Storks on the Hunt

Avalus is doing some fieldwork with his new camera and he’s spied this flock of storks. He tells me that they’ve been around for awhile and hints that we may see them again.

©Avalus, all rights reserved

©Avalus, all rights reserved

©Avalus, all rights reserved

©Avalus, all rights reserved

©Avalus, all rights reserved

All the Pretty Little Flowers 2: The Slopes

As you may recall, our house is built on pretty steep terrain. The ground floor windows in the front are the first floor in the back. From there you have another treeish metres height difference to the garden. last year we had the stairs remodelled, since the old ones were rapidly becoming accidents waiting to happen. The slopes on either side are still steep and this year we started to stabilise the left hand side so we can put a lamppost on top.

The small area created at the top has been sown with “butterfly meadow” and “wildflower mix”. You can buy these seed mixes easily in Germany as many people are trying to bee more friendly. I also always toss a few handful on the rest of the area, which remains in pretty disarray.

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The dark side of the pumpkin patch. That area is more or less permanently in shade and this year we just didn’t have the nerve to look for something that would thrive there after the slugs ate the first round of plants. Suggestions welcome. But you can see the structure well.

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The pumpkin/squash/courgette patch. they are coming along nicely with several promising plants already. Only I never know what is what. You can also see the bane of my gardening existence: Horsetail. A plant that survived the dinosaurs. Common gardening advice is “nuke it from orbit”. It spreads through rhizomes that are also very fragile and will snap quickly so you’ll never get them all out. But you can make some wonderful fertilizer out of it: put the plants into a bucket with water and let it rot. Stinks like hell, but 100% organic, free and efficient.

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Different Hardening Methods for N690 – Experiment

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

© Charly, all rights reserved. Click for full size

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

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

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

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

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

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

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

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

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

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

What can I deduce from this? Several things.

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

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

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

All the Pretty Little Flowers 1: The frontyard

Pz has been raging and ranting about lawns and lawnmowers and I wholeheartedly agree. It also prompted me to do a bit of bragging about the sheer beauty of not having a lawn. Let’s start with the front yard, which was carefully weeded when we bought the house. Here’s another aspect of those lawn and front yard regulations: To keep them up to “standards” you need time to do it or money to hire somebody else to do it. I quickly reduced weeding to an absolute minimum. Nobody touches a dandelion in MY front yard. One thing that happened quickly was that wild strawberries overtook most of the ground. They do many things at once:

First, they protect the ground from drying out.

Second, they provide flowers for pollinators.

Third, they taste so good.

©Giliell, all rights reserved

In spring I built a plant tower in an empty space that had previously been occupied by some useless evergreen bush that got thankfully eaten by caterpillars. I also planted some regular strawberries there.

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Guarded by my little dragons

©Giliell, all rights reserved

M

If you want to make bees happy, plant lavender. It will also make you happy. Lavender is low maintenance, just cut off the dry stalks in autumn and ok with dry weather. I don’t know if it can survive Minnesota winters.

©Giliell, all rights reserved

©Giliell, all rights reserved

Probably no German frontyard is complete without a hydrangea. They are lovely, but high maintenance (needing much water, cutting, right ground) and absolutely no good for insects. Like most plants here they are a leftover from the previous owner. I figure that with so many bee friendly plants around I can afford a couple that only look nice.

©Giliell, all rights reserved

I have no idea about most of the plants that grow here. They were already well established when we moved in. Some of them have already bloomed long ago. I basically get flowers from March to October.

©Giliell, all rights reserved

©Giliell, all rights reserved

©Giliell, all rights reserved

Also one corner has been taken over by some wildflowers. I like them, the insects like them. We’re good.

©Giliell, all rights reserved

Oh, and btw, the next door neighbour has a lawn (I’m not criticising her, she’s 90 and still living all alone). It’s a sad brown area right now and the grass always creeps into my yard which means that I have to do the weeding there.

A Wee Bit of Bee Butt

Story and pictures by Avalus

I noticed earth-bees emerging and vanishing between two stone plates in the paveway in the garden, so I crouched down and waited for the next bee to come out. But the inhabitants were not that sure about the sudden appearance of a strange black block in front of their door and so cautiously just poked their heads out only to retreat again. (first picture and the detail cut out, with a head of a bee eying me suspiciously visible) Then after five minutes or so one of them had enough of the paparazzi, moved out and took off just as I moved in a more comfortable position and so I nearly missed her. As you can see, I just captured her butt :D.

photo 1 ©Avalus, all rights reserved

Photo 1 (detail) ©Avalus, all rights reserved

Photo 2 ©Avalus, all rights reserved

Photo 3 ©Avalus, all rights reserved.

 

 

 

 

Quenching Jig

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

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

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

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

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

© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

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

© Charly, all rights reserved. Click for full size

© Charly, all rights reserved. Click for full size

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

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