Convex Edges with a Gen 3 Pro

[NotSharpEnuff]

These first two pictures are the knife sharpness results and the Goniometer picture after sharpening.

The edge sharpness is better than my target 130-150 but the convex bevel is not as consistent as I would like along the whole edge.

The knife blade is so thin that it starts to deflect about 2 inches either side of the clamp even with very light pressure.  To get a more even convex bevel I would have to sharpen it in 3 sections and blend them together.

Last two pictures are the knife in the clamp.

Ed K.

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wickededge, Organic

[tcmeyer]

I don’t think a perfect convex is necessary.  It’s more about knocking down the bevel shoulders and polishing the surfaces to make it easier for the edge to move through the material being cut.

Judging from your photo (Ending _Bevel), it looks to me that at the lowest angle, you are removing enough metal to erase all the facets before it – and the goniometer seems to confirm that – one side more than the other.  I can’t tell if it’s the same side as shown in that photo.

I also can’t tell what the magnification is on the same photo, but I’ll question what grit you sharpened the apex with.  It seems pretty coarse compared to my edges, which I polish out to 3 micron film.

Thin blades usually aren’t that flexible unless the blade is narrow (from spine to edge), so I’m surprised that you still have that problem.  I haven’t used a Ram rig on my Gen 3 Pro yet, but I think a much better arrangement would be for you to clamp with the tip as close to the vise as possible (and still not hit the vise with your stones) and use a Ram clamp to hold the handle solid.  On my non-Gen 3 Pro rigs, I mounted a Ram ball to the base in front of the blue base.  With the Gen 3 Pro, I think it’s possible to mount a Ram ball with a suction cup to the bench in front of the rig’s base and use a long double socket arm with the RAM Small Tough-Claw to hold the knife’s handle.  If it doesn’t reach high enough, you could add an extra double-socket arm and double ball adapter.  Or you could remove the shelf section to drop the base of the rig down onto the bench top.

[NotSharpEnuff]

Tom,

I agree with your observations.  Looking at your video, you sharpen in a seated position and work each side one at at time.  I sharpen standing up with the vise on the bench.  Even though I think I’m using the same pressure, I must be leaning in with my shoulder on one side more than the other.

I also can’t tell what the magnification is on the same photo, but I’ll question what grit you sharpened the apex with.  It seems pretty coarse compared to my edges, which I polish out to 3 micron film.

Those pictures were from the Celestron microscope – I think it is the same one you are using.  So I think the low magnification is 50X.  The scope I have been using is a cheaper Pluggable.  I have worn a large divot in the plastic ring from rolling it from one bevel to the other.

Thin blades usually aren’t that flexible unless the blade is narrow (from spine to edge), so I’m surprised that you still have that problem. 

I measured the spine and at the handle it is about .0925, mid blade is .068, and an inch from the tip is .045.   I would be interested in looking at a Ram clamp if you have a source.

BTW, I completed the Gen 3 micro adjust mod last night.  Having the adjustment on the outside of the riser is much easier especially with the larger knurled knob.

Ed K.

[tcmeyer]

NotSharpEnuff wrote:

Those pictures were from the Celestron microscope – I think it is the same one you are using. So I think the low magnification is 50X. The scope I have been using is a cheaper Pluggable. I have worn a large divot in the plastic ring from rolling it from one bevel to the other.

I found that toothy edges (as when working with any stones below 1000-grit) will chew up the clear polystyrene cowl.  I stick a couple of tiny patches of heavy UHMW “slippery” tape – one on each side.  When they get chewed up, I replace ’em.

Thin blades usually aren’t that flexible unless the blade is narrow (from spine to edge), so I’m surprised that you still have that problem. I measured the spine and at the handle it is about .0925, mid blade is .068, and an inch from the tip is .045. I would be interested in looking at a Ram clamp if you have a source.

I was referring to the width of the blade from spine to edge.  Wider blades are more resistant to bending.  Check my post on “Flexible Kitchen Knives” for the RAM parts. 

BTW, I completed the Gen 3 micro adjust mod last night. Having the adjustment on the outside of the riser is much easier especially with the larger knurled knob. Ed K.

I’m very pleased to hear that it’s working well for you, Ed.

[Pinkfloyd]

Tom,

Did my Messermeister Mini Chef with your technique. Turned out amazing. Thanks!

Used EvilTwins method of positioning knife in clamp

 

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wickededge, tcmeyer

[Marc H]

“Eviltwins” method of positioning in clamp?? Share with us a link please!

Marc
(MarcH's Rack-Its)

[Author]

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