Bizarre Sharpmaker behaviour

A

Aelius

Joined
Sep 18, 2006
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94
Interestingly, my Sharpmaker works excellently on my SpyderCo Endura (ZDP-189 steel); it shaves hair with no problem. However, when I try to sharpen my SpyderCo Stretch (also ZDP-189 steel) it does not end up sharp like the Endura.

  • Both knives are plain edge (not [partially] serrated)
  • I'm using the technique as demonstrated in the video that comes with the Sharpmaker. Namely, 20 strokes on the rougher grind's edge; 20 on the rougher grind's face; 20 on the fine grind's edge; 20 on the fine grind's face
  • I've not made any modifications to either of my knives since I bought them new a few months ago
  • I bought my Sharpmaker new about two months ago

Any idea why my Endura's getting satisfactory results from my Sharpmaker, but not my Stretch - which by the way is over twice the price of the Endura?
 
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Have you cleaned the heck out of the hones? They will quit working completely when they get really dirty.
 
Try the Sharpie trick. It is possible that you are not yet to the edge on your Stretch II.
 
Sorry, what is the magic marker trick and the sharpie trick?

udtjim, now that I think of it I remember having to stop the video short before I could finish it. I remember the guy mentioning that he'll explain later how to clean it. I'll check it out, thanks for reminding me.
 
Aelius said:
Sorry, what is the magic marker trick and the sharpie trick?

udtjim, now that I think of it I remember having to stop the video short before I could finish it. I remember the guy mentioning that he'll explain later how to clean it. I'll check it out, thanks for reminding me.
Click to expand...

Check this out:thumbup:
 
Okay I rubbed a sharpie all along the edge of my Spyderco Stretch. I did a few strokes with the Sharpmaker rods in the 30 degree slot. It removed only the marker from the shoulder where the edge meets the main grind. I then tried on the 40 degree slots, and yet again after a few strokes it still didn't take the marker off the whole edge, just the shoulder.

I then did the marker thing on my Endura and on the 30 degree slots the left edge (with the knife pointed away from me and the edge down) had its marker stripped clear but the right edge still had its marker on all but its shoulder.

So what does all of this mean?
 
It means that your Stretch is ground at more than 40 degrees inclusive, and your Endura's left side's grind is (almost) exactly 15 degrees from vertical, while the right side's grind is more than 15.

The solution to all of this is to invest in an assortment of wet-dry sandpaper, from as coarse as you can find up to... I'd say 1000 grit, but you can probably get away with less. Cut strips from the sandpapers about as long as your Sharpmaker "rods" and four or five times as wide, wrap them around the "rods" with the excess smooth side to smooth side coming off one of the edges, and clip them in place with binder's clips. Voila, Sharpmaker "rods" as coarse as you want, for WAAAAY less than the cost of the replacement diamond "rods", and switchable/replaceable to boot.

Now, it's almost 3AM, and I'm not sure how much sense that all makes, so drop me a line if you're confused, and I'll do a quickie movie to show you what I mean.
 
You need the edge bevels to meet in order for the knife to be sharp. You need to remove metal from the entire face of the edge bevel in order to make the bevels meet. the sharpie shows you where you are and are not removing material.

If you are removing material from the edge only you might want to try a steeper angle. If you are removing material from the shoulder you may need to try a larger angle.

If you are changing angles it will highlight your progress and show where you need to do more work.

The Sharpmaker is not the best tool when changing angles or rebeveling a blade to match the Sharpmaker angles.
 
So what's the best way to change the bevels if the Sharpmaker isn't good at doing that?
 
Try this:

Use the corner of the mediums in the 40 slots for the Spyderco Stretch. Apply the marker to track your progress. Then set the knife up against the left stone and start up and down strokes. Just work on one side, up and down, repeated. Keep the blade vertical as customary and keep the same side up against the stone continuously, always touching. Keep making the up and down strokes with moderate force gradually building speed and control until you are at about one cycle per second. Continue this for a few minutes and then check your progress. Continue until you have shaped the entire bevel to the correct angle. Proof positive that you have bullied the thing into submission will be when the marker is all gone. Even better, most knives will raise an obvious burr when the abrasive action breaks through to the opposite side. At that point, start working the other side the same way. Once both sides have reached the edge at the correct angle, you can "take off your gloves" and start finessing the edge with light alternating strokes to clean off the burr.

I've found that this aggressive style will reprofile edges faster than you would suppose. The corners of the stones don't seem to load up and lose their bite.

It doesn't matter if you plan to bevel at 30 someday cuz you will have to bring it down to 40 from where it is now anyway.

You only have two other alternatives. One is to avoid rebeveling. You will have to sharpen by matching the existing angle so the conventional use for the sharpmaker will never work. The other option would be to rebevel with some other tool like a coarse bench stone or DMT or sandpaper. You would do much the same as desribed above, but you would have the advantage of a more aggressive tool. You can lean bench stones against the shapmaker stones to match the angle.

For the Endura, you could start with the 30 slots since it is already close for that setting.

Keep in mind that the chances of flinching and scratching the blade is greatly increased when rebeveling aggessively like this.
 
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After about an hour of working on my Endura's right side with very little result, I think I'll try it with the sandpaper. I understand what you're saying except for the bolded part, could you rephrase that please?

Lucky Bob said:
Cut strips from the sandpapers about as long as your Sharpmaker "rods" and four or five times as wide, wrap them around the "rods" with the excess smooth side to smooth side coming off one of the edges, and clip them in place with binder's clips.
Click to expand...
 
After over 3,000 strokes on the stone corners applied to just to the right side, were you able to see some progress? The remnant marker should be getting smaller.
 
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Aelius said:
After about an hour of working on my Endura's right side with very little result, I think I'll try it with the sandpaper. I understand what you're saying except for the bolded part, could you rephrase that please?
Click to expand...

Maybe this crude drawing will help (an artist I ain't :o)
 
My Stretch II was right at 30 degrees included from the factory. I kept it sharp on the SharpMaker using the 15/30 slots for a couple of weeks as an experiment. When I managed to dull it severely (which is inevitable for me), I went back to freehand on my diamond hones.
 
A CORRECTION TO MY EARLIER ADVICE ABOUT JUST WORKING ONE SIDE:
As you work one side to create the new bevel angle, you should keep the bevel widths equal on both sides. If the bevel on the first side grows too wide as you grind, switch to the other side, even if the other side is already at the correct angle. This way you end up with a symmetrical edge with equal bevel-widths on each side.
2n66kpe.jpg
 
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