Ceramic knives

[Arrowhill]

Hi
Can you sharpen ceramik knives with TORMEK?
// Anders

[jeffs55]

Jeff Farris, the resident guru says that you can. I have never done it or heard of it except by him. If you attempt it, I sure would like to hear of your adventures.

[Smitth8273]

I sharpen ceramic on the Tormek -- works just fine. I go slower and gentler, and raise no burr, but otherwise it's all the same.

[Herman Trivilino]

I sharpen ceramic on the Tormek -- works just fine. I go slower and gentler, and raise no burr, but otherwise it's all the same.

That raises an interesting question.  (I sometimes run into this problem when sharpening some types of steel).

When I see or feel the burr it signals me that it's time to stop grinding on that side of the knife.  What is your technique for knowing when to stop grinding if there's no apparent burr?

[Jeff Farris]

There's nothing foolproof, but the concept is to grind equal amounts off both sides and have the bevels meet. If you grind equal amounts off both sides, but they don't meet, you have trapezoid, not a triangle. Take a little more off each side until the bevels meet. If the bevels are roughly equal to begin with, you can use equal amounts of time on both sides to be your guide.

Also, the world will not go spinning off its axis if your bevels are not perfectly equal. The closer the better, but the knife will still cut if it is sharp, but has uneven bevels.

[Herman Trivilino]

The only way I've found to determine if I've gone past the trapezoid and reached the triangle is to examine at 40X with my scope, and then test for sharpness.  The problem is that some steels are so hard that it takes a long time, and it's easy to wonder if maybe you're doing something wrong.  Because you grind a long time but the knife seems to never get sharp.  It's enough to ruin your day.

[Jeff Farris]

If the steel is that hard, open up the stone (use coarse side of grader) and do it in two steps. I find most knives cut easily enough that I don't do that, using just the fine cut and the honing wheel. But, if I run into something hard, instead of spending a lot of time on it, I'll just open up the stone and Git 'er Done. 

[Herman Trivilino]

I recall having had to do that myself.  It's amazing that one element, iron, can be made into steels with such a variety of hardness.

[Smitth8273]

No bur is a bit of a bummer. I grind both sides equal -- then judge sharpness by feel.

Many -- or most -- ceramic knives will have a nick or two, so after those are ground off the bevels have more than met already.

[Herman Trivilino]

When I got a 40X dissecting microscope I was able to see for myself when the two bevels met to make an edge.  It was an education to see that reaching the edge takes quite different amounts of time for different types of steel.  It gave me confidence that I was doing things correctly, too.

I've yet to try a ceramic knife.  I may buy one just for the experience of using it and sharpening it.