Ignorant Sharpening Question

[Quirt]

Okay, so I'm starting to learn how to sharpen knives - I mean really learn and take this seriously. I'm currently using a Spyderco Sharpmaker (SM) with the standard grey and white stones at 20 degrees. People are donating knives to me to experiment with and to learn on.

My Benchmade knives are getting adequately sharp on the SM but I've run into a snag on this one knife. I was given a 3.5" Paring Knife, it is a Mundail 5601-3% Stainless Carbon. It is an inexpensive professional chef's knife. It is so dull there is no edge, it won't even cut paper. So I've been trying to build a new edge on it using the course stone of course at the fixed 20 degree inclusive that comes on the SM. I notice the edge of the blade is now breaking off and it is extremely jagged. Big chunks are missing (relative to the rest of the blade) and I cannot seem to get it to take an edge so I can progress onto the next stone.

So what does this mean oh wiser ones than me? Does this mean my angle is not steep enough (need to go to a 15%) or do I need to continue working it with the courser grit. Do I need to progress on to a different sharpening system - paper wheels, Wicked Edge, stones? Is this a poor example of a knife to practice on? I wanna learn - enlighten me please.

 

[Jason B.]

Sounds a bit challenging for a basic SM to handle, a coarse stone would help greatly to re-establish the edge. The coarse stones you are using now are not really coarse but a medium grit.

The edge shouldn't be breaking away though, that knife has softer steel, do you see any pitting?

 

[me2]

The only knife I've seen do that was very old, had never been sharpened, and had been used frequently and heavily steeled. I had to remove 0.002-0.004 inches off the edge to get to good material. You will probably need a coarse stone remove the damaged metal within a reasonable time.