How would you go about sharpening an M390 blade that's not super dull but has a few rough spots? I'm ordering a KME sharpener but have no idea where to start. Specifically, what grit to use and what type of stone? I'm thinking diamond? And how do I determine the factory angle?
Thanks!
ibrow, which brand and model m390 blade do you have? Use the diamond stone set Ron has to start, and practice on a cheap knife first, WITH A LIGHT TOUCH. YouTube is your friend and Ron has good introductions there for his KME along with a bunch of his customers vids. I found the manual easy to understand along with one of the sons. Because you are practicing on cheap knives, go ahead and run through the sequence of stones:140, 300, 600, and 1500.
Now with a few sharpening experiences- If you were happy with the m390 edge when you got it, follow the KME instructions for mounting the knife in the clamp, use a sharpie on the bevel as a visual indicator of where your stone is contacting the bevel, set the angle by guesstimation and if you hit the edge but not the top of the bevel, lower the angle adjustment. Vice a versa if you're hitting the top of the bevel but not the edge. Maybe you will choose to start your m390 with a 600 grit because the rough spots are not chips but left over burrs or rolls.
We use a free iOS App called iHandy to set, reset, repeat factory grinds, and document angles. We also use a 10-30x LED loop to train fingers on burrs. We do not freakout over the degree or so difference between bevel hilt to tip, and have discovered slight variations in blade geometry side to side on one of the Adamas's, which has led to discussions of context, for not letting perfect be the enemy of good.
Our experience with the KME has been outstanding. My son just re-profiled a Benchmade 275 working through all four diamond stones in the kit, 140 through 1500 and then a DMT XXF Stone (~4microns) which I had to cut shorter to fit Ron's stone holder. The bevel was so polished you could see the Christmas lights on our tree like the bevel was a mirror (first for my son, i'm fine with 1500 grit edges).
Before that work, I had documented used and re-beveled 5 Benchmade's in D2, S30v, m390, and 20cv. I cut bevels at 30 to 36° for awhile, but the last five knives have come off at 38-40° inclusive, and I can't say the difference is discernibly obvious to me. And were talking about significant Delta in blade geometry: Adamas's all the way down to the 940–1501. After learning the kit there are a bunch of mods, dongles, and stones, films, emulsions you can play with. We just ordered a 1200 grit Venev Bonded Diamond Sharpening Stone for KME (2.5micron).
