Dropped a 210mm gyuto, 61 HRC, and lost about 3mm of the tip at an angle, leaving a small stub instead of a point. The rest of the edge is fine. I have a 220 diamond plate, a 1000 and a 5000. I can either grind the tip back into shape and end up with a slightly shorter, blunter profile, or take the whole edge down to match a new tip. Which is less of a mistake?
The blend length is the whole game. If you grind only the last 5mm you get a visible step and a weak tip. Aim to feather the change out over about ten times the length you removed, so 3mm lost means blending across roughly 30mm.
One more: after reshaping, the new tip area will be thicker behind the edge than the rest. Thin it on the 1000 before you finish or it'll cut noticeably worse in that section and you won't know why.
One practical note on heat: a diamond plate on a thin 61 HRC tip will get hot enough to matter. If the tip discolours you've cooked the temper and the new tip will be soft. Wet the plate, light pressure, frequent breaks.
Swarf wipes off. A straw or blue tint that stays after cleaning is heat. If you're checking often enough to ask, you're probably fine.
How do I tell the difference between a bit of swarf staining and actual discolouration?
Slightly against the grain: on a knife I use daily I'd just round the stub into a functional low tip and carry on, then fix it properly the next time it needs a full session. A shortened tip on a gyuto is cosmetic for most home cooking.
@whetstone_wu · 4mo ago · 3 replies
Don't take the whole edge down. Losing 3mm at the tip and blending it over roughly the front 40-50mm of the blade will look almost invisible when you're done and costs you a fraction of the steel. Work on the spine side, not the edge side: you're reshaping the tip by removing metal from the top profile so the point comes back to meet the edge. Go slowly on the 220, dunk the tip in water every 20 seconds because thin steel at the tip overheats fast, and stop before you think you're done because it's easy to overshoot.
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@skillet_sig · 4mo ago
Grinding the spine rather than the edge hadn't occurred to me and now it's obvious. Cheers.
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@burr_hunter · 4mo ago
Adding to this, mark your target profile with a marker on both sides first and grind to the line. Freehanding a tip shape by eye is how you end up with a needle you didn't want.
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