Youtube Video: Medieval ASSASSIN’S CROSSBOW (Balestrino) ASSEMBLED & TESTED!

I could not decide between multiple videos, as usual, and last-minute decision fell on this one. It is a nice piece of engineering and the video is reasonably short and packed with interesting information.

It might also be Halloween appropriate? I have no clue, since I originate from and live in a country with no Halloween tradition whatsoever and honestly I do not understand what Halloween is supposed to be about at all. But I read something about murderers and monsters the other day, so maybe an (alleged) assasin’s weapon might fit in.

I have a day off and I planned to do some knife-work, but I have to pass on that since I am still not well.

How Typically American

So White House has published a pamphlet about the evils of socialism. I have not read it in full and I probably won’t since I have better things to do with my life than to read drivel from Trump administration, but on casual glance it seems to insinuate that the disastrous attempt at socialism in former Soviet bloc invalidates everything with the word root “social” in it. Therefore since badly implemented socialism in Ukraine has led to famine in 1921, “socialism” in EU in 2018 is just as bad.

That is of course complete non-sequitur.

The whole document also seems to be rather American-centric and comparing apples with pineapples, or perhaps even bananas. Like this infographic:

Whitehouse infographic about Costs of Owning a truck

Now I admit I have zero personal experience with any of the countries on that infographic except with USA.

But my experience with USA is that people there own pickup trucks in about 80% of the cases just to own them, not because they actually, really need them. I mean, I have seen them used for grocery shopping in big cities, with the deck empty and the groceries being put in a bag on the passenger seat. People commuted daily to work in them. Most owners of pickup trucks in USA could do just as well with only ordinary cars and for those rare occasions where they really, really might need something bigger (like buying building materials for house repairs etc.) the options available in for example Germany (i.e. renting a truck or goods trailer at the shop for a few days) would suffice ample. Further populations in EU are much more tightly knit than they are in USA, there are not many far-off farms and isolated homesteads that really need pickup trucks. I am not sure how this is in Nordic countries, but I still suspect that a real need for big pickup truck there is smaller than in US just due to the USA’s sheer size and wast empty places.

Thus this infographic is used either ignorantly or dishonestly to scaremonger. Or both.

As far as the economic side of the pamphlet goes, I will leave the critique to an expert who says everything better than I ever can:
Are the Danes Melancholy? Are the Swedes Sad?

On the whole I get the feeling that this pamphlet starts with the assumption that everything USA=good and everything socialism=bad and tries to spin evidence to appear to validate those assumptions.

How typically American of them, to ignore all context an only seek ways to put USA at the center of the universe. Again.

Whom Will They Blame Next, Unicorns?

I have never watched Fox News when I was in USA, and of course I have no incentive to watch it now. However the stories that I read about it on the interwebs are truly bizarre.

This one trumps them all: Fox News host: ‘Anti-Semitism from the left’ is the real cause of hateful attacks on Jews

Where exactly does this “virulent anti-Semitism from the left” happen? Where do roam these elusive creatures, these leftist antisemites? Where exactly is the land of “fringe of the progressive side.”?

How come that someone spews such a weapon’s grade bullshit on air and is not immediately challenged for providing evidence for it? Any person who says such inane claptrap should be discredited and mercilessly mocked.

Making Kitchen Knives – Part 8 – First Evaluation

First thing first – today I tested the very nearly finished knife when I was cooking shrimp for lunch.

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

It handles well and cuts OK, but I really suspect it won’t hold an edge as well as it should. But the cheapo wood looks way more posh than I expected it, ammonia fuming really, really improved its looks.

And now to the boring stuff.

What I am doing here is actually a small-sized DMAIC project – an abbreviation for Define-Measure-Analyze-Improve-Control. It is a process used in industry to bring some logic and use of scientific method into improving manufacturing processes. Although as everything in today’s corporate culture it is used wrongly and heavily abused and misunderstood all over the place, because american-trained managers …. wheef, do not get me started on american-trained managers.

Aaaaanyway, in the first phase, Define, you should either define your problem or your goal or both. In my case, I have a specific goal – to get my manufacturing time of this type of knife under five hours of manual labor.

In the second phase you should acquire all measurements that you need in order to do something about it – in my case I have measured the manufacturing time of each distinct step in the process.

And now, in this post, I am performing the Analysis of said data. Total manufacturing time: 10:46, or 646 minutes.

A picture is worth a thousand words, so here is a picture.

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

There are of course multiple approaches one might use, but in this specific case I think that this suffices ample enough – it is so-called Pareto Graph. The balks are actual times in minutes for each step, ordered from the highest to the lowest. The black line is a sum of the relative proportions of these times to the total as one progresses from left to right. As you can see, I have ten distinct manufacturing steps and from those five steps constitute 90% of manufacturing time. These are the steps where I have to concentrate on actually reducing said time, because here my efforts have the biggest payoff. That does not mean that improvements in the other five steps are not worthy pursuing at all, but they are not worth pursuing at this time.

I have done one thing that is not normally done, that is I sorted from get-go the steps into two categories – low hanging fruit, where I think I can do improvements without too much hassle and without obtaining expensive or complicated equipment, and high-hanging fruit, where I can save time only through acquiring new skill or new equipment or where I think saving time is not actually possible in a meaningful way.

Now comes the next phase, which is  to improve the process. I will try to implement some of the ideas for that I have expressed and make a batch of multiple (~10) knives with improved process. We will see how it turns out.

Making Kitchen Knives – Interlude 1 – The Little Great Polishing Experiment

I will share with you a proper analysis of the acquired data, but I just finished a little experiment and I am too eager to share the results.

Without too big analyzing of anything, it is clear at even a casual glance that polishing is the most time-consuming part of the job. It is also the most boring part, in my opinion, because not much can be done and the opportunities for a mess-up are numerous. It is necessary to go through the laborious process for fancy knives, like Ciri’s dagger, but for a kitchen knife without any ribs or facets it is a waste of time.

For over twenty-five years, ever since I read about the technique in ABC as a kid, I wanted to try a process that goes under many names, “tumbling”  being probably the most known one. I have even mentioned the device for it in the article “The Handmade Dilemma” as a “polishing drum”. It is a technique that has been in use for thousands of years, literally – for example Bohemian Crown Jewels contain precious stones that were polished this way. And it has been tried and used for knife finishing both on commercial and hobby scale. All that it takes is having the polished things in a rotating drum where they tumble over each other, sometimes with the help of a polishing medium, sometimes without. A very simple machine, and had I lived by a stream I would build a water powered one years ago. Unfortunately I do not live near a stream and wind is too unpredictable so I am stuck with using electricity, and I have not got my hands on a motor with the right properties yet.

But I got lucky, my colleague has bought small toy tumbler for his son when he was little and they do not need it anymore, so he lent it to me a few months ago. As you can see, it is not big enough to hold a knife, not even a small one, so after I let it run with a few pieces of unhardened steel with very mixed and generally unsatisfactory results, it has collected dust again.

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

But here was the second stroke of luck – I have bought a slab of high-carbon tool steel and I started to make myself a set of better hardness measuring gauges than the impromptu ones I have made from an old saw blade. I have already ground and hardened these little chisels to HRc 62,  and I only cleaned the two big facets and sanded them up to 150 grit – that is the grit up to which the grinding and polishing is relatively quick and the blade does not heat up too much. I was not intending to high-polish these, since that would be silly. But I remembered the lent tumbler and checked if they fit in – and the did!

So I chucked the blades into the polishing drum with a spoon of jeweler’s rouge and half filled it wiht crushed walnut shells, mixed it all up and let it run for one day. Bugger – it got blocked after unknown time and I only found out next day. So I started it again for one day. And the change in surface was remarkable. It was not polished, but the perpendicular sandpaper scratches were no longer visible and the surface has got a very nice satin sheen to it. But I like my blades mirror-polished, so I started it for another day. I took another chisel out and subjectively there was no change against the first day, so I assumed that this is as good as it gets (but I will let it run for one more day). But I also assumed that since there are no visible perpendicular scratches anymore, I can quickly buff it to mirror polish with the three buffing wheels that I have  – and I was correct.

Here you can see four pictures taken with my digital microscope (courtesy of our quality department who tossed it away because they lost the installation CD – so I took it home and downloaded free software). Each picture represents a section approximately 10 mm wide in reality.

After 150 grit belt – parallel scratches perpendicular to the blade are very clearly visible.
©Charly, all rights reserved. Click for full size.

 

After one day, scratches from the sandpaper are no longer visible with the naked eye, but they are still visible under the microscope.
©Charly, all rights reserved. Click for full size.

 

After two days, the scratches from sandpaper are no longer visible even under the microscope unless you really look for them.
©Charly, all rights reserved. Click for full size.

And after just a few minutes with the set of buffing wheels the scratches are no longer visible and the surface is so polished that the microscope photographs itself.
©Charly, all rights reserved. Click for full size.

Making Kitchen Knives – Part 7 – Assembly and Finishing

After leaving the handle scales in the ammonia overnight, I took them out the next day,  washed them in running water and quickly dried them. First by letting them for an hour above the stove in my workshop and when they were nearly dry, heating them carefully in 10 sec intervals in the microwave until there was no steam coming out. I do not count this time into the manufacturing time, because I have been doing it this way only to be able to proceed quickly and get the knife done this weekend. Normally I would let it  dry by itself.

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

When dried, the scales had to be fitted to the handle – that is done by carefully sanding the faces that are glued on the tang on a flat stone as long as it takes to get them nicely flat. Then I screwed the handle scales without the blade together again and sanded and polished the two forward facing facets, because once the scales are on the tang, nothing can be done about them.

As far as the metal goes, I cleaned most of the scale from the tang with 80 grit sandpaper and then I cut two pins from 6 mm brass rod, hammered them through the holes in the tang and tried whether the whole assembly fits together without unseemly gaps. I was prepared to eventually sand a bit here and there, but it was not necessary, it fitted nicely. So I slathered generous amount of quick drying epoxy cement on all adjoining surfaces and squeezed the whole assembly gently in the vice. I cleaned the epoxy that got squeezed out, first by scraping of the excess with a piece of wood and second by washing the blade with paper towel soaked in alcohol. A piece of epoxy on the back and belly of the handle are not a problem, since those areas will be sanded anyway, but a real care must be taken in cleaning the blade and the forward facing facets of the scales thoroughly, because again, any mistake there cannot be easily corrected.

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

The epoxy that I was using was hardening quicker than I was happy with, but our local Baumarkt has “optimized” its wares selection a few years ago and they are only selling quick-setting epoxies now and I will probably have to order some slowly setting epoxies over the internet. I got lucky and I managed to get everything important clean before the glue set, but it was a race with time. That means I could not make any pictures of that process, so what you see is status just before applying the glue.

After the epoxy has hardened – in this case about 15 minutes later – I have made final shaping and polishing of the handle. I did not go above 150 grit sandpaper though, because that would be a waste of time with this wood.

Because the used wood was extremely porous, I had to stabilize it. Marcus has already mentioned the recent fad in knifemaking that consists of infusing the wood with resin. That would be ideal here.

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

Well, I lack the equipment to do that. But I wanted at least somewhat stabilise the wood even so. And I wanted to use the same finish that I have used on my mother’s knife, because it has proven itself to be very resistant. So I took the boat varnish and diluted it with acetone at a ratio approximately 1:4. You can see on the picture that the undiluted varnish is a lot thicker than acetone and it has sunk to the bottom of the jam-jar. However after mixing it did not separate again for a few days by now.

For the first dip I have put the handle in the heavily diluted varnish and I waited approximately 20 minutes until no visible bubbles were rising. Ideally It would be better to do this in a vaccuum-chamber, but acetone is very good wetting agent and this should be enough for at least a few mm penetration. After that I took the handle out and cleaned any varnish from the blade immediately with acetone. Then I have let it dry in a dust-free and well heated room. All that is left now is this week each evening after returning from work giving the handle a slight polishing with 150 or 180 grit sandpaper, dipping, cleaning, leaving it dry again until I am satisfied with the surface. I am not going to measure this time exactly because it is scattered a few minutes each evening over a few days. Lets say it is 30 minutes overall, including final signing of the blade.

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

That makes it 1:30 or 90 minutes for all of the work described here. That also makes the knife done for the purpose of measuring the time of my actual manufacturing process, so next time we can look at the data and look what (if) can be done there to make it more efficient.

Making Kitchen Knives – Part 6 – Basic Shaping of the Handle

I have decided to make the handle on this knife from an old piece of wood I have cut from a palette that stood outside for quite a while. I do not know what wood it is, I suspect birch. It is extremely weathered and looks kinda crap. But there is a trick to make such old wood look very fancy.

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

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

I have done most of the work per hand, first splitting the piece of wood along the visible crack, then cutting it with small hand-held saw to very roughly the final shape and drilling the holes for pins. So far this work was pretty uneventful and straightforward.

As you can see on the picture on the right, I have fixed the two halves with screws to make the final shaping. This is where things stopped being uneventful. The wood was not overly hard, but it was very tough and I could not shape it on the big belt sander because that is running too fast and the wood tended to gum up the belt and burn. So I have been stuck with using handheld tools. I thought that it is not a problem because I expected to do it quickly even so.

I was wrong. It took me 1:50, or 110 minutes, to get the handle scales into a nearly finished shape. I should have used my small belt sander, it has slower running belt and is better suited for wood.

Of course it would not be nearly as long work if I have made ordinary rectangular handle and not this ergonomically shaped one. However I consider the handle shape to be an important, even defining, component of this design. Simplifying the handle shape in the name of saving time would in my opinion strip the product of its uniqueness and I see no point in hand-made completely generic knives.

I think that I could reduce this work significantly by working on multiple knives at once, cutting the outlines with band saw and rough shaping with the small belt sander. Due to confined space in my workshop I need some time for setting those two devices up so it is not always worth for a one-off action. But should I prepare say 20 handle scales in one go, It would certainly be worth it.

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

Before proceeding to finishing the handle I had to use my magic trick to improve the looks of the wood. That trick is called “ammonia fuming” and consists of putting the scales into a big jam-jar with a bit of ammonia solution and leave them in it overnight of for a few days, depending on what your goal is – the longer the wood is in the ammonia, the darker it will become.

In this specific instance I have left the wood sit directly in the ammonia solution, letting it to soak it up. It is also possible for example to only let the wood above the solution in the fumes (hence the name).

I have experimented in the past with multiple solution treatments and I have at my disposal a few such processes to alter the wood to warying degrees – from mild color change to actually making the wood compacted and a lot harder. The advantage of these methods over staining the wood with a dye is that the color change goes deep into the wood so it does not get scratched off. It also looks a lot more natural in my opinion.

However, to wrap up, this step took more time than I expected it to, but I think I can put it in “low hanging fruit” basket, because I expect working in bulk should reduce time here significantly and I already have the machinery necessary for that.

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.