Broken Tip Repair Help

[DamageInc]

Well, crap. My Hinoura gyuto slipped out of my hand while wiping it and dropped 10cm tip-first into the sink. Tip snapped off, being the knife is insanely thin.

I've never fixed a broken tip before. Any pointers other than to stop being a clumsy jackass? The only coarse stone I have is a JNS 1000. I also have an atoma 140 diamond plate.

Any help would be very much appreciated.

 

[aboynamedsuita]

I'd wait until others can chime in who've done a lot more rehab work, but you'll probably want to drop the spine to the (new) tip to avoid altering the profile on the cutting edge

 

[pkjames]

get your self a fine grit slow grinder (tormek is great, but a bit expensive) or even just a variable speed orbital sander benched mounted, and drop the spine. Done properly, you can hardly tell it is ever chipped.

 

[DamageInc]

I'd wait until others can chime in who've done a lot more rehab work, but you'll probably want to drop the spine to the (new) tip to avoid altering the profile on the cutting edge

Yeah that's the only thing I know about repairing tips is dropping the spine instead of raising the edge.

get your self a fine grit slow grinder (tormek is great, but i bit expensive) or even just a variable speed orbital sander benched mounted, and drop the spine. Done properly, you can hardly tell it is ever chipped.

Thanks pkjames, I'll keep that in mind.

 

[Asteger]

Your 140 Atoma will knock off that spine pretty fast, don't worry. I mean it will take more than a few minutes - 30 mins, 1 hour? - but I think suggestions to buy some sort of grinder are silly when you've already got your Atoma.

When you get the shape you want, you could then use a non-diamond coarse stone to smooth out the reduced spine. However, you only have a 1000 and nothing lower, so maybe not. Instead, just get some coarser sandpaper. No problem.

But there is one problem, you will be wrecking the uniform KU finish in the affected area. The finish on the spine will of course go (you could rub off the rest of the KU along the spine for consistency; I received a new knife that was pretty much like this, so not 'strange'). You'll probably wear away some KU near the spine on the sides, though, especially if you sandpaper by hand with your fingers instead of rubbing the knife onto flat sandpaper as you would a stationary stone.

 

[knyfeknerd]

Your 140 Atoma will knock off that spine pretty fast, don't worry. I mean it will take more than a few minutes - 30 mins, 1 hour? - but I think suggestions to buy some sort of grinder are silly when you've already got your Atoma.

When you get the shape you want, you could then use a non-diamond coarse stone to smooth out the reduced spine. However, you only have a 1000 and nothing lower, so maybe not. Instead, just get some coarser sandpaper. No problem.

But there is one problem, you will be wrecking the uniform KU finish in the affected area. The finish on the spine will of course go (you could rub off the rest of the KU along the spine for consistency; I received a new knife that was pretty much like this, so not 'strange'). You'll probably wear away some KU near the spine on the sides, though, especially if you sandpaper by hand with your fingers instead of rubbing the knife onto flat sandpaper as you would a stationary stone.

Yes, This!
:goodpost:
Don't be afraid, you'll be so proud of yourself after you fix it.

 

[DamageInc]

Thanks for the words of encouragement.

Here is what it looks like after around 20 minutes on the atoma and a bit on the 1000 grit. Gotta keep going some more. God, how I hate the feedback on the atoma. Feels and sounds like death and destruction.

 

[ThEoRy]

Do something like this..

 

[Asteger]

Looks like you're doing it at angles. Nah, just work on the shape by wearing it down along the spine with the knife perpendicular to the Atoma. After, you can easily round the corner edges to resemble the rest of the spine. Don't round them now. Get the shape/profile nice.

 

[DamageInc]

I got the spine down to where I want it. Now I'm thinning spine near the tip to the thickness it used to be. I bit more and I should be about done. Then I'll probably consider some sandpaper to even the finish.

Apart from screwing up the kurouchi, anything else I did wrong?

 

[knyfeknerd]

Looks pretty good to me.

 

[Asteger]

[/I got the spine down to where I want it. Now I'm thinning spine near the tip to the thickness it used to be. I bit more and I should be about done. Then I'll probably consider some sandpaper to even the finish.

The line of the curve looks pretty good I think. As said, you should have just worn down the spine to this profile shape at a direct perpendicular angle, and then just smooth it out, including rounding the edges on it just a bit and only as much as the rest of the original spine, which is very little usually. Unfortunately, looks like you're halfway to creating a second edge where curved portion of the spine should be, and so you lost more of the KU than you needed to.

 

[DamageInc]

The line of the curve looks pretty good I think. As said, you should have just worn down the spine to this profile shape at a direct perpendicular angle, and then just smooth it out, including rounding the edges on it just a bit and only as much as the rest of the original spine, which is very little usually. Unfortunately, looks like you're halfway to creating a second edge where curved portion of the spine should be, and so you lost more of the KU than you needed to.

Yeah that was pretty much what I thought. Sharpening habit kicked in and I started sharpening the spine like it was the edge instead of just going straight on the spine. Oh well. Learned something for next time (which is hopefully never). I have now flattened the spine and the thinness is were I want it.

I hope someone else can learn from my errors... But to be honest, it looks worse than it is.

 

[DamageInc]

Whole blade

Just gotta even the finish near the "fixed" area.

 

[Asteger]

Yeah that was pretty much what I thought. Sharpening habit kicked in and I started sharpening the spine like it was the edge instead of just going straight on the spine. Oh well. Learned something for next time (which is hopefully never). I have now flattened the spine and the thinness is were I want it.

I hope someone else can learn from my errors... But to be honest, it looks worse than it is.

Absolutely. Don't worry. Consider it a 'custom' now

... Wait, actually. I think it'd bother me the way it is. I still think you could have it look pretty much like new. Try the perpenticular re-shaping and go for this:

 

[chinacats]

From my phone it appears that there is a small "hump" in the spine. If it were mine, I'd probably address that as well...you won't lose any more edge. ..our you may like it as is.

Either way, cheers for just doing it.

 

[DamageInc]

Absolutely. Don't worry. Consider it a 'custom' now

... Wait, actually. I think it'd bother me the way it is. I still think you could have it look pretty much like new. Try the perpenticular re-shaping and go for this:

I just might go ahead and do that. I think I'm gonna use the knife for a bit first though.