Diamond Rods In The Sharpmaker?

Razor

Razor

Joined
Dec 8, 1999
Messages
3,975
On one of my folders in M390 steel I thought I would touch up the edge on the SM with the diamond rods. The folder really wasn't dull, I guess I just want to see if I could get it sharper. When I tried the knife on the SM it seem that one side of the blade was being sharpened and the other was just kinda sliding on the rod. After 4-5 strokes on both sides of the blade the knife felt REAL sharp. Any idea what was happening? I guess I could have touch the blade with a black marker and it would have told more.
 
That 'sliding' feeling on one side probably indicated only the area behind the apex was making contact, such as on the shoulder of the bevel. That's what it feels like, if the bevel isn't flush to the rod (held angle slightly lower or more acute than the actual bevel angle on that side).

On the side that felt like it was being sharpened, that was making contact with the apex, meaning the held angle was flush or slightly wider than the actual bevel angle on that side. In effect, you tuned up the apex from one side, which still made it sharper, as you noticed. If looking at it under magnification, you would probably see some asymmetry along the edge, with fresh grinding marks at the apex on one side (might see a new microbevel there), and fresh grinding marks at the shoulder of the bevel on the other side, with the apex itself left essentially untouched.
 
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Yes, one side looked like it was touched and the other one was not. Is this good or bad?
 
Razor said:
Yes, one side looked like it was touched and the other one was not. Is this good or bad?
Click to expand...

Could be either. It may be that one side's factory grind for the edge was already in pretty good shape, i.e., more acute and fully apexed from that side, and the other side maybe not so good. This could imply it was asymmetrical from the factory, which happens a lot.

At the very least, you know you improved the edge from the one side. More improvement could come in re-doing the other side to match, if/when you can confirm the two sides are not yet ground to the same angle.
 
Mark the edge with a sharpie. Do 5-10 strokes on each side. Check edge and see where the stones are taking material off. You'll probably have to completely reprofile the blade to match the sharpmaker angles. Use the 30 degree slots to do this, then use the brown stones and microbevel at 40 degrees.
 
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