GarageBoy wrote: ↑
Sun Sep 13, 2020 9:29 pm
Any tips for reprofiling all the way to the tip on the sharpmker and still keeping it pointy?
Freehand, I have a bad habit of sharpening holding the stone michael Christy style (I learned on 1x6 dmt stones, and old habits die hard) and I'm either getting frustrated and making a bevel too steep (I can see my scratch patterns only on the bottom half of the bevel), and I keep blunting the tip right off...
If you look at Michael Christy’s early videos, you’ll see that he had already reached a high degree of competency in sharpening knives on benchstones placed in the conventional way on a flat surface, before he decided to challenge himself in learning to refine his handheld stone technique.
It’s certainly a valid technique, but I’d suggest that he is making minor adjustments of angle and pressure placement as he sharpens, which are not readily apparent to the casual viewer.
So, I’d recommend placing your stones on a flat, level surface for what I’m about to describe to you.
It’s easier to see where your pass finishes and it removes some potential variables, while you’re working on refining your technique.
Also, I’m assuming you might have followed the much repeated advice by sharpeners here and have equipped yourself with a Sharpie and a good jewellers loupe at around 10x magnification. This will speed your learning considerably.
Acquiring a few inexpensive knives with proper heat treatment, decent steel, and thin edge thicknesses to practice with, like Opinels, Victorinox paring knives and SAKs, or Old Hickory knives will help too.
I’ve noticed that the main obstacle which hinders the development of people learning how to sharpen better is actually the preconceived limitations they place in their own minds, not a lack of more expensive gear.
Once you’re confident with your technique, you’ll be able to get decent results off the bottom of a ceramic plate or coffee mug, a $2 piece of sandpaper, or a cheap diamond hone.
So, basically the trick to achieve a nice consistent needle-like tip on benchstones, is to imagine that as you are guiding the knife edge across the stone, the angle that you are grinding at is always perpendicular to the edge. This is easiest to imagine on a straight edged Wharncliffe style blade, of course.
Now if we take a curved blade like the PM2, you obviously make a curving pass across the stone.
When you reach the end of the pass, you never want to continue past that point where the grindlines will be at exact right angles to the bevel at the tip of the knife.
I hope that makes sense.
Here’s a pic of my 52100 PM2 to illustrate:
The ruler shows an extension of that line that you shouldn’t go past.
(I’m a lefty, so just reverse the images in your mind’s eye, if you’re right handed.
If you do go past that imaginary line and your angle is slightly high, you will round over the tip.
If you go past that line and your angle is slightly low, you will grind a ‘wolf’s ear’ above the bevel.
You can see a slight ‘wolf’s ear’ effect on the tip of this knife, my ‘problem child’ S30V PM2, which I’ve written about earlier in this thread. If you look carefully, you can see I’ve slightly overground it on the coarse 140 Atoma diamond plate:
And so if we now look at a fairly curved blade, like a skinning knife, it allows more of an arc in your pass, but again, you should not go past that imaginary right angled line to the end of the blade edge. (The edge is to the bottom of this pic):
This EKA skinning knife is one I sharpened some time ago, and I actually haven’t cleanly ground the tip area, as it’s not really essential to the part of the edge which is mostly used.
I hope that makes sense.