A Walnut Collecting Thingamajig

Collecting walnuts is a really unpleasant chore each fall. For a week or so we have to pick up several hundred walnuts each day from the ground and put them into a bucket, putting a big strain on back and legs. Two years ago I have improvised a little thingy that makes this work a lot easier, and this year I have perfected the design and made two pieces.

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It is nothing complicated, just a ladle with a very, very long handle. The handle should be so long that when you hold it against the ground at a comfortable angle where you can scoop up the walnut, it should be almost balanced at the point where you hold it, just a few cm before your hand. That way it requires almost no strength to manipulate and you can pick up the walnuts from the ground and put them into a bucket with minimal effort. It works so well that even my mother was able to do it even though she cannot walk around without a cane anymore.

The first prototype was made from a tin can and an aluminum pipe for window curtains, the second prototype was an old soup ladle with an old broom handle.

For the final version, I bought two cheap stainless steel ladles with flat handles. Then I took two willow branches, stripped them from bark and let them dry for a few days indoors over the radiator. When they were sufficiently dry, I have scraped and sandpapered them to a smooth surface finish so there are no splinters anywhere.

There are several options on how to fix the ladle to the end of the stick. I have simply cut about 15 cm slit into the thinner end of the sticks it and I also cut a piece of pipe that fits snugly around it. Then I inserted the ladle handle into the pipe, then into the cut in the stick and I hammered the pipe over the stick as a bolster. It does not need to be super strong, just strong enough to hold the ladle in place. Should it ever get loose, it should be possible to fasten it either by hammering the pipe further up the stick or by inserting a wedge.

As a final touch, I have screwed two steel hooks on the end so I can hang it in the shed, and I covered it with linseed oil to protect against moisture.

I have chosen willow, because it is extremely light and porous, dries up quickly and is for me relatively easy to get at appropriate size. But you could also buy shovel handles for this if you decide to make your own. They will be slightly heavier, but they will work. Broom handles would work too, but they are straight, and that is not optimal.

As you can see, these sticks are not straight, they have a slight bend to them, just as a shovel handle does. This helps a bit because the ladle naturally balances to a position where the nut stays in it. So you only need to exert force when picking up something, or tipping it out, not to keep it in. But one of the sticks was not only bent but downright crooked in all kinds of directions. And I did not guess the balance correctly when cutting the groove for the ladle handle on that one. That one tended to twist in the hand, causing it to not function comfortably.

So I had to re-shape it.

In case you ever need to correct a bend in a piece of wood, here is the most minimalist way:

1) Fix the piece of wood to your table or in a vice near the portion where you want to bend it, with one end freely accessible.

2) Hang some weight on the end of the stick and make any adjustments so it bends the stick in the desired direction. Here you can see me using a bucked and two bricks with a rope. That also allows me to regulate the extent to which the wood will bend – when the bucket rests on the ground, bending stops.

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3) Wrap the area where you want to bend the stick with a towel – paper or cloth, does not matter – soaked in water. Really soaked, water should drip from it. Then wrap the towel tightly with tinfoil, but do not squeeze the water out of it.

4) Try and build something around the tinfoil that will help to keep hot air to hold in place there for a bit. Here you can see me improvising with fireclay bricks and a piece of aluminum profile.

5) Heat carefully the tinfoil with either heat gun or propane torch at least until hot water starts boiling and dripping out of it around the edges and then some more. With a heat gun at 550°C it took me about two minutes. The wood gets soft and pliable under the foil and as long as it is hot, it can be bent a lot more than it would normally be without cracking.

6) You can either let it cool wrapped or if you are in a hurry, remove the foil and wet towels without burning yourself. The wood cools quickly and when it does, it will retain most of its new shape.

7) Repeat on different parts of the stick as many times as it takes to get it right.

Making Kitchen Knives – Interlude 2 – Picklin’ Scales

Today I took a bit of time and I have chosen and cut to size some wood for the handle scales. Among the species that I have chosen for this experiment are: Black locust, Cherry, Jatoba, Black elder, Larch, Oak and some unknown semi-rotten wood, probably birch.

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Because the purpose of this project is to gather information, I have taken all these various pieces of wood and I have given them into a jar with a mixture of ammonia and alcohol. I have written about this process before as “ammonia fuming”. The ammonia reacts with acidic lignin compounds in the wood and thus artificially ages it. In some woods the effect is really subtle – and I already know that using it for maple is a waste of resources – but on some woods, it can be really profound by giving the wood significantly darker and richer color. Oak should get almost ebony black after a few days. The rule of thumb is that if the wood has differently colored heartwood, then it is worth a try.

Some color will leech out into the solution, as you can see already (it was not a fresh solution), but that should not be a problem, it will not seep into the wood itself any more than any other pigment would. What is important here is the chemical reaction, if the wood does not react with the ammonia, it won’t change color significantly no matter what.

Ideally, only ammonia fumes would be used, with the sitting wood above the solution. But I cannot do that comfortably yet, for that I will have to make a grit of sorts that I can put into the jar. If I will ever bother, because whilst that process is a bit safer, it is a lot slower.

That is why I have added alcohol to the solution. It reduces the swelling of the wood during the soaking and subsequently reduces shrinkage and risk of cracks when drying. Plus it makes the subsequent drying a bit faster. That is something that I have tested already on two pieces of fresh birch which I have subsequently put away somewhere in my wood stash and now I cannot find them.

I will take the pieces out of the solution after a few days and let them dry outside for a bit (they stink like hell as you can probably imagine). Then we shall see what has happened to which wood. Some effects can already be seen after a few hours.

Bonsai Tree – Well, Thats Officialy Weird…

Previous Post.

Today, the terminal bud started definitively growing. There is no longer any doubt that it is alive and that last years’ growth did not go down the drain. Persimmon seeds are rare, so I am a bit fussier about this tree than I am for example about pomegranates or hibiscuses. So these last two weeks I was worried that the terminal bud is dead.

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However, I did not worry that the tree itself is dead. Because it did, in fact, begin to grow just one day after my last post. Only it did not start to grow at the tip. It sprouted a second trunk near the base. Which grows slowly, but steadily, ever since. This week the leaves started to get bigger and I have started to turn the plant 90° clockwise daily in order to achieve straight growth.

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However, this is not something that I expected. From pictures on the internet I have assumed that Diospyros kaki are small to medium-sized trees with strong apical dominance, akin to apples or pear trees. But this type of growth, where new suckers start growing at the root base and outpace in growth the main stem is usually the domain of shrubs and bushes, like the common hazel Corylus avellana. And even there it usually does not happen during the second year already, it usually takes a few years to establish the main stem first.

I can only speculate about the cause, so here goes: The root-trimming stopped the inhibition of one of the two buds at the base of cotyledons. Those remained underground in this plant, unlike for example in apple, where they rise above the ground. And since cotyledons are modified leaves, they have buds at their base, only those are usually extremely inhibited and do not start growing unless the main stem is damaged.

This gives me some information about the plant.

First, I will see next year what the root system looks like, but this might mean I will get multiple plants out of this, or one plant with multiple stems. Or that it will be very difficult to get bonsai out of this plant at all because the plant has insufficient apical dominance for that.

Second and more important – it means this species should be strong enough to handle even severe trimming and should be able to start growing even from older wood from extremely inhibited buds. That is, in fact, a very good property in a bonsai tree, because those might need to be scaled back occasionally by trimming several years old branches.

So while this was really unexpected and it is a bit weird, It is not bad news and it makes me hopeful that it will go well. We’ll see how the growth pattern develops from now on, I won’t interfere with the trees shape for at least a year at all.

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.

 

“It is just a flu” Should Never be Comforting Phrase in the First Place

I do not know whether this applies to the anglophone world, but in Germany, and to the same extent in CZ, “flu” and “cold” are treated as more or less synonymous. And because the common cold is, well, common, most people when they say they came down with flu, what they really want to say is they had/have a bad case of the common cold.

One of my former colleagues thus thought that flu is something trivial and she always disparaged me when I said that flu is a serious illness and not something to be flippant about. I do not know how she managed to live for over thirty years and get herself a kid without encountering real flu, but she was among the lucky ones in this regard I guess. A healthy, strong woman in her thirties.

But in 2008 her luck ran out. In the morning she came to work as normal, but just mere two hours later she began to have fever and chills and got a splitting headache. She excused herself from work at noon and went home and did not return for two weeks.

When she came back, a rare thing happened – she acknowledged that she was wrong and I was right in our previous discussions about this. She just had a case of real flu and for a few days during that time, she actually feared for her life, because there were times when the fever made her see double and she was barely able to go the loo.

It is a sad reality that some people – I dare say many people – actually, really need to experience some hardship first hand to be able to believe it is real. Be it flu, or poverty, or discrimination.

When some people were saying that Covid-19 is just another flu in a derogatory and dismissive way, I rolled my eyes so hard I nearly strained them. Even if Covid-19 were just a new strain of flu, a new strain of flu would be terrifying. Even old and established strains of flu can be terrifying when they encounter an unvaccinated person who never got flu before.

“It’s just another flu” should have been a call to arms, not a placating head pat, even if it were true.

Bobbin Lace Moth

Go big or go home. I have drawn and then made a bobbin lace moth of a little advanced design.

First I browsed the net for inspiration and I looked at especially the beautiful saturniid moths and then I made a sketch, with a biro on paper.

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I scanned the sketch and in Photoshop I went through several modifications and experiments with color. In the end, I have drawn a template which I subsequently printed out. I forgot to draw in the positions for pins this time, so hopefully, I won’t forget next time, because it was a pain in the ass to get the pins symmetrically.

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The next step was, of course, the work itself. I did not time it precisely, but I worked on it this whole week from Monday till today, so I estimate it at somewhere around 30 hours. The outer parts of the wings were very time consuming, each side took me about 8 hours. It is 20 bobbins lace after all. Here you can see the work in progress, as it was today a few hours before the finish line.

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The last step was to frame it. We do not have too many fabrics that could be used for background, but from those that we do have a shiny grey worked best.

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Learning Bob in Lace

Since I could not work too much in the workshop and the garden, I have decided to learn how to make bobbin lace from my mother. It is a bit frustrating because as much as I love my mom, she is terrible at explaining things. But I have learned how to make lace as a kid, and once forgotten things are easier to learn again, so I have succeeded somewhat and I have learned two basic lace-making techniques.

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These are bookmarks. The green leaves are meant to stick out of the book. I have decided to learn by making these because they are a bit useful whilst being enough boring to learn the necessary muscle-memory. And the eleven curves were excellent exercise – that part took three times as long as the straight part.

The red and blue ones are made with technique “plátno” (canvas). I started with the red ones, that s why those have three different colors in them, so I can easier keep tracks of the various threads. On the blue ones, I was more confident so the body is made entirely of blue with just the outer line white. The yellow ones are made with technique “polohod” (half-throw) and are the last ones I have made. I already knew sort-of what to expect and the colors were chosen for the looks.

In order to keep my hands functioning, I will have to interrupt knife-making and gardening with easier tasks, and bobbin lace seems to be a good fit. It can be interrupted at almost any time, it is easier than drawing or painting, it can be done whilst watching a movie and once prepared it can be done either just a few minutes a day or a few hours a day, whatever one can fit into the schedule. And it does not strain fingers, which is why my mother could continue doing it even after having metacarpal bones in both thumbs destroyed by arthritis to the point they had to be replaced by plastic ones.

Only now I have nine bookmarks without actually needing more than one. Well, I have more knives than I need too…

Bonsai for Beginners – Part 5 – Last Bit of Tree Physiology (possibly)

Previous post.

You didnae thunk I was done, didya?

I talked about the influence of apical dominance on tree buds, I talked about types of growth, but I did not talk about tree buds themselves. So let’s do that now.

Not all tree buds are created equal. As written in the last article, in some trees the buds are just small leaf-precursors bunched up together, in some trees they are covered by modified leaves to protect them during winter and in some trees they contain thus hidden precursors to whole twigs. However, there is more, much more, to them than even that.

You have probably noted that most buds form at the base of leaves and needles, but that is not the only place where they form. They can occasionally also form on injuries, from the meristematic tissue, just like roots can in some plants. And while the buds that form at leaf bases, but do not develop because they are inhibited by apical dominance sometimes may lose their ability to grow altogether, but in many trees, they can be re-activated and start growing under the right conditions. In some trees, buds can even form on roots, and that is where suckers come from – and those can be pretty annoying.

As a beginner, you are best off with plants that have at least one of these two properties – either forming meristemic buds on injuries or waking inhibited buds. They are both godsent. Plants without these properties can be grown as bonsai, and indeed are grown as bonsai, but they require often specific approach and advanced techniques.

The reason for this is simple – contrary to what I found to be a popular belief, bonsai do not grow slowly and keep their shape. They do grow slower than they would normally, but this is achieved in part by cutting the roots and by cutting the twigs. When you stop pruning your bonsai, in a few years you get a huge mess (which many people find out when they buy the mass-produced little trees sold as bonsai in supermarkets). And when you plant it in free soil and stop pruning, in a few years you get a normal-sized tree. This means that bonsai get bigger each year, but you once they reach the size you want, you need to keep them near that size for a long time. And that means occasionally having to cut back to older wood, removing twigs and branches and growing new ones in their stead. In some plants, this can only be achieved by grafting.

That is, unfortunately, another strike against coniferous trees, especially pines and spruces. I have seen what seemed like a revived old-tree bud sprout from a spruce trunk, but it is a rare occurrence that I think happens only under very exceptional circumstances. On a pine that cannot happen at all.

That is still not all. There is more to tree buds than that.

Many trees are grown as bonsai not for the beauty of their foliage, but for their blossoms. But trees often require special conditions in order to form blossoming buds. Sometimes it is given by the age of the tree, sometimes by the position of a tree-bud on the twig, sometimes by both and some more like the temperature in winter etc. This issue is quite species-specific and cannot be summed up succinctly.

So for a beginner, the best option is trees that can grow back from older wood and that are not grown for their flowers but for their leaves/needles. That does not mean however that you should avoid other plants altogether, it only means that once you start seeing any success with those, you are no longer a beginner.

Next, I will write where to get your first tree and write a short list of species/genera suitable for beginners. Later on, I will write about each of those in more detail.

Bonsai Tree – Wake up Already Dammit!

Previous post.

The persimmon tree did not change leaves color at all in the fall, which is a bad sign, but eventually, they fell off and did not dry on the plant, which is a good sign. I have stored it together with my citruses and other subtropic plants at 10-15°C, but about a month ago I have re-potted it together with my Ulmus parvifolia bonsai because those both started to grow already due to the abnormally warm winter.

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

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

During that, the plant had very nice and healthy roots. The main root was not overly long and it was not carrot-like at all, which is the worst that can happen. As you can see, it had nice and bushy side-roots on the whole length, an ideal situation. So I have cut off half of the main root and the cut was, again healthy-looking, white and wet. I covered the cut with lots of charcoal and I planted the tree in a wider and shallower pot than it was before

Lastly, I moved it into my room to be able to better control the substrate humidity to avoid root rot. I have expected the tree to wake up in the warmer room and start growing, but so far nothing and it is making me anxious. After all, my Ulmus parvifolia grow like mad despite being in the coldest room in the house.

And today I realized that I need not try and cope with that anxiety alone, so here you have it, now you can be anxious too. Ain’t I grand?

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The terminal bud is still bright green and the top leaf is soft to touch and that is a good sign.

But it does not grow, dammit. Maybe this tree reacts to daytime length before it starts growth?

Bonsai for Beginners – Part 4 – Another Bit of Tree Physiology

Previous part.

This bit is, alas, often not discussed in bonsai literature as much in detail as it should too. Some books mention it in passing, some do not mention it at all. The talk is about types of tree growth. (note – the used terminology is my own, I have long since forgotten the official technical terms and anyway I am too lazy to search for them in foreign language)

There are three basic types that every bonsaist needs to be aware of, and it is vital to know which type each of your plants has because they determine what kind of care they require to get turned into a bonsai and survive the procedure.

1 – Continuous growth.

This does not mean that the plant grows continuously throughout the year, although usually when a plant does grow the whole year, it has this type of growth. But the growth might slow down or stop completely in certain conditions, like drought or cold or insufficient daylength. However, when the growth slows or stops, it does so without any apparent change in the plant’s physiology. No special structures develop, the plant just stops growing and when the conditions get right again, it continues. The “buds” are simply a bundle of small leaves/needles bunched up together.

In temperate regions, typical representatives of this type of growth are some evergreen conifers, like junipers or thujas. It is most typical for many subtropic trees – citruses, olives, and hibiscus. And of course tropical plants and succulents, like a ficus and money tree. This type of growth have mostly evergreens, although there are deciduous plants with it – for example, russian olive (Eleagnus angustifolia) and fig tree (Ficus carica), but they are the exception, not the rule.

2 – Continuous growth with a hibernating stage.

During the season, these plants just grow like the first type, adding leaves to their twigs continuously and growing in length. But when the conditions start to signal the end of the growing season, not only do they stop growing, they create specialized wintering buds. These buds then contain a relatively undifferentiated beginning of the next twig. When the hibernation ends, the buds shed their protective layers (modified leaves) and from them emerge twigs that again start to grow in length and adding leaves as much as they can manage.

This type of growth is typical for deciduous trees in temperate regions, like willows, poplars, maples, hazels and many more. I am not aware of any evergreen with this type, maybe holy (Illex sp.).

3 – Growth in spurts.

Some trees take the hibernation stage to the next level. The wintering buds do not contain just the beginning of a new twig, but a complete one with non-differentiated buds. At the beginning of the growing season these whole twigs emerge from the buds, they stretch in lengths and gain girth, but they do not add any new leaves or buds – the number of those has been determined previous year already.

This is typical for firs, pines, spruces and many other coniferous trees of temperate regions. From the top of my head, I only can remember one deciduous tree with this growth type – beech (Fagus sp.).

For a beginner, types 1 and 2 are the best option. Those are comparatively easy to manage, they mostly heal easily from pruning and the pruning itself can be often done at almost any time of the year or in wide enough window not to need to fuss about it too much.

Type 3 is difficult, and thus alas another point against pines. These types of trees cannot have twigs trimmed just anytime and anywhere, they often require being cut during very specific time otherwise the next year’s buds will form where you do not want them.

The worse in this regard are spruces, whose growth is nearly completely unmanageable. That is why you won’t see many very old spruce bonsai trees. More on that later.

From a File to a File Guide

I do not know where and when, but I have gotten a broken and rusty file that was too small to make a usable knife, but I thought I might find a use for it. Then, somehow, somewhere, I got another, very similar one. Almost as if I CTRL+C CTRL+V it.

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I even nearly forgot about both, but the learning batch of kitchen knives is giving me some grief and I realized that among other things I do need a file guide for making ricassos if I am to make knives reasonably fast and comfortably (all 12 knives have mistakes now, but their whole purpose was learning and it was to be expected – these will be given out for free anyway).

And since I have to heat my workshop nowadays to do anything, I have used that opportunity and I tossed them both into the fire. I got them nice red-glowing and I let them cool down very slowly in the stove.

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The next bit was pretty straightforward – I cut off the tangs with angle-grinder and I ground the rest flat-ish on the belt grinder with a pretty chewed-up 40 grid ceramics belt and nothing more. I do not have grinding attachment for flat surfaces yet, so I had to grind simply against the platen, but I have managed a flatness that I estimate about ~0,1 mm – there was a tiny bit of light coming through when I put them against each other and looked against a lightbulb – which is definitively good enough for its purpose.

Next, I have drilled two pairs of 5 mm holes down the center of one piece,  10 and 22 mm from each end, and I copied the holes into the other piece. To keep the holes reasonably aligned I have first drilled one hole, then used a 5 mm drill bit to keep the pieces aligned, drilled the opposing hole and so forth.

The four holes were not perfectly in line, but that does not matter that much and in the end, it has proven a bit of a blessing – the slight miss-positioning serves as a visible sort-of poka-yoke. However, I had to make temporary marks with a file on both pieces to keep their alignment in check without having to fumble each time I take them apart during the work.

With four 5 mm holes in both pieces, I have cut M6 threads in the inner pair on one piece and the outer pair on the other. The other four holes I have widened to 6 mm and chamfered the edges with an 8 mm bit.

I have found two M6 screws with wide-socket heads in my drawer, but I could not find any 6 mm steel stock. I thought I have one, but I thought wrong. I also could not find any M6 screws that had the non-threaded part thick enough for a good fit. So I had to make one. I started with a 6 mm thick old, bent and rusty nail and I cut out the approximately 100 mm straight part. Then I have ground it down to 5.8-5.9 mm using running slack-belt on my belt sander and spinning it with a cordless drill. And then I polished it a bit with old and used-up trizact A-65 belt.

Of course, staged, neither device was running for the photo-op. © Charly, all rights reserved. Click for full size.

I cut the resulting round piece in half and then came the most challenging part – to cut about 4 mm of M6 thread into one end of each bit. I failed at this, both shafts have the thread a tiny bit at an angle. I guess one of my future projects will be making a jig for cutting precise concentric threads, cause I certainly cannot manage it by hand.

But I could assemble the whole thing after that and it worked, although I cannot fasten the leading-rods too much due to the badly cut threads. But when assembled, it had no sideway wobble and that is all I needed. So I have assembled it, tightened the screws and ground the outside-facets into perfect alignment. And here is the nearly finished thing, gleaming in my grubby hand.

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Now for hardening. I did not know whether the files were surface hardened or thorough-hardened, and of course, I had no knowledge of the carbon content of the nail I used for the leading rods, only that it was very, very soft. And even so, I wanted to make it as hard as I possibly can.

Therefore for the hardening, I did not go for simple heat-quench. I went for carbonitriding, which is the hardest I can make a steel surface in home-setting. For this, I took the whole thing apart again and I put the two flat-pieces and two rods into a steel tube together with a mixture that would, when heated, enrich the surface with both carbon and nitrogen.

Commercially this is usually done with various cyanide salts, but not only do I not have those. I don’t even want to have them. I have the training to handle cyanide properly, bot I do not have the means and the desire to do so. Luckily many ordinary things will do the same – leather scraps, bone and hoof dust, hide glue, soy flour etc. Anything organic that contains a mixture of carbon and nitrogen compounds. But I have not used any such improvised mixtures, I went for a 1:1 mixture of urea and dehydrated sodium carbonate. These two chemicals react together to produce sodium cyanate when heated. Despite the very similar name, this chemical is not nearly as toxic as sodium cyanide – its LD50 is about half of that of kitchen salt. And it works for carbonitriding.

I compacted the salt mix around the parts as well as I can.

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Next, I put a cap from an old pea-can on it – it need not be air-tight – put it in the forge and the whole assembly went into the fireplace, because the first circa 20 minutes it produces rather noxious smoke that I am not too keen on inhaling.

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It sat there for two hours with the burner on the lower setting. Temperature between 600-800 °C is enough for this and after two hours I should have a hardened layer of at least 0.2 mm.

When the time was up, I took the container out of the forge, took the lid off and dipped its contents into a bucket of cold water. A slight explosion took me a bit by surprise – either not all salt has evaporated yet or a piece of glowing hot fireclay dropped out of the forge (my forge, unfortunately, died in the process, the inner lining has finally disintegrated completely), but it was just a little bang and nothing dangerous.

All the pieces were successfully hardened, although one flat piece developed a very slight bend – a few tenths of an mm. But I could still assemble everything together, so I did that. I tightened the screws and tempered the whole thing for two half-hour cycles in boiling water – I wanted to relieve some of the stress so it is not as brittle as glass, but I also want it to retain as much hardness as possible.

A few passes with scotch-brite wheel cleaned all the crud off and buffing with abrasive pastes polished the scratches enough for a bit of protection against pitting corrosion.

And that is it, I now have a file guide. Despite my lax attitude to precision, it does not wobble but it opens/closes easily, the surfaces are hard enough for ordinary files not scratching them and it is from recycled materials, which is my favorite kind of material to use for such thing.

© Charly, all rights reserved. Click for full size

 

New Forge Build – Watching the Cement Dry

As a mold for the inner chamber, I have used a piece of a paper tube of slightly bigger diameter than is my goal and a bottom made of plywood with supports that could hold the forge on its side like an impromptu bucket. I have covered the plywood and the tube with a plastic paper bag to make it waterproof. For the inlet-outlet channels, I have inserted into the orifices plastic tubes at an angle. Both tubes are at an identical angle, slightly inward and off-center. The idea is to create a rotating vortex of hot air in the forge since in the previous one I got the best results when I have managed to achieve this. Both channels should be approximately the same.

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

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

After that, I have mixed ordinary fireclay with pearlite at a ration 1:3 to the consistency of dry cement and stuffed the whole structure almost full, with only about 5-10 mm gap at the top (at the bottom the gap is taken care of by the thickness of the plywood. I think I have used too little binder (water glass) – I have used the amount recommended for the fireclay and I forgot that the dry pearlite will suck out most of it – so the result is not very strong and it is a bit crumbly. But I hope it won’t be a problem since it is not a load-bearing structure and I will make 5-10 mm hard coating on top after it dries. It did not crumble when I have carefully taken out the tubes and the plywood bottom after three days.

Now it will take its time to completely dry. Today it is over a week and still, it is very wet. I have added a fan to blow air through it to aid the process a bit, but even so, I suspect it will take at least a month to dry properly. Luckily I have twelve knife blades hardened and in work now, so I won’t need the forge for some time. Plus soon there will be more than enough work in the garden to keep me occupied for weeks.

So, in the meantime, we all can watch cement dry.

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