Do I need to worry about heat with a Ken Onion work Sharp?

[Rey HRH]

I'm considering getting one to make reprofiling easier and faster should I want to change from factory angles to 15 degrees or less.

Do I need to worry about heating up a blade too much? And would dunking the blade in water every 15 seconds be a simple solution?

 

[samuraistuart]

I am not a fan of powered sharpening at all. There have been a few studies done, Roman Landes coming to mind, that showed that any and all powered sharpening will over temper those last few edge microns, if not deeper than a few microns. Lubricated power sharpening helped tremendously, and if you do any powered sharpening I would say use some sort of lubricant. If the system doesn't allow lubricant, I won't use it.

IIRC, this study went so far as to show that HAND sharpening on a stone without lubricant can/will over temper those last few microns. I was surprised to hear that, but figured it was so with powered sharpening. When I first saw that device introduced at market, I cringed.

With that said, I know of many pro knifemakers who sharpen their knives on their 2x72 grinder! Many use a mist system because of Roman's study. Many do not. It's up to you, but my opinion is stay away from it. But I'm more of a "purest" or OCD anyway.

What the study is saying is that keeping water handy in a bucket to dunk it in isn't going to help when sharpening. The heat being generated when contact is made with the belt, and immediately dissipated when lifted off. (at the edge micron level....not the whole blade). If the whole blade is warmed up by powered sharpening, my guess the very edge is already over tempered.

My two cents. I guarantee there are other opinions of powered sharpening.

 

[Rey HRH]

I'm thinking of just using it for reprofiling and not final sharpening. And since the worksharp advertises it goes down to 15 degrees, that's still more than my target of 12.5 degrees so I'm just trying to save the time it would take from the factory 20 to 15. Then I'd still have to take metal off to get to 12.5.

 

[Spey]

I'm thinking of just using it for reprofiling and not final sharpening. And since the worksharp advertises it goes down to 15 degrees, that's still more than my target of 12.5 degrees so I'm just trying to save the time it would take from the factory 20 to 15. Then I'd still have to take metal off to get to 12.5.

Based on what you have written in your posts, I would I believe this is not the tool for the job.

Example: when you place the blade into this sharpener, material is removed most easily along the thinnest area (the edge). By your description, you don't want any material removed from the edge, and instead want material removed from the transitional shoulder between the primary & secondary bevels effectively lowering the secondary bevel by ~5-dps. Without a platen, and with relatively low belt tension, I think it would be extremely frustrating attempting to use this tool without the belt making any contact with the cutting edge.

I have two knives and a hawk in for sharpening where the owner has been maintenance sharpening on KOWS system. ALL are heavily fat convex edges, meaning very steep near the cutting edge. This seems to be a typical condition as there is no platen for the belt to ride against on this tool, and relatively low belt tension allowing a significant amount of deflection in use.

For reprofiling, as you have described, it would seem to me that you would achieve best/easiest results using a flat stone of some type (or a belt system with platen). Flat stones possibly freehand or combined with a jigged sharpening system. Two popular systems include Edge Pro Apex and Wicked Edge. For a typical 3-4" blade a reprofile like you description is about a 15-min job and results in a very controlled and repeatable geometry.

 

[Rey HRH]

Based on what you have written in your posts, I would I believe this is not the tool for the job.

I see the wisdom of your insight. Thank you for sharing and saving me $129!

 

[Spey]

Then again, if you also were to purchase the $99 accessory attachment that includes a platen this tool could serve your intended purpose. But at that point, that much $ "might" be spent elsewhere to greater effect ... :-/

 

[bgentry]

I think the concern about destroying the temper at the "micron level" of the final edge is misplaced. I haven't read the study, but I know that most major blade manufacturers use belt sanders to set the edge on their blades. So every blade from every major manufacturer (Spyderco and Benchmade included) would be "burned" at the edge. I highly doubt the edges are burned on all their blades. That just wouldn't make any sense would it?

I have significant experience with the WSKO and haven't noticed a problem with the blades I've done. I've used it to work on several blades that I do a lot of cutting with and I haven't noticed a difference in edge holding with any of them. I *might* have noticed a small improvement in edge holding actually; but it's a small improvement *if* it's there. I didn't use a scientific method to test it.

As for reprofiling, yes it's a good tool for that. Not as fast as a bigger belt sander, but it's definitely capable of dropping the included angle to whatever level you want. I don't use the guides, so I can drop the angle to where ever I think it should be. ...and this whole idea of "belt sanders make convex edges" is WAY WAY over emphasized. Yes, the edges are lightly convexed. But it's barely discernible on the blades I've done. If you're picturing a blade with an edge that looks like an apple seed, you're way off. No offense Spey, but I just don't see it and I've used this system a LOT.

Now don't misunderstand me: I do think that significant heat is a problem with belt sanders. I wouldn't run the WSKO full speed for minutes at a time on a blade. That would certainly overheat it. If you take your time, and use speeds less than full, you can get the job done correctly and in a reasonable amount of time. I use my fingers as a guide for how hot the blade is, and I VERY rarely find a blade getting to the level that I think it's more than warm. Mostly when I'm using a 60 grit or 80 grit belt and really hogging off metal.

I wouldn't recommend using water, as I don't think the belts are waterproof... but maybe I'm wrong about that particular point.

If you're careful, the WSKO is a fantastic tool.

Brian.

 

[Spey]

Brian,
No offense taken. Your points are valid. I too use belt grinders for various tasks, depending on project goal.

It sounds like you have much higher level of proficiency with WSKO than the owners of knives I have received. As always, a tool is never any better than the user is capable ... and for many they can use fairly ordinary things as tools to accomplish very good results.

I think it interesting that you choose not to use the bevel attachment provided with the WSKO (I suspect that attachment is a fairly expensive component of that system) and was a fairly significant upgrade from the original configuration of that tool. Do you mind my asking why you don't use that attachment when sharpening & reprofiling as you have described?

 

[samuraistuart]

I am not a Spyderco fan. They have good steels and a good heat treat, and they can make a knife sharp. But most factory knives, my experience is the factory edge does not last NEAR as long as when you resharpen it by hand. I'm not talking about relief cutting, back bevels, changing geometry, but simply hand sharpening the factory angle. It's not an absolute, but is very common. Can't get around physics. And think about it.....our edges are on the micron, and some cases, sub micron level. The finer the grit, the quicker the heat buildup. I finish many knives at 12k grit (J), imagine a belt that fine running against a micron edge at those speeds dry.

You have to remember that a factory is trying to run knives out the door as fast as they can, as best they can. Powered sharpening is not near the best edge, by simple physics, but the factory must weigh how good is good enough. When I sharpen the knives I make, I don't consider powered sharpening, other than the slow speed wet grinder with a 320 grit stone to set the secondary. That is obsessive for sure, and does NOT work with higher alloy steels, would take forever, when I then go to soap/water lubed diamond plates.

There is nothing wrong really with the Ken Onion system and powered sharpening in general. My recommendation is to simply understand it's limitations as well as benefits.

 

[bgentry]

I think it interesting that you choose not to use the bevel attachment provided with the WSKO (I suspect that attachment is a fairly expensive component of that system) and was a fairly significant upgrade from the original configuration of that tool. Do you mind my asking why you don't use that attachment when sharpening & reprofiling as you have described?

From the moment I saw the WSKO I thought it might be really good to use as a miniature version of the belt sanders that so many people use to sharpen blades. I don't have a dedicated work space right now, so it being small and portable was an important factor. In the future I'll probably end up with a 1x42 sander mounted to a work bench or something like that, as it will be much faster. But the WSKO still has the advantage of variable speed which can really help in controlling grinding speed and correspondingly, heat production.

Advantages of the guide: Mostly a controlled angle.

Disadvantages of the guide: Almost no control over contact force against the belt. Possibility for grit to lodge between the guide and the side of the blade, scratching the blade. Limited range of angles. No practical way to grind selectively on certain parts of the blade.

Said another way, using the machine freehand gives me a lot of freedom and capabilities that I wouldn't have if I used the guide. I especially like that I control the contact force and that I can grind any little part of the blade that needs it without overgrinding the rest. I'm super happy with the system if you can't already tell.

Brian.

 

[Spey]

bgentry,

I appreciate your honest reply. Pretty much agree with everything you stated. Basically when using the "system" as a package the way it is presented there are numerous potential issues that can wrack havoc on an edge (especially when folks begin to get frustrated when attempting to do more than simply touch up an edge & start increasing pressure).

What you described (problems/issues related to the guide) are directly responsible for the issues on customer knives I get in for work/repair. Example: how can a user set an angle adjustment and expect consistent results when the guide changes angle with pressure against it. Also, how many folks take into account that the guide is resting along the primary bevel (and therefore add or subtract the primary bevel angle effectively in their end results inclusive sharpening angle goal I wonder?

Considering the fact that you use this devices sans guard (effectively free handing), have you ever compared to say a Makita belt grinder (like models 9031 or 9032)?

 

[bgentry]

^ Spey, that's interesting that you think the guide is the source of the problems you've seen. Hmm. I don't have a problem with guided systems. I'll probably own an EdgePro or a Wicked Edge eventually. But the guide on this one just doesn't appeal to me. For all of the reasons we've discussed and a few more.

I haven't tried the Makita's you listed; honestly I hadn't even heard of them until you mentioned them. Seems like I'd need to build some sort of jig to hold them in place, but it's hard to tell from pictures. That's something the WSKO has going for it: The belt runs in a position that's easy to use for sharpening and it will stay in place with the trigger locked. Well... I use a piece of shelf liner under the WSKO, which holds it in place pretty firmly. Without it, it tends to "walk". I've demoed this in my WSKO freehand video.

Thanks for the discussion.

Brian.

 

[Spey]

bgentry,

I know the guide is the source of most the edge problems I have seen.

Pre-release I spent a lot of time in emails with questions related to the attachment. There was initially a lot of "trust us, we know sharpening ...". When the WS folks could not answer the specifics of my questions they began forwarding to the designer for reply (I don't know if this was Ken O. or maybe the guide may have been by another person). Bottom line, my questions and associated reservations about the guide were unresolved (and somewhat now have been proven in my mind).

I decided to wait for the blade grinder attachment to be released b4 buying a WSKO. WS stated to me that they would not sell me the grinder with the blade grinder attachment (minus the guide we are discussing). Well as a result I have chosen not to waste my money as I believe $250 could be spent for better long term value - maybe a Veil, etc.

I am sure there are folks out there that are using those original guides to their personal satisfaction. We all have our personal levels of acceptance when it comes to the tools we use to achieve our desired results and various levels of "acceptability" ;-)

Thank you also for the open fair discussion.

Regards,

 

[chiral.grolim]

Regarding the WorkSharp, I'm not sure I understand why people aren't simply getting a 1x30 belt-grinder from HF for ~$40 and adding belts as needed...

Regarding water-cooling the edge while sharpening, I certainly understand where the study could have some relevance concerning trying to achieve the crispest and narrowest apex on a cutting tool... But I do not buy into the practical advantage gained if the results are the same whether power-sharpening or hand-sharpening. When i cut-up cardboard boxes, the blade gets too hot for me to touch. If the blade is unable to hold a reasonable edge during cutting tasks for which it was designed, that is very poor manufacturing, yet the blade continues to cut even as it dulls and consequently generates more heat. When i run a chainsaw or ANY saw or even a file, significant heat is generated, but those blades can keep cutting for a LONG time (i.e. many many cuts) before sharpening or replacement. So my question is, why is the heat-generation relevant if it is unaviodable and also not noticeably detrimental? Straight-razors are given extremely fine edges and are stropped dry in a manner that surely generates substantial heat at the submicron level... So what?? They still shave. Scalpels are power-sharpened dry as well.

That is not to argue that edges cannot be "burnt", I have done that myself on my 1x30 HF by really leaning into a worn-belt, and we've all seen the video of the BRKT chop-stik test, haven't we? But as already mentioned, there are good ways and bad ways to use a tool. And there are also steels more amenable to high heat than others ("high speed" steels are designed for that very purpose). I am not convinced that grinding on a belt is as evil as Landes seems to suggest, I certainly don't buy his story about the "burned eye", but i will still advocate that users avoid power-sharpening except for major undertakings, and then to use new/sharp belts with light pressure and consistent motion to reduce heat build-up. That's my $0.02

 

[bgentry]

Regarding the WorkSharp, I'm not sure I understand why people aren't simply getting a 1x30 belt-grinder from HF for ~$40 and adding belts as needed...

My reasons are:

1. The HF 1x30 is extremely poorly made by all reports. It's a junky belt sander that's cheap.
2. The HF runs at one speed and that speed is *FAST*. That's good if you're very skilled. Not so good if you're not as skilled. Lots of metal removed very quickly.
3. The HF isn't portable or light.

The killer combo on the WSKO for *me* is:

1. Portable and light.
2. Variable speed from really slow to really fast.
3. Great range of available belt types and grits.
4. Well made.

It's all about what you're after. For my requirements the HF doesn't make sense. Others might get good results and enjoy it. It's just not for me.

Brian.

 

[chiral.grolim]

My reasons are:

1. The HF 1x30 is extremely poorly made by all reports. It's a junky belt sander that's cheap.
2. The HF runs at one speed and that speed is *FAST*. That's good if you're very skilled. Not so good if you're not as skilled. Lots of metal removed very quickly.
3. The HF isn't portable or light.

The killer combo on the WSKO for *me* is:

1. Portable and light.
2. Variable speed from really slow to really fast.
3. Great range of available belt types and grits.
4. Well made.

It's all about what you're after. For my requirements the HF doesn't make sense. Others might get good results and enjoy it. It's just not for me.

Brian.

Very reasonable :thumbup: How low is the low speed? I don't think of my HF 1x30 as "*FAST*" but I would certainly appreciate variable speed, especially when polishing smaller blades with high-grit belts. As for portability, the WSKO isn't cordless, perhaps that will be the next edition? I lug my HF 1x30 in a duffel-bag if I need it elsewhere and that's no more difficult than lugging around my cordless drill-set or my dremel and workstation ... but the latter tools could fit in my Sitka if needed, the HF certainly wouldn't So I see where you're coming from. I just watched the Twang'n'Bang review and admit it looks pretty handy:

[video=youtube;h8Yl_Z-oRkU]https://www.youtube.com/watch?v=h8Yl_Z-oRkU[/video]

 

[samuraistuart]

Chiral, I think maybe you are misunderstanding/misinterpreting a few things. First of all, when you cut up cardboard boxes, your knife is warming up for sure. What temp is at the apex? I don't know....but your knife is DULLER now!!!! Now for sure this is due to a few reasons, like adhesive wear maybe, or abrasive wear for sure. But you said it...it warms up in your hand....and is duller. It isn't the same, and of course it isn't sharper. It is duller. Is some heat playing a part in over tempering the apex when cutting cardboard so much the whole blade is "Too hot for you to touch"????? Probably. I can't say that I have ever cut so much cardboard (or anything for that matter) that I couldn't hold on to it, but can see how that could happen. Remember our knives (carbon steels anyway) are tempered in the 400-450 range usually. That temp can be reached pronto, on an edge, with powered sharpening if not careful.

Chainsaws and files are not on the micron level of a knife edge. No where NEAR as keen.

Straight razors......stropped, by hand. Yes, dry, but by hand. Not a powered stropping system. ????????? Would YOU power strop your straight razor? I didn't think so. And stropping is misunderstood by most everyone out there anyway. Not relevant to this discussion, but very true.

It's good not to buy into everything someone says. But Mr Landes has done WAY more study than anyone out there. He has done the tests and came up with results. Much more than I can say for myself for sure, and 99.9% of the rest of us.

"but i will still advocate that users avoid power-sharpening except for major undertakings" BINGO we have a winner. Now you are understanding the reasoning of my post. I'm not here to argue. I'm not here to say, "Look at me". I'm here to offer info.

To those who are interested in the powered sharpening systems, again, just understand they have SEVERE limitations on what you can do in sharpening a knife. There is NO FREAKIN way that I would use one with fine grit belts for sure. NO WAY. The only time I consider powered sharpening is when I have a thick edge on a new knife that needs to come down. Say a chopper with an edge of .035" or whatever. I might consider my belt grinder, with very coarse belts, never apexing. I would probably use a 120 grit belt and barely approach the apex, then switch over to hand sharpening. Just NO WAY would I apex an edge using powered equipment. To do so, in my opinion, is asking for it. Now some might argue, "What difference does it make on a chopper?" To which I would agree. On my White steel kitchen knives......NO FREAKIN WAY.

I'm sorry if capital letters offend you. They're a quick, good way to show my emphasis on certain phrases!

 

[chiral.grolim]

Chiral, I think maybe you are misunderstanding/misinterpreting a few things. ...

...Remember our knives (carbon steels anyway) are tempered in the 400-450 range usually. That temp can be reached pronto, on an edge, with powered sharpening if not careful.

Chainsaws and files are not on the micron level of a knife edge. No where NEAR as keen.

Straight razors......stropped, by hand. Yes, dry, but by hand. Not a powered stropping system. ????????? Would YOU power strop your straight razor? I didn't think so. And stropping is misunderstood by most everyone out there anyway. Not relevant to this discussion, but very true.

It's good not to buy into everything someone says. But Mr Landes has done WAY more study than anyone out there. He has done the tests and came up with results. Much more than I can say for myself for sure, and 99.9% of the rest of us.

"but i will still advocate that users avoid power-sharpening except for major undertakings" BINGO we have a winner. Now you are understanding the reasoning of my post. I'm not here to argue. I'm not here to say, "Look at me". I'm here to offer info.

To those who are interested in the powered sharpening systems, again, just understand they have SEVERE limitations on what you can do in sharpening a knife. There is NO FREAKIN way that I would use one with fine grit belts for sure. NO WAY. The only time I consider powered sharpening is when I have an edge thickness on a rough/tough type blade that needs to come down. Say a chopper with an edge of .035" or whatever. I might consider my belt grinder, with very coarse belts, never apexing. I would probably use a 120 grit belt and barely approach the apex, then switch over to hand sharpening. Just NO WAY would I apex an edge using powered equipment. To do so, in my opinion, is asking for it. Now some might argue, "What difference does it make on a chopper?" To which I would agree. On my White steel kitchen knives......NO FREAKIN WAY.

I'm sorry if capital letters offend you. They're a quick, good way to show my emphasis on certain phrases!

I have no problem with capital letters, I use them all the time :thumbup:

1) Landes related a story of a friend burning his eye from hand-sharpening a blade and having a bit travel the distance ... His study results need proper interpretation regarding the limits of their relevance, just like his edge-stability tests. Much respect, yes, but also a healthy level of skepticism and in depth interrogation.

2) Cutting cardboard and stropping at a very fine grit both generate a LOT of heat VERY quickly, because the heat is generated exactly the same way as when power-sharpening - i.e. through friction along the bevel faces. If your edge is getting sharper and you aren't using a coolant, then your apex is also getting hot, much hotter than the surrounding material through which it dissipates. Frictional heat generation is reduced through less application of force, e.g. fewer and more precise surface contacts as provided by a fresh belt. Stropping by hand is often done at relatively high speed (lots of friction) and VERY fine grit = heat generation. What is "burnishing"? Rubbing-action that generates frictional heat until the yield-strength is exceeded (maybe because the apex is being tempered softer?) and the material plastically deforms ... resulting in a finely polished bevel that is maximally sharp!! I can cut a LOT of cardboard and quickly with a knife and not lose a shaving edge, depending on the steel, despite the heat generated. Paper-wheel sharpening/polishing is common ... lots of complaints about edge-performance?

My point - while power-sharpening CAN result in a "burned" edge, even use and HAND-sharpening can generate heat sufficient to potentially impact the temper at the apex... and that is not necessarily detrimental. The real TEST is to sharpen whichever way and see if you repeatedly notice an impact on cutting performance. If there is NOT an obvious impact, then the heat being generated isn't relevant.

3) Chainsaws are powered chisels, they should be sharpened accordingly for maximum performance, micron-level keeness is advisable. Under-sharpening results in decreased performance, increased load on the motor, and increased damage to the chain. Who told you it was otherwise?

Scalpels - How it's Made: (power-grinding at ~2:30, i can't see any coolant )

[video=youtube;V89F7_MLKqM]https://www.youtube.com/watch?v=V89F7_MLKqM[/video]

 

[samuraistuart]

Dude, a chainsaw is sharpened on a grinder wheel. We offer that service at our family store. It is NOT a micron edge at low angles. It certainly has an apex to it, but it is certainly not anywhere near close to the edge a knife has on it. Back to sharpening chain saw chains......it is usually done with a special chain saw sharpening grinder. All that is is a metal cutting wheel held at the right angle, with a guide for the chain to run thru. You bring down the grinding wheel that is spinning at a trillion and one rpm onto the chain tooth. You can quickly make a chain tooth glow if you're not careful. But the chisel edge of a chain saw chain tooth again, is not anywhere near what we are talking about.

Stropping is done by hand on a piece of leather about a foot long. How much heat do you really think you can generate by hand, stropping a knife on a piece of leather a foot or two long? Roman will tell you that hand honing without lube can generate the heat we are talking about. I wouldn't think so, but who am I to so no? I haven't done the study myself. As far as paper wheel sharpening and who complains.....I can by personal experience say that it DOES matter. At our family store, when I was there anyway, we offered knife sharpening. I was the only one who knew how to do it. Well, me and one other guy. We had the paper wheel set up. One wheel had an abrasive compound/wax. The other wheel was polish. I could take a very dull knife and make it screaming sharp in no time at all with that set up. Did customers come back and complain about their edges. No sir, they certainly did not. But I can tell you for a fact that 99% of those customers had NO IDEA what a great steel with a great heat treat and excellent geometry could do for a knife. 99% of them had NO idea how long an edge should last! So I had NO complaints! But I certainly noticed it.

I had a sheepsfoot swiss army knife that was my box cutter at the store. Loved those knives. Just a single sheepsfoot blade. Sharpened on the paper wheel the edge was just crazy sharp, but wouldn't last very long. When I sharpened it on our DMT display stones, the edge lasted WAY longer. This was before I even knew about steel, heat treating, etc.

I think we agree fundamentally. Even if we don't, that's OK! I still love you!

 

[bgentry]

I'm not here to argue. I'm not here to say, "Look at me". I'm here to offer info.

To those who are interested in the powered sharpening systems, again, just understand they have SEVERE limitations on what you can do in sharpening a knife. There is NO FREAKIN way that I would use one with fine grit belts for sure. NO WAY.

I'm with you about my intention of being here. I love sharpening. I want to be as good at is as I can possibly be and I'm interested in most of the crazy low level details. I've had really exceptional results with my WSKO. So my experience contradicts what you're saying. Namely that powered sharpening will produce a poor edge in some way. Burned, weak, not long lasting, or perhaps something else.

The question is, what are you saying will happen and how can we test it? What do you propose will happen when I use the WSKO to sharpen knife X and test it with methodology Y? I'm not into some long protracted testing procedure that takes forever. I'm also not interested in debating why you think it happens with the information you cite. I'm interested in real world results.

I'm not trying to make this into anything it's not. I'm just trying to bring this to reality and how blades cut. I'm interested in your reply.

Brian.