Overgrind or Undergrind?

[The_Real_Self]

I recently read mention here from people about the phenomenon of 'overgrinds' on Fujiwara knives, possibly others. The funny thing is when I got the following knife my thoughts were that it was in fact 'underground' in that I'd have preferred them to take off much more material than was done in general. Sure there are some low spots from the grinding that was done but I'm not sure I'd call that an 'overgrind' more than just a failure to grind evenly. .

The photo below (top) is after I put in some work on stones to thin the grind a bit, it's clear there's a low spot below the logo. Bottom photo is after I put about 40 minutes on this bevel using my 220 grit Tormek grinder on it freehand using a rocking motion. Even with the rocking motion I still ended up with a very slight hollow which is not a problem to me and it cuts much better now. That said, I still want to take this further as I feel the grind is still too low for performance.

Bottom line? If you recieved the bottom photo knife would you feel like you didn't get a high quality knife? If you got the top and realized it wasn't even would you feel cheated?

 

[Pie]

Maybe not so much over grind as high spot/low spot? Both will exist on almost every handmade knife imo. Fwiw the tip on my denka was ground like crap.

My question, freehanding on the tormek - does that introduce some non-flatness along the bevel, as in new low spots? It no doubt performs better after the treatment, but taking metal from a low spot will make it lower and exacerbate any issues it may cause. I think I do see a good amount of cladding taken off the low. I’m not super familiar with tormek so forgive me if it’s not an issue, or can be avoided with technique.

To answer the question, I wouldn’t have expected the top knife to be even to begin with I think. Bottom knife, I’d like to see what’s going on at the tip and heel but there’s other considerations to decide whether it’s high quality or not. If that’s cladding all the way to the edge I might not be so happy. Hope that helps!

 

[The_Real_Self]

Maybe not so much over grind as high spot/low spot? Both will exist on almost every handmade knife imo. Fwiw the tip on my denka was ground like crap.

My question, freehanding on the tormek - does that introduce some non-flatness along the bevel, as in new low spots? It no doubt performs better after the treatment, but taking metal from a low spot will make it lower and exacerbate any issues it may cause. I think I do see a good amount of cladding taken off the low. I’m not super familiar with tormek so forgive me if it’s not an issue, or can be avoided with technique.

To answer the question, I wouldn’t have expected the top knife to be even to begin with I think. Bottom knife, I’d like to see what’s going on at the tip and heel but there’s other considerations to decide whether it’s high quality or not. If that’s cladding all the way to the edge I might not be so happy. Hope that helps!

Just to clarify in case the OP wasn't clear. Both pictures are the same knife, 1st pic is after light thinning on stones, 2nd pic is after the Tormek. It is cladding all the way to the edge and I've never seen this before. Does it affect anything? Probably not, would be my expectation.

There was a bit taken off the low but I actually took probably a good bit more off all the other spots and you really can't tell. I do believe it's pretty good as far low spots go without checking to verify. I'm actually planning on taking this further and doing the other side before I get there. This was my first go and I ended up getting water all over my bench somehow in the process so I stopped early as it started pouring off.

If you continue moving the knife laterally across the length of the blade it doesn't tend to do this much. If you hover it will for sure get low quickly. You ultimately need to bring this to a coarse stone after this sort of work because as you mention it's difficult to see the low spots without something perfectly flat. When you find the low spots then you just hit those further on the grinder before cleaning up to finish on stones.

 

[stringer]

There are two potential issues with cladding going all the way to the edge. First off, cladding won't take an edge. So if what you are seeing is the core steel offset to the point that it doesn't reach the edge then the knife won't function very well. On the other hand, if the core steel is centered and the cladding goes all the way to the edge then the knife is probably much thicker behind the edge than it should be and it wont perform very well. Think about it like sharpening a pencil. The pencil is going to work best if the graphite is free of wood all the way around the point. If the wood goes all the way to the tip then the pencil won't write well and the point won't be sharp.

From the pictures it looks like you thinned the knife aways up the blade, raising the shinogi. But you didn't really raise the bottom cladding line to expose more core steel which is essential for performance in my opinion. As far as low and high spots on the wide bevel, to me they are secondary to making sure the profile and geometry behind the edge make sense. Low spots only matter if you are chasing kasumi or if they are deep enough to create a hole in the edge or create a situation where cladding is too close to the edge.

 

[RRLOVER]

I have an old Carter Hg that is very similar to this...I have never had an issue with it...Come with the territory of San mai and warikomi.

 

[ian]

What's the other side of the knife look like?

 

[The_Real_Self]

What's the other side of the knife look like?

 

[ian]

Cool. Well, it doesn't seem to me that the cladding close to the edge is a problem, but if it eventually becomes a problem, or if you're worried about it, you can thin more on the left side and push the edge over a little so that there's a more equal amount of core on both sides.

Re: your original question. Grinds are hardly ever even unless they're advertised as coming with a stone polish.

Stringer's post is good. Can't tell from the pics how thin the knife is behind the edge, but as he says, that's what'll matter for performance.

 

[The_Real_Self]

Cool. Well, it doesn't seem to me that the cladding close to the edge is a problem, but if it eventually becomes a problem, or if you're worried about it, you can thin more on the left side and push the edge over a little so that there's a more equal amount of core on both sides.

Re: your original question. Grinds are hardly ever even unless they're advertised as coming with a stone polish.

Stringer's post is good. Can't tell from the pics how thin the knife is behind the edge, but as he says, that's what'll matter for performance.

It's definitely hard to tell because the part behind the edge is actually convex before it gets a bit hollow higher up the blade. I actually mainly thinned the part there directly behind the edge on stones prior to working this on the Tormek. That being the case I was trying to avoid actually impacting the apex directly to preserve the profile of the blade pattern as it will easily take mm's off if you're not careful with it. It still needs more taken off there as I generally take them to roughly zero grinds for cutting ability.

I don't think the cladding is a problem either, sort of happy that it's not perfect so I can have some practice being at peace with things in life I have little control over. I had that thought about grinding more on that side if the edge disappears into the cladding but then again I might just contact Fujiwara if that were the case as I'd definitely call that a defect and see if they offer a replacement for it. I'm going to work the other side of the blade on the Tormek and see how well I can get this fixed up. If I didn't have this Tormek I'd probably be tempted to sell it and get another knife lol.

 

[MowgFace]

You got a choil or nose shot up close? Let’s see the centering of the core.

Many times what you will find is a knife may be FORGED “handed” whether left or right. Meaning more cladding appears on the dominant blade face in order to have more drastic grinds.

If this knife’s core is off centered opposite it’s grind, it could help direct you into how deep a project.

Also, @stringer ’s post.

 

[cotedupy]

Overgrind or Undergrind? Wombling Free!​

Great Uncle Bulgaria he say...