A Q. Regarding Chipping

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cotedupy

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Unfortunately my better half decided this afternoon (despite frequent explanations to the contrary) that my Chinese vegetable cleaver was exactly what she needed to go through pork bones.

I know a few people have talked about a few different ways to sort out chips but just thought I'd ask advice for this circumstance: The chip is about 1.5mm - 2mm deep. It's not an expensive knife so won't be too hard, nor does it matter if I feck it up. And because of the shape, I'll just need to re-do the bevel and edge after, rather than the entire profile (I assume).

Can I just run it over a belt sander at 90 degrees until it's worn down? And would I need any special belt for that, or will a normal 40 or 80 grit work? Or should I try to sharpen it out on a rough stone, I have one for tools that's about 150 grit I think?

Any thoughts much appreciated!
 

captaincaed

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I'd be careful doing that for fear of snagging the belt on the edge of that chipped out spot on the blade. A shredded belt going fast can be pretty dangerous.
I'd opt for a 45 degree angle or so to the belt, as if you're stropping the edge at a high angle. Then you can alternate sides to maintain some control of the process.
When I watch the pros work on belts with a blade that's already been heat-treated, they're quenching the blade in water every few seconds to avoid burning the temper out.
When I reprofiled a knife, I started with files (too soft), then went to the edge of my super course stone, and worked at it like I was sharpening, but at a higher angle. Took a project day, but it worked out all right in the end.
 

Nemo

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Photos will help.

Which steel are we dealing with?

If you breadknife the edge as you described, you may well change the profile and you will still need to thin behind the edge. My approach is to thin behind the edge, keeping the (reducing) edge bevel even until the chip is mostly gone. This maintains the profile and roughly maintains the grind. The chip doesn't need to be completely gone because you will then re-set the bevel which will take off a little more metal.

If you have almost reached the edge with your thinning, and you need to go further, it's not a bad idea to re-grind the edge bevel as a guide for further thinning.

Any decent coarse stone should be ok for this job. I have moved to using coarse sandpaper on the Kasfly device nut I have done a similar job on a Chosera 400 (one of the least aggressive coarse stones).
 
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Nemo

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If you use a belt sander, be super careful of overheating the blade, especially the edge, ruining the temper. Most pro knifemakers have a heat finger that they place at a strategic spot near the edge to warn them when the edge has heated up too much, then they cool in water.
 

captaincaed

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Listen to Nemo's wisdom. I had the thin the knife above quite a bit after I re-did the profile. You're going to remove ALL that metal, one way or another, or your knife will be far too thick behind the edge to cut well. It's just a matter of whether you want to:
1. Reprofile then thin
2. Reprofile and thin all at the same time

Good luck! Share progress pics.
 

Nemo

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Oh, and thank your better half for:

1) Learning this lesson on an expendable knife.
2) Giving you the opportunity to learn quite a bit about how to maintain a knife's grind.
3) Giving you an excellent excuse to nerd out on knives for a few hours without any guilt at all.
 

cotedupy

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Thanks guys. Sounds like I'll give it a try on a very coarse stone first, and see how I go, and maybe move to sanding if it's taking too long! (I have already thinned behind the edge on this knife when I got it, and it didn't take forever.)

Will update with some pics when I've done...
 

Nemo

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Thanks guys. Sounds like I'll give it a try on a very coarse stone first, and see how I go, and maybe move to sanding if it's taking too long! (I have already thinned behind the edge on this knife when I got it, and it didn't take forever.)

Will update with some pics when I've done...
Take some before you start. Then some more at each milestone in your repair.

Thank me later.
 

cotedupy

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Oh, and thank your better half for:

1) Learning this lesson on an expendable knife.
2) Giving you the opportunity to learn quite a bit about how to maintain a knife's grind.
3) Giving you an excellent excuse to nerd out on knives for a few hours without any guilt at all.
Haha! All of these points did actually occur to me. It's hard to irritated when I'm probably going to quite enjoy the whole process ;) And if it all goes wrong I have another brand new one of exactly the same.

(It's literally a 15 AUS$ Chinese Cleaver, so no idea of the steel, other than it's carbon rather than stainless.)
 

Nemo

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I guess you could make it into a bone cleaver by breadknifing it & not thinning then putting a 30 degree per side edge bevel on it.
 

juice

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Take some before you start. Then some more at each milestone in your repair.

Thank me later.
You can never have too many photos - you can delete ones you don't want, but you can't add in the ones you didn't take. (Paranoid former wedding photographer lessons...)
 

cotedupy

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So either I was slightly overplaying the problem, or I've just followed superb advice, well. But this took me very little time. Here it is before...

IMG_1050.jpeg


Five or so mins of quite aggressive action on a very coarse stone...

IMG_1060.jpeg


Then a few mins on about 500 grit, and a couple on 1000. Back to push cutting through paper quite happily, and I'll tidy it up in the morning.

IMG_1063.jpeg


Ain't the poshest knife in the world, but I really like it. So thank you everyone for the advice!
 

ian

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How much actual thinning did you do versus just edge work? That is, was the knife flat on the stone? How high up were the scratches you were making?
 

cotedupy

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How much actual thinning did you do versus just edge work? That is, was the knife flat on the stone? How high up were the scratches you were making?
Not a huge amount of thinning this evening (a little bit but not much), I had thinned it a bit before. Most of it on the coarse stone I probably did at about 35 or 40 degrees I guess...
 

ian

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Well, it makes sense that it was so fast if you didn’t do any thinning. Thinning’s what takes time. If you removed 2mm without thinning, you’ll probably notice a negative difference in how well it cuts now. Good luck with the project! I love these threads.
 

cotedupy

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Well, it makes sense that it was so fast if you didn’t do any thinning. Thinning’s what takes time. If you removed 2mm without thinning, you’ll probably notice a negative difference in how well it cuts now. Good luck with the project! I love these threads.
I'll report back tomorrow, but it looks and feels quite good hopefully. I thinned it a bit again this evening to even things up, but I had done quite a lot behind the edge already, so didn't need a massive amount more I don't think. Vamos a ver...
 

Twigg

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Glad to see you were able to remove the chip. Out of curiosity, what did she make using the pork?
 
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