Ceramic rod dulling a mirror polished edge?!

FlaMtnBkr · Mar 24, 2009

I have been using paper wheels for awhile and can get my knives to easily push cut newspaper and pop hairs.

I have read of the benefits of a coarser girt edge and thought I would take a knife I have put a mirror polished edge with the paper wheels and use my Lansky V ceramic rods to put a coarser edge on. I used the gray (coarser) rods in the Lansky and made a dozen light strokes alternative sides.

After I did this the knife would barely shave. Any idea why this would happen? It obviously was making contact at the very edge because it dulled. The system is similar to a sharpmaker but uses round ceramic rods instead of a triangle.

Any thoughts or suggestions? I dont mind the polished edge just thought I would try something new. Thanks!

Ryan

Roger999 · Mar 24, 2009

A polished edge will always shave better than a edge with teeth, the point of going up in grits is to make those teeth go away so you can get a sharper knife.

Ben Dover · Mar 24, 2009

you basically ruined a sharp edge. and, IMHO there are no advantages at all to a coarse edge. Polished, refined edges cut better.

FlaMtnBkr · Mar 25, 2009

There have been numerous posts about a coarser edge being better for some things like rope because it has "micro serrations" and yet will still shave.

I have gotten factory edges that have a coarser edge and will still easily shave.

And the Lansky ceramic rods are far from coarse. Just more coarse than a mirror polished edge. I have gotten knives to shave in the past on these rods quite well before moving onto the fine ceramic rods.

So what I am asking is why would a sharpening system that can get a blade to shaving sharp take a hair popping edge and make it not shave at all really. Light pressure should not dull the edge I would not think.

I am just trying to figure out what is going on besides ruining the edge. I got it back to hair popping sharp in 30 seconds on the cardboard wheel so it's not like I wasted a bunch of my time.

richard j · Mar 25, 2009

flamtnbkr, you cant beat the paper wheels for putting an edge on a knife. if you are not able to use the wheels, then use the ceramic rods until you can get back to your wheels.

matt321 · Mar 25, 2009

Well, like you said in your second post, under the right circumstances you can get shaving edges after using relatively coarse stones. So it may not be just the coarser finish at work here. Was the original edge convex? How well did the crock stick angle match the bevel? Were you just scuffing the shoulders of the bevel or grinding the entire bevel? Were the crock sticks clean?

You could try again, but maybe the knife just isn't going to behave well with this combination. It's fun to see how an edge will respond to various strategies. Sometimes it works like you think it will, sometimes it doesn't. Try the same thing but use a medium diamond hone or sandpaper instead of the ceramic, you may get a better results. The best coarse edges I get usually involve a DMT hone somewhere in the process.

The coarse edge versus polished edge issue is a long standing debate. Like you, I like to experiment with both. Years ago I watched a guy sharpen a dumb, old machete with a bastard file. That edge was brutally aggressive. It was scary to touch.

spidyman · Mar 25, 2009

simple, the edge angle was off. The angle you got on the wheels did not match the angle you used on the rods.

thombrogan · Mar 25, 2009

Might be too much pressure with the ceramic rods. I bet you're going very lightly, but if you look where the edge of the blade touches the rod, the space is very small so any pressure will be magnified.

richard j · Mar 25, 2009

spidyman, thats what i told ryan yesterday when i called him. i think if he worked up a burr with the coarse rod and removed it on the paper wheel it might give him what he's looking for.

sodak · Mar 25, 2009

I'd be interested to see if you get the same results with a ceramic stone. I find they are easier to use since they spread the pressure out on the edge more.

Edges can be funny things. I've had some didn't feel sharp, wouldn't slice paper well, but would tree-top trim hair, pass the free hanging hair test, push cut newspaper 3 inches from my pinch, go figure. I've had some that wouldn't shave arm hair very well, but were smoother than silk slicing newsprint.

At the risk of seeming OCD, you can try keeping a log of the knife, steel, hardness, and type of sharpening you did, so you can get a record of what works well for that particular knife. Not that any of us have done that...