well and I had outlined two knives very quickly, in fact these three steps took a lot less time than I expected – just one hour overall. And I even see big time-saving potentials here:

  1. For drilling I could make a template for guiding 6 mm drill bit instead of punching the holes for each blade separately. So for next run I will first fish around in my scrap pile if I find a scrap piece of the right shape and size. Then I can stack and drill more pieces in one go. I will lose some time by stacking, but save time drawing and punching. Also next time I will first drill all stacked pieces with a 6 mm drill bit for the finger groove as well. That means changing the bit once, but I think it will be more than made up by the time saved from drawing and punching.
  2. I can probably stack at least two, maybe even five, pieces before cutting all the excess with the angle grinder.  Five pieces would be 9 mm thick, and an angle grinder should be able to grind through that without big trouble and without too much reduction in speed. And I will waste less time per blade by repositioning the piece in the vice for each cut.
  3. Ditto for the belt grinder. A new 40 grit belt should be able to grind five pieces at once with only marginal reduction in speed. That would also improve reproducibility.

So I am putting this in the “low hanging fruit” basket, since the 30 minutes per blade is significant 10% of my goal time and I estimate I can cut that easily down to half or maybe even less.

Making Kitchen Knives – Part 1 – In the Beginning…

… there was a bar of steel.

After a short break due to harvest I have started two knife making projects and I will share the progress on them as I go along.

The first one is about developing a viable process for making small-batches of kitchen knives.

The knife that I have given my mother for Christmas has proven itself to be an excellent cutter. It held an edge for half a year and still shaved hair when my mother requested honing the edge because it had a few blunt-ish spots. The handle does not show any sign of deterioration too. And it is used daily, by at least two people, on everything from fine chopping veggies to de-boning chicken. So I think that with some adjustments (mostly making it look prettier) it might be a saleable product.

I reckon (I will not bother you with the math and reasoning, some of it has solid rational basis, some of it I pulled out of my nether regions) that in order to be able to eventually barely survive whilst making knives, I would have to be able to make a passable kitchen knife in under five hours spending with the fun work, i.e. manual labor. The lower the better. Rest of the working day would in such a case be eaten by the unfunny part of the job, the actual business of business.

But developing a viable production process is something I have a professional experience with and so I want to have a go at it, even though right now making knives is just a hobby. And I will be sharing with you all the failures as well as the improvements in trying to achieve my time goal.

The first step is straightening the steel. For this project I am using N690 steel 1,8x50x500 mm and all the steel bars had a slight bend to them that had to be corrected. Currently the only way for me to do this is to use a vice and three thick screws. Had the plates had a kink, I would place the middle screw straight on that kink and bend it with ever-increasing pressure until after taking the steel out of the vice it would be straight-ish. However these did not have a kink, they were nearly universally bent in a very slight regular arc.  To straighten that, I first tried to bend the bars slightly at multiple points. It worked, but it was time-consuming and unreliable. Later I have tried to close the vice only slightly on the steel bar and then pulling it through the screws – essentially using it as an improvised roll bender. That worked much faster and reasonably well.

Even soo, all in all it took me less than 1 hour to straighten 12 knives worth of steel. That is less than 5 minutes per knife. I think that building a small roll bender specifically for straightening these thin long bars should not be difficult and it could potentially shave off quite a reasonable chunk off of that too. But right now, I am putting this into the “high hanging fruit” basket, since despite the clearly impromptu setting it takes only about 2% of my time goal. That means, I will ignore this step in the process for now and not bother about improving it.

For the first knife made let’s write down 5 minutes for this step and move on to the next.

Youtube Video: Pictish Crossbow – discussion and shooting

I would love to someday to build a crossbow. It definitively is on my ever growing to-do list.

Not that I feel particular inclination to be armed, but the simple yet not easy to make mechanism of a crossbow (or even a bow) intrigues me.

Tod Todeschini not only makes crossbows, he also likes to share his extensive knowledge about them. Here he uses that knowledge to speculate a bit about how pictish crossbows could look like.

I Was NOT Photographing Spiders!

During my photo walk previous week I tried to take “flash at dusk technique” of a dried up stalk of Heracleum sp. A bit before than, when the sun was still shining strong despite being low over the horizon, I tried to take a picture of a late blossom of Ranunculus sp.

However, as it transpired, I must put the pictures bellow the fold.

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Why Did You not Try to Stay in USA?

As readers of Affinity know, I was growing up until 13 years of age in a totalitarian state with little real autonomy, an effective satellite of USSR. I also grew up in a poor family so it was a bit of an uphill financial struggle for me to get a university education.

Towards the end of my education I had to decide how to actually start my independence and one of the options that presented themselves in 2000 was to go to USA with a “Work And Travel” program and J1 visa. I might write about my American adventure maybe some more later, today I wish to only briefly discuss the question in the title, which in various forms was posited to me in later years from many people here, old as well as young.

Even before venturing to USA I was of the opinion that it is a proto-fascist state and my opinion was further solidified by my experiences there.

So my answers at that time were these four points:

  1. Crappy healthcare. I have met ordinary people fearing that a simple case of flu might send them down the spiral of personal bankruptcy. I have seen outrageous prices for one course of antibiotics. I knew that USA had, in contrast to European countries, no universal healthcare, but seeing it first hand was a real eye opener. Fear of loosing even the crappy health insurance provided by the employer kept many people in essential slavery, when the were putting up with blatant abuse by their managers. For my friends I summed this argument up as “if I have grown up in USA, I would not live to become an adult, because my parents would not be able to pay for the medication I needed”.
  2. Crappy education. I have already mentioned that for me to get a university education was an uphill struggle. I was not bad student, but I am not so intelligent as to be able to study and work (not to mention that job availability was not that great – unemployment rate 8%), so I had only negligible income and I had to rely on my parents, which was hard – I had to live by with about 100,-$ a month to pay for my lodgings, food, books etc. For my friends I summed this argument up as “in USA I would not get a university degree, because even without tuition fees it was not cheap and with tuition fees it would be ruinous”.
  3. The mony that I made n USA was worthless there, it only had worth here because of the very favourable exchange rate. In US, the measly 5.50$/h were to barely live by – even though as a student I was tax exempt. So staying in USA would mean to lock myself into perpetual poverty. I find it incredible how many of my peers with university education failed to grasp this reality, that money’s worth is contextual and 1.000,-$ monthly income in USA is shit, whilst being absolutely amazing and nearly unattainable here.  I tried to sum it up as “for the money I was making there, I could not even rent a flat. And I would be forced to do work well bellow my qualification even for that. Here, I could use it to at least repair my house.”
  4. Absolutely inane laws and judiciary process. I have always thought that outcome of a judicial case should not be decided by a bunch of barely literate amateurs and that precedent law should not still be employed in any civilised country. And what I particularly did not admire was the “sue happy” culture in USA, where people try to win the lottery by suing each other for money. And the lack of properly functional system for “ex officio” advocates for people who cannot afford to pay. I summed it up as “any time you could get sued by some idiot over some trivial thing and if they could afford better lawyer than you, you are screwed”.

And mind you, this all was in 2000. The only progress that I see from behind the Atlantic was on health care, everything else got  much worse since then. And it seems that USA is managing to drag back the rest of the world as well – in last decade or so the main American exports are jingoism and creationism.

The USA was never democracy and never free. It only managed to convince its enslaved citizens that they are free. I am entirely content with my decision to not even try to live there permanently.

Bobbin Lace Masterpiece

I would like to share a both inspiring and gloomy story this time.

My grandmother was abandoned as a child by her family, who did not want to raise her – she has lost her leg and staunchly religious catholic matriarch of the family refused to take care of a “cripple”. So they gave her to a cloister to be raised by nuns. She learned there bobbin lace making style specific to that region of Domažlice.

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

This piece is a tablecloth circa 60×80 cm and was started by my grandmother in that regional style. But she managed to only make some of the edges and corners before she died. My mother has kept those pieces and she intended to finish it at some time, but she could not get the right thread. After decades of searching both in real life and on the internet she found a vendor still selling what appeared to be the correct thread and she bought it.

Unfortunately, the new thread pieces did have slightly different color than the antique 50 years old ones (to be expected), so she could not simply continue her mother’s work. Therefore she started from scratch, only using grandmothers template for corners and edges.

For that I had to scan the template first.

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

And then make it black-white, so my mother can take it and draw a new one with the time-tested technique of taping it on glass under a new sheet of paper and tracing the lines per hand.

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

When the edges and corners were finished, she had to design the center part. She was not satisfied with her attempts and she requested my creative input. I proposed that chain of ovals with lobed edges around three stars, and she went with that idea and expanded it. They have a slightly different style, but I think it all works together.

So you see in effect a piece of art that took three-generations to complete, if you count my minuscule input. In the end, my mother has spent over 100 work hours making it, and used up over 1 km of thread. It is absolutely invaluable – and she gave it to me for my birthday this summer. I do not wish to use it as a tablecloth, so I framed it as a picture and I am in search of a piece of wall big enough to hang it on.

Sadly with me the bobbin-lace tradition in our family will die. I tried to learn it as a child and I was not bad at it, but I have way too many interests as it is so I forgot it again – and since probability of me ever having family converges to zero every year, I would not pass it on anyway.

But in the meantime, you can enjoy the pictures.