Making Kitchen Knives – Part 4 – Heat Treatment

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

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

 

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

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

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

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

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

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

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

Making Kitchen Knives – Part 3 – Basic Grind

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Even When Not in Doubt Marcus Knows

Yesterday Giliell posted about the wonderful gift of acrylic casting supplies that she received from Marcus, noting that she’d been considering trying this art form.  Well, I received the same gift from Marcus last week and I wasn’t even thinking about trying resin casting. Marcus just knows. He knows that I have a large collection of seaglass and that this is the perfect medium to pair with them. I can’t wait to try it, but I’ve been rearranging my cabinets and my work table is buried under a ton of paper crafting crap right now so I haven’t gotten past the gazing in wonder at it all yet. Well, I have watched a few how-to videos (link below) that have given me lots of ideas for using seaglass and more. I love the bracelet Giliell made and it’s made me even more anxious to try it. Alrighty then…time to clean up the mess and play. Tune in over the weekend to see if I can make something as pretty as Giliell did. Thanks, Marcus. You definitely spread sunshine.

Resin Obsession (a very good site)

Wow, Thank you Marcus

Yikes! The bigger picture (my work table is under there somewhere)

 

 

Making Kitchen Knives – Part 1 – In the Beginning…

… there was a bar of steel.

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

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

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

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

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

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

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

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

When in doubt rely on Marcus

I’ve been in a bit of personal debate recently about whether or not to get me some sort of starter kit to cast things in resin, with the arguments in pro being that you can create beautiful stuff, and those in contra being that I already have half a house full of crafting supplies.

The argument was resolved nicely when one of Marcus’ boxes of wonder arrived this week which included everything you need to get started, including the proper gloves (not pictured).

Crafting supplies to cast things in resin

Oooohhhhhhh…

You can see the resin, moulds, colours, glitter, some of Marcus’ gorgeous abalone shells, some dried and coloured flowers and even gold leaf, which peasant me almost spilled on the floor because peasant me had no idea what it was. I’m not sure about those rectangles, I guess they are a work surface for mixing small amounts with colour.

Of course I couldn’t wait to get started. I thought that this would be a great way to use our “mermaid tears” that we collected at the beach.

resin bracelet with colourful driftglass

Very first bracelet

As you can see it’s not perfect yet. I think I didn’t stir the mixture for long enough and my ratio was probably a bit off. Also the pieces all sunk to the bottom. I think I need to cast something like this is two or three sittings, which will probably test my patience a lot.  But I’ve also got a lot of ideas already.

Thank you very much, Marcus. You’re definitely at least as crazy as me, but I love you all the more for it.

Masterclass Horsehair Braiding

I don’t think I would have the patience or the dexterity to do this type of art, but Kestrel has it in spades. She’s sent us a gorgeous example of the horsehair braiding that she does and I’m in awe. Thanks so much for sharing, Kestrel.

 

Years ago a lady had me braid a horsehair bracelet for her from her horse. She told me she was really having trouble with a watch that she truly loved: an Ecclissi watch that was just simply falling apart. She told me she had bought it over 30 years ago but loved to wear it. This is how it started out:

©kestrel, all rights reserved

You can see the chains were falling apart. The lady asked me if I could possibly repair it with braided horsehair. She said she would really like it if it looked like twill. I set to work counting hair and working out how to perform this repair.

©kestrel, all rights reserved

The finished watch had 4 bands of 8-strand braiding on each side of the watch. Because I used two different colors I got the twill effect.

©kestrel, all rights reserved

 

 

 

 

 

 

 

Youtube Video: Forging a Viking Dane Axe – With Tord of Thor’s Forge (part 1)

I enjoyed this video immensely. Tord of Thor’s Forge in Sweden shows a process of making a two-handed Dane Axe blade the traditional way – from recycled wrought iron and carbon steel, both refined by bending and forge-welding. As close to a Viking-era technology as possible.

I learned a lot just by watching and I hope that some day I will have a chance to try out some of those things myself.

Video is 40 minutes long and there is about 4 min introduction by Matt Easton. Take that into account if you decide to watch.

Chinese Fabric Art

Opus has sent us a special treat… a few pictures taken while he was visiting China. The photos are full of energy and bright, bold colour and I can’t help but think that it must have been very special to see this art with people who understand its true value. Thanks so much for sharing, Opus.

 Pictures from Lijiang in southern China.  I visited with a couple of fabric artists who wanted to see the work done by local women. We were not disappointed!  The woman with the elaborately embroidered headwear is Naxi, best I can remember.  Lijiang is on an ancient trade route, the Tea-Horse road, which was used to trade tea from southern China for Tibetan horses.

©Opus, all rights reserved

©Opus, all rights reserved

©Opus, all rights reserved

Making a Rondel Dagger – Part 17 – Finale

When I have made my first, very crude, knife some twenty years ago, my friend’s father commented:

Charly, people want it to be handmade, but they do not want it to be immediately apparent that it is handmade.

That advice stuck in my mind so when I have read Feet of Clay from Terry Prattchett much later, following line resonated with me:

The thing looked like the kind of pots Igneous despised, the ones made by people who thought that because it was hand-made it was supposed to look as if was hand-made, and that thumbprints baked in the clay were a sign of integrity.

It is not impossible to get a handmade thing to look just perfect, but it takes great skill and experience and I am not there yet, although I might be heading in the right direction. The pictures hide some of the mistakes and imperfections that were not intended and are apparent – for example the blade is not symmetrical against the handle and the hand guard, so when it is in the scabbard the upper part of the guard sticks out more than the lower, and it is visible. Despite my best efforts the blade got a scratch from a grain that got somehow into the scabbard, and the handle got scratched too in the meantime. Which was inevitable if ever the knife were used, and I do intend to use it at least somehow, to see how it fares.

 

But enough of that, let me present to you the dagger of one of the most kickass characters in fantasy literature known to me, Cirilla Fiona Elen Riannon, aka the Lion Cub of Cintra, granddaughter of queen  Calanthe Fiona Riannon of Cintra, aka the Lioness of Cintra and daughter of Pavetta Fiona Elen and Emhyr var Emreis, Deithwen Addan yn Carn aep Morvudd the Emperor of Nilfgaard. This is my interpretation of the dagger worn by her as a sidearm in the computer game Witcher 3 – I noticed that dagger right on my first encoutner with her in my gameplay and I immediately wanted to make one. I photographed it on a bobbin lace doily that my mother has just made for her sister’s birthday. Bobbin lace is period/theme appropriate and I think it provides nice contrast and improves the quality content of these pictures by no small amount.

 

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

I tried to tie the leather strap as close to how it is done on the in-game model as I could manage. The only significant difference from the game model is the red leather on the scabbard, instead of brown.

 

If you look closely, here you can see that the hand guard does not stick out symmetrically on both sides of the scabbard.

 

Overall length ca. 395 mm, blade ca. 257 mm long, 23 mm wide at the guard, single-edged. Good cutting ability although not as good as a dedicated cutting blade would have. It is still a stabbing weapon.

 

Handle is turned out of maple wood. Rings are allingend perpendicularily to the blade so the shiny lignin spots are symmetricaly with it on both sides of the handle.

 

Rondel has ten hammered grooves giving it a daisy like look. All metal parts are polished to mirror finish and buffed with jeweler’s rouge.

 

Although the handle looks massive, the knife is weighed towards the tip when put on a flat surface. I guess it could be thrown, but I do not intend to try it for fear of the blade breaking.

 

My signature for knives from now on – my initials in Glagolitic script. This is also the writing used in the Witcher games, so it also thematically appropriate.