Jump to content

Aiden CC

Members
  • Content Count

    445
  • Joined

  • Last visited

  • Days Won

    6

Everything posted by Aiden CC

  1. The most effective time to straighten is right when you pull the blade out of the oil, as the steel takes some time to fully harden (martensite formation), and is still ductile enough to bend gently in a vise or with thick gloves. After that, the best time is during a tempering cycle. I like to temper once at a low temperature (like 350 F) then clamp the blade to a piece of angle-iron with shims to bend it in the opposite direction as the warp. Then I temper again slightly higher (~25 degrees F), and often that is enough, especially for simple warps. If I can't get all of a warp out in one or two tempering cycles, I carefully heat spots along the spine until the oxides turn blue then counter bend it with a three point jig in a vise. The hotter you get the steel the easier it is to undo a warp, but the more hardness and strength you lose through tempering, which is key to keep in mind with these techniques.
  2. When you are working with thin steel, you’re going to have to deal with some amount of warping. I can only think of a couple of times I had a long (>6”), thin knife come out of the oil exactly how it went in. I found that using a larger container for my oil helped immensely (an old ammo can as opposed to a capped pipe), as it allowed for more even cooling. Another thing to note with thin knives is that they will move under their own weight for a brief period while the martensite is forming and they are still ductile (you can also gently straighten them in this phase). If you leave them to cool in a way that allows them to sag, warps can appear from out of nowhere. My philosophy with warping has been to learn how to both prevent and fix it, since sometimes it is almost unavoidable. Do you have any pictures of the warps? That might also help diagnose the problem. Hope this helps!
  3. This is from a project I worked on a little while ago and might be a helpful visual for this topic. These stress-strain curves are for 4130, which is lower carbon than the steels in knives for the most part (though still hardenable to the mid 40s), and shows what some of this stuff looks like in a qunatitative sense. The unhardened samples are very ductile and show a higher toughness, but much lower yield strength. The quenched and tempered sample has a fairly similar overall behavior, but with roughly double the strength and a lower elongation at the break. The untempered sample had too high of a strength for the tensile testing machine (actually, too high of a cross-section) and maxed out the load cell, so I unfortunately I don't have a full curve for it. However, you can see the substantial difference in strength from the tempered sample . By the time the test maxed out, it had already stretched almost 1.5x as far as the lower strength tempered sample at yield almost three times as far as the unhardened samples.
  4. Glad it helped! I always sharpen scandi grinds before assembly. It's much easier to sharpen that way and, as you mentioned, you can get a better finish initially. In old knives, they were often ground with a slight hollow, which eventually gets sharpened flat, and then ends up convex. All of the originals I have show some signs of a slightly convex edge. Knives almost always come off of a sander a bit convex, which you can keep, or you can use sand paper on a flat surface to get it flat(er). This makes the first resharpening easier and look better (since the knife will be flat on the stone). In the past, it seems people cared less about keeping the bevels perfectly flat and just ground it on a stone until it was sharp again.
  5. Like any knife, the profile changes when you sharpen it. Having the grind go all the way to the bolster/handle lets you get a bit closer, but just like with a ricasso, there will inevitably be a little "dip". Some old Scandinavian knives had shoulders stick out above the bottom of the handle which helped with this a bit. An old very well used puukko next to my reproduction guessing at he original profile. It you look at pretty much any knife which has been used and resharpened for years and years, it will have some kind of concavity on the edge from sharpening. I haven't noticed it on any of my hard-use scandi knives yet, but the oldest one is only about 3 years old.
  6. Thank you for the information! I've spent some time looking for the "Material and Spiritual Culture" book (using both the English and Russian title), but haven't had any luck finding a physical or digital copy anywhere (looks like only 2500 were printed). The book you sent a link to had some good information and I found one picture of the knives in it. I also watched some of Alexey's videos, and they are very helpful. It looks like for some of his knives he leaves scale inside the groove (though the inside is always smooth, either forged or filed)? I'll probably reach out to him to ask some questions. Is there a way/place that it is best to talk with him? I don't have a ton of time for knives right now, but I will probably do some drawings and maybe forge a few blades. I have been able to find some decent pictures on line, but haven't been able to find the original source of any of them: I especially like the narrow knife in this one, and may try it. I like the shapes of all the knives in this image, and will probably use them for inspiration at some point. These are such a unique type of knife, that I've really enjoyed, and it also seems like they are tied in to a sense of regional pride/cultural heritage. When replicating old knives I like to put a bit of my own style/skills into the final product, but I try to stay fairly faithful to the original form/function.
  7. Thanks! The puukko was described as being from the 19th century where I bought it. There wasn't anything that jumped out at me to disprove that, but I don't have a good way of actually seeing how old it is. There have been knives that look like that for a very long time. The birch in that knife came in the form of these planks I got from Brisa, and I've found that it is much more figured (and much cheaper per knife) than the blocks that you can buy of the same wood.
  8. Thanks for the info! I've heard the translation before, interesting that it signifies it isn't made by a specialized bladesmith. I find puukkos pretty useful as well, especially in knife making and wood working. I find the maasepän puukkos the most interesting, probably because they were really made to be used. I've found that they are much more difficult to find, especially for sale. I did manage to find one, but it was in pretty rough shape. I did my best to make a replica to get a sense of what it looked like when new: I think it had two "tramatic" events; one where the tip broke off, and a second where the handle busted open and the knife was discarded (though that could just be due to rusting of the tang).
  9. Thanks! Thank you, for the sheath I switched up my technique a little bit. I used to make the holes for stitching by pushing the awl through both sides of the leather in one go, but this time I made the holes on each side individually (still one at a time though) and found it yielded a much more even look (also I poked myself in the thumb much less). I found the Sakha knives fun to make, and they checked off the boxes of "interesting to forge" as well as "easy to grind and polish, which are what I am finding defines a lot of the knives I enjoy making the most.
  10. Thanks! I'll take a look at older topics here, I actually first found about these knives from Jake when he brought them up in a thread of mine about wedged handle construction. I'll have to try that, at least for projects with more narrow fullers. It seems like it would let you get more even sides and especially ends that just bending in a swedge block.
  11. These knives are usually referred to as "Yakut" knives, but it seems like the people prefer to call themselves "Sakha" or "Saha" (though I don't know much about the issue), so for recognition I'm using "Yakut" in the title, but will say "Sakha" from now on. It's been very difficult to learn about these knives, and I've been trying my best to find pictures of originals, although they are buried in a sea of not-particularly-faithful modern versions. I had the best luck searching in Russian with the help of Google Translate and my girlfriend, who speaks Slovak/Czech and can sound out Cyrillic which has often been close enough for translating text which was in images/videos and/or hand written. Anyways, what I made was primarily based on images I found of two knives: Compared to modern knives in this style, these appear to be narrower, have wider handles, and have much cleaner fullers. In the first example, I have a hard time telling how the fuller was cleaned out. Maybe the corner of a grinding wheel/belt? Maybe a flap-disk or just a file/hand abrasives. At first I thought the second knife was left handed or had no groove, but now i think that it might have a shallow and highly polished fuller. Anyways, here's my version: I was able to get a nice clear groove, but couldn't find a good way to polish it, so for this knife I left it black. Is that every seen on historic examples? I have had a hard time finding pictures of old Sakha knives, and if someone knows of any good sources of information, I would be very interested in finding out more. Blade is 138 mm (5.4in) long, 17mm (0.68 in) wide, and 3.4 mm (0.15 in) thick. The handle is 118 mm (4.65 in) long, 31 mm (1.25 in) wide, and 22 mm (0.86 in) thick. I like how the sheath turned out, but I don't think it is close to originals. I think I made the insert too large/square. This picture kind of shows the "egg" shape of the handle cross-section. The wedged handle construction. This last pictures shows two earlier attempts. I wish the handle had come out a bit more like the one in the middle, I tried putting in a bit of a taper, but I think it ended up a little bit too small. Any critiques are welcome, and my main questions are: 1) Is the overall profile (blade and handle) good, especially whether the handle is too narrow? 2) What is a good/accurate way to finish the inside of the fuller for future knives? 3) Is the blade too thin? It is rigid and doesn't have too acute of an edge, but still wondering. 4) How should the edge be aligned with the plane of symmetry of the handle? I gave mine a slight "angle of attack" (counter clockwise when looking down on the tip), to help it "bite" a bit more and not require as much wrist rotation. 4) Does anyone have recommendations for places to look for pictures/dimensions of and information about originals,? When replicating a style of knife, I usually like to have one to look at, hold, and measure, but I don't think that will be possible for this style. Over all, I very much enjoyed learning about and making these knives, and hope I can learn more and maybe also inspire some people to try out making these themselves. Thanks, Aiden CC
  12. Over winter break I finally had some time to work on knives, so I got a few done. Last year I made 12 over break, but I decided to tone it down this year and made half that many. Here they are: From left to right: chef's knife in 80crv2 and olivwood, three Sakha (Yakut) knives from leaf spring/80crv2 and curly birch, a replica of an old puukko I have from 80crv2 and curly birch, a kitchen knife my girlfriend forged (though I ground it and finished the handle) with an 80crv2 blade and walnut handle, and finally a paring knife in 80crv2 and olive. I've really been appreciating the design and appearance of Sakha knives recently, and the leftmost one is my attempt at some degree of historical accuracy, and I'll probably start a design a critique thread about this type of knife with pictures of the originals I've been looking at and some questions I have about the style. I also made a couple of sheaths as well, I'm particularly proud of the puukko one. Both have wooden liners for the blade. I've had trouble with these seams in the past, and I think this is my best one so far. A side by side with the original. As you can see, the exact blade shape is a guess, due to the missing tip, and change in profile due to sharpening. I also opted to have wider "flats" on the blade to make up for the fact that they likely have shrunk as the blade was sharpened over time. The handle took even more guesswork, since on the original it is split open in a way which makes it difficult to see the original dimensions. I did my best o measure and extrapolate and am fairly pleased with how it came out. A photo showing the wedged handle construction on the Sakha knives. A comparison of a fuller produced with a ball-pein hammer and the more consistent one made from a swedge block. I like the latter much better, and though the one left is like what you see on most modern versions, I haven't seen any pictures of originals that look like this. Also, a picture of the other side of these knives (when I was first researching these it took me a very long time to find a picture showing what the non fullered side looked like). A quick comparison of different materials/finishing techniques. Left and center are curly birch bought by the block, presumably from larger trees, which the right one is from birch I bought in the form of planks from very small trees, and although it contains some heart wood, the figure is otherwise very tight and good looking. The right two are tests of a new finishing technique where I burnished with 800 grit sand paper once, and then several times with fine steel wool. My original process (left) was just to use the sand paper. I thick the new processes closes the surface better and brings out more figure. All are finished with 50/50 boiled linseed oil/turpentine. Finally, a nice little knife I helped my friend make, which I'm posting since I think he did a really good job. Other than some trouble in glue up where I had to step in slightly to save it, it was all him. Blade is 80crv2, handle is ebony and copper. Thanks for looking, questions, comments, and critiques are always welcome!
  13. It could have something to do with the fact that a satin finish looks more "hand made" than mirror. All of the knives I have sold have been satin finished, however some of the knives I've made to use myself, including my EDC folder, have mirror or near-mirror finish because I like the look and think it has some practical benefits. Water rolls off better keeping the knife dryer/making it easier to wipe off, the finish is more corrosion resistant, there is (very) slightly less resistance cutting through food, etc. For me, I never felt that the time it would take to get a good mirror polish on a blade, particularly something as large as a chef's knife, would add enough to the value to be worth it. Something I've done recently, especial kitchen knives, is a satin buffed finish achieved by sanding to 600 grit and then buffing with emery. I've found that this finish only adds another 10-20 minutes to making the knife and doesn't alter the look that much while also getting some of the benefits of a mirror polish. A forced patina is another way to give the surface some protection and, as Joël's knives show, can be very attractive when done well.
  14. I believe this is silver maple, so I'll expect some movement. The sealer I found is a wax suspension, and I applied a liberal coat, so hopefully it works. My college owns a plot of woods and any dead wood is fair game, and I've found some neat spalting in standing-dead trees and stumps, particularly in an elm tree cut down by beavers. When I cut it open on the bandsaw, a bunch of ants poured out, which was pretty shocking to say the least, definitely a disadvantage of found wood . The nicest wood I have found was a piece figured ash, but it's still drying. I also recently found some curly elm in a stump that I need to prep properly next. I also found a burl in a big tulipwood stump, a blank from which dried quickly enough to make this last year: I'm actually somewhat looking forward to the snow storm this weekend, since all the trees/branches that fall into access roads get cut up into manageable pieces and hauled to a compost pile which makes it much easier for me .
  15. Yeah, I can see how bugs could be a bad time. I was hoping the bark would peel off like some other wood I’ve worked with, but it took a bit more work. Also, decided to cut off a few smaller blanks so I can start working with this stuff a bit sooner. Also, when I was cutting this I broke a saw blade (one of the thin Japanese style ones) because of binding in the wood, and I went to a wood working supply stood and got a replacement plus some end grain sealer. Also, a neat effect in the root wood, with some natural staining, possibly from minerals in the soil, making for an interesting two-tone effect. The chemistry lab at my school has a drying oven I’ve used in the past, so maybe when it’s time I’ll use that. When you say unstable, does that refer to changing size with humidity? I’ve never worked with stabilized wood, but it could be worth trying.
  16. A neighbor’s tree got blown over recently (a big maple), and they let me cut up some of the stump. I saw some curly grain at the break by the root so I cut two large pieces from there and one from the root. The middle of the tree was rotted out, so the pieces are about 3” thick. Basically, my question is how should I set this up to dry to minimize checking/other damage. Warping isn’t that bad, since it isn’t straight anyways. Should I cut it into smaller pieces? Remove the bark? Square off/seal the ends? I’ve dried wood a few times before, but always in smaller pieces so I’m not sure where to start. Thanks for reading, any advice is appreciated!
  17. It probably depends on how you define big. The mill I interned at last summer made a lot of long products (coils) and since most of them were over 15 tons, each melt was very large, and the melt was done with an electric arc furnace. I was in the hot mill, not the melt shop, so I'm not sure as to the exact size, but the melt shop gantry cranes which carried the ladles were rated for several hundred tons.
  18. Great job, especially for a first! My college just got a CNC milling machine and learning how to use it I've really gained an appreciation for the time that goes into programming a part, let along making something as complicated as a whole knife. From what I can tell, pretty much anyone using a ball end mill for roughing cleans up with a belt sander afterwards. Alex's advice about sanding before heat treat is solid. Steel is much more abrasion resistant after hardening, especially when it has additional carbide formers added. Depending on how much of the surface needs to be removed, a fine cut file may help. I remember seeing someone who would rough bevels with a flat end mill by using a jig to clamp the blade blank at an angle. That would introduce the complexities like building the jig and finding a good way to set the origin, but it seems like that might be able to get a somewhat closer to final surface finish.
  19. That's it for the most part. Slip joints are the knives that benefit the most from liners resisting forces applied to pins, with lock-backs having similar forces, but to a lesser degree (much lighter springs, you could probably get away with out liners depending on the scale material). Liners also act as a durable bearing surface for smoother action (though washers are often used for this instead).In addition to forces from the mechanism, there are additional forces from use. With friction folders, the tang pushes the pin into the thicker part of the handle perpendicular to it, whereas forces from cutting with slip-joints and lock-backs will be along the long axis of the handle. With a friction folder, you may actually be better off without liners if they have less friction than your grip material would. Interestingly, liner locks are a type of locking knife where the load applied by the mechanism is relatively low. I've seen examples with only one liner (the locking one), and just a washer on the other side. One thing to note is that over time wood will compress, change volume with humidity, and wear in, all of which can change the characteristics of a friction folder, so an adjustable pivot might be nice. Hope this isn't too much!
  20. I’ve been working on my Swiss Army Knife project and ended up having to re-make the springs (one broke because of bad geometry so I figured I should re-make both). I’m currently setting the spring pre-load before I send them out for heat treat (steel is CPM 154), and I was thinking about how hardening will change how they flex. Basically, my question is: does hardening actually have any significant effect on the weight of a spring? If I understand it correctly, in most cases hardening doesn’t change the Young’s Modulus, so it seems like it wouldn’t change the weight of a spring, just how far you can bend it before it yields. The practical thing I’m wondering is if I can gently feel the force from the springs as I adjust pre-load and get it close/a little heavy before I send them out for heat treat. Thanks, Aiden CC
  21. Ok. I think red paper micarta/phenolic (same thing?) might be what I go with. It seems like you can’t really see the layers in a knife handle so it should look similar to the originals.
  22. That's an unfortunate trade off. It seems like composites made with phenolic resins are fairly resistant to solvents and also bond reasonably with epoxy (something like this: https://www.knifemaking.com/product-p/ph641.htm). I have only made one two knives with phenolic (G10) scales/liners and both of them sold a while ago, so haven't had much experience with the long term effects of anything on them.
  23. Did you have any problems with it being dissolved/cracked by acetone? Acetone is my go-to solvent for cleaning epoxy off after glue-up, so ideally I’m looking for something that doesn't crack/fog up from being cleaned with the stuff (which may be a tall order from a plastic).
  24. As some of you may know, I started a Swiss Army Knife build last march. I finally have enough time that I might be able to do it justice, and one of the things I left off on was picking/purchasing handle material. At the moment I'm torn between sticking to the traditional red-glossy plastic (probably nylon, although I haven't been able to track down any red nylon sheet, so another plastic may have to do), the same thing in black (Victorinox makes some in black that look pretty slick and black nylon is much easier to find), or picking some other material and giving it bet of a less faithful look. Any advice/opinions on any of those choices definitely welcome. If I went with that last option, I would want something which would be strong enough to not need bolsters and have blind pins (so dimensional stability is very important, any bowing would likely shear the epoxy). For those reasons, my guess is it would need to be synthetic. Also, since the blades are stainless, I think a low maintenance material would be a good fit. Also, I've been thinking about potential ways to put some kind of shield/inlay into one of the covers (though I'm not 100% sold on the idea) and any ideas on that would definitely be welcome. Thanks, Aiden CC
  25. For me, not much deeper (I'm going to anneal a few samples to look at recrystalization and then move on to steels), but there's certainly a lot of other stuff I could look at here. This is a micrograph of sample at 50% reduction, viewed parallel to the rolled surface. You can see some grain elongation, but not as much as in the next image. This is a closer image, and I just realized I forgot the scale bar but its 5x higher magnification than the one above. It is also looking at the cross-section instead of the top, and I think the reduction is somewhat more apparent. This is a top view of a sample reduced by 80%. I don't have a cross-section mounted yet since it's too thin to stand up on-edge in the mounting press, but there are some steel clips I plan on using to take a look from that angle. Closer look at he same thing. On Monday, the lab director and I are going to try an other water pour, mostly because we want to see if we can make it work. I definitely want to try working some of this stuff by hand. With how fun it was to roll, I can imaging it will move nicely with a hammer. I may do a comparison of rolled vs. hammered samples, but it will probably be a small side-project.
×
×
  • Create New...