Pros and cons of Hollow grind?

marrenmiller · Oct 12, 2018

Lapedog said:
No it’s not a sloppy production error. It is by design so that way once the material “jumps” over the thicker edge it is no longer in contact with the sides of the blade. The David Boye hollow grind will have the material always be in contact.

You can test it yourself. Pinch the blade on either side and pull your fingers down past the edge until the blade slips out of your pinched fingers. You will feel that little “speed bump” yiur fingers go over right before they pass over thr edge. So basically you are pinching in the hollows on either side of the blade and slowly pulling your knife upwards out of the pinch.

I've done what you're asking and have never encountered any thickening immediately before the edge on any hollow grind I've owned, including the Umnumzaan I just bought. I don't think that's nearly as common as you're suggesting.

Also, how does anybody here know for certain what Buck actually intended to do with their hollow grinds?

Do you use micrometers to measure this supposed increase in thickness?

Lapedog · Oct 12, 2018

marrenmiller said:
I've done what you're asking and have never encountered any thickening immediately before the edge on any hollow grind I've owned, including the Umnumzaan I just bought. I don't think that's nearly as common as you're suggesting.

Also, how does anybody here know for certain what Buck actually intended to do with their hollow grinds?

Do you use micrometers to measure this supposed increase in thickness?

I can feel it on both my Sebenzas and my Inkosi. I’ll check more hollow ground knives when I get home. Its not alot of thickening. Maybe you’re not doing the test right. i’ll include some pictures showing you how to do it when I get home.

marrenmiller · Oct 12, 2018

Lapedog said:
I can feel it on both my Sebenzas and my Inkosi. I’ll check more hollow ground knives when I get home. Its not alot of thickening. Maybe you’re not doing the test right. i’ll include some pictures showing you how to do it when I get home.

I understand what you're saying to test, I've just never observed it. Currently I have a hollow ground recon 1 and an Umnumzaan that I've looked pretty closely at, and I don't see any thickening. I also can't feel any increase in drag or change in thickness to the edge. As noted, I've ground a hollow buck 110 down to 10 dps or so, and even then there's no thinning going on above the edge, which would surely be shown by such a reprofiling.

pinnah · Oct 12, 2018

@Marley: Here's a link to a discussion of the semi-hollow grinds used by Buck. Many of the posters here are hard core Buck collectors (I am not).
https://www.bladeforums.com/threads/bucks-grinds.1355452/

Lapedog : I believe we are talking about differences in scale. I think the flare you are seeing is very small. The flare I'm talking about in the semi-hollow grind is very big. David Martin notes this difference in post #16 in the link above.

marrenmiller · Oct 12, 2018

pinnah said:
@Marley: Here's a link to a discussion of the semi-hollow grinds used by Buck. Many of the posters here are hard core Buck collectors (I am not).
https://www.bladeforums.com/threads/bucks-grinds.1355452/

Lapedog : I believe we are talking about differences in scale. I think the flare you are seeing is very small. The flare I'm talking about in the semi-hollow grind is very big. David Martin notes this difference in post #16 in the link above.

How do we know that anything they are discussing is actually true though? I see lots of assuming why things are done, and not a whole lot of Buck stepping in and telling anyone why they do what they do.

bikerector · Oct 12, 2018

pinnah said:
Lapedog, can you name some brands (other than old bucks) that have this thickening above the edge?

The sheeps mini-grip has this geometry to the hollow grind. It's very obvious.

Lapedog · Oct 12, 2018

pinnah said:
@Marley: Here's a link to a discussion of the semi-hollow grinds used by Buck. Many of the posters here are hard core Buck collectors (I am not).
https://www.bladeforums.com/threads/bucks-grinds.1355452/

Lapedog : I believe we are talking about differences in scale. I think the flare you are seeing is very small. The flare I'm talking about in the semi-hollow grind is very big. David Martin notes this difference in post #16 in the link above.

Yes the flare I am talking about is very very small. You could not see it with your eyes. You can only barely feel it with your fingers by pinching the blade and dragging your fingers over it.

marrenmiller like this in the photos. Normally you would hold the handle of course but I needed that hand to hold the camera. Double check what you are feeling. What you might think is just the edge passing through your pinch is likely actually that tiny flare. That little sensation you feel if you pay attention is being felt ahead of where your fingers clear the blade.

If you feel a hollow grind that doesn’t have it you will feel the difference. I can feel it on any of my hollow ground knives I check. I’m not sure about the buck 110 because I don’t own one. The flare is very small so if you’re not paying attention closely you won’t feel it. I’m not sure if the Zaan has it or not but I imagine it does as other CRKs do.

marrenmiller · Oct 12, 2018

Lapedog said:
Yes the flare I am talking about is very very small. You could not see it with your eyes. You can only barely feel it with your fingers by pinching the blade and dragging your fingers over it.

marrenmiller like this in the photos. Normally you would hold the handle of course but I needed that hand to hold the camera. Double check what you are feeling. What you might think is just the edge passing through your pinch is likely actually that tiny flare. That little sensation you feel if you pay attention is being felt ahead of where your fingers clear the blade.

If you feel a hollow grind that doesn’t have it you will feel the difference. I can feel it on any of my hollow ground knives I check. I’m not sure about the buck 110 because I don’t own one. The flare is very small so if you’re not paying attention closely you won’t feel it. I’m not sure if the Zaan has it or not but I imagine it does as other CRKs do.

Yeah, that's what I do to check. No thickening of the edge found. Got a micrometer laying around?

pinnah · Oct 12, 2018

marrenmiller said:
How do we know that anything they are discussing is actually true though? I see lots of assuming why things are done, and not a whole lot of Buck stepping in and telling anyone why they do what they do.

Well, we could ask how know anything and go the rabbit hole of epistemology...

Several of the posters to that thread (not me) are long time members of the Buck Collectors Club, have access to catalog and news letter archives (pay walled) and are on a first name basis with current and past Buck presidents and designers.

marrenmiller · Oct 12, 2018

pinnah said:
Well, we could ask how know anything and go the rabbit hole of epistemology...

Several of the posters to that thread (not me) are long time members of the Buck Collectors Club, have access to catalog and news letter archives (pay walled) and are on a first name basis with current and past Buck presidents and designers.

Fair enough. I just meant that I have no idea who these people are, or their relationships with OEMs. There's too much bad info floating around on this forum from decades past for me to just trust what is said there immediately.

GatorFlash1 · Oct 13, 2018

Another question is how often will you use your knife to cut an item so thick you are actually using the whole width of the blade? I think most of the stuff I end up cutting is rarely to or above the top of the hollow grind portion of the blade. And this probably works with both push and slice cutting.