My first Commission – Part 3 – Quality Control

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

The “better” blade looks now like this.

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

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

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

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

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

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

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

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

 

Tree Tuesday

Chic Choc Mountains, Gaspe Peninsula ©voyager, all rights reserved

There’s one more reason to love trees. A new study from The Crowther Lab, ETH Zurich, published in the Journal of Science, July 2019, says that targeted reforestation could isolate 2/3 of human-made carbon emissions and would be the best way to mitigate the effects of climate change.

The researchers calculated that under the current climate conditions, Earth’s land could support 4.4 billion hectares of continuous tree cover. That is 1.6 billion more than the currently existing 2.8 billion hectares. Of these 1.6 billion hectares, 0.9 billion hectares fulfill the criterion of not being used by hu-mans. This means that there is currently an area of the size of the US available for tree restoration. Once mature, these new forests could store 205 billion tonnes of carbon: about two thirds of the 300 billion tonnes of carbon that has been released into the atmosphere as a result of human activity since the Industrial Revolution.

Calculations were made based on current conditions and cities and agricultural areas were not included because those areas are necessary to support human life.

According to Prof. Thomas Crowther, co-author of the study and founder of the Crowther Lab at ETH Zurich: “We all knew that restoring forests could play a part in tackling climate change, but we didn’t really know how big the impact would be. Our study shows clearly that forest restoration is the best climate change solution available today. But we must act quickly, as new forests will take decades to mature and achieve their full potential as a source of natural carbon storage…. The study also shows which parts of the world are most suited to forest restoration. The greatest potential can be found in just six countries: Russia (151 million hectares); the US (103 million hectares); Canada (78.4 million hectares); Australia (58 million hectares); Brazil (49.7 million hectares); and China (40.2 million hectares).

I encourage you to check out the Crowther Website where you can read the report in full. The site also offers a tool that allows you to pinpoint any area on the globe to find out about its reforestation potential.

 

via: Science Daily

Jack’s Walk

By the lake. ©voyager, all rights reserved

It’s a gloomy overcast day with rain on the way, but the heat wave has broken and the temp is a pleasant 24°. Shade isn’t necessary today so we walked the path beside the lake and listened to all the children playing in the water on the other side. The far side of the lake has a camp ground with picnic and swimming areas and my city has just done away with the $10.00 fee to use the facilities. It’s always been busy on that side of the lake, but since the fees have been waved it seems to be getting even more use.

Jack and I prefer the quiet side of the lake. Jack can swim without kids bugging him and I don’t need to worry about Jack looking for cuddles when he’s soaking wet. Jack just doesn’t understand why people don’t want to love him up when he’s wet. I’ve tried to explain it to him, but Jack keeps telling me that it’s only water and that it makes him extra adorable. Alright, Bubbs, we’ll go with that and just stay over here on our own. I don’t mind the solitude a bit.

Making Kitchen Knives – Part 12 – Playing with fire

Last time this part of the process gave me some grief and I also have expressed some skepticism with regard to how much time it takes me. Yesterday I have calculated that unless I get this time under 12 Minutes per blade, it is not worth doing from a financial point of view. So, how did I fare today?

I had 13 kitchen knives and 2 hunting/camping knives to for hardening. I wanted to harden one half in foil and one half with a new experimental protective coating, but I only got enough foil for five blades, so I used it for both hunting knives (those will be sold, so those were more important to not mess up) and three kitchen knives. The rest got the new experimental protective coating.

I started by properly preparing my workplace in order to not needlessly waste time. On the left, you see a can with oil, a water bucket, several pliers and the blades. On the right is my mini gas-forge on my circular saw table, which is metal and thus non-flammable. I had to work indoors, there was a threat of homeopathic rainfall.

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

First I let the forge heat for fifteen minutes empty and then I started to put blades in it. In order to give the steel the soak time it needs (30 minutes), I started by putting in one blade every five minutes, always putting the last blade on the left side, pushing all the blades inserted before that to the right towards the burner. After half an hour I could quench the first blade and I continued with 6 blades in the fire at once.

Blades in the forge. © Charly, all rights reserved. Click for full size.

Unfortunately, just like last time, the temperature was a problem. I tried to insulate the forge a tiny bit better, but it just did not help, this burner is too small. I got over 950 °C, but that is still some 70°C short of the minimum for this steel. It got hardened alright, but probably not to the fullest potential. That I will not know until I have cleaned and tested the blades, and that will take a while. So far I only could take each blade and try if it scratches into a piece of unhardened steel – and they all did. (A side note to temperature measurement – I tried to look it up, and oxidized steel at this temperature has an emissivity around 0,9, so my IR thermometer should give accurate enough readings in default settings.)

I knew that my oil container is a bit small, so the oil will heat up way too much in due course, that is why I quenched the blades double – first in oil, then in water. That way I also extinguished any flaming oil clinging to the freshly quenched blade. It is a bit risky, but I did not hear the tell-tale cling of the cracking blade this time, so maybe I got away with it. We will see if some cracks show later on.

Hardening the blades in foil was a bugger. For the kitchen knives, I pulled them out of the foil before hardening, and they all warped in quench something awful. The camping knives got quenched still in the foil, and they surprisingly still got hardened rather well. Maybe the next step has helped? I do not know.

For the next step directly after quenching (after quenching all blades, which took me 2:25 or 145 minutes) I packed all pieces in plastic foil and gave them into our freezer at -20°C. Ideally, I would put them in liquid nitrogen to cryo-freeze them, but I do not have that kind of equipment to play with. So I looked at the internet and I found that in some steels of similar composition simple freezing below 0°C is enough, so I reasoned – it costs me no money and no time either, so on the off-chance that it does something I will do it. I have no way of measuring whether it helped or not, but it did no harm for sure.

After about two hours in the freezer, the blades got out of there and into the kitchen oven at 150°C for 1 hour.

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

After that, I left them cool down to room temperature and when they cooled off and lay for one hour at RT, I tried to fix the warpage on the three kitchen blades by clamping them between a few pieces of steel before the second tempering, which was again one hour at 150°C.

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

It did not help, the edges remained warped. So I clamped them again and tomorrow these three blades go into the oven again, this time at 200°C for one hour. That means they will be less hard still, but hopefully they get a bit straighter.

If not, then what I have here is a case of “knifemakers do not make mistakes, they make smaller knives”. The mistake that I did not make this time has, in my opinion, nothing to do with the use of protective foil, it was in my opinion just a coincidence that all foil-wrapped knives warped. I think I have simply ground these blades too thin – remember how I complained about my abysmal skill with the belt grinder?

At least I had no banana-bending to one side, which means that my grinds were symmetrical.

The protective coating actually did dissolve significantly in hot water this time, so I think that I am on the right track there.

And what was the time? All in all, with packing some blades in foil and coating some with badly prepared mixture whilst chatting with my brother and my sister in law, and preparing and cleaning away the whole workplace, it took me about 15 minutes per blade. That is an excellent result. 75% improvement compared to the last time. I think with a few more tweaks I can actually really get this to the 11 minutes per blade that I need. I am not there yet, but I think it is possible.

The next part is the polishing. The biggest time-eater and finger-breaker of them all.

T is for Teal

From Nightjar,

T is for Teal ©Nightjar, all rights reserved

Teal.

I’ve noticed that some of my succulent plants display a teal hue that almost glows under certain light conditions. I tried to capture that here, although this one required a bit of post-production to bring it closer to what I had in mind. I still liked the result.

 

Link to previous alphabet post

Behind the Iron Curtain part 31 – Freedom of Speech

These are my recollections of a life behind the iron curtain. I do not aim to give a perfect and objective evaluation of anything but to share my personal experiences and memories. It will explain why I just cannot get misty-eyed over some ideas on the political left and why I loathe many ideas on the right.


If you have read enough of my writings and comments, you know that I am no free speech absolutists. I do think that there should be legal limits to what, where and how is discussed because unregulated free speech is actually not free at all – it allows toxic ideas to spread at the detriment of sensible ones. The old paradox about tolerating intolerance does definitively apply.

However I do on occasion wonder how much of this attitude is due to my growing up in an environment where freedom of speech was de-facto nonexistent. Oh, people were allowed to say anything they want about whatever they want – as long as it did not contradict the official party opinion on the matter. Criticizing USSR or the Communist Party was not allowed and the punishments for transgressions were not trivial either.

During my life, the regime has mellowed a lot already, so people did not just disappear overnight for saying something wrong, but they still could get into trouble if they said something critical of the regime and it got to the wrong ears. And it could be enough if one of your kids babbled in the school about how one of their relatives was criticizing the communist party.

I have found myself in this situation as a kid. One of my uncles was a fervent follower of the party in the 60s, then he got shortly out into West Germany in the 70s and after seeing the standard of living there in comparison to our “socialist paradise”, he made a U-turn in opinion. The only reasons he and his wife got back were their two sons, who were still small and whom they did not have with them – and whom they might not get back if they emigrated illegally.

Ever since that he did not have a kind word for the Communist Party and he vented often in front of the TV during the evening news. I was present a few times for that and it caused me great discomfort to hear what he said. It was in direct contradiction with the “truth” that was told in school, with the “truth” printed in Pravda, and with the “truth” on TV. He was critical of all those amazing and all-knowing party officials! At the time I had no way of discerning on whose side the actual truth lies, but luckily I did not go to our teacher for answers, but first to my parents. Who have told me that I should try not to think about this and to never tell anyone what my uncle was saying because he could go to jail.

After the fall of the Iron Curtain, this was summed up in a saying “One of the most difficult things in parenting was to convince your kids to tell the truth at home, and not to tell it in public”.

Finding the right balance between unregulated speech and an iron grip on what people are allowed to say is not an easy task and I do not have the answer where the exact line lies. I have seen both extremes in action in real life and on the internet and both extremes do not work in the long run. Too much regulation and you end up with an isolated bubble, an echo chamber (and I do not mean state regulation only). But too lax or absent regulations lead to toxic environments overrun with those who shout the loudest and who have no squabbles to spout lies faster than they can be reasonably debunked. So I can only say the balance is worth seeking.

Midwinter Blooms

Some pretty-in-pink winter flowers from Australia courtesy of Lofty.

Although its midwinter here there are still plenty of bright little things to see on the non rainy days. These little flowers are around 1/2″ or 12mm long and were trying to hide in a dark corner, but a sunbeam surprised them. Described here: https://en.wikipedia.org/wiki/Epacris_impressa

Epcaris Impressa ©Lofty, all rights reserved