why is cheap steel harder to sharpen?

Why is cheap steel harder to sharpen? I bought some cheap knives to practice with, but I have been advised that I will learn nothing practicing on cheap stainless steel. I'm skeptical, so I'd like to hear the explanation.

 

Some is super hard and a pain I. The butt to sharpen. It's brittle and you can't go real fine.

Or it is super soft and the edge just keeps rolling over and once again can't take it too fine.

Poor blade thickness and geometry can make a blade a pain in the butt to get really sharp. If the blade is really thick and you can't get that steep of an angle on. Or else you have to thin and thin and thin... An example of this is a camp knife I was working on. It's a jack of all trades knife. Clean a bear, split kindling and make dinner. I couldn't get it as sharp as I would have liked. It was a bit thick piece of steel- nice steel- but just too thick to get amazingly sharp.

 

It applies only to cheap stainless, I agree. Badly controlled composition, poorly mastered Heat Treatment and you get accumulations of large carbides in a soft matrix where these carbides will tend to break out of. It won't support any fine edge. The only way is to build a very coarse edge and cleaning it up a bit by some buffering.

 

John...you're DEAD on on the steel issues, but the thickness isn't really a factor. I can sharpen one of my camp/hunting knives to tree top arm hair. The factor there is most maker's camp/hunting knife is about 58HRC. This is for durability and ease of sharpening in the field. All a guy needs out there is a basic level of sharpness, so he doesn't technically need 63HRC.

 

Thickness can indeed be an issue in difficulty, though not in potential. Softness too is mostly an issue of difficulty, rather than potential. You can get a piece of copper to shave well, for a very short time.

Thickness leads to difficulties in sharpening technique...more strokes or greater pressure due to increased surface area of the bevel leads to more mistakes, inconsistency, and damage. It is one reason sharpening thin kitchen knives is relatively easy by hand, and thick edged folding knives and such benefit from fixed-angle jig systems when sharpening acutely.

 

This is a much better way to put it Robert. I honestly haven't bothered trying to sharpen cheap knives much beyond 'functional'. Taking it beyond that is pointless because as you said, the edge doesn't last more than two cuts anyhow lol.

For thicker edges I always just blend into a full convex right to the edge and work it like that. Makes for easier long term sharpening, and a better overall edge. I've never been one for a fixed system, and a blended edge ensures I'm HITTING the edge. This also eliminates your main issues mentioned above. No increased surface area and no need for greater pressure. Once you get the convex established you're good to go.

 

Yep...my thicker-bladed pocket knives are all convex edges. I'd like to thin them down but am too lazy, and the convex gets the job done well enough if not cutting very deeply through something tough.

 

Get a cheap and coarse stone.
Bought one for £1 and it does the trick on cheap and soft knives.
I can get them shaving sharp in 5 minutes. (Even thou' those edges won't last but my colleagues were amazed. )

 

Old carbon knives in the antique stores and flea markets for a couple bucks each are where it is at for practise knives.

I did six or seven old hickory knives my uncle picked up at he flea markets. Some needed a little sand paper but they all sharpened up great and better than he expected.

Sabatier's and old Dexter Russell's demand a higher Mark up but they sharpened up nicely as well.

 

When it comes to cheap kitchen knives made from softer stainless (and I MEAN softer at 45-48 HRC) it becomes quite a problematic to sharpen them with whetstones (compared to knives in the in 58 HRC and higher). So instead of wasting time on whetstones, one could get a cheap pull through sharpener and it will get a working edge on cheap stainless in no time. And then use steel to maintain the edge and align it back into shape.

So it's not really harder, it's just a bit different from what you'd normally do with knives in higher HRC.

 

My experience with soft steel vs hard steel is akin to trying to put an edge on an eraser vs putting an edge on a piece of chalk.