How many sharpenings can an 8inch chef knife take before its useless?

Any self respecting knife is heat treated virtually evenly throughout the entire blade. There is probably another issue going on. There really is no number of sharpenings that'll cause a problem until the edge starts to get geometrically obtuse.

 

The answer is probably 2564

 

I'm still using carbon steel knives that I inherited from my parents (my father was a profesional sous chef) that they used at home and in a restaurant, when I was a child over 60 years ago.

Some of them were sharpened by my father so much that there is not much left of the original blade shape but they still cut any meat like butter when freshly sharpened.

So, I say the useful life of any knife is a easily at least 2 lifetimes, if not more, and is not something anyone really needs to worry about . . .

as long as you are sharpening them by hand and aren't using a grinder. LOL!

 

Don't know a number but I have seen Japanese cooking knives that continue to be in use after 30 years.

 

It'll sharpen until long after you get bored of the knife. Once you get it set the way you like it you really don't need to remove all that much steel during sharpening. If you grind it down to a nub you are doing it wrong.

 

Infinite numbers of sharpening with stones and patience
Once or twice with a belt grinder - if you're not properly trained

 

With a WorkSharp, about 2 months.

 

Until it ends up a boning knife

 

That's how old paring, boning and filet knives got their start!
Back before people had money to throw around, knives would get passed down generations.
You can also see reprofiled knives in a sushi restaurant. When a sushi chef has spent thousands on a knife, it doesn't get thrown away.

 

I have my grandma and grandpa ,(dads parents) knives.

Used on their farm to butcher their own cattle and hogs, etc.

They are well over 70 years old.

Still going strong. The huge knife is a new one.






I doubt your kitchen knives are differenrially hardened. If they were, you would know it. And would have to sharpen about 1/2 of the knife away before hitting the softer steel.


Now, you may have to refresh the edge with a stone. If you are only using a steel to realign the edge, every so often a stone is necessary. But most modern "steels" are actually designed to remove metal.

Smooth steels are less common.

 

Iron Chef Morimoto sharpens his knives before and after shift (what is going on between shifts?) and has taken out his knives - new, 1year, 2 years, etc.
So he starts with gyuto to shorter gyuto, to petty knife, to paring knife.

 

The greater likelihood is that the 'gummy' steel near the edge might eventually be ground away, leaving more stable & stronger steel behind it. This is because many factory-ground blades often have some heat-damaged steel near the edge, due to overheating during final grinding or by 'buffing' the burrs off the edge with powered apparatus. This means many of them will exhibit weak edges early on, until that heat-damaged steel near the edge is ground away. That's when the edge should begin to sharpen up more predictably and behave in a more stable manner.

As mentioned, the vast majority of knives are hardened fully throughout the blade (the tangs underneath the handles might be softer). So, there shouldn't be any concern about the heat-treated edge being lost, due to many sharpenings.

Edited to add:
The possibility of heat damage at the edge could also be happening if you're using a powered grinder for sharpening practice, BTW.

 

Try a coarser stone before moving to a finer. I have a L.C. German, sabatier that I got as a gift in 1980 and it's still in good shape. It's seen a lot of use. DM