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.

My first Commission – Part 2 – Conjunction of Projects.

I did not expect to get a commission this early. I am not quite there yet to be able to make a good quality knife in a reasonable time. I am confident I can get the “quality” part right, but time – definitively not. My original plan was to perfect my manufacturing process with the kitchen knives, which, if you remember, I have left this spring at a phase where the outlines of the blades were established, but nothing else.

But I need to work on both projects now because apart from the time I also need to use my resources – electricity, propane gas and charcoal – in a more economically savvy manner. That means hardening multiple blades in one go for example. And that means I have to establish the primary bevel grind on the commissioned knife as well as on the kitchen knives so I can harden and temper all those blades together.

But the whole point of the kitchen knife project was to develop a viable manufacturing process, and establishing the primary bevel was the part where I knew I have to develop and build a fixture first. You have seen my very first attempt. It did work, but not very time-effectively, I wasted about a minute each time I needed to flip or change the blade. That is a lot, considering that for the basic grind I need to go through five belts on both sides. It was clear I need some way to hold the blade steady, but being able to dismount and re-mount it quickly.

The second attempt was this.

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

The idea was that the hinge and two screws will allow me to set the tilt, and the knife-blank can go into the slot where it will be held by the levered screw. It did and did not work. That is, it worked for one knife and then it broke. The problem was moisture which caused the wood to deform and split. But even without that, fixing and releasing the blade was still not as easy as I would like it to be. I got an idea on how to improve this design, and I already bought the materials to try it out, but then I got sick and everything got put on hold for a few months as you know. All I could do was to think about it.

And then my parent’s hard drive died and I got the idea to use those strong neodymium magnets. But for that, I need first to develop a system on how to switch them on/off, and that needs more time than I can spare right now for fooling around. The customer is not in a hurry to get the knife – they know I still have my day job and that I can only do this in my spare time – but still I think I should not strain their patience. So I needed a fixture, fast.

Luckily I got an idea utilizing things that I already have – the first attempted fixture and a few cheap, weak magnets. There is a way to make weak magnets a lot stronger, at the cost of reach – by concentrating the magnetic field to one side with two slabs of iron/mild steel. It is also possible to make longer arrays with this system.

Magnets and pieces of steel. © Charly, all rights reserved. Click for full size.

So I took six of those cheap magnets and cut nine pieces of mild steel exactly as long as the magnets, but a few mm wider. Then I covered a piece of steel with masking tape and glued the magnets and steel together into three blocks, each consisting of two magnets and three pieces of steel, with the magnets facing each other with the same pole. That means the magnets oppose each other in the middle of the array, forcing the magnetic field of each magnet to the side.

Magnets arrays stacked and glued together. © Charly, all rights reserved. Click for full

The masking tape has stopped the magnets from glueing onto the steel, and the steel was there to get nice alignment on the backside of the arrays. The frontside has the steel pieces overlap a bit, and the spaces were filled with epoxy and sawdust mixture.

Spaces filled with epoxy. © Charly, all rights reserved. Click for full size.

Whilst the epoxy was curing, I took the first wooden fixture and attached a long strip of aluminum to it for the spine of the knife to rest against, and I chiseled out three spaces for the magnet arrays to be glued into. After the epoxy has cured I ground the front faces nice and flat and glued the arrays into the wooden block, again with using a piece of steel covered with masking tape to hold all three on one plane. I used a lot of fast curing epoxy that day, all the while completely forgetting to take pictures of the process. So the next picture is the finished fixture with a knife blank attached to it.

The fixture with knife blank attached. © Charly, all rights reserved. Click for full size.

To get the tilt the fixture has four screws on the downside (up in the picture, not visible).

And the fixture works.  The magnet arrays are strong enough, but not as strong as neodymium magnet arrays, so it is still possible to comfortably detach the blade by hand. It allows me to apply a lot more even pressure on the blank, for a longer time without cooling it because I do not burn my fingers (temperature not being of concern at this stage). There is still room for improvement – the aluminium stop is a bit too fat for kitchen knives, the screws for tilting do not provide stable enough support and they are a bit finicky to get right. But you can see it allows for making nice, flat and even grind.

Established primary bevel. © Charly, all rights reserved. Click for full size.

Added bonus is, that after two hours of grinding not only did I do more work than before, but also my fingers hurt a lot less because the fixture gives my hands more material to hold onto. I am definitively going to use this a lot, and perhaps there will be other uses for this concept as well. I have an idea for sharpening gizmo in my head for about a year by now…

My first Commission – Part 1 – An Offer.

I am still in a prolonged battle with my garden and my workshop, but it seems I am ever so slowly reaching a level of order that allows an actual work to be performed again. The whole workshop, the garden shed and essentially the whole garden were a huge mess whose cleaning took me the better part of my free time for, by now, a whole month. And I need to clean it up because I need to get to making knives pronto. I got my first commission.

I have sent the potential customer pictures of my past work and they chose a design, with a few requests for changes. It is, in fact, the sixth knife I have ever made and one that I am using personally until today – you can see it in the article “Knifesharpenophobia”. I think it is a good design for an all-purpose camping knife but also exactly because of that long time of me using this knife personally, I thought that the blade geometry can be improved, so I did exactly that – the blade is a tiny bit slimmer and the point is more centered and pointy than in the original.

I have drawn a sketch in photoshop, with two different wood variants. Then I made a pretty pdf and sent it to the potential customer to look at and, of course, a price list for the variants portrayed.

They chose and ordered a knife with stainless steel handguard and pommel, peened, full tang and a simple leather sheath. The grip from cherry wood, leather colored accordingly.

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

I hope to do it justice. This blade has somewhat complex geometry and it was not exactly easy to make it back when hand tools were all I had. Making it on a belt-grinder should be faster, but it also allows for easy mess-up. So I will probably start making two blades and if two knives come out of it, good. I need at least one top-notch blade. And if I get two blades out of it, the second one will be fitted differently and sold in an auction for the Richard Carrier defense fund.

As a result, of course, I do not expect to meet the manufacturing time that I used for price calculation – I have used the expected time after I get some more experience under my belt, and the offer alone took several hours to draft because I had no templates for calculating the prices or drawing the designs. But right now it is not about making enough money to live by, right now it is about getting more experience, getting better acquainted with my tools, optimizing my manufacturing processes and getting some satisfied customers. We’ll see what comes out of it.

The Tactical Kitchen Auction

Have you always wanted a kick-ass knife that can handle any kitchen task with ease and also protect you from Ninjas? If so, then you should head over to Stderr where Marcus is auctioning off 2 of his handmade knives, here and here. The auction closes on May 5/19 at 10:00 so be sure to check it out soon.

All of the money raised will go towards paying off the legal bills from the Richard Carrier lawsuit. The ridiculous suit is finally done and gone, but the bills didn’t vanish with it so if you’re in the market for a tactical kitchen knife now is the time to buy. You’ll get a fabulous knife (seriously, both knives are wicked) and you’ll be supporting Freethought Blogs. That’s what I call win-win. Of course, if you just want to make a donation to the fund that’s easy too. Just click on this link to go to our Go Fund Me page.

Good luck to you and thanks.

Even More Books…

Well, one more book. I have about twenty knife and swords books in the sights for future purchases, but I am still in the middle of reading the first seven I already have purchased. The flu-like illness that has been bugging me on and off for two weeks is unfortunately not very conducive to reading, especially to reading in a foreign language.

But Marcus was so very, very kind and has sent me this beauty, which I have not seen offered anywhere here. I must say it is a lovely book on first sight and it became a cherished possession instantly.

Now I had not planned on buying a book specifically about japanese knives, because I intend leaving making japanese knives to the Japanese, but there is no denying that they have a reputation of being superb tools so it won’t hurt to know about them. Quite the opposite, I am sure there is a lot of knowledge in this book that will be beneficial to me and I am very much looking forward to reading it.

However this makes me think a little – all the knives that I have made so far and that I intend to make in the future are my own designs and represent my aesthetical preferences as well as my style of using a knife. And whenever I look at works of other knife-makers (which I do not do very often), often I see that everyone develops a distinctive style. For example Bob Loveless has been renown for drop-point small hunting knives, Walter Sorrels sells mostly very pointy and straight, tanto-style all-purpose knives, Stefan Santangelo seems to like knives which have a slight forward angle between the blade and the handle with a little kink in it etc. I have no doubt that all these knives are perfectly functional and comfortable to use. There is no single “correct” knife design.

I find it remarkable how expressive can be a piece of craft that is essentialy just a sharpened sheet of metal with a piece of wood to hold it with, even when looking at just the outline.

Incidentally you can see two things in the last picture. Firstly, my left middle finger is nearly completely healed. There is still slight swelling and an area with tickling-burning sensation when touched, but it gets constantly, albeit very slowly, better. Secondly, in case you are wondering, that is my school pencil-case, about thirty years old by now.

YouTube Video: Tod’s Workshop

“You make one knife, you make another, and you never stop.” True words.

Tod Todeschini has put out a very short lovely video promoting his workshop.

I do not think that I will manage to pull it off with making knives for a living, to be honest. As in every endeavor, a bit of luck is required and the competition is tough. So even if I manage to do everything right (which I won’t, I never do), success is not guaranteed.  But I am definitively going to give it a try, because I am more than fed-up with being corporate drone.

And when I will be forced to seek employment again, I will do my best to avoid US owned shareholder companies like the plague they are.

Why I (Almost) Always First do and Then Learn

I have an acute case of opinions, and I have a platform. Therefore I am going to inflict them on you. Lets get ready to ramble…

During my life I have learned a lot of different stuff – building and installing computers and programming in VBA as well as masonry, plumbing, carpentry etc. Jack of all trades and all that. That is nothing exceptional, most homeowners here have at least the basic of some of those skills. But some of the skills that I have tried or intend to try my hand on – like knife-making, leather work or wood carving – require not only a lot of finicky skill, but also a lot of knowledge.

My approach to acquiring said knowledge was, is, and will remain, maybe somewhat illogical from an outsider’s point of view, but I found out that it works the best for me. I hasten to add though, that I am only using it when there are not real stakes regarding safety and/or urgency to be had in the matter – if there are, I pay for experts and craftsmen to do the job quickly and properly the first time.

That approach is this – I start with some rudimentary knowledge and dive right into it, start big, fail on so many levels and end up with a result that has so many flaws that it is pitiful at best (like my first knife, that I regrettably lost).  Then I think about what went wrong, read some more information, try again, start again big, fail a bit less and get something that I need not be ashamed of, although it is of course still very short of being a masterpiece, even an “apprenticepiece” – like my second knife:

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

All those failures do not stop me of course from ramping up the ambitions for the next project(s), where I learn from my previous mistakes and boldly introduce completely new ones. Like in the knife I have made for my father’s fiftieth birthday and a knife I made for myself:

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

 

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

And so on and so forth. Only after each failure, will I really seriously start to research and read some serious theory on the things that I just tried to do and see what the actual craftsmen have to say. And through this process, where I first try, fail and then read, I eventually get to something half-decent, like Ciri’s dagger, which nevertheless is still somewhere in the middle of my learning curve (and probably everything ever will be).

One reason for this approach is fairly mundane – books are expensive, our local library is crap and internet with a lot of information freely available was not a thing for first half of my life. But I hold onto it even now – for example I will start reading on leather work only after I actually start to do some work in it, not before (I have actually done some small leather work – the two last sheaths shown, but nevermind). The same plan goes for engraving metal, or inlaying etc. Why do I persist in this manner of doing things, where I inevitably reinvent the wheel multiple times over? Could I not save myself a lot of trouble and time learning the theory first? After all, that is how a lot (not all) of our school system works – a huuuge chunk of theory upfront and then maybe some medium to big-ish chunk of praxis.

Well, even discarding the fact that reinventing the wheel for yourself is tremendous fun, and having fun is the whole purpose of a hobby, I think following chunks of praxis with theory and not vice versa has a practical advantage as well, at least for me.

I have read first three books out of my new purchases, those on the left in the picture. Most of the info in them was not new to me since I already tried like 90% of the techniques shown and I knew all the theory. So I only got about 10% worth of new knowledge, which does not seem like much – just a few tricks, really. But if I started with only these books without having any clue whatsoever about how thinks work in praxis, I would get a lot less out of them on first reading, most of the content would go over my head and I would forget it straightaway. And when later on trying to put the things into praxis, I would have to get back to them and re-read them, maybe multiple times, whilst trying the things and failing at them anyway. Whereas having a lot of failures and intuitive understanding as well as theoretical knowledge of the matter already has allowed me to read them fairly quickly and absorb the little info that I did not yet have much more permanently (I think) because it connects smoothly with my past experience and knowledge.

There is of course one trapping to this “try first” approach, and a big one, that should be avoided – developing bad work habits that have to be un-learned. The distance between trying something and learning the accompanying theory should not be too big either way, because it is detrimental to learning both ways.

New Books to Read Arrived

The situation at my work slowly deteriorates further*, nobody is sure whether they will have work tomorrow or not, management assurances to the contrary notwithstanding (we have been lied to before). I have already decided that should I get the sack, I will not be looking for a new job forthwith but I will dedicate a year to learning and perfecting my crafts – knife-making and wood-carving.

I already have decent knowledge of metallurgy, some rudimentary knowledge of history and even some skill, but there is a lot of potential for improvement on both the practical and theoretical side. And to expand my knowledge of theory, I have just invested non-trivial money into these beautiful books.

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

They arrived today and I am eager to dive into them. I expect to already know some of it, but by far not all, or even most, so I hope to get a real knowledge boost. Which will be of course mostly forgotten afterwards, but that is the way of the world. I still should get out of it ahead knowledge-wise. I glanced through each, some are more pictures than text, some the opposite, but they all seem to be cramped with information on each site and right now I have no regrets of buying any of them.

If anything I still think they are not enough, I wanted to buy much more, but many books that I have got my eyes on were not available. Well, after I am done with these, I will look again. These should occupy me for a few weeks, or even months.

If you have some recommendations on the theme of blade making and blade history, feel free to post them in comments.

  • Honestly, in the pursuit of their greed, american corporate managers are capable of dying of thirst by refusing to drink when given a bottle of water instead of the lake they demanded.

How I did not lose a finger (twice)

You probably noticed that I did not write much anything this last week, and you might not notice the why in TNET. Here it is.

Content warning – description of injuries and first help.

Since I was 10 years old, I was working with sharp instruments in the house and around the garden on nearly daily basis – knives, chisels, axes, shears, sickles and scythes. My father gave me a small pocket knife for birthday and he taught me how to take proper care of it and how to work safely.

I started wood carving that year and I never hurt myself with a knife in a manner worth to mention until a few years later. That one time I was slicing a piece of paper out of sheer boredom, I got overconfident, I misjudged the distance and sliced into the tip of my index finger by accident. I nearly cut the tip off on one side. My father went into full panic mode, but he nevertheless managed to compress the wound, stick a patch on it and haul me off into the town to my mother’s workplace (this was still behind the iron curtain, we had no car and no phone either). There we got a ride to the hospital where the wound was deemed not worth stitching up, just a tight enough patch will do. It turned out later that I actually have damaged a nerve, and the piece of flesh that was nearly cut off, although it grew back together nicely, was completely numb afterwards. But about three years later I got back the sensitivity, so it was only a temporary hindrance.

I have learned my lesson and for next 25 years I again did not hurt myself in a manner worth to mention. I did get a small nick with a knife or a chisel now and then, but nothing that won’t heal with a simple patch in a few days. And almost never when working, mostly during sharpening. I was always careful. The history repeated itself nevertheless.

The weekend before last I was splitting wood for starting fire. I have done this a thousand times before, and an axe is actually one of the instruments that never got to taste my blood so far at all, or at least I do not remember it (I definitively got a splinter under my skin more often). But a piece of wood had a knot in it, i did not notice it, and the axe instead of going through and slicing of a nice splinter went to the side and into my left middle finger. In nearly the same manner the knife did all those years ago.

One advantage of having really, really sharp tools was immediately apparent – I did not feel a thing. I immediately put a pressure on the wound with my thumb so no blood came out. I went up from the cellar, asked my dad to go and start the fire and my mom to prepare disinfectant, a bandage and a patch. Only after I disinfected the surrounding area, i have let go of the pressure and allowed some blood to flush out any debris the axe might have dragged into the wound. I also got a good look at the damage. Then I again applied pressure with my thumb, cleaned of the blood, applied pressure with a gauze and wrapped it tightly with an adhesive patch.

I have thought it to be prudent to not play a hero and get stitches, so I wanted a surgeon to get a look at it. Nowadays we have a phone and a car. For a wound like this I did not think to be necessary to call an ambulance. But since neither of my parents can drive, I had to drive myself to the emergency surgery at the hospital 40 km away, with my dad in the passenger seat in case it all went wahoonie shaped and it turned out I need an ambulance after all.

The nurse was a bit bad-tempered, but I am used to that. It is a difficult profession having to deal constantly with idiots like me, so I do not care for sour faces from medical staff that much. But I attached the band-aid very tightly and she got irate that she cannot find the end and unwrap it, so she said “Well, when you wrapped it so tightly, remove it yourself!”. What could I do but laugh “Taking it off was the least of my worries at the time”? I could not find the end either, so I asked whether they have scissors. “Not ones that would get in there!” which is a statement I very much know to be false but fuck it, I was not in a mood to argue. I took out my multitool, opened the blade and removed the bandage. It turns out there is an advantage to having a very sharp knife that can be opened with one hand only after all.

I got three stitches and a tight bandage on top of that. The surgeon was nicer than the nurse and when I said my goodbyes “Thank you and I wish you an uneventful and boring rest of the weekend” she laughed a bit (the nurse did not move a muscle).

For last ten days I was unable to write properly due to the thick bandage. I learned ten finger typing in high school and I am so used to it that writing without the use of my middle finger was very difficult – I could do it, but I kept tangling my left hand into a pretzel all the time. But that particular torture is hopefully over for now. I got no complications, the wound is healing nicely and I got the stitches out. I only have a small band-aid now and I have full use of my fingers – with care, of course. I will have second crescent-shaped scar and maybe partial numbness in the tip for a few years. That remains to be seen, so far it seems I might not have even that.

The lesson I learned from this is that I never ever should get too confident in my skill and lose vigilance. Shit can happen anytime. Second lesson, or perhaps experience, is that I still can keep a cool head in such situation, whether the injury happens to me or to someone else (at least that was luckily the case so far). That is somewhat comforting. Third lesson I knew already – a really, really sharp tool is better and safer. A blunt axe might cause shallower wound, but the edges would not be clean and easy to stitch, there would be some blunt trauma on top of it and a much bigger area for dirt and an infection to get a hold on. And it would probably hurt a lot more – I banged my thigh on a table edge the same day and it hurt a lot more than this cut ever did.

I hope this weekend to be able to do my share of writing again.

Making Kitchen Knives – Part 10 – Shaping the Outlines

I have not forgotten or discontinued this project, only when it is cold I have to first heat up my workshop before doing any work – which wastes a lot of fuel and a lot of time. Therefore in winter I never manage to do as much work as I would like to. But I managed to do something in the last two months – like building the tumbler (that has run for five days straight by now btw. and it has made a very nice satin finish on the broken blade).

But I could not do much actual work on the knives themselves, because first I must focus on making the necessary improvements. I managed only one step in the process and one failed improvement in the next one.

The step that I have managed with success is shaping the outline of the blades. Last time I ended up with three stacks of blanks held together with screws. So I took them to the belt grinder and ground the outline of all three stacks. After that I disassembled the stacks and cleaned up any irregularities, burrs etc.

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

I ended up with a stack of 12 knife blanks. They are not all identical, but in three shapes – next time I will have to think a bit more about how to get reliably reproducible results. To save my self trouble when cutting the handle scales I have marked the blanks in each group on the tang with letters T, V and X. Why these letters? Because they are easily distinguishable from each other and can be scratched with just two lines.

This step was not actually very time-consuming before – just 10 minutes per blade, or 1, 55% of the whole process. Theoretically not worth improving. But I hope that having three groups of four reasonably identical handles will save me some time when shaping the handle – which took 110 minutes per handle, or 17% of the whole process.

Nevertheless, shaping four blades at once did bring some minor time-saving in itself – I have spent only 5 minutes per blade now, so I have saved 5 minutes from my process. This has confirmed that this was indeed low hanging fruit – it was a very easy improvement.

Next step is basic grind of the blade – and this is where I have my first failed attempt at improvement to share in my next post.

Lets Get Ready to Tumbleee!

I hope this will work. If not, I am determined to fiddle with it until it works.

I found an old asynchronous motor in our cellar. It is a small thing, mere 140 W, and it lacked wiring, any elements to fix it to something and cam wheel completely with wedge. But I have managed to convince my father to connect a cable and a switch to it, and it was working. So last few weeks, whenever I have got an hour or two, I was building a tumbler. I did not document the building process, because there is not much to it, really.

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

Just like with my belt grinder, I started with a particle board leftover from kitchen renovations, which was the base for my old drill press. It is a nice >2 cm thick board, covered with waterproof plastic on the upper side. Stable, strong, simply ideal as a base for a machine. Because the motor lacked any flanges or wings or whatevers to fix it and only had 4 M5 threaded holes, I took two pieces of steel that had 90° angle, straightened them to about 120°C angle and screwed them onto the motor. This provided me with two ears, that could be screwed on wooden blocks connected to the base plate. The switch was attached to the plate by its standard holes, plus two wooden pieces to better secure the cable.

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

As I mentioned, the motor lacked cam wheel. So I stood in front of a choice – to buy V-belt cam wheels and V-belts, or try something else. I tried something else, because I deemed it easier and cheaper. I bought two PP furniture wheels of different sizes. One got attached onto the motor in the standard way – with a steel wedge ground from a piece of spring steel and a lot of cursing. The diameter of the axis was slightly smaller than the inner diameter of the wheel, but I was able to fill the space with a piece of steel pipe. For the bigger wheel I had more luck – it had inner diameter 15 mm. So I could just buy a 15 mm steel pipe and further I could put to use two old ball bearings that also had 15 mm inner diameter. With a bit of banging and a lot more cursing I was able to fix the two ball bearings and the big PP wheel onto the pipe (the PP wheel is further fixed with a nail, so it dos not hold on only by friction). Next step was to fix the ball bearings on two wooden blocks onto a separate particle board plate.

At this stage I also took a strip of leftover flooring PVC and glued it onto the PP wheels for better traction. It is actually nearly impossible to glue anything on PP with reasonable strength, but there are adhesives on the market that manage this task strong enough for this kind of application (I think). If it goes pear-shaped, I can always screw it on later.

For the tumbling drum I took a 100 mm diameter PP pipe and again I glued on it a few layers of PVC for better traction. The PVC lays directly on the steel pipe in order to reduce the fast rotations of the motor as much as I can.

Two small furniture wheels aid in keeping the tumbling drum in place whilst allowing it to freely spin. The tumbler thus lies between the axis and the two wheels and holds in place purely by its own weight.

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Last week I cut a piece of thick leather 1 m long, 3 cm wide, and I cut the ends at an angle so they overlap whilst the overall thickness remains the same, and I glued it together with epoxy. Hide glue would probably be better, but the weather was way too cold for messing about with hide glue. Today I took last few hours in adjusting the positions of the two wooden plates against each other to have adequate tension on the belt without it wandering in one direction or the other. As of now, it has been running for an hour without problems.

It has about 120 rotations  per minute, which might be a bit too fast. I put in shredded walnut shells, a soft coarse polishing compound and a broken blade from my failed machete build.

We will see what comes of it.

Making Kitchen Knives – Part 9 – Starting Again

As I said last time, I am going to make multiple knives in parallel, because I think that a non-trivial amount of time can be saved just by that. I had all my steel already straightened, so I could go right away to drawing, drilling and shaping. First thing to be done was to draw and drill one blade on one half of one steel bar. That I have subsequently used as a template to drill holes in the other half and in all the other steel bars.

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For the drilling I clamped the template firmly with the drilled steel bars and before proceeding to the other side I inserted a steel pin in the drilled hole so the bars do not shift and slide. This has saved some time, despite it being a step with negligible time in the analysis, but my main hope here is that this work on multiple pieces in parallel brings better reproducibility regarding the hole positions and and that better reproducibility could save me some time later on when shaping the handle scales.

I have learned two lessons, one of them rather expensive. First lesson was that for this I have to take the 6 mm drill bits as de-facto consumable material, because I blunted and subsequently broke one towards the end despite using copious amounts of cutting oil. And I do not think it can be avoided.

Second lesson was that I really have to buy a new drill press, and preferably one with continuously regulated speed at that. My jury-rigged press with a very old hand drill has only two speeds and both of them are apparently too high for drilling 16 mm hole in 1,8 mm steel. Towards the end of the work the step drill bit overheated and it got irreversibly blunted on the 16 mm step. Ouch. That drill bit costs 40,-€. I think this investment is unavoidable, if I want to save time I cannot take the bit out and dunk it in water after each drilled hole, slower rotations would be better. And I cannot buy 40,-€ drill bit for each dozen of knives I make – that money be best saved for grinding belts. Hobby or not, at this rate I would spend the price of an acceptable small to middle sized drill press (300-400,-€) on the drill bits rather quickly.

Cutting the blanks in half and roughly cutting the outlines of the blades with an angle grinder did not take long at all. and working on multiple blades in parallel seemed to work comparatively well. But for the sake of precision, next time I will halve the blanks individually – two came out somehow too short and two too long. Not by much, but it is noticeable. The end result were three stacks of four roughly cut blades.

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Before this step took me 15 minutes per blade, now it was 10 minutes per blade (teasing out broken 6mm drill bit and fruitlessly trying to drill a hole with blunted 16mm drill bit included). So I would call it a semi-success. I learned some do’s and dont’s and I achieved my two goals – the holes in the tangs align across all 12 blades nicely and I have saved some time without even really trying to.