Blade design advice

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Will Estes

Joined
Apr 25, 2022
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I'm designing this knife for a friend of mine, and I am having some trouble on the blade. I drew it on 1/4" graph paper if that helps visualize it. I am thinking of just grinding all the way up and if I think it needs it then I could do a top swedge. I am worried that if I keep it flat then it will look like a big empty space, but I am also a little worried that the swedge will make it look like a giant dagger, and I don't like that look. I am looking to keep the general shape of the blade, but I will probably tweak it a bit as I work on it, especially on the point end. I am going to ease off the curve so it will end up between the current mark and the erased section. I am going to satin finish it, if that helps. I don't want to do any sort of hollow grinding on it, but I did consider doing a small fuller along the spine. I'm not good enough at hollow grinding to put it on something for someone else, so I want to keep it to a flat grind. I may also just grind the primary bevel and then go from there. If I think it looks good then I will stop there, but if it could use something else then I might add something else. What do you think? Also, does anyone have any tips for designing bigger knives? I mostly do smaller bushcrafter-style knives, so it feels like there is a lot of empty space whenever I do something this big. Thanks!
 
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ADBrown said:
+1 on this. In fact it would be great if you could create a post with photos of your progress. I’d love to see how it turns out! Good luck!
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Will do! All the materials should get here tomorrow or Sunday, so I can post the "before" and after, along with progress pics of I can remember to take them! Most often I will get so caught up in it that I will take a picture of the drawing and I'll be gluing it up before I remember to take another one! 😆
 
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fishface5 said:
Distal taper
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I've never done a distal taper. Do you have any tips on that or maybe could you recommend a good thread on that? I'd hesitate to do one on this knife since I've never done one before. Usually if I am trying something like that I will try it out on an experimental knife I make for myself.
 
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Spey said:
Additionally, LEO's and the court system would most likely see a false secondary edged blade as a weapon vs. tool which could prove significant.
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That's just silly.

30+ years as a LEO, I have yet to see where ANY knife that was otherwise legally carried and/or legitimately being used as a tool, became an issue because of the blade profile or modifications. If double edged knives are legal in your area, then you are fine. If they are not legal, then an UNSHARPENED top swedge is.

Don't be a moron with your knife - ANY knife - and you have nothing to worry about.

WILL - if you are designing this for someone specific as you indicated, measure his hand width. You don't want the handle distance from the pommel to the guard to be much longer than the width of his hand. Proper handle fitting makes all the difference in the world for balance and control and elimination of hot spots, especially on a largish knife. Everyone talks about steel - and no one ever talks about a properly fit handle. It's important.

Other than that, I like the original blade profile that you erased. I also like a small sharpening choil, as you indicated in your drawing. It cleans up the ricasso-to-edge transition nicely. Some hate them, I think they look professional.
 
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Will Estes said:
I've never done a distal taper. Do you have any tips on that or maybe could you recommend a good thread on that? I'd hesitate to do one on this knife since I've never done one before. Usually if I am trying something like that I will try it out on an experimental knife I make for myself.
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Distal taper is pretty straightforward, I did one last week. You can do a trial run on a piece of scrap. I profile the blade at full thickness and scribe the center line on the edge. Then I figure out how much taper I want from ricasso to tip. For example from 0.25" to 0.125". This means removing 1/16" from each side at the tip, but less and less towards the ricasso. I make mine a simple linear taper. I scribe both sides of the spine and both sides of the edge with where it needs to be ground to. I make short scribe marks every 2" on a large knife. Using a flat platen I grind directly on the flats until I approach the marks. Stop frequently to check with calipers. Measure up and down along both sides to be sure it is equal on the spine and edge and changing smoothly along the length.
I hope that doesn't sound complicated, it's pretty easy and does remove weight. Only takes me about 10 minutes for a large Bowie using a 36 grit belt. Of course it changes the balance, so be sure that is what you want.
 
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Richard338 said:
Distal taper is pretty straightforward, I did one last week. You can do a trial run on a piece of scrap. I profile the blade at full thickness and scribe the center line on the edge. Then I figure out how much taper I want from ricasso to tip. For example from 0.25" to 0.125". This means removing 1/16" from each side at the tip, but less and less towards the ricasso. I make mine a simple linear taper. I scribe both sides of the spine and both sides of the edge with where it needs to be ground to. I make short scribe marks every 2" on a large knife. Using a flat platen I grind directly on the flats until I approach the marks. Stop frequently to check with calipers. Measure up and down along both sides to be sure it is equal on the spine and edge and changing smoothly along the length.
I hope that doesn't sound complicated, it's pretty easy and does remove weight. Only takes me about 10 minutes for a large Bowie using a 36 grit belt. Of course it changes the balance, so be sure that is what you want.
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You explained that really well! Thanks! I think any balance shift would be beneficial in this case because it will be blade heavy in the current state. What is the thinnest you'll usually taper at the tip? My stock is 3/16" thick, but I wouldn't really want to go thinner than about 1/8-1/10, at least for my first try. Also, when you grind the primary bevel do you keep the same angle all the way down or do you adjust so the grind line stays even the whole way down? I like my grind line to be parallel to the edge all the way down, so I would need to grind at a thinner angle at the tip to get that appearance. Although, If I ground all the way up then the grind line will go past the blade at the tip then the appearance would not really matter. Also, I will add that I never tried distal tapers or anything like that before because I had a harbor freight 4x36, which was so chattery and inaccurate that I wouldn't want to try something this precise. I just switched to a 2x72, so I am interested to try out some more advanced grinds!
 
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Yes, I wouldn't take it to less than 0.1" at the tip. Since the profile narrows there you need to be careful not to slip, twist, or apply too much pressure and take off too much. When you grind the bevels and optionally a clip, the tip will get slightly thinner also.
Don't overthink the fact that the bevel angle will evolve slightly down the length. It is true if you analyze the geometry, but isn't really perceptible when grinding. Just walk the grind up nice and straight and get the edge thickness where you want it before heat treat.
 
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Photos of the process

I tried out the distal taper on a knife I had been thinking of making for myself! It was a little rocky, but that was fine because it was my first one. I also tapered the tang, which went really well. I think I may start doing that on some of my bushcraft knives. I think I accidentally ground the tip a little too thin, about 0.0625, but it did fine until heat treating. When I was grinding the bevels, I did one side and then the other, and by the time I had finished that the blade had a really noticeable warp to it. I heated it up and adjusted it back to normal before heat treat, though, so I started that off well. I quenched it and it turned out a little warped, so I put it in the vise and jiggled it with my tongs while it cooled......aaaand I snapped off the first 3/4" of the tip. 😆😢That was the first time I had a major warp that I had to fix like that, though, so when it snapped I got to look at the grain structure and it actually looked pretty good! The grains were pretty small and even and I couldn't see any dark spots down by the edge that would indicate a crack. I guess that means that the steel was perfectly fine, and it was just my manhandling it that snapped it, so that's good! After I broke it and it cooled off the rest of the way, I went ahead and reprofiled it to match the original tip shape just shorter. It skated a file and it was also really hard to grind it, so that's a good sign! The blade is really light, so I think that will be good for the balance of the big one. I ended up not grinding off much when I beveled the end, because I think it would have ended up really thin. It ended up pretty thin anyway, but I broke that part off so I got to re-do that! The tang ended up super thin, but that doesn't matter as much. Also, when you grind a distal taper are you able to get it perfectly flat by grinding perpendicular to the platen? I tried that but they sort of ended up curved, so I ended up putting it parallel to the platen to get it as flat as I was able to. I'm sure there is a better way to do it, but that was the best way I could think of.
 
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Some people lie it along the platen (you can find videos of people doing the tang that way), but I actually do better grinding it perpendicular, I go back and forth varying time and pressure, and measuring frequently. It's a matter of what works for you. You might find the disc grinder useful also, especially to clean up at the end.
 
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Richard338 said:
Some people lie it along the platen (you can find videos of people doing the tang that way), but I actually do better grinding it perpendicular, I go back and forth varying time and pressure, and measuring frequently. It's a matter of what works for you. You might find the disc grinder useful also, especially to clean up at the end.
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yeah, a disc grinder is in the running for my next big tool. I have never really needed to use it for anything other than flattening scales, but I had a granite block for those. I can imagine that it would work really well for this, though.
 
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If you can have your buddy try out various handle styles/sizes you can get a feel for what feels right to him.

me personally, I like the blade shape.
I think it would look better without the drop at the tip.
although I like straight backs and bolos. :D
 
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KHi8Daa.mp4
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Ok, I know this isn’t the knife this thread is about, but the inspiration to try the distal taper on a knife came from the thread and this is the one I tried it on! (Also I just thought it was really cool and I wanted to share it!) This one is 1095 and the balance centers right at the front of the handle, so it feels really nice. I think this is also one of my favorite handle patterns that I have done so far, so I am interested to see how that carries through to other designs. I have barely started on the actual thread knife because when I was in the middle of profiling it, I snapped my last grinding belt and I have to order more. 😭 once I move on with that, I will post the photos here. Does anyone have any advice on how to get the taper perfectly flat on both sides? Someone suggested a disc sander, but I don’t have one so I had to use sandpaper on a granite block. Does anyone have a better way?
 
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Ok, it’s finally finished! I took a pretty big break on it because I was setting up a temporary shop, but once I got settled it it went pretty smoothly! I’m uploading a few of the progress pics, so hopefully they all show up. If not, I’ll probably just post them again and see what happens. If anyone has any questions, tips, or whatever else I’d love to read them! If there’s anything I can do better (and I’m sure there will be) I’d love to know what it is! I was initially worried about the balance of it, but it ended up turning out well, balancing right about at the front of the handle. I asked the guy how he would like the handle, and he said it would be awesome if I could make it to fit his right hand instead of being symmetrical, so I took a shot at that as well and it turned out pretty well! Has anyone else ever done that? It was my first time trying it out and I’d love to hear if anyone has any tips for that. Personally, I like the look of the symmetrical handle better, but if it works better for him this way, then I’ll do it this way! This was also my first time doing double liners on a knife, and I was a little surprised that it went as well as it did! I think the trick was using actual good epoxy. I bit the bullet and got some G-Flex epoxy instead of the cheaper stuff I had been using, and boy does it work! It made gluing up the handle a lot easier than I had expected because it takes about 45 minutes for it to even start getting a little bit tacky, instead of the 7-or so that I’m used to. I really wish I had switched sooner!


Progress pics
 
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