Weird edge geometry on ZT0450

[kaozer]

i have just received my ZT0450 and while i really do like it i had found it a bit dull out of the box. So i went to give a quick fix on my sharpmaker, expecting being just a quick touch up. While i can easily get a good sharp edge on the flat of the blade, as soon as it curves up i cannot seem to be able to sharpen it at all. should i get it rebeveled?

Ps i am using the spyderco sharpmaker to sharpen my knives.

 

[Gaston444]

Many knives have an edge base that grows much thicker as the belly rounds out, getting even duller towards the point: This is actually very typical of factory edges, and typically starts with the edge belly rounding going forward.

Using a guided sharpener will easily keeps the angle exactly the same all over such a short edge, which will result in the bevel growing hugely tall at the front, this through no fault of the sharpening...: It is the knife that is at fault, but many will always try to implicate the tool or the owner...

The only remedy is a full re-grind by a pro. If you had calipers you would be able to measure how much thicker the edge shoulders get towards the tip.

Gaston

 

[TravisH]

Use a Sharpie marker to blacken the edge then sharpen on the Sharpmaker to verify that it's matching the edge's angle along its entire length.

 

[Gaston444]

Likely he will find the knife's edge angle changes to more open towards the tip: This mean the constant angle sharpener should NOT match it...

Gaston

 

[chumaman]

maybe .....

 

[115Italian]

You have to increase the angle as you go toward the tip of the knife. For example when freehand sharpening, you start to raise the knife as you get to the last 1/4 of the blade toward the tip. I would touch it up for now at a steeper angle and use it since its new. The first time you sharpen it reprofile the egde on a guided system to one consistent angle.

 

[Gaston444]

maybe .....

That's an exceptionally broad bladed folder with a deep belly and a very broad tip devoid of swedge or sabre grind, so the edge is far more likely to not thicken towards the tip (1 mm average is very thick for a folder anyway, and this would be so even for a large 10" fixed blade, so thanks for posting this informative picture!)

The OP's Model 0450 knife is narrower blade, and the geometry of the tip is more likely to thicken since the swedge carries closer to the tip. Given his description of the problem, I have trouble seeing what else it could be...:

Gaston

 

[kaozer]

yeah, that was right i got it rebevelled today when i went in town. the issue was indeed the bevel being wider toward the tip. the edge isnt as pretty now but its more functional so i can live with it.