Recommendation? Location of plunge related to sharpening notch

ashwinearl

ashwinearl

Joined
Nov 9, 2006
Messages
520
Is there a convention for the location of the plunge relative to a sharpening notch? I've been putting the notch right in front of the plunge using a round file after the rough grind.

I just used a drill press to drill a hole before profiling. I am also trying heat treating first and will grind after. I now have a nicer file guide so can place the plunge better.

Is centering the plunge on a half round sharpening notch something to strive for?
Thanks
 
ashwinearl said:
Is there a convention for the location of the plunge relative to a sharpening notch? I've been putting the notch right in front of the plunge using a round file after the rough grind.

I just used a drill press to drill a hole before profiling. I am also trying heat treating first and will grind after. I now have a nicer file guide so can place the plunge better.

Is centering the plunge on a half round sharpening notch something to strive for?
Thanks
Click to expand...
wrong subforum I believe
 
You see many variations of where to place that notch. I prefer the plunge to be in-interrupted and have the "notch" in front of the plunge. On fixed blades, I use a round file as well and then clean up post HT with sandpaper wrapped around the round file.

On slipjoints, I cut or grind in a rough triangle notch and then HT. I will then grind the blade, keeping my plunge line behind that rough notch (i.e., closer to the tang). I will put the blade in my surface grinder (clamped in a toolmaker vise) and sneak up on that plunge line so that ideally, the plunge line goes straight and the notch is exactly in front of the plunge. I still struggle with this process a bit, but that is how I do it now. It erks me when I have that notch interrupt the plunge line on a slipjoint.
 
split the differenc. Depends on what you are trying to do. On he second knife, the notch is moe of a mini-choil. IMG_0737.jpgIMG_0635.jpg
 
I cut the sharpening notch after correcting the plunge so it is in line with the bottom of the plunge line...

n0F2TRC.jpg
 
It can vary depending on the style and blade. I like to bisect the notch with the plunge on smaller and medium blades. On larger blades, it looks better in front of the plunge … at least to me it does. Otherwise, I don't think it matters.
 
I do it like E.Carlson. I use my 1/2" small wheel and like the round section to be longer just like his. I think when cutting things like plastic, a tarp or a deer hide if the half round is too small when cutting the plastic or hide it will get caught in it if you happen to be cutting that far back with the knife. It also lets me sharpen the knife without worry of hitting the plunge.
 
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In a discussion with a knifemaker i couldn't convince him where to place the sharpening "notch" (actually in common dictionary terms, "choil" is indeed the proper specific word) correctly. I found image links of bad examples:
  • Bark River Knives issues many of their knives with sharpening choils, properly located, but not so on this model: bad1 (please doht argue that this notch isn't supposed to be a sharpening notch; just study the other models of this model seriez and you'll know better)
  • Viper Knives issues most of their knives with sharpening choils, properly located, but not so on this model, the Viper V5840CB: bad2 (again doht argue)
  • a Michael Zieba knife with a "properly located" sharpening choil which doesn't make original sense: bad3 (original sense, what's that? oh please omg)
  • a China-made complimentary gift knife given away by geman brewery Jever: bad4 (just hilarious location)
  • on the Strider the left start of the notch is perfect: notbad5 (the heel should be cut off imho)
  • a perfectly located and sized notch: notbad6
  • this pic makes you understand why the notch is there (location, size, meaning): notbad7
  • this pic makes you understand that the bottom of the plunge line cannot be apexed which is why it is the very location where to place the notch: notbad8
I made this post for my own reference and if i happen to find more commercial bad examples i'll add them to the 852 numbered list.
 
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kreisler said:
In a discussion with a knifemaker i couldn't convince him where to place the sharpening "notch" (actually in common dictionary terms, "choil" is indeed the proper specific word) correctly. I found image links of bad examples:
  • Bark River Knives issues many of their knives with sharpening choils, properly located, but not so on this model: bad1 (please doht argue that this notch isn't supposed to be a sharpening notch; just study the other models of this model seriez and you'll know better)
  • Viper Knives issues most of their knives with sharpening choils, properly located, but not so on this model, the Viper V5840CB: bad2 (again doht argue)
  • a Michael Zieba knife with a "properly located" sharpening choil which doesn't make original sense: bad3 (original sense, what's that? oh please omg)
  • a China-made complimentary gift knife given away by geman brewery Jever: bad4 (just hilarious location)
  • on the Strider the left start of the notch is perfect: notbad5 (the heel should be cut off imho)
  • a perfectly located and sized notch: notbad6
  • this pic makes you understand why the notch is there (location, size, meaning): notbad7
  • this pic makes you understand that the bottom of the plunge line cannot be apexed which is why it is the very location where to place the notch: notbad8
I made this post for my own reference and if i happen to find more commercial bad examples i'll add them to the 852 numbered list.
Click to expand...

I see that (for whatever reason) you used a picture of one of my knives where it is photographed from a less than ideal angle regarding the choil. Here ( https://image.jimcdn.com/app/cms/im...2741e8dfc1fbc7d0/version/1596140891/image.png ) you will find what it really looks like. But I can see what drew you to the incorrect conclusion and I agree that many choils are placed not ideally. (And yes, I think this one could be moved back even further and I would do so if the customer didn't tell me that he likes it that way.)
 
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oh, the choil looks well placed on your knife, well done!

:cool: :thumbsup:

and sorry for my false criticism:oops:

:(
 
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Seedy Lot said:
I like to forgo the notch completely, is it not a potential stress riser?
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A lot has been said about stress risers in knife blades, and certain styles of knives like hidden tangs being weak at guard and breaking. I have an old beater 4" drop point in my shop almost identical to the knife I posted above, it's 3/16" ATS-34 heat treated with cryo to 59-60. I clamped it in my vise one day right above the guard and pushed and pulled on it a bunch of times with both hands as hard as I could and found out I couldn't even flex it, much less break it. I guess you could consider a choil, sharpening notch, plunge line, or the shoulders where your blade meets the guard all stress risers. I think if you keep a good radius to things, and with a good heat treatment you won't have any weakness issues with a blade.
 
Seedy Lot said:
I like to forgo the notch completely, is it not a potential stress riser?
Click to expand...

IIRC, carbon steel blades are more prone to breaking due to stress risers that high alloy and stainless blades. Rounded notches are far less of a stress riser than any pointed notch ( triangular or straight cut). There is no apex for the energy to concentrate in in a smooth curve. Technically any notch is worse than no notch, but small rounded notches are very low risk. It is best to avoid any deep groove or notch in the ricasso area, where the stress is the highest.

Every type of indention is a potential starting point for a crack to propagate across the blade and cause it to break. When using thumb grooves, saw backs, choils, finger grooves, upswept ricassos, etc. minimize possible issues by rounding the apex of these notches ( even minutely) and allowing sufficient blade thickness and width to resist breaking. HT is the main place where you adjust for toughness to decrease the possibility. On a blade that will be batoned, round the spine edges slightly to avoid the same issue.
 
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