Reply To: micro bevel to eliminate tear-out -Spyderco Paramilitary CPM-S110V

[000Robert]

Henry wrote:

I’ve got an interesting twist / update to the theme of microbevels…. Be careful what you decide to micro-bevel. It may be a permanent geometry. So, as I progress and get more experience and confidence as well as broken in stones, I’m moving to some of my better knives while still avoiding the powdered steels… I decided to go at my Shun Yanagiba which has been hand, whet stone sharpened for probably 25 years. It’s a VG-10 steel and it has had a micro-bevel for a long time. When I did that, it was done to ease sharpening and make quick work of refining it back to what I thought was sharp. Now, it was phone book paper push-cutting sharp, but I wanted to restore the knife to its original geometry with a 16 deg primary bevel. What a F2c*ing pain in the A$$ that was! No kidding, I probably put 5-6 hours in on grinding away at 100 grit diamond to finally hit the apex. It literally took me 2 days with multiple breaks between grinding sessions so ( have no exact hour count). I tried to keep the pressure light in spite of cursing in multiple languages in my head as I ground away. I had the knife in the low angle adapter and of course was only grinding a single side. Occasionally, after a few hours of thinking I was close to the apex, I’d break out the 3k and lightly stoke the backside ( flat, non-ground) to break any burr. Of course, this was a mental exercise of futility and I hadn’t hit the apex. Finally, after what seemed like my 100,000’th look at the apex on the usb scope, I was really really really close and could smell the fine edge wanting to appear. Yet alas, I grind and grind, edge leading, edge trailing, scrubbing, cross cross to try and introduce “smaller areas that need to be broken off”. I’d flip the stone upside down to try and use as close to 100% of the surface area as possible. I’d swap out to the other 100, again, in efforts to use all 100 grit stone surface evenly, or as evenly as possible. Eventually I thought I had eliminated any or almost the entire micro bevel and moved to the 200 stones as I kissed the apex. For some clarification, I’d guess the initial micro bevel was at max 1 mm wide while the primary bevel is maybe 4 mm ( I didn’t actually measure…) There are 4 points to this note: 1. Careful when deciding to use a micro bevel. It’s really permanent unless you have the patience of Jobe and want to put in the effort required to restore the original geometry. I really should have gone to my Tormek to do that work, but I was interested in gaining WE experience. 2. Is VG 10 really that hard to deal with with diamonds? I had sharpened 2 other shun vg10 blades quite easily. A paring knife and the mate utility knife. 3. Could I possibly have worn out the 100 grit diamond stones in this endeavor? the stones don’t really seem worn out, they’re still making dust, but if a stone is expected to last 200-600 sharpening based on some bell curve of user skill/tactic and amount of steel removed, I’m certainly guessing these 100’s are, um, at least well worn in! 4. Lock that micro-adjust jamb nut tight and, realize that with enough steel removal your angle will change and you may want to adjust your angle slightly to stay on 16.00 deg. Late in my second day of grinding, I broke out the phone, hot Amazon, and ordered some 50/80 stones that I’ve already semi-broken in on my beater cheap steel survival knife. The initial 50 stokes per stone surface were really quite painful to listen to, but eventually that very course/agressive stone set seemed to settle in and with reasonable technique put a quite nice edge on some cheap presumably Chinese steel. I can’t imagine I’d ever hit a quality knife anywhere near the apex with the 50/80, but had I had it while re-profiling the Yanagiba, I probably would have used it in hopes of saving hours and a lot of frustration let alone 100g stone wear trying to restore the original geometry. So, how would you all go about restoring a VG10 Yanagiba to original geometry? Would you bother? Do you use microbevels with intentions to making maintenue sharpening easier and not even thinking about any desire to go back to the initial geometry? – edit was to use forum formatting bold vs. IPad text bold which does not actually bold the text… Cheers, Merry Christmas, happy Hanukkah , and / or happy holidays

Personally, I don’t use microbevels anymore – I really don’t see the point, though I could be wrong. I’ve never sharpened a Yanagiba, but I feel your pain. I had that problem reprofiling my chisels. I finally gave up and ordered some 50/80 stones. Man, did they save me a lot of time and wear & tear on my elbows and shoulders!

But they leave some deep gouges so, I would stop before I got too close to the edge apex with the 50 grit stones. Then take the edges almost to the edge apex with the 80 grit stones. And then on to the edge apex and form burrs with the 100 grit stones, depending on the blade. For my nicer blades, I will take the 100 grit stones to very near the edge apex, and then use the 200 grit stones to reach the edge apex and form my first burrs.