THIS is more important than heat treatment of steel!

this video is sponsored by the following people please click the links in the description below today we're going to talk about geometry of knives this is one of the most important things when you want to make high performance knives maybe even more important than steel and heat treatment just maybe depends on which borders you're looking at but it is no kidding one of the three most important things if you want to make knives that perform well and that the user is actually going to have fun using my name is Tobias hangler I am an Austrian bladesmith and trained intelligence I've been making and using culinary knives for well over a decade about 14 years ago I started and I've been a full-time knife maker blade Smith for about two and a half three years now in general the knife geometry will not only depend on the knife that you want to make it will also depend a little bit on the user who will be using when we talk about the geometry we don't only speak about this view of the knife which has its place and which is important but most importantly we are talking about cross-sectional thickness of the knife how thick is the spine of the knife how thick is it before you start sharpening it and what geometry do you use for the knife so in general I try to make a simplified but realistic cross-section of each of the different grinds if we keep the spine thickness and the blade height the same so this might make sense on some grinds it might not make sense on other grinds but to keep these two parameters the same and to show okay what is this type of grind individually I made them all the same first up we have the scandi grind a scandi grind is basically not used for culinary this is not a grind that you would make in exactly this late height it's typically shorter knife so the grind would look something like this section and it is typically used for Bushcraft knives outdoor knives and for some woodworking tools so the characteristic is that I have full thickness all the way and then I have just one bevel that leads right into the Cutting Edge so when you sharpen you have to sharpen the entire face here you have to sharpen the entire level so while it it is very good for woodworking it can be a little bit trickier for resharpening this grind would be much too steep you would have way too much resistance if you cut any foods if you have for example three three and a half millimeter spine and you want to do a scan the ground on the knife on a kitchen knife you will just not be able to cut a carrot or an apple or anything it's just going to split like with an X [Music] next up the full flat grind what does that mean basically full flat means that you have one bevel that goes all the way from the edge to the spine of the knife this is one bevel that could for example be three four five six degrees in total and you have the full thickness of the spine only at the very top of the blade why is this different than this candy grind obviously it's going to have a completely different cross section it's going to be very thin so it's actually good if you want to cut through dense foods dense materials like squash or a carrot and then one important performance factor of this is as well the thickness behind the edge this is just an example here we have 0.22 millimeters behind the edge that means that right there on a smaller level there is the sharpened bevel which we're actually going to resharpen and that is very very small like you could for example see on these knives the actual secondary bevel that is sharpened the shiny part here is very small because we are very thin behind the edge you can use a full flat grind on culinary knives basically The Cutting performance will be very good you will have a lot of Lifetime before you have to thin out the bevels again because it's a very flat grind especially on higher blades you will have very little resistance again with solid food the disadvantage is though through the flat bevels you will have a lot of food sticking to the side of your knife like a slice of squash or potato or onions everything will just stick because it's slightly wet and it creates kind of a vacuum underneath it it's just going to stick to the blade and that can be very annoying in use [Music] foreign next up the flat grind so how is the flat grind different from the full flat basically your primary bevel only goes to a part of the blade so we have full thickness of the spine for a certain part of the knife and then we start beveling down for example if we look at this knife you could see that this is the forged finish all the way here and then the primary bevel is only in the lower part so this is for example a flat grind that means you have a transition here where the food will easier more likely fall off so it will not go all the way up it will actually be more likely to fall off in this region it's still going to have a shallower angle as you can see if you only grind part of the blade if you only do a partial flat grind with the parameters all the other parameters being the same you will have a much steeper angle here which makes the blade more robust but it also will give you a little bit more resistance if you cut very dense foods it really doesn't matter if you have meats or fish anything that is a little bit softer this angle and the thickness behind the edge will not be as important but if you cut dense foods the more cross-section you have in the lower region the more resistance you will feel during the cut foreign next up is the convex grind a convex grind means that we have this is not a linear bevel but we actually go in the slide outwards curve so it's beveling and a convex surface to the edge and then you will have a secondary bevel right behind the edge again it's kind of similar in how much mass is where if you compare it to the same flat grind so it's actually just a kind of rounded form of a flat grind you could say but what you get can be very well performing knives because you have the effect like if it's a severe convexity that the foods will fall off easier you will have a very robust blade basically and you can have still very thin edges so you can grind it very thin in this part so it's very easy to resharpen it will just take a couple of Strokes because you take very little Material off the front of the secondary bevel another shape of a convex grind that don't have on this picture but we will show you digitally is the valksliff the valksliff is a traditional German grind which basically is a convex grind that will also continue to be convex in the upper side so it actually starts becoming thinner at the top too so you lose some of your spine thickness and the food will be even more likely to fall off this can be especially important in knives in the tip area where you want the food to to glide through easily to have low friction and also to fall off easy because you don't want to have a very thick convex blade in the front so you can do a valksliff in the front section [Music] thank you The Hollow Grind is more typical for outdoor knives for folders because it basically enables you to have a very thick spine and then quickly come down to a thinner Edge so like on a folder you might want to use three four millimeter uh spine thickness then you want to come down to something that is relatively thin so you can get decent cutting performance what is it good for so on the Hollow Grind you can have very thin cross section in the lower area which will mean that you have very low forces for mechanically splitting the material because if you have a thicker geometry and you have a dense food you have more resistance for splitting basically the thinner your knife the more action will actually happen at the tip this doesn't matter too much within with softer foods but with denser Foods this can make a difference so the Hollow Grind is very thin it's very acute Edge and it has a big advantage that you can actually resharpen the knife for a very very long time and the thickness behind the edge will barely change which can be very good for maintenance also for many other types that I'm not too familiar with but I'm sure you've seen plenty of hollow grinds on outdoor knives and folders where you have the thick spine and then you just want to come down really quick it also looks pretty cool so next up the S grind this is a very aggressive form of an S grind so we have a very strong profile this is I think very good for demonstration it also is a well-performing geometry it's not the dimensions aren't exactly what I would use usually but it shows the cross section very well so we have a flat on the top of that blade which basically provides some weight and some rigidity that the knife doesn't flex and then you have a double Hollow Grind in the middle of the blade like here here's the Hollow Grind which will take away a lot of the mass which will make your knife lighter and which will also make the knife thin pretty much in the entire lower area in the front section you basically have what is a flat grind what can be a Hollow Grind so basically you can grind the geometry like glass blind or convex grind and then afterwards grind away these Hollows so that the blade becomes lighter and that you get a better food release because you can imagine if you cut through a cucumber a carrot whatever you make a slice it's just gonna fall off here in the lower area already because it can't make the curve and stick to the blade because the blade is making changes in the geometry any slice that will be thicker than one or two three millimeters it's just gonna fall off sometimes you have like the super thin slices that will still manage to adhere to the blade but that is less likely let's say like the majority will fall off to the side it's not 100 but it is the majority there is different versions of this obviously you would get even better food release if you have a straight corner right there this is a little bit trickier to make it's called a hook grind Benjamin Cayman does some of these and I'm sure other people too my personal take is I rather make the S grind because it's easier to finish in a nice way like I can make a nice The Mask Damascus pattern with that as well I could use the contact wheel to finish out pretty much to 600 and higher and then I just have to do some light hand sanding and also I don't like any sharp Corners in my knives in general and I also don't like any deep structures because that will basically be where it's hard to clean where it's hard to dry off and I don't want to go into the corners um every time I wash them but performance wise probably even a step up [Music] last grind type that we're gonna talk about is the sea grind it can also be an asymmetric s grind basically so we have two sides on this knife We have basically a flat grind or a slight convex grind on the one side that is basically the inside or it's the side of your non-dominant hand so this is a right-handed knife and then we have the Hollow Grind here and in this instance we have actually a compound grind so we have the initial grind on this surface so the finger can rest against more material and we're not resting against something very thin here so it's actually more comfortable to use because the heel is going to be a little bit more a little bit beefier this again takes away some material takes away some weight but you will still have enough weight in the blade on the spine so that's what I also like if you do chopping you don't want your knives to be too light you want some mass that you don't get stopped purely by friction and the thought behind this is that every surface has its purpose so we have the weight in the back we have the general grind that goes towards the small secondary grind on both sides I leave the surface flat for the surface where my fingers rest again so when I guide the blade and I cut vegetables I have a smooth surface on this side and then I have a Hollow Grind in the region where my food is typically going to be so everything is functional Weight Food release keep the heel a little bit thicker and then just the primary bevel you can rest your finger here and this is a little bit more comfortable in my opinion than a grind like this where I have the hollow all the way down on this plate it doesn't matter too much because the hollow is further down so here my finger doesn't rest in the reaching where it's very thin whereas on a on a not as high Blade the lowest part of the S grind would go be right where my finger and also on this side I would have a little bit harder time to guide the blade nicely again this plate is so wide that I still have some good surface this knife I would be right in the structured area if I was using it left-handed so it's not perfect right-handed perfect for me every surface has its function everything needs to be the way it is foreign starting out you want to learn a new Grind you want to Perfection it you want to make it your own it's always three parameters that I look at the most one is the spine thickness if you want to get better spine thickness is something that you always have to take care of not only the thickness in one place but also also how it changes towards the front so the taper second parameter is thickness behind the edge so how thick is your knife right behind the sharpened Edge and the third parameter that you should look at very consciously is what are the angles of your bevel and that is going to change with the height of the grind with the spine thickness and with the front so it's basically the fine geometry geometrically even if you do convex grinds or if I do convex grinds I first start out with a flat grind I measure the angle or keep the angle consistent and then I will start rounding it in but I will still know the approximate angle that I started with to make sure that I get consistent results that I can make changes in in a systematic manner so they get better try to be very intentional with your changes make a knife use it take notes how it turned out take notes how you like it in comparison to other knives does it perform well on carrots does it perform well on softer Foods what are the advantages with these three parameters you can just systematically change until you are happy with the result and then be sure to also check your results in the future that you stick to this geometry if you got a working set of parameters the good thing is that you don't really need to cut to test cut every knife because if you keep all the parameters the same the knife will perform very similar or the same as your test knife so you don't have to be worried that's one type of quality assurance that I would definitely recommend you don't need anything but just calipers check your Dimensions check your angles it's super important other than you and me you know who else loves sharpening Tomic did you know that Tomic holds close to 20 patents a day what does that mean it mean means Innovation is in the center of what they do tormec is a leading brand that offers a complete sharpening system for everything you want shop this means easy to use jigs attachments to help you fit all sizes forms and shapes of tools you want to show up in including kitchen night development engineering work and production are all made in Sweden this means that you get the highest quality in sharpening Innovation and the best modern manufacturing technology check out tormic.com thank you very much to our sponsors for making this video happen I hope you found that video informative and entertaining what knife geometry will you be practicing next your thoughts and feedback are always appreciated if you want to watch Tobias make a go my knife with an asymmetrical s grind check out this video over here see you in the next video yeah I love the geometry

Channel: UK Bladeshow

Views: 38,880

Keywords: knife geometry, knife grinding, s grind, c grind, best cutting knife

Id: nrhhhFOwY6s

Length: 16min 6sec (966 seconds)

Published: Sun Feb 19 2023