Advise for sharpening with Sharpmaker

Marblo said:
Ill make the video today later how I do it (no rotating left or right, just rorating forwards) and maybe you guys will see something what I dont. I just cannot hit the tip without rotating left/right.
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Marblo said:
OK, here is the video. No tilting or rotating left/right and Im still hitting the very tip at the edge of the stone. I tried to rotate it more forwards but the results are pretty much the same. Thanks for the help :)
https://www.dropbox.com/s/l1ofwxpac5p6jxq/20140528_190138.mp4
Click to expand...

That's pretty common (very, actually). The edge angle near the tip is wider (more obtuse), and tilting the blade to get flush contact is therefore necessary. This is the same as 'lifting' the handle of the knife when sharpening tips on a horizontal benchstone; it's an expected aspect of sharpening, with most blades. The alternative would be to hold the same vertical angle throughout, and keep grinding until the tip is thinned sufficiently to make flush contact. The SM isn't really the best tool for that, UNLESS the diamond rods are utilized. The trade-off will be that the bevels near the tip will become wider, as the edge angle is thinned down.


David
 
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In regards to not blunting the tips on the SM, I've gotten into the habit of making the stroke in the opposite direction, when working the tips. Carefully lay the bevel of the tip flush against the FLAT of the SM's rods at the top, and PUSH forward and down, instead of drawing the blade from heel-to-tip. Work only the tip portion, to maintain control; don't worry about stroking along the full length of the edge at this time. Done this way, the tip never has an opportunity to slip off the edge of hone, blunting it. I don't like using the corners of the SM's rods for the tips, at all; too easy for it to slip off.


David
 
That looks like good technique, I wonder if the grind on the blade is uneven from the factory, in which case your going to have to make a lot of strokes to reprofile the bevel before you get to the edge.

One more thing, if the blade is really flexible it may be that the tip is bending enough that you're just hitting the top of the bevel and not the edge. Try a few REALLY light strokes and see if you can get the marker to rub off.
 
It's a little hard to see in the video, but it looks like the very tip never had the marker removed at the edge. The last 1/4" to 1/8" is what it looks like. Am I seeing that right? If so, you're not touching the edge there for long enough to remove any marker, or metal. I find that two things happen with the sharpmaker and tips:

1. Because of the geometry and mechanics of the system, it's harder to apply pressure at the tip, so it tends to get sharpened less than the rest of the blade.
2. The tip of a blade is naturally used more by *most* people. This means that the tip is usually less sharp then the rest of the blade at the start of a sharpening session. So you have to spend more time on it as a result of it being more blunt to start with.

These things combine to mean that you have to spend lots of extra time grinding the tip, in order for it to get as sharp as the rest of the blade. I like to do 5 to 10 extra back and forth strokes of the last 1/2" of the blade for every 2 or 3 up and down strokes of the entire blade. This seems to balance it out correctly on most blades for me.

But you need to start with working until you can actually get the marker to come off of the blade along the full length. From what I can tell (and it's hard to see) you didn't remove marker from any part of the blade in the last 1/4 to 1/8". Maybe I'm missing something in the video. If I've got it right, you need to increase your handle lift at the end until you can get the tip to touch the stone at the end of the stroke. You might try doing it slowly and observing up close and/or from the side to make sure.

Good luck and let us know what you come up with!

Brian.
 
Obsessed with Edges

I tried and it works great, I think it will be better than drawing the blade heel-to-tip.


onetrickpony

Its really flexible and even after really light strokes the mark did not rub off :)

bgentry

Youre right, thanks for the tip :)

I used to use DIY sharpmaker with circle shaped rods and hitting the tip and not blunting it was easier then here on SM :D

Here is a video how I could sharpen a real knife, you guys approve it? Its difficult to hold a knife in one hand and hold the phone in another but I hope you get the idea :)

https://www.dropbox.com/s/m4fwc0fj84oczqf/20140531_134105.mp4
 
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