Getting blade chipping while sharpening 154CM

[Jason B.]

First thing I would recommend is stop spending so much time sharpening, if you can't do it in 15 minutes then you are wasting a ton of steel. That poor knife is going too look like a tooth pick when your done.

 

[Bugout Bill]

My suggestions to the OP:

-Make sure that the the stone is flat and doesn't have any hollows.

-cut into the stone to remove the chips.

-Sharpen it at a more obtuse angle (40 degrees inclusive). If the edge won't form cleanly at that much of an angle, there is something wrong with the steel and you should probably contact benchmade.

-Use light pressure when sharpening.

What is happening is pretty abnormal, a burr wouldn't be causing a length of the edge to chip out.

The idea that the stones are too hard for this steel is nonsense. I've sharpened 154CM, S30V, and S35VN on this exact stone, both soaked and dry, and never experienced that problem. The "too hard" thing primarily refers to problems people have had with ZDP and Japanese carbon steels with relatively extreme geometries sharpening on the corners of ceramic rods. The chipping in those cases is due to increased pressure, not hardness of the stones.

 

[SunOfAtom]

First thing I would recommend is stop spending so much time sharpening, if you can't do it in 15 minutes then you are wasting a ton of steel. That poor knife is going too look like a tooth pick when your done.

Come on now, give me some credit. I created a very small flat-ish edge along the back 1/2 of the blade while grinding out the recurve. When I switched back to my 15° angle to resharpen the blade, the stone just did not seem like it had any bite (as has been the case all along with this 154CM). It is not that I was grinding away large amounts of steel for two hours, it was more that the knife was sliding across the stone with little affect. I was making slooooow progress, so I kept at it. I was maybe about 75% towards having a decent edge along the knife when I switched over to the fine India stone. That remaining 25% went much quicker. In hind sight, it probably would have taken me significantly less time to do all of that work on the fine India stone, which to me says something is going on with the coarse stone. I remove/replace the oil regularly, so I don't think it is clogged. I could use more force, but it seems like much more and I will start introducing flex and then creating geometry problems.

I agree that the sharpening should take much less time, I just don't know why I am having issues with this steel. I can use this same stone to sharpen AUS-8 or 8Cr13MoV without issue. Even VG-10 is not causing problems like this. My best guess at this point is that all this time spent running the knife across the stone is having some other affect on the 154CM edge. It is not doing much to remove steel, but it must me doing something else. Generating heat? Doubt it, it never feels warm and the blade should be able to handle plenty of heat. Fatigue from vibration? Maybe.

When I get the new Crystolon stone this weekend, my hope is that it cuts the 154CM much more quickly and because of that my chipping problems go away. I could try sharpening my other 154CM knife, I am just not sure if that is going to create another headache. It will tell me if two different versions of the same steel are behaving differently on this same stone, but it could also just leave me another dull or chipped knife that I need to repair. We'll see how motivated I feel after a beer or three

Dave

 

[SunOfAtom]

My suggestions to the OP:

-Make sure that the the stone is flat and doesn't have any hollows.

It is definitely flat, it is not that old and I just recently re-flattened it (though I doubt it actually needed it)

-cut into the stone to remove the chips.

What do you use to cut into it? A nail? Any knife that needs sharpening? I am certainly up for trying this.

-Sharpen it at a more obtuse angle (40 degrees inclusive). If the edge won't form cleanly at that much of an angle, there is something wrong with the steel and you should probably contact benchmade.

That has been something I was planning, but I was trying to not change too many variables at one time so that I could figure out exactly what the issue is. If I still have issues with a Crystolon stone at 30°, I'll definitely try again at 40°.

-Use light pressure when sharpening.

If anything, I may be using too little pressure, though I doubt that.

What is happening is pretty abnormal, a burr wouldn't be causing a length of the edge to chip out.

Agreed, I just still can't figure out what the problem is. Funky steel or heat treatment? Unlikely, but possible. User error? More likely, I just don't know what I am doing wrong.

The idea that the stones are too hard for this steel is nonsense. I've sharpened 154CM, S30V, and S35VN on this exact stone, both soaked and dry, and never experienced that problem. The "too hard" thing primarily refers to problems people have had with ZDP and Japanese carbon steels with relatively extreme geometries sharpening on the corners of ceramic rods. The chipping in those cases is due to increased pressure, not hardness of the stones.

While I have not had issues sharpening some of the softer steels and decent success with some VG-10 on this stone, this is the first time I have tried resharpening 154CM. At this point it could be the steel, the stone, or me. I am the most likely culprit, but I just can't see what I am doing to have such different results from all the other successful sharpening I have done with this stone.

Dave

 

[Bugout Bill]

When I say to cut into the stone, run the edge of the knife to get down to fresh steel. If you get the same results, try the same thing with the Crystolon stone. If it is still chipping out, contact Benchmade.

Unless there is something seriously wrong with the stone, or you are really laying into it while grinding, the steel is mangled. Either there were issues with heat treat or they burned the steel while grinding.

 

[Chris "Anagarika"]

I think OP has done that previously (cutting into stone).

 

[cbwx34]

When I get the new Crystolon stone this weekend, my hope is that it cuts the 154CM much more quickly and because of that my chipping problems go away. I could try sharpening my other 154CM knife, I am just not sure if that is going to create another headache. It will tell me if two different versions of the same steel are behaving differently on this same stone, but it could also just leave me another dull or chipped knife that I need to repair. We'll see how motivated I feel after a beer or three

Dave

If this doesn't work, you might consider sending it to one of the gurus here on the forum, (probably a faster turn around than Benchmade), that would help eliminate some of the factors causing this.... pretty much tell you if it's the knife steel or not.

 

[Bugout Bill]

If this doesn't work, you might consider sending it to one of the gurus here on the forum, (probably a faster turn around than Benchmade), that would help eliminate some of the factors causing this.... pretty much tell you if it's the knife steel or not.

If the steel is messed up, Benchmade should know about it.

 

[Obsessed with Edges]

If the steel is messed up, Benchmade should know about it.

Agreed.

HeavyHanded, when I am moving the blade across the stone, I do not let the end of the blade hang off the edge of the stone. In other words, I have the blade angled so that any part of the blade that is level with the stone is actually on the stone. Is that what you were asking?

(...)
Thanks!

I had overlooked this earlier; another thought occurred to me last night, on this note. If you're saying the heel of the blade never overhangs the edge of the stone, does this mean the heel & flat portion of the edge is continuously on the stone, or is it sweeping off the edge of the stone somewhere into or near the end of the stroke? I ask this because it may be possible the flatter portion of the edge, to the rear of the belly, is actually being overworked if your stroke doesn't sweep through the length of the edge, and off the stone. If so, it could create a large burr. I've always found a sweeping stroke, from heel to tip in a continuous motion, works much better in keeping pressure and scratch patterns as uniform as possible. I'd also think, in order to sharpen up the belly and tip, the rearward portion of the blade will have to sweep over the edge of the stone at some point. Some of the damage being done could happen when it does, if pressure at the edge of the stone is too heavy (what may feel like 'light' pressure will be magnified greatly on the corner of the stone).

If I'm misinterpreting what you're actually doing, disregard this. Just hoping this isn't a contributing factor; might be easy to fix, if it's just a matter of adjusting the stroke or pressure used.


David

 

[SunOfAtom]

I think OP has done that previously (cutting into stone).

Yes, this I have done. I originally read that as a process of removing a smooth surface from the stone.

 

[SunOfAtom]

If this doesn't work, you might consider sending it to one of the gurus here on the forum, (probably a faster turn around than Benchmade), that would help eliminate some of the factors causing this.... pretty much tell you if it's the knife steel or not.

This is certainly a possibility if I don't have better success with the new stone. I think I would actually send both the knife and the original India stone, in the event that there is something up with the stone. In the unlikely event that it turns out to be something wrong with the knife steel, I'll definitely send it back to Benchmade so that they are aware of the issue.

 

[BluntCut MetalWorks]

I agree with David/OWE's suspicion that you over worked the edge. The image from my earlier post the 'hole' has scratch pattern matched your clamp guided sharpening strokes. Whereas factory edge grind usually in the same line as scratch pattern on the blade (perpendicular to apex). Since you kept the blade off the stone edge, so your scratch pattern is around 45* bevel shoulder to apex/edge. And not correctly remove the large burr in the 'dip/recurve', lead to this thread.

This hole got dug probably from your push/guide (hand) fingers, placed on the clamp and right below it. Too much pressure in 1 place will dig a hole. Now, do as I suggest before and move your guide fingers evenly from heel to belly in the sharping process.

New SiC will amplify the 'hole' problem because SiC will cut much faster than your current AlO stone.

From looking at your bevel from belly to tip, it looks nifty good. Which mean your freehand (w/o a clamp) is sufficient, so why not give freehand a try... trust yourself! Ask yourself - what the worse thing can happen to -it's just a knife-

 

[SunOfAtom]

I was trying to respond to OWE's message for the past few hours, though the forum seemed to be having technical difficulties. My post is irrelevant now, since the issue is definitely resolved. This new coarse stone is fantastic and a night to day difference from the old one. I was able to do in about 4 minutes what was taking be hours on the old stone. Since I was not recognizing that there was an issue with the stone, I was spending way too much time on it with the knife. Though I was not using too much pressure, I was apparently still over working the blade. I'll post some new pictures when I finish the knife.

Any thoughts on what is going on with the stone? Any ideas on how to condition it?

 

[Jason B.]

I doubt you have a defective stone. My continued guess is that you have a blade that was ran a few points harder than normal, this is not a bad thing but will change things with sharpening.

 

[SunOfAtom]

Bluntcut, I do hope to switch to freehand at some point, but I figured that the clamp would help me get a feel for the correct motions. Hopefully when the clamp is removed, I'll recognize when I am not keeping a steady angle as I move the blade along.

Knifenut, I guess it either has to be an extra hard steel or a stone that lost its bite. I can still try sharpening my other 154CM knife on the old stone and see if it behaves any differently. At least now I know I can fix it if I get the same result. Do you think there should be a huge difference between the standard Norton coarse stone and the Crystolon, at least with a hard steel like this? I realize that the Crystolon has the added advantage of being new and fresh, but the difference between the two is shocking.

 

[Jason B.]

The Crystolon stone is silicon carbide which fractures when abraded and is a harder abrasive. With those features it allows the stone to remove metal faster and cleanly cut harder alloys. It is much faster than the India stone.

 

[HeavyHanded]

Any thoughts on what is going on with the stone? Any ideas on how to condition it?

I am not a big fan of the coarse side on the India stone. One of mine came slightly glazed from the factory, underperformed relative to the fine side (like yours) and had to be lapped for best effect. I use a tile rubbing stone - can be had at Home Depot or other tile supply for under 10 bucks and should be used with a loose grit. I use 120 grit silicon carbide lapping compound made for sharpening reel mowers, valve lapping compound will work. A less aggressive material like some sandblasting grit might work as well. Important thing is to have plenty of fluid, a loose grit, and a flat stone surface to lap against. The hard aluminum oxide stones can glaze up and it really ruins their ability to grind cleanly.

Once I conditioned the stone by lapping it good, the coarse side is very effective, though as knifenut mentioned, will be no match for grinding fast vs a silicon carbide stone.

 

[Obsessed with Edges]

I was trying to respond to OWE's message for the past few hours, though the forum seemed to be having technical difficulties. My post is irrelevant now, since the issue is definitely resolved. This new coarse stone is fantastic and a night to day difference from the old one. I was able to do in about 4 minutes what was taking be hours on the old stone. Since I was not recognizing that there was an issue with the stone, I was spending way too much time on it with the knife. Though I was not using too much pressure, I was apparently still over working the blade. I'll post some new pictures when I finish the knife.

Any thoughts on what is going on with the stone? Any ideas on how to condition it?

I had the same difficulties in posting that last reply, with many unsuccessful attempts over the span of an hour or so. Think it was sheer luck, when it finally went through (using a different browser; that may've just been coincidence).

Seeing HeavyHanded's comment about possible glazing of your stone, that was on my mind as well. Based on how slowly it's apparently cutting, it reminded me of a very 'inexpensive' aluminum oxide stone I have. I've never been able to do anything productive with that one, as it just won't cut steel aggressively at all. And trying to lean into the grinding to speed it up just introduces all the problems related to too much pressure, like heavy burring or edge-rolling or chipping.

Very good to hear that your new Crystolon is apparently working as it should. I still don't have one of these, but have been tempted for quite some time. :thumbup:


David

 

[SunOfAtom]

I'll definitely look into lapping this coarse stone, as it would still be nice to use. There is quite a big jump to go from the Crystolon stone to the fine India, so having a functional coarse India between them would be great. I sharpened a friend's Persistence last night and tried just that. When I switched to the coarse India, it felt like I was using a hard Arkansas stone. No noise, no bite. I am not sure what happened to the stone or what I might have done to cause it, but I am glad you guys helped me figure it out. Sharpening a knife just went from an all night affair to a fun small project.

If you think you have a use for the Crystolon stone, David, I highly recommend it. For me, that was $25 well spent.

Thanks again guys, I appreciate all the information and patience.
Dave

 

[ichbinbir]

Sorry to ask this novice question, done some minor searching, but can't find the answer I want. When y'all say 30 degrees inclusive, you're referring to the angle of each side adding up to 30 right? I.e. both sides sharpened to 15 degrees. And when you say sharpened to 20 degrees, that's the individual side?
Again, slightly off topic, but thanks for the help...