Picking up bad sharpening habits. Halp!

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DisconnectedAG

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Hi folks,

So I recently realised I've picked up a very bad habit of introducing a flat spot near the tip of knives I sharpen, esp my smaller knives. Annoyingly, I have taken conscious care to try to do the tip, but clearly I have not managed my pressures and angles correctly.

My sharpening skills I would describe as average. I can get all my knives shaving sharp, do the grape and tomato tests, cut kitchen roll etc. I haven't done a lot of polishing yet, so in that area I'm very much a noob.

I've taken a picture shrew it's more visible on my petty.

Any tips that you guys can give me? I haven't come across this particular pitfall in videos or on the forums before.

It's a learning journey for sure, so now that I know I'm doing it I'll pay more attention, but any advice appreciated.
 

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nutmeg

kasumi nut
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This won't happen if you sharpen with strokes that are parallel to the axis of the edge.
 

Benuser

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With the coarsest stone, I stay perpendicular to the edge, which makes me turning the blade when reaching the belly and tip. For the tip, lift the blade as well to reach the very edge. Check with a marker and a loupe.
 

DisconnectedAG

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Good points. It's sharpie time. I have a gem loupe, so that can be used as well.

Thanks for the tips. It's the rotation that I think I haven't gotten right.
 

big D

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What does rotation mean here?
IE: Handle in hand, spine towards you, edge on stone. While entering the curve of the blade from the flat with edge leading strokes, starting to lift with your hand, one rotates (starts pulling the handle towards your body allowing the tip to move forward at a faster rate). If you sharpen with edge towards you, again edge leading, then when entering the curve and starting to lift your handle, rotate (twist) so the handle moves away from your body. (Allow the tip to come to you at a faster rate}
Basically, if you have the blade 90 degrees to the stone while doing the flat, rotating{twisting) holds the same angle to the stone as you follow through the curve. (again not edge angle). Keep twisting all the way through while you increasingly lift.
Picture knife square to stone 90 deg. Now think of the curve consisting of a multitude series of small flat spots. Take a center spot and draw a line square to that spot. It is a different angle than your primary edge. Therefore by twisting(rotating) you are keeping the edge square to the stone at all times, when of course you are rotating at the correct speed/timing.
Hope I was able to describe this clear enough.
D.
cleared up a few things I think--- edited
 
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ian

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IE: Handle in hand, spine towards you, edge on stone. While entering the curve of the blade from the flat with edge leading strokes, starting to lift with your hand, one rotates (starts pulling the handle towards your body allowing the tip to move forward at a faster rate). If you sharpen with edge towards you, again edge leading, then when entering the curve and starting to lift your handle, rotate (twist) so the handle moves away from your body. (Allow the tip to come to you at a faster rate}
Basically, if you have the blade 90 degrees to the stone while doing the flat, rotating{twisting) holds the same angle to the stone as you follow through the curve. (again not edge angle). Keep twisting all the way through while you increasingly lift.
Picture knife square to stone 90 deg. Now think of the curve consisting of a multitude series of small flat spots. Take a center spot and draw a line square to that spot. It is a different angle than your primary edge. Therefore by twisting(rotating) you are keeping the edge square to the stone at all times, when of course you are rotating at the correct speed/timing.
Hope I was able to describe this clear enough.
D.
cleared up a few things I think--- edited
thanks, that makes sense.
 

bahamaroot

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This highlights the importance of making sure you have an even burr along the entire edge when sharpening. It shows that you are removing an even amount of steel across the entire edge and not more in some areas than others.
 

Benuser

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And, if I may add, the use of a loupe with the marker trick, to verify whether the ink has really gone.
 

DisconnectedAG

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This highlights the importance of making sure you have an even burr along the entire edge when sharpening. It shows that you are removing an even amount of steel across the entire edge and not more in some areas than others.
I agree, but I always thought I have a decent burr consistency and have achieved good cutting performance along the whole length of the blade. Clearly you are right, as the facts point to me not having removed enough metal at the tip, but just feeling for a burr isn't enough in this particular case.

I've found a solution though. I'm just going to blame it on the VG10. That way I don't have to improve my technique. Sounds like a perfect way of doing it.
 

ITKKF

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This video from Jon@JKI illustrates a tip sharpening technique. Worked well for me. Good Luck!
 

Keith Sinclair

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There are diff. Techniques for tips. What ever works. Knives like Santoku with little sweep at the tip to knives with a lot of sweep. You adjust your tech. some with diff. knives.

On DB knives use Dave Martell's thinning a little behind edge at low angle say 3 degree than finish with higher bevel. I teach an even bevel & steady spine heel to tip. When get to curve of blade two fingers sweeping blade length of the stone. The spine angle stays the same. You lift your handle hand to continue contact with the stone. Do not lift the spine to make contact at the tip, that will give you uneven bevel at the tip. Same goes for thinning & final bevels. Main thing is you are making contact during your sweeps all the way to the tip.

Your flat spot at tip comes from moving blade up & down stone same all the way to the tip. Because there is less steel in the tip it flattens out & you can even get bird beak tips over time. Simply a little tip sharpening with even bevels you can maintain good knife geometry over the years when steel is worn off the knife you still have a nice even blade.
 

Benuser

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Little warning in addition: some blades get thicker at the tip. E.g. Robert Herder's. Use a marker, and a loupe (8-10x).
 

kayman67

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Well, getting to feel the bevel along the length of the blade is really important, but also understanding that the contact area has a huge impact on pressure and some points have a great less contact, increasing the pressure even if by hand you apply the same all-over. Combine these two in an unfortunate manner and you get some nasty spots fast.
 
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