Am I expecting too much of the KME sharpening tool?

M

mgh24

Joined
Mar 24, 2022
Messages
8
Have had the tool for 4 days now, and cannot clamp any knife well enough that it will not still pivot after clamping. I mean pivot in the same way as the blade pivots into the handle, holding onto the handle and pushing outward away from the clamp handle, and inward towards the handle. This is not the direction most of the pressure is applied to when honing, but I have had one knife change position, so I had to start all over again.
This knife was a cheap Civivi Brazen with a funky (swedge?) grind on the top of the blade. Brutally difficult to get clamped securely.

I have also tried clamping 2 $20 Gerber knives that had a pretty flat top to their blades, and an old Buck pocket knife. The Buck knife is probably the most secure in the clamp.

I have watched at least half a dozen YouTube clips, including the excellent one below, and the one posted by KME. They are all pretty similar, and the procedure seems pretty straight forward to me. Positioning my Para3LW in the way the person in the video below does it, makes it pretty secure. I can still work it out of the clamp, but I think it will be secure enough to stay in place, though I am not nearly confident enough in my technique to put the Spyderco to the hone!

Another issue I finally noticed, is that the knives, especially the Civivi, do not clamp evenly. On one side of the clamp, the blade will be tight against the rubber lining, but on the opposite side, there will be a slight gap, resulting in my grind on one side of the blade being higher than the other side. This is less likely to happen if I put less of the blade inside the clamp, but that then makes it pivot out of position easier! I am turning the clamping screw as tight as I am able to. I got a decent edge on the Civivi while practicing, even with all the trouble I am having.

Am I expecting too much? Is it unreasonable to think the clamp should hold the blade securely enough that it will not pivot?
I understand I should not be putting pressure on the hone to blade, let the weight of my hand do the work, and I will continue to try and focus on using a light stroke, but I expected the clamp to be much more secure than what I am seeing.

Frustrated to say the least, but it must be something I am doing wrong, as so many folks reviewing the tool love it and get excellent results. I have looked and looked for a solution, but so far have found nothing that has helped.

Thanks for any help!

 
I never sharpen a full flat grind blade on a system with a clamp. I can’t get the blade secured properly. Try a saber grind blade and see if you’re still having the problem. I think the clamps work best when the blade has flats.
 
I never had an issue with the KME clamp being too loose. It sounds like you're not tightening down hard enough. Are you cranking down on the plastic knob as hard as you can?
 
Try using some masking/painters tape on the blade where it fits into the clamp. That helps secure the blade. You might have to use a second strip on a ffg blade.
Works for me.
 
many clamping systems have clamping parallels (only), so they have that issue in common. full flat grinds (no flats) could be taped to produce flats for the clamp, or use a rubber band to fill in the symmetrical voids.
some guided systems have table platforms (edge pro apex) and people buy it because there's no such clamping issue.

the 1 advantage of clamps is that you can switch blade sides fast , without realigning\reclamping the blade.

yeah
 
The KME clamp self-adjusts to fit full flat grinds, so that shouldn't be a problem. In order to make that work, you should pinch the front of the clamp towards the corner that faces the point of the blade as you tighten the retention screw.
 
This is a hot topic that comes up very regularly, and KME fans often get riled up when discussing the shortcomings of the KME system. Firstly, I have to say that the KME is a great system and it has its gilded place in the sharpening world. It's convenient, tool-less and quick to learn to use. But the truth is that there is no way on earth that the standard KME jaws can properly and securely clamp many knives. This is a simple matter of geometry. It has a back plate that restricts the amount of opening the rear part of the jaws can accomplish, and this limits the angle of the clamp and what it can conform to. The reason they have the rubber inside, is to try and compensate for the shortcomings of the geometry of the jaw. The rubber does help reduce the amount of play there is, but it cannot take all of it away. It is a simple geometry problem.

KME owners love the system, they use it for most of their lives and they will furiously defend it and argue away the shortcomings with all their might. I respect that, but unfortunately that also convinces KME that their system is perfect just the way it is and that they do not have to work on the obvious shortcomings. I really do hope one day that KME will look at the problem more seriously and work on upgrading or adding more options to their clamping system.

There are some knives that I love sharpening on my KME, but only a very select few clamp 100% properly and securely.

I have collected and use most of the top sharpening systems available on the market, a KME system being one of them. I also have a collection of just about every knife clamp that has been made and I have designed a fair amount of clamps myself, so I can honestly compare the differences. Most other clamps also have some limitations, but not as many as the KME clamp.

A two clamp system like Hapstone, TSProf, KakBritva, Kazak, etc (when used correctly and with no rubber inside the clamps) work much better. If you use one clamp on a flat section like the ricasso and a second clamp closer to the tip, most knives can be clamped 100% securely. When you have a knife properly and securely clamped this way, and you feel what it is like compared to a KME clamp, then you truly understand the limitations of the KME clamp.

I know this post is going to open the proverbial can of worms as it always does, but I have to be honest here and state the facts.
 
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If you could post a couple pics of where you have your knife clamped in, it might help. I could be you're just not tightening it down enough. You can crank on it pretty hard. Full flat grinds are the hardest for a KME. You want to pinch the front of the clap around the blade and crank it down. Then make sure there is no play in it. The rubber should compensate for the blade shape. I line the spine of the blade up with the second (deepest) line across the clamp. That's about all I can think of to try off the top of my head. Let us know how you make out.
 
777 Edge said:
This is a hot topic that comes up very regularly, and KME fans often get riled up when discussing the shortcomings of the KME system. Firstly, I have to say that the KME is a great system and it has its gilded place in the sharpening world. It's convenient, tool-less and quick to learn to use. But the truth is that there is no way on earth that the standard KME jaws can properly and securely clamp many knives. This is a simple matter of geometry. It has a back plate that restricts the amount of opening the rear part of the jaws can accomplish, and this limits the angle of the clamp and what it can conform to. The reason they have the rubber inside, is to try and compensate for the shortcomings of the geometry of the jaw. The rubber does help reduce the amount of play there is, but it cannot take all of it away. It is a simple geometry problem.

KME owners love the system, they use it for most of their lives and they will furiously defend it and argue away the shortcomings with all their might. I respect that, but unfortunately that also convinces KME that their system is perfect just the way it is and that they do not have to work on the obvious shortcomings. I really do hope one day that they will look at the problem more seriously and work on fixing the shortcomings of the clamp.

There are some knives that I love sharpening on my KME, but only a very select few clamp 100% properly and securely.

I have most of the top sharpening systems available on the market, a KME system being one of them. I also have a collection of just about every knife clamp that has been made and I have designed a fair amount of clamps myself, so I can honestly compare the differences. Most other clamps also have some limitations, but not as many as the KME clamp.

A two clamp system (when used correctly and without any rubber inside) with one clamp on a flat section like the ricasso and a second clamp closer to the tip, works exceedingly well and works securely with most knives. When you have a knife properly and securely clamped this way, and you feel what it is like, then you truly understand the shortcomings of the KME clamp.

I know this post is going to open the proverbial can of worms as it always does, but I have to be honest here and state the facts.
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I've sharpened scores of kinves on my KME, and about a dozen on my Hapstone, so that's my universe of experience with fixed angle systems (except a Lansky I had 20-30 yrs ago). I've never run across a blade that I couldn't securely clamp on the KME. A blade like the PM2's might be the worst case scenario with it's full flat grind, distal taper, and angled spine, but I can clamp that in the KME and shake the whole unit by the knife's handle and there is no movement of the blade in the clamp.

The main limitation with the KME system is its size, which effectively limits it to blades 6" long or shorter. If it could accommodate longer blades then you would want it to have a second clamp to prevent flexing.

On the other hand, there are blades I can clamp in my KME that will not fit in my Hapstone system, simply because the spine is too thick. But my Hapstone can accommodate blades up to 19", so that's a big deal.

Overall the Hapstone R1 is the better system because it's much easier to set repeatable angles, it uses bigger stones, it takes longer knives, and the rod operates more smoothly due to the ball bearing system. But I do miss the ability to hand-hold the KME sharpening unit, which allows me to look at the edge under a USB scope while mounted, and even check sharpness with the BESS tester without dismounting the blade. Maybe I should try the magnetic table for the Hapstone which would allow that functionality, but moving the blade around like that just seems squirrely to me.

As far as scratches, I never used tape and never scratched a blade with the KME clamp. Unfortunately, I can't say the same for the Hapstone, although that was my fault for not using wide enough tape. And tape is an absolute necessity with Hapstone.
 
3D Anvil said:
And tape is an absolute necessity with Hapstone.
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I don't use any tape for my Hapstone or other metal clamps and I don't scratch my knives.

It is critical however to make sure the knife and the inside of the clamps are very clean before clamping. Any bit of metal swarf, diamond, CBN, silicon carbide, aluminum oxide or other hard particles will scratch the blade when they come between the clamp and the blade.

As far as clean clamps are concerned, if for some reason you were to clamp non-hardened steel in them, that would scuff or mark it. If you clamp a hardened blade in them, the clamp steel won't scuff or scratch the hardened steel (the clamp aluminum / steel is softer than the blade steel) unless there are harder particles in between the steel and the clamp.

When you put rubber on the inside of a clamp, yes it will assist in grip but it also means there will be a slight bit of play due to the nature and compressibility of rubber. The other risk is, if you do have rubber coated clamps and clamp them onto a knife while they have some stone particles or swarf in them, it can embed itself so deep into the rubber (depending on the rubber and particles of course) that it becomes near impossible to remove the particles lodged into the rubber. It won't happen if you keep them clean, but it is a risk and it does happen to a lot of rubber coated clamps.

It's the same if you want to clamp a small item securely in a bench vise, locking pliers, G-clamp or any other clamp. As soon as you have a soft surface between the object and clamp to make up for imperfect clamping, you will have some play and a sub-standard hold on it. Try sticking rubber on the inside of a pair of locking pliers, adjust them until they fit around a bolt and then try to use them to tighten on loosen a very secure bolt. Yes, the rubber can compensate a little bit for the gap but it will never be as good as using the locking pliers' steel in direct contact with the steel on the bolt. Same concept applies to knife clamps.
 
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777 Edge said:
I don't use any tape for my Hapstone or other metal clamps and I don't scratch my knives.

It is critical however to make sure the knife and the inside of the clamps are very clean before clamping. Any bit of metal swarf, diamond, CBN, silicon carbide, aluminum oxide or other hard particles will scratch the blade when they come between the clamp and the blade.
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That's probably what happened with mine. I'd say that's another disadvantage of many of these non-KME systems ... that the blades are canted toward the spine when clamped, which allows the swarf to roll across the blade and towards the clamp. It's also not the easiest thing in the world to clean that central clamp on the R1, since it's fastened together with no fewer than eight screws.
777 Edge said:
When you put rubber on the inside of a clamp, yes it will assist in grip but it also means there will be a slight bit of play due to the nature and compressibility of rubber. The other risk is, if you do have rubber coated clamps and clamp them onto a knife while they have some stone particles or swarf in them, it can embed itself so deep into the rubber (depending on the rubber and particles of course) that it becomes near impossible to remove the particles lodged into the rubber. It won't happen if you keep them clean, but it is a risk and it does happen to a lot of rubber coated clamps.
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No doubt there is a tiny bit of play introduced by the thin rubber inserts, but I think it's quite minimal. I think there's significantly more variation introduced by the flexibility of the Hapstone and TSProf clamps than there is from the thin rubber inserts in the KME's jaws.
 
3D Anvil said:
... that the blades are canted toward the spine when clamped, which allows the swarf to roll across the blade and towards the clamp.
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Good point 3D Anvil 3D Anvil !

Many systems, like the TSProf K03 as an example, has the knife clamped level.
 
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Didn't realize were more posts here helping me out!

Funny thing is, the one flat grind I have, a Spyderco, locks in the most securely when I use the technique described in the video.

I am having better luck being very, very careful not to put too much pressure on the knife, and never, under any circumstances, touch the knife when rotating the clamp, only use the clamp to rotate.

I am putting as much pressure as I am able to by hand on the tightening screw. Once I got it so tight I was not sure I was going to get it loosened!

The Civivi was in such bad shape that I re-profiled it. That takes patience with 140 grit, even with D2 steel. Now I notice that every knife I have put in this sharpener has an uneven bevel, even this knife that I re-profiled, it is obvious that the bevel reaches further up into the blade on one side than the other, and this is after being as careful as I can when clamping and rotating. Every single blade that I have put in this tool looks like this.
They are coming out decently sharp, they will cut paper, and shave hair (though not very well).
There is no way I am putting my Spyderco in this tool at the point I am at now!

I tried taking pictures of the clamp not touching the blade, but was not able to get enough detail to show what was happening. I will try again, and see if I can get some pictures of the uneven bevel.

Many thanks!
 
Something doesn't sound right. You shouldn't have to worry about touching the knife when you're flipping it. It should be holding the knife tight. It almost sounds like something is off with your clamps. You can take it apart and see if anything looks like it's not right with each half of the clamp.
 
It sure is a struggle right now getting a knife to clamp well.

I have emailed KME about the "issue" I am having with bevel higher on one side than the other, and it sounds like that is a problem of my own making, probably working one side more than the other, or not correcting the bevel from the factory as the first step I took when beginning the sharpening process.

They have been extremely helpful via email, so have to give them credit for great customer service. Tomorrow I'll ask about what I can do to improve clamping. They did note to clean knife and clamp with some alcohol, but that had not effect at all.
 
You're not missing the round metal collar in front of the tightening knob are you? That puts pressure on the clamp. I could pick mine up and throw it around if I wanted to and nothing will move.

I've found the most factory bevels are a little off at the heel or tip of the blade. I think you mean you're getting one side wider than the other. Could be you're Sharpening one side more than the other...or something to do with the knife not getting tight in the clamp.
 
No, it shouldn't be moving like that. Try clamping something flat in the jaws and see if it hold it tight for you. I also noticed from the pic that your knife has a slight recurve to the blade, at least it looks like it. Not sure if it came like that, or you sharpened more of the middle of the blade, but it's going to be a little more difficult to get a good edge now. Anyway, first thing you need to do is get it to hold a knife without it moving in the jaws. Just going to be chasing your tail if it keeps moving on you.
 
3D Anvil said:
I shouldn't be moving that like that, but part of the problem is that you don't have enough of the blade in the clamp. The blade should be deep enough that the second line of the clamp is at or below the spine.
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When I place the blade further into the clamp, it appears to not center. There is a gap on both sides of the clamp at the outer-most edge of the clamp, and that gap is greater on one side than the other. I thought that was what was making my bevel rise higher on one side of the blade than the other, though I may be completely wrong with that assessment.

At any rate, it unfortunately does not hold the knife any more securely when I place it deeper in the clamp :(

I am putting as much pressure on the tightening knob as I can comfortably. I am not a strong guy by any means, but I would think it should be enough to hold it securely.

Thanks for the help, it is appreciated.
 
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