Over sharpening?

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Jul 16, 2007
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I just got a Spyderco Sharpmaker and I've been goin crazy with my BM551. I just wanted to make sure there's no such thing as over sharpening? Am I going to hurt the knife if I constantly sharpen it?
 
Eventually you can sharpen the blade to a nub. This takes an extremely large amount of sharpening.
 
Yes, it is actually possible to sharpen your knife away. On a a sharpmaer it would take probably a few hundred years of constant sharpening (ok maybe an overstatement, but still would take awhile on those ceramic rods), but you can still damage your knife. Sharpening is basically removing the metal, so over-doing it can definately hurt your knife.

Cody
 
Once you get it sharp reshaprening it is more likely to dull it than anything.
 
Once you get it sharp reshaprening it is more likely to dull it than anything.

:confused:


Really :eek:


This is just not true. You will not ever over sharpen a knife in your lifetime, on a Spyderco sharpmaker. :cool:
 
For me impulsive sharpening of a sharp knife makes me go at a bad angle and get a dull blade. I do freehand anyways.
 
I would say it depends on how old you are and how long you think you'll live. If, say, you're 40, and you think you'll live 'til 90, you might lose an 1/8" of blade. If you're 40, and you think you'll live 'tll 75, you could lose a 1/16". Either way, your knife is already shot. Toss it out or mail it to me. PM for address....

(((:D)))
 
I just got a Spyderco Sharpmaker and I've been goin crazy with my BM551. I just wanted to make sure there's no such thing as over sharpening? Am I going to hurt the knife if I constantly sharpen it?

No, you won't hurt it, unless you do something really *unnatural* with the Sharpmaker :D. But if you're becoming a compusive sharpener (like me), you could pick up a couple of cheapo knives that you don't mind trashing and use your sharpening time and energy experimenting with different edge bevels and sharpening techniques to improve your skills.
 
I just got a Spyderco Sharpmaker and I've been goin crazy with my BM551. I just wanted to make sure there's no such thing as over sharpening? Am I going to hurt the knife if I constantly sharpen it?

Why would you want to constantly sharpen your knife? Knives are to use or at least admire, not just to sharpen for your amusement.
 
You are going to hurt your wilingness to sharpen any knife :)

If you think you enjoy sharpening let's try to keep your kitchen knives in shape. Average family is able to dull them again in under Planck time :D
 
Yep,
Kitchen knives need constant attention. Use a cutting board religiously and make a point to keep the kitchen knives as sharp as possible at all times.

If that isn't enough for you, then get a straight razor and learn to use it and keep that sharp.
 
My two cents:

A knife is essentially a piece of mechanical equipment. Use it, sharpen it, etc. and it will eventually wear out. How long it will take depends on how and how often you use it.

If you sharpen properly, there is very little, if anything, you can damage by oversharpening. If you don't sharpen properly you may damage or dull it, but it will be worth it because this means you need the practice and experience it provides. (It also means you may want to buy a couple of really cheap knives to practice on.)
 
I could be very wrong, but for me a lot of cheap knives will not get sharp IMHO ;)

But, give me some S30V, VG-10 ie. a higher grade knife steel and they will come around............:cool:
 
I have had and still have trouble with some knives, but I believe the problem is usually technique and/or use of inappropriate equipment. For example, by trial and error I have discovered that super hard Japanese knives should not be sharpened with ceramic stones.

As for cheap, I was able to get a 18-8 tableknife (part of a 20 piece, 4 place setting for $1) really sharp without too much effort. But something like the Victorinox/Forschner paring knife is my favorite for experimenting.
 
As you sharpen, you move further up into the primary grind. Sharpen enough and the blade will noticeably thicken and will in fact cut worse. That's a very good reason to microbevel your knives.
 
Benchmade edges tend to be somewhat obtuse. I would expect that your effective sharpening has been in the 40-degree edge angle (20 degree honing angle per side) slots. If you are mostly honing at 20 degrees the blade thickness at the top of the honing bevel will get thicker and thicker over time. This is the bad result that hardheart is describing. The good thing is that at an angle this high you will mostly cut off steel cleanly and not form a burr.

For higher performance cutting you can reprofile the edge (back-bevel as Spyderco would call it). The Sharpmaker instructions tell you to do this by setting the rods in the 30-degree slots (15 degree honing angle) and honing until you get up to the edge. They don't tell you that this can take an awfully long time with ceramic hones. If you reprofile some at 15 degrees and hone at 20 degrees your cutting performance will tend to be higher than when you bought the knife. This combination of angles will also tend to avoid creating a weak edge burr.

If you go whole hog and decide to really thin down your edge you can run up against a common overhoning problem, burr formation. If you hone very frequently at a low honing angle some of the steel bends away from your hone as you work. If you remove a bunch of edge material you tend to develop a slowly lengthening residue of unremoved steel along the apex of your edge. This is known as a burr. If you don't remove the burr it lengthens in proportion to how much honing you have done. Burr formation can happen at any honing angle, but it at low honing angles it is a problem even with easier to sharpen steels.

The solution for burr formation is to not sharpen at low honing angles for long intervals without stopping to do a microbevel to remove the burr. For example I commonly lay a triangular honing rod crosswise under my Sharpmaker base. This allows me to tip the Sharpmaker left and right by about 5 degrees as I hone. I do this such that I do my back bevel at 10 degrees per side rather than the 15 degree minimum. If I do serious honing on a dull edge I expect to create a burr by this method. About every hundred strokes I stop, set the Sharpmaker base flat on the table, and do a few light strokes at either 15 or 20 degrees per side. I may then go back and do some more 10 degree back beveling or I may move on to creating my final edge microbevel. I do that at 15 degrees (or sometimes I play games with the Sharpmaker to do my final microbevel at 12 degrees).

So for really low honing angles or with bad steel you can over sharpen. If you start to head down that road interrupt your honing with a little elevated angle deburring now and then.

Oh yeh, you can also damage your edge if you are applying too much force on your Sharpmaker. The section of edge that contacts your hone is small on the flats of Sharpmaker rods and extremely small along the edges of the rods. If you apply heavy force while you hone you will be flexing the edge back and forth and also in sort of ripples as you drag the edge across the hone lengthwise. This can cause metal fatigue and make your edge brittle and cause microchipping. Be sure to use only moderate pressure as you hone on the flats and even lighter pressure along the edges of the rods.
 
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