# Your opinions regarding this chip...



## cotedupy (Nov 4, 2020)

Just wanted to canvass some of the expertise on the forum about what you'd do with this...

A friend bought this round yesterday. An old Trumpet Sab with a fairly significant chip. It's a large knife - 250mm, and the chip is pretty big. Maybe 2mm deep, and about 3mm long. I figure I'm going to have to grind off most or all of the finger guard and take the length down. But I just wanted to ask, how much of the length do you reckon you would aim to lose in this process? If anyone wants to draw a new shape on this picture that would be great!

The blade itself is *very* thin, much thinner than my old Sabs. Which I hope will mean the metal removal won't be _too _tricky (apart from the finger guard), and then won't need much reworking of the edge. Or am I being a bit optimistic...?

Many thanks for any input!


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## kbright (Nov 5, 2020)

Decide how much flat (semi-flat) edge you want from the heel, and how much curve that you want for rocking. If your blade width at the heel is 50mm, I would reduce that heel a few mm. That new edge would lower your tip, so then you need to shorten the length and grind a new tip, maybe higher. Do you want to keep the length as long as possible? or prefer a 230-240mm final length? 

This was a similar Sab.


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## inferno (Nov 5, 2020)

i would start grinding about halfway between the chip and the heel. to keep the height. then a gentle sweep. lose maybe 0,5cm length or so?


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## cotedupy (Nov 5, 2020)

kbright said:


> Decide how much flat (semi-flat) edge you want from the heel, and how much curve that you want for rocking. If your blade width at the heel is 50mm, I would reduce that heel a few mm. That new edge would lower your tip, so then you need to shorten the length and grind a new tip, maybe higher. Do you want to keep the length as long as possible? or prefer a 230-240mm final length?
> 
> This was a similar Sab.
> View attachment 101815



Well yours went alright eh? That's lovely! Has definitely made me rethink what can be done next time I come across an old Sab/Sheffield in an 2nd hand shop with a massively over-steeled belly. (Assuming I don't completely mess up my friend's knife this time.)

I think he did want to keep it as long as possible, I was anticipating that I might need to lose at least 2cm, but from what you and @inferno have said that doesn't seem necessary. Thank you both for the advice.


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## cotedupy (Nov 5, 2020)

Oh and one other pretty basic question - am I right in thinking that because this kind of thing isn't san mai construction I don't need to worry too much when re-doing the edge beyond just 'putting an edge back on it'...?


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## Midsummer (Nov 5, 2020)

Grind a curve that removes the chip and then bevel the edge. Final length depends if you want to preserve height of the blade or length.

If you want a longer blade, remove metal from the bolster to the chip and make a suji. If you want height; then grind from the defect forward significantly reducing the length but leaving a shorter gyuto. It will be some work and the knife will never be the same. But it still could be good. Best...

PS thick behind the edge is a different experience from thin behind the edge.


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## cotedupy (Nov 5, 2020)

Midsummer said:


> Grind a curve that removes the chip and then bevel the edge. Final length depends if you want to preserve height of the blade or length.
> 
> If you want a longer blade, remove metal from the bolster to the chip and make a suji. If you want height; then grind from the defect forward significantly reducing the length but leaving a shorter gyuto. It will be some work and the knife will never be the same. But it still could be good. Best...
> 
> PS thick behind the edge is a different experience from thin behind the edge.



Ta! Yeah I think he wants to keep it more gyuto than suji, but with as much of the length still as poss, so will see what I can do. It sounds like people are suggesting I won't have to remove any of the finger guard, so that's good  And mercifully the knife is very thin for most of the height of the blade!


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## ian (Nov 5, 2020)

Idk, I’d worry that if you start grinding halfway between the chip and the heel and try not to shorten it much, the knife’s going to be too flat in the front half. You should just try drawing some profiles on it though. And draw one in sharpie before you start grinding so you have something there to aim for. You’re gonna have to do some real thinning, though. Probably more work than the reprofiling.


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## cotedupy (Nov 5, 2020)

ian said:


> Idk, I’d worry that if you start grinding halfway between the chip and the heel and try not to shorten it much, the knife’s going to be too flat in the front half. You should just try drawing some profiles on it though. And draw one in sharpie before you start grinding so you have something there to aim for. You’re gonna have to do some real thinning, though. Probably more work than the reprofiling.



Ta, I'll have a play around with a sharpie. I suspect I probably will have to start at the heel, but hopefully not take too much of the fingerguard off. But good to hear various opinions about possible options, as it's not something I've done before.

The knife is already so thin that I really don't think there'll be much to thin out. Even after the chip's gone it'll still be thinner behind the edge than my old Sabs. So I'm hoping once the re-profiling's done, I won't have a massive amount of edge work. Fingers crossed!


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## Benuser (Nov 6, 2020)

Lovely knife, I must say. That chip is quite serious. I guess it's a 'migrant carbide' as it occurs from time to time with vintages. Anyway, I would start by repairing the tip by working from the spine. Easiest with automotive sandpaper, P240. Remove steel from the spine until the edge has been reached again. Takes only a few minutes.
I would build a secondary bevel at the lowest possible angle and go on until the bevels meet. Verify with a marker and a loupe whether the chip is really gone. I would start with a 220 stone. I use a Shapton Pro. 
For the time being, don't touch the first 2“ until the final sharpening.


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## cotedupy (Nov 6, 2020)

Benuser said:


> Lovely knife, I must say. That chip is quite serious. I guess it's a 'migrant carbide' as it occurs from time to time with vintages. Anyway, I would start by repairing the tip by working from the spine. Easiest with automotive sandpaper, P240. Remove steel from the spine until the edge has been reached again. Takes only a few minutes.
> I would build a secondary bevel at the lowest possible angle and go on until the bevels meet. Verify with a marker and a loupe whether the chip is really gone. I would start with a 220 stone. I use a Shapton Pro.
> For the time being, don't touch the first 2“ until the final sharpening.



Cheers! Sorry for a stupid q - when you say the first 2 inches, you mean the tip of the knife right? (Not the heel.)


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## Benuser (Nov 6, 2020)

cotedupy said:


> Cheers! Sorry for a stupid q - when you say the first 2 inches, you mean the tip of the knife right? (Not the heel.)


For the time being I would stay away from the heel section.


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