With controlled angle sharpeners, like the Lansky and KME, the edge angle that is used to sharpen will change from the center of the blade to the tip or heel of the blade. For an 8" knife, the change can be 3 to 4 degrees.
I've been considering buying one, but this concerns me.
I guessed at the dimensions to do my geometry, but this does seem to be an issue. Has anybody considered this before?
Controlled Angle Sharpeners
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Re: Controlled Angle Sharpeners
You are correct about the angle sharpeners increase variance for longer blades. One way to make it more consistent is to reposition the knife as you go, working the blade in sections. Overall it’s not an issue as long as the knife is always anchored close to the same spot as the previous stone (regardless if you do it in sections or not). However you chose to do it, just repeat the same anchor position as the first stone. Repeating the same anchor pattern on the blade helps ensure you’ll be working the apex and removing any burrs. Same goes for thinning a knife on these systems if you’re working at a more acute angle than what’s already on the knife.
https://www.waterstoneknifesharpening.com
Lincoln Nebraska
Lincoln Nebraska
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Re: Controlled Angle Sharpeners
I started off with the Lansky system in the mid 1980's and you are correct regarding longer blades....which is why I switched early on to the the Spyderco Sharpmaker. I've used that system for at least 25 years before starting to learn to free hand sharpen earlier this year. If you decide to go the controlled route, consider the "free hand" controlled Spyderco Sharpmaker. It is stupid simple to get a sharp edge (but you are limited to either a 15 deg or 20 deg angle) and blade length does not make a difference. Bonus is that you can sharpen scissors and serrated knives quite easily. I've recently spent a chunk of money on water stones and gear but I keep the Sharpmaker in a kitchen drawer for the just in cases
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Re: Controlled Angle Sharpeners
I can only talk about the EdgePro in this regard, which does have some in-built factors that can cause something of a change in angle. Generally for a well looked after EP these changes are pretty small, certainly less than "3 or 4 dps". The Madrookie Mod Rods address most of those.
Also for the EP the actual length of the blade does not change the grind angle (within the design limits of the EP) and this has been covered extensively on the old forum. What does change the grind angle on the EP, is the actual profile of the cutting edge of the blade, heel to toe. (It changes the length from the blade edge to the stone arm pivot.) As atang says in his post, changes / modifications to sharpening techniques eg sectioning and blade placement / setup, can reduce this to within 1 dps or less.
HTH
Also for the EP the actual length of the blade does not change the grind angle (within the design limits of the EP) and this has been covered extensively on the old forum. What does change the grind angle on the EP, is the actual profile of the cutting edge of the blade, heel to toe. (It changes the length from the blade edge to the stone arm pivot.) As atang says in his post, changes / modifications to sharpening techniques eg sectioning and blade placement / setup, can reduce this to within 1 dps or less.
HTH
Cheers Grant
Just because you're not paranoid doesn't mean they're not going to get you!!
Just because you're not paranoid doesn't mean they're not going to get you!!
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Re: Controlled Angle Sharpeners
'Radar' has this pretty well stated. You want to measure the angle along the length of the stone arm rather than perpendicular to the edge and you will find that the angle stays quite constant.
Ken
Ken
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Re: Controlled Angle Sharpeners
Lansky is a great start!
If you want the full 9 yards, go for wicked edge and never look back.
You'll pay a bit of premium on stones and won't have as much choice. You gain near 100% reproducible results. Even good hand sharpener can have worse variance.
Yes guided systems sometimes vary angle with knife length ... But it's really not very much and actual angle doesn't matter as much as consistency. Consistency is key for a great sharp knife. (Ala exact 15 degree heal and 13 degree tip is better then a roughly 15 degree edge +/- 3 degrees in various spots).
If you want the full 9 yards, go for wicked edge and never look back.
You'll pay a bit of premium on stones and won't have as much choice. You gain near 100% reproducible results. Even good hand sharpener can have worse variance.
Yes guided systems sometimes vary angle with knife length ... But it's really not very much and actual angle doesn't matter as much as consistency. Consistency is key for a great sharp knife. (Ala exact 15 degree heal and 13 degree tip is better then a roughly 15 degree edge +/- 3 degrees in various spots).