Sharpening the TIP to a Point on a Zero Ground Convex Knife?!

S

stoffi

Joined
Jan 14, 2008
Messages
967
Hi,

I've asked this question before (a year or so back), but I never fully got a good answer to this.

I've studied a lot of video clips on YouTube, I've read the Bark River convex sharpening guide and so on, but most of what's out there seems to be for convex edges and not specifically for zero ground convex blades. Perhaps it's the same procedure for both types? Basically, I've reground pretty much all of my production knives (full flat grinds, saber grinds, scandi grinds) to full convex zero grinds.

I'm using a hard mousepad and sandpaper (40, 60, 80, 100, 120, 240, 400, 1200), which I'm mounting taught with hard clips to a flat desk with 90° edges.

So far, I'm getting hair-poppin' edges and I'm really happy with the results, save one area — the tip. I'm having problems getting the last small fingernail-sized area toward the tip sharp without rounding off the tip.
I've tried everything from light to hard pressure, different angles and whatnot, but I'm still getting a ever so slightly rounded tip. I want it pointy. The rounded area on the tip is very small (1-2mm), but it's there, so I'm definitely doing something wrong.

How do you do it? Moreover, how do you do it with a blade that already has a rounded or broken off tip?
 
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Are you sharpening choil to tip with your movement, or tip to choil?

When useing sandpaper I always start with the tip. Sometimes on certain knives with a lot of belly you have to go at a slightly steeper angle at the tip to get it correctly.

I've personally never had a problem with rounding any tips though, so I'm not sure exactly what's going wrong for you?

-If the tip has been broken or rounded badly and you want it to be crisp again, you'll have to grind it back into shape. Easiest way on most knives is to simply grind the spine at the tip of the knifedown until you have your pointy tip back. Clip points are a bit different though.
 
@BryFry

I'm doing it heel to tip, but I don't slide the tip diagonally or anything like that. I lay the blade flat on the paper and with light pressure, like the weight of the blade or a bit more, I drag the blade along the paper spine first. When I get to the tip, I turn the blade a little bit (hard/long to explain without pics). I've tried all kinds of directions, but the one that seems to be working the best is if I turn the heel of the blade, letting the point stay where it was and drag along. Basically, I watch the hair-fine line/shadow which shows against the paper and edge and see to it that I'm making contact all the time.

@Richard J,

Thank you for your kind offer! I've sent you an email.
 
Using a firmer backing for the sandpaper helps. The tip of the blade will more easily dig in with a softer backing, making it much harder to sharpen without rounding it off. Try a piece of firm leather, 1/8" thick or less, as opposed to the mouse pad, for the backing. I know some people like to use mousepads, but to me, they're just a little too soft.
 
You can use a thin piece of spring-temper sheet metal between your soft backing and the sandpaper/film. The metal will only allow the sandpaper to curve along one axis, providing the effect you want.
 
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