# Scientific sources on tempering or done by electric grinders for chef knives?



## atatax (Jan 8, 2015)

It is so often cited that you don't want to use an electric grinder because it will mess with the temper of your knives. But how much is this an old wives tale? Like after a knife is stamped or forged I'm pretty sure even the highest end knives are shaped and then sharpened by electric sharpeners. If they destroyed knives tempers that wouldn't make any sense at all. Don't get me wrong, I have stones, and I use my stones on all my nice knives and almost all of my Japanese knives. It's just in my experience I am probably the top 1% of cooks with sharpening experiance and knowledge and I can't justify using stones on some of my knives. And We are scaring kids barely able to afford rent and telling them they'll ruin their knives if they sharpen it on a friend's electric sharpener?


----------



## phatch (Mar 29, 2002)

I would say the cumulative wisdom has merit. Usually the out of the box sharpness is lesser and the edge holding improves once you sharpen past that overheated initial edge usually applied by power tools.

A skilled person can create a great edge quickly, thin a worn blade and all that. But the skill takes experience and time to develop. And it's easy to injure yourself and ruin blades too.

I would go for a linisher over any wheel system. One that can take a platen (i think that's the term) and do slack belt work.

Bladeforums.com would be a better source to look at for deeper data.


----------



## phatch (Mar 29, 2002)

At about 1:30 they are hand grinding,sharpening. Note it's bare hand and hand on the blade to feel the temperature. Note he dips in water to cool it down and keep it away from temps that would effect temper.


----------



## Transglutaminase (Jan 9, 2019)

I use a Ken Onion belt sharpener once every year (or two or three) - on some new or old lousy edge knives.
Other than that, the steel or stones.
Opinions will differ.


----------



## benuser (Nov 18, 2010)

In knife production tempering — the reduction of hardness after quenching —of simple carbon steel is done at some 200⁰C — 400⁰F. Temperatures like that are very easily reached with a thin edge, that has a thickness of 1/10 of that of tin-foil. No need of powered tools to destroy the temper. Even man-driven grinders easily reach high temperatures. Had vintage carbons where some 5mm — 3/16" — got to be abraded before the steel could only take an edge.


----------



## foodpump (Oct 10, 2005)

Grinding on stone wheels—in a factory or production setting is assisted with water. Usually the grinding wheel runs in a trough of water. Not only does the metal keep cool, but abrasive dust is kept out of the air and out of lungs and nasal passages.

There are many smaller wheel grinders intended for sharpening that are water cooled and very slow rpm. Tormek makes great water cooled grinders, the Japanese have had them for decades as well, and then there are the knock offs that mimic the Tormek and use it’s proprietary jigs and accessories..

Many knife makers and sharpeners use belt grinders, utilizing 24”-36” long belts. The thinness of the belts and the huge surface area of the belt help in dissipating heat.

Hope this explains things a bit better


----------

