How do you keep from rounding off the tips with crock sticks?
I see people who apparently think that it is important to move the knife quickly and violently while sharpening. I've seen a few who almost slash at the sharpening device with the knife. This isn't necessary or desirable. Also, it's not desirable to apply hard pressure on the knife because that makes it hard to control.
Even with conventional flat stones--when the tip slips off the edge of the sharpening surface it will cause some level of damage. But you are correct, a stick type sharpener is even more likely to cause this issue because it requires more care to keep the tip from going off onto the rounded sides of the stick which is what causes the tip profile to be damaged.
With proper pressure and a controlled sharpening stroke, the knife can be controlled so that the tip doesn't stray far onto the rounded sides and stays on the top "line" of the stick.
Try a demo with a pencil or pen and a business card. Hold the pencil horizontally so that it's parallel to the floor. Now the "top" of the pencil's cylinder forms a line that is also horizontal and parallel to the floor. Pretend the business card is the blade and push it across the "top" of the pencil as you would when sharpening a knife. With a controlled stroke and reasonable pressure, it's easy to stop the stroke with the corner of the business card/tip of the blade still on the "top" of the pencil and without running it off the side of the pencil. Obviously this exercise is a lot easier the "fatter" the pencil is.
The same principles apply to a crock stick. The sharpening surface on a crock stick should be viewed as a straight line down the stick. The knife blade, during the sharpening stroke, should trace down that straight line and shouldn't slide significantly off to the side at the end of the stroke when the tip is being sharpened.
By the way, I'm not saying that the stick has to be horizontal, I was just trying to describe things so it was easy to understand.
There are three takeaways:
1. Controlled strokes are important, especially for crock sticks, but also with any sharpener.
2. Don't press so hard that control becomes difficult.
3. A fatter crock stick is easier to use, just as a larger bench stone is easier to use.
