Thought I had sharpening cracked...


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redrob

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I sharpened my new-to-me Opinel #8 a while back using some 800-, 1000- and 2000-grit wet/dry sand paper supported by some newspaper by dragging the blade lightly over the surface in a manner similar to stropping. I got it hair-shaving sharp in about 1/2 an hour. I repeated the process on a blade I forged and got the same results. This weekend, I noticed the blade wasn't removing hair like it did so I broke out the sandpaper and while the blade polished up nicely, the hair-shaving sharpness did not return. I tried initially with just the 2000 grit paper and when that didn't work, I tried going back to the 800 and working my way up. When that didn't work, I went back to 600 and worked my way up. No love. It's reasonably sharp, but I am annoyed that this technique didn't seem to work again. Any thoughts on what I might be missing this time around?

Thanks,
Rob
 
I'm no expert and I could be wrong, but it might be helpful if you stropped after sharpening. I think I read somewhere that after sharpening you get a wire edge that (in your case with the 2000 grit) is extremely thin and cuts really well at first, but after some use loses its ability to cut as well. Stropping would probably fix that.

As for trying to regain the sharpness, I don't know what could be causing that other than maybe inconsistent angles when you sharpen. Again, it could just need stropping. I know how you feel about this sharpening thing, I'll think I've finally got it down only to turn around and completely dull the next blade:2:. Keep us posted it you find out something that works.
 
I find that my biggest problem is putting too much pressure on the blade both while on the stone and on the strop. Not sure if that's what's going on, but maybe try using almost no downward pressure and see if that helps?
 
Does it still do what you need it to? I never got the whole shaving sharp thing, I don't shave with my knives. Anytime when I got a blade to shaving sharp when I actually went to use the knife it didn't stay sharp long. Maybe it is just my sharpening skills(or lack of).

If I can get an edge that does the tasks I need it to and it holds that edge I call it good.
 
Personally I never liked sharpening with sand paper and mouse pad/news papers/soft under layer...I prefer stones...simple Smith's Tri-hone with coarse, medium and fine stones then going to the leather strop charged with yellow "Flex Cut Compound", then a white rouge charged strop and finally to a green rouge strop....by going this route...I sometimes think I maybe getting my knives too sharp!
 
sharping problems

When something like this happens to me I go back to stones coarse then back to paper, remember get it to a burr.
 
I have had the same problem. I no longer use a soft substrate ( ie;mousepad) when using it. I switched to a hardwood block. Very little pressure also.

I start at 400 , the go to 600 , the strop with compound. Other than that method , it's back to the 'ole Norton India.

I don't bother with the super-fine 1000/2000 anymore.
 
My farther was a wiz at sharpening. He sometimes used sandpaper but always over a square of plate glass. Perfectly flat and hard. Worked for him.
 
Its not a blade problem, your hair grew back thicker and stronger :D
 
petrifiedwood said:
I think the problem with sandpaper sharpening on a soft substrate is that it converts the "convex" (technically ogive) edge from a tangential ogive to a elliptical ogive, thereby making it a blunt edge.
Click to expand...

hahaha in layman's terms: "ya durn dummy ya done dulled it" haha woo...

this has happened to me, I love to exert too much pressure on everything I do and the sandpaper mouse technique has been a lesson in patience and light touch. It's a good thing. You'll notice in Iz's sharpening videos he mentions how he uses the same sheet for many sharpenings.
listen for the pitch difference in the sccccrrraaatttccchhh noise, you can hear when the edge makes contact.
you may already know all this, just thought it bears voicing.
but I betcha didn't know 'elliptical ogive' meant 'dull'. haha..man that was good.
 
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