Does Sharpening with a Grinder Ruin Your Edge?

I like this article. It flies in the face of conventional wisdom and it substantiates what I have observed. :thumbsup:


so many people who claim that sharpening on a dry grinder doesn't burn the edge don't control their edge angles, don't perform meaningful tests and aren't able to actually make meaningful measurements, so they never see the problem and assume that it's not there.

If someone will simply sharpen a knife slow and wet and sharpen another dry and throwing sparks and control their edge angles and make some test cuts the difference is usually pretty obvious.

this is the first step in optimizing a heat treat. If you're burning your edges that's an uncontrolled variable that adds noise to the data.
 
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interesting article. i would be too scared to run a belt fast enough to make sparks while sharpening in the first place. i run mine really slow and just enough pressure w/120 grit to make a burr on each side, then finish with a lansky by hand. hopefully my blades edges are unscathed.
 
I sharpen 200-1400 knives a week on my 2 x 72” I use slow speed, dip the blade in water before each pass, and use sharp fresh belts & keep the blade moving, with great results. ———-I can see how the work sharp may get things to hot..
 
Here is an old report from Global's site about this same thing. They had CATRA test many knives, including their own, in the factory sharpened condition vs. whetstone sharpened. Across the board the hand sharpened cut longer, sometimes by a ridiculous margin.

Michael
 

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Thanks Michael that information is perfect for adding to the article. Is there an original page somewhere I can link to?
 
Larrin said:
Thanks Michael that information is perfect for adding to the article. Is there an original page somewhere I can link to?
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It was on Global's website. It is since been taken down, but maybe it can be found via the internet way back machine, or possibly from one of your contacts at CATRA?

Michael
 
OK I will do some searching.
 
Great to finally see some solid proof that sharpening the old ways is still best. The anecdotal water cooler talk has for far too long been in need of some solid info on the subject. I know FAR too many makers, including some mastersmiths who do 100% of their sharpening from belts, with one MS i know using a worn 400 grit for his final sharpening. many others going to stropped 2x72 leather belts, and other's using a fresh xxx grit belt to finish it off.

Anytime i've questioned a maker using powered sharpening for final they just shut down and don't even want to talk about it as "their way is best". Personally, i think too many makers just don't want to take the time and learn how to do it by hand. Which is pretty messed up frankly. Not naming names but i know of some chef knife makers who sell $1-2k knives where that edge was finished off with a 2x72 belt all the way up to the point of stropping it. All that craftsmanship, time, effort, and skill put into some of the best kitchen knives on the planet, but then sharpened, and performing no better than some factory made knife you could buy at bed bath and beyond for 5% the price. Customer shouldn't be needing to send their $1k+ knife out to a real sharpener to get the knives full potential, the maker should be doing that from the get go. Otherwise, what's the point?
 
i belt sharpen most of my blades but run slow and so wet water flows off the blade. this said no way any of my razors or single bevel kitchen knives would ever get that system. i have water stones for those blades
side note larrin glad you made it to the ECG
 
Larrin said:
Worn belts are particularly good for building up heat so that is an odd choice.
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A truly worn belt is no good. But the new fresh belts are very sharp and are immediately wrecked by the small surface area of a knife edge, the grit is simply raked off. There are some applications where only a fresh new belt is good, such as fixing a mistake on a bevel or getting a clean even finish grind with one or two passes on a new belt to finish a grind. These very sharp new belts can cut a wide area with low PSI and are still fairly sharp after a few light cuts. Considering the abusive nature of sharpening on a belt (belts are friable and fracture readily with relatively low pressure) there is no real difference between a new belt and a lightly used belt. They're both the same after a fraction of a second of sharpening so it's a common economical use of a new belt to save new abrasives for finishing and use slightly used abrasives for sharpening. Because sharpening wrecks a belt very quickly regardless. If you can get 20 passes on a belt while sharpening you might save the first pass or two for a finish grind on a bevel. But yes, a dull belt isn't good for much more than deburring.
 
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