CS Rajah 3 - Is there a reasonable way to improve the choil?

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Feb 8, 2022
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Preface: A lot of people dislike this knife and that's fine, but critiquing the concept or design is not what I'm posting about.

The product images for this knife look like this in the sharpening choil area:


The one I recently bought (and another I've seen around a year ago) look like this:



The plunge line in the product image is more abrupt than the two production ones I've seen.

I like the knife but absolutely hate the look of the "fake" sharpening choil. I realize one way of getting rid of it is to just remove material up to the edge, and I may do that, but I'm trying to think through the options.

I believe I can see why they did it this way in the factory: most of the knife measures 0.9mm at the grind right above the edge bevel. Measuring the knife I have with calipers, they've ended the edge bevel at the exact spot where it gets thicker, and it's at about 1.6mm by the end. In other words, to do it any different, the person putting the edge on would have to accept the edge bevel getting much taller there, which most would consider weird-looking.

I've been contemplating doing it myself. I assume the practical way of doing this would be diamond files. There's not a way of reaching that area with a stone because it would hit the edge and ricasso. (Theoretically I could use the edge of a stone I guess, but that seems terrible). I don't have a belt grinder, and if I did it would be the same problem I believe.

If I were to file it, what are some ways I could fixture it to do it neatly? The vernier protractor shows about a 16 degree edge angle, and I could get that as exact as needed. I can imagine bolting the blade by the pivot hole to a piece of wood, clamping in a vice, and rotating it so the edge is level, then trying to manually keep the file level. Is there a more clever way than that? What are some things that could go wrong, other than obvious ones like not actually being able to keep the file level? The plan for maintaining centering would basically be go back and fourth between sides and do it visually. I could scribe a line where the edge should be, but I don't know how helpful that actually is.

I do realize that because of the recurve, I'm never using a sharpening method on this that benefits much from a sharpening choil anyway. Part of the point of this for me is the problem-solving and another is just to improve the look of the thing.
 
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I can see why you'd want to do the modification, as that is certainly an eyesore.

I think you have the right idea with the files, but I would certainly go slow, and tape up the blade to prevent scratches.

You are going to end up with a very large choil if you try to mate a new one with the factory one.

I would probably skip that and just file in one where the edge grind terminates.

It may look weird but is going to be the least amount of work and steel removal.
 
That's gonna be a long & tedious job with a narrow little diamond file. Know anyone with a Dremel? I'd Dremel it down and then use a file and narrow stone just for the finish work. I've done it and you can keep the edge pretty straight by eyeball/ freehand, even just holding blade in one hand and file in the other. The angle will however be a lot steeper in that section if you want it to remain the same width as the rest of the edge - matching the same edge angle would require a really ugly wide edge in just that section, a cure maybe worse than the disease.
 
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Diamond files can work, it would just take awhile.

I'd use a Dremel with a grinding bit.

I did this choil with a 3/8ths" bit (#8175). Steel is D2, 59-60 HRC. I went slow, frequently dabbing the area with a folded up paper towel dipped in ice water.

Then I finished up with sand paper wrapped around the butt end of a drill bit a little smaller in diameter than the choil.

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That's gonna be a long & tedious job with a narrow little diamond file. Know anyone with a Dremel? I'd Dremel it down and then use a file and narrow stone just for the finish work. I've done it and you can keep the edge pretty straight by eyeball/ freehand, even just holding blade in one hand and file in the other. The angle will however be a lot steeper in that section if you want it to remain the same width as the rest of the edge - matching the same edge angle would require a really ugly wide edge in just that section, a cure maybe worse than the disease.
I do have a Dremel. I was kinda coming at this from the angle of wanting to go slow and keep everything thought through, since things can happen fast with them and I only mostly trust myself to keep the heat under control.
 
Thanks for the help everyone. I did some triangle math and now see that if I do keep the angle the same all the way through, I believe the edge bevel height is going to run way deeper than the choil notch, which seems bad and hardly an improvement, as fishface5 pointed out. I think it's outside my skill set to do a good job of keeping the edge bevel height constant and smoothly varying the angle - I could imagine doing that by twisting, sweeping motions on a round file (right?), but doing it in a way where the apex and the bevel height both stay where I want seems a little beyond me at this point.

I think the answer may be to extend the choil notch a little deeper and wider, such that I can keep the angle constant but not wind up with too crazy of a bevel height.
 
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