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TOPIC: How to go more Obtuse?

How to go more Obtuse? 1 year 6 months ago #9082

  • Geocyclist
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I just finished sharpening a knife to 15 degrees. I would like to go more obtuse, say 17 or 20 degrees. Anything I need to know, any tips? Or just dial in the new angle and start grinding down the edge.

How do I know when I am done? Sharpie marker and look for full removal of the mark? By done I mean I want to get all the way back to 1 bevel per side and not have 2 bevels per side.

In case anyone is wondering why I want to change the angle, 1. I find a 15 bevel on on this knife too sever looking, and 2. I am pushing the limit of the steel for the use. I am seeing some edge deformation after little use.
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Re: How to go more Obtuse? 1 year 6 months ago #9083

  • Mikedoh
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I defer to our " sharpening betters"

But in the interest of saving steel, why not just use a secondary bevel untill you eventually grind down to it being your primary?

I know this doesn't address your question, just curious.
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Re: How to go more Obtuse? 1 year 6 months ago #9084

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Sharpie marker and look for full removal of the mark? By done I mean I want to get all the way back to 1 bevel per side and not have 2 bevels per side.

Sounds right to me.
But in the interest of saving steel, why not just use a secondary bevel until you eventually grind down to it being your primary?

A very valid point for sure!!

The only thing i'd suggest possibly is instead of using course stones 100>400 use the 800 or 1000 grit to re-profile the edge in your case. Because you are increasing the angle and cutting the top of the the apex-ed edge you wont need to do too much work unlike going from 20 degrees to 15 degrees and having to cut into and bevel the grind/side of the knife; and it'll save you time later polishing. i'd even try the course ceramics for that kind of re-profile depending on how much time you have and how ocd you are about a polished edge. anyways just a thought that came to mind not sure if it'll actually be beneficial.
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Re: How to go more Obtuse? 1 year 6 months ago #9086

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This the Benchmade?

Can you post any pictures?
Last Edit: 1 year 6 months ago by cbwx34.
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Re: How to go more Obtuse? 1 year 6 months ago #9093

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I had thought about using a secondary bevel. I have thought about micro bevels before, never done one and decided against it as I would rather have sharper over longer edge retention. (not trying to hijack my own here). However, the 940 is a an EDC knife and a user, so I am open to this. While this is a good knife I am willing to experiment with it. I was also thinking about how much steel I would loose.

I am back and forth as to whether the bevel visually looks too big. I doubt there is anything wrong with it, just how it looks proportionately. I am not sharpening 100% for aesthetics, I sharpen first for sharpness sake as I use knives to cut. I don't do a lot of heavy work (I have bigger blades when I do), so I like the acutest angle that the steel will support while looking good. Therefore, on the 940 I would be willing to go more obtuse to 17 or maybe even 20 for the sake of good looks. 17 would still be razor sharp. I am just cutting EDC stuff, not shaving so 17 is acceptable.

The bevel in question is a 940 S30V at 15 degrees, 2 photos, 1 is close up. For comparison, I also have 1 photo have a Ritter mini grip in CPM M4, the bevel here is also 15 degrees but looks just right proportionately to the blade. I guess this is almost getting into the art aspect as for me it comes down to how the bevel looks on any knife. Until I had the WE I could not go exactly to 15 or 17 or 17.5 degrees. Until I didn't think about that a 15 degree edge would look different on different knives.


Here is the knife in question, Benchmade 940, S30V at 15 deg.


Close up...


For comparison, a Ritter Mini Griptilian also at 15 deg. I think the look of the bevel fits perfectly here.
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Re: How to go more Obtuse? 1 year 6 months ago #9096

  • PhilipPasteur
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I think that it looks great, actually. But I tend to like a wider nicely polished bevel. However, if the S30V is not up to it, you need to do something. I think I would start by trying a micro bevel and see how the edge holds up.. Really, to me it looks fine, I mean real nice! If you went with maybe a 17 to 18 degree microbevle, you would not lose that much in sharpness. I wonder if you would even be able to notice it. I tend to think that you would not.

I haven't gone below 16 degrees on any S30 V blades that I use, but at that angle I have had no problems.
I have a bunch of S30V knives, but no Benchmade blades There are lots of people talking about using 15 degrees and eve 12 degrees without problems. I even read somebody saying that Benchmade would replace knives that showed any chipping or edge problems at 15 degrees. If you are seeing edge deformation, maybe your blade did not get heat treated properly? You could call them.

Curious,what were you cutting when you noticed the edge failing? What kind of deformation are you seeing? It seems that the majority of complaints that I have read are regarding chipping...or micro chipping... what ever that term actually means, rather than rolling of the edge.

Phil
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Last Edit: 1 year 6 months ago by PhilipPasteur.
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Re: How to go more Obtuse? 1 year 6 months ago #9098

  • cbwx34
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S30V? I was thinking of the D2 Benchmade you asked about the other day.

I'm with Phil, I think it looks fine. Give it a chance, it'll probably grow on you. You could maybe clamp the tip a little closer so it doesn't widen out so much... that might help how it looks. Nice polish job BTW. :woohoo:
Geocyclist wrote:
I had thought about using a secondary bevel. I have thought about micro bevels before, never done one and decided against it as I would rather have sharper over longer edge retention. (not trying to hijack my own here).

A microbevel on a 15 deg. bevel will be sharper than returning the whole bevel to 17 or 20 degrees. (Not to mention the metal loss). If deformation is an issue, I'd try the microbevel first. If you thin a blade and add a microbevel, it'll cut better than just sharpening at that angle. In other words, if you added one to this knife, the edge will hold up better, and I doubt you'll notice much difference in how it cuts.

Thanks for posting the pictures. Add it to the Database? Be nice to add and link to this thread so others can see what it'll look like.

Good info!

Edit: Also, what progression did you use to polish it out?
Last Edit: 1 year 6 months ago by cbwx34.
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Re: How to go more Obtuse? 1 year 6 months ago #9107

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How is the best way to post or link photos to the knife database?

Thanks for the compliment on the polish job. This photo is after already cutting cardboard a few times and stropping once by hand, so I am sure I have added a few scratches.

"Failing" was probably too strong a word. Whittling some UHMW plastic (ultra high molecular weight - hard plastic for machining stuff out of) I noticed a very faint bur. This bur was very faint, only enough to tell in 1 spot. When I run my finger left to right the edge is smooth. I was able to hand strop this out. Before using the WE this micro bur was normal after a day of moderate cutting, cardboard, etc., anything much more than just envelopes. So I would say some spots of the edge started to roll or bend slightly. I notice M4 is tougher in this regard.

The 940 in D2 steel has not made it on the WE yet. I will wait to decide for sure on the looks of the bevel before starting the next 940. May go 17 on it just for looks. And I need to slide it forward some. I had this S30V 940 all the way back where the vice was next to the thumb studs (had to remove the studs anyway). I think this was B.5++. So I might try a little more back in the vice, B.5 to B. How much do you need to move back/forward to notice a difference? I moved 1/4 inch and couldn't tell much on a different knife.

The progression was, 100-1k diamonds, 400 to 10k chosera, 5 to 0.5 strops. This takes me at least 12 hours, normally spending 4 hours+ times 3 sittings.

I did make a goof in the progression. I did all stones at 15 deg. I did the strops at 16, where I meant to go 14 (checked later that 14 is not possible with this knife, too much interference). With the Choseras you slide the rods "out" to get the same angle. I must of slid the rods out instead of in with the strops. Saw "16" and thought I had my angle +1 instead of -1 from 15. Even at 16 it polished all of the bevel and the edge felt just as sharp as before stropping. So I don't think I rounded the edge any which was my initial fear.
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Re: How to go more Obtuse? 1 year 6 months ago #9108

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Geocyclist wrote:
How is the best way to post or link photos to the knife database?

There's a place to enter a URL... just link it back to this thread.
Geocyclist wrote:
So I might try a little more back in the vice, B.5 to B. How much do you need to move back/forward to notice a difference? I moved 1/4 inch and couldn't tell much on a different knife.

Not sure the answer to this... other than following the instructions on the Finding the Sweet Spot page, and checking as you reprofile if needed.

Thanks for the info on how you did it.
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Re: How to go more Obtuse? 1 year 3 months ago #11254

  • KenSchwartz
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A vote for a more obtuse microbevel. You can gradually increase the angle to a more obtuse angle. Why do the whole bevel only to redo it again to yet a more obtuse angle. Besides as you continue to use the knife you will have to thin behind the edge. This way that work is already done.

Remember that it is far more work to go more acute than to go more obtuse.

---
Ken
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