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Hollow ground blades
- Thread starter KyleTuck
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DANTHEMAN123
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flat ground is like a kitchen knife where both sides of the knife are flat, hollow ground is like the cold steel voyager you talked about where the blade is 'hollowed out' on either side.
Cliff Stamp
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The hollow grind gives several benefits, you can hollow out a relief on a flat grind to increase the cutting ability and ease of sharpening as it can thin the edge dramatically, blades can be under 0.020" thick at 0.25" back from the edge :
That is a full hollow grind, blades like that can be sharpened flat to the stone, honing angles of 3/5 degrees per side. The cutting ability is extremely high and they are also very rigid for their weight.
They generally get a bad name for cutting ability because of the sabre ground tacticals which are left with thick and obtuse edges and way too much flat stock. Plus many have a drastic "T" shape which causes binding at the top of the grind.
-Cliff
That is a full hollow grind, blades like that can be sharpened flat to the stone, honing angles of 3/5 degrees per side. The cutting ability is extremely high and they are also very rigid for their weight.
They generally get a bad name for cutting ability because of the sabre ground tacticals which are left with thick and obtuse edges and way too much flat stock. Plus many have a drastic "T" shape which causes binding at the top of the grind.
-Cliff
DANTHEMAN123
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what so a full hollow is flat on both sides but at an angle of 3-5 degrees?
Cliff Stamp
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A hollow doesn't really have an angle, it is just a hole in the blade. That angle is basically the angle of the blade if it was fully flat ground. Full flat primary grinds are around 3-5 degrees usually. Because the blade is hollow you can hone flat to the stone and still make minimal contacts, the Japanese hollow out the backs of their chisels for the same reason and many people do the same when sharpening as well to the front.
-Cliff
-Cliff
DANTHEMAN123
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so wheres the hollowed out bit on your picture then? it looks like a fullflat to me or am i getting confused?
DANTHEMAN123
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i just thought flat was like a spyderco para, and hollow like a persian and the blade has a secondary/primary grind as supposed to just the gring thats sharp. r you saying that those knive that can be sharpened flat on a stone ar like say samuari swords where there is no second grind the blade is brought from the side to the edge instead on having a seperate gring for sharpening?
I think there is a distinction you should note between sharpening and grinding for the sake of discussion. Sharpening here really only concerns the edge angle. Grinding removes material to make the knife thinner in profile.
The scratched up area indicated by the arrow on the left as well as above and below the hollow is the flat part that has been ground (as opposed to sharpened) flat against a stone.
Cliff's knife show a microbevel, as you can notice the different light reflecting properties right at the edge.
I assume he sharpens and touches up the knife at the microbevel angle. When the has worn away some material and finds the edge getting thicker, he'll grind the flat again to thin up the edge.
He could sharpen the whole knife flat for a very small angled edge, but that'll be too high maintanance.
The scratched up area indicated by the arrow on the left as well as above and below the hollow is the flat part that has been ground (as opposed to sharpened) flat against a stone.
Cliff's knife show a microbevel, as you can notice the different light reflecting properties right at the edge.
I assume he sharpens and touches up the knife at the microbevel angle. When the has worn away some material and finds the edge getting thicker, he'll grind the flat again to thin up the edge.
He could sharpen the whole knife flat for a very small angled edge, but that'll be too high maintanance.
Cliff Stamp
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The primary hollow grind just allows the edge to be sharpened in that manner, it doesn't have to be, you can make the secondary edge bevel as obtuse as you want.
Yes for some knives, my small Sebenza is sharpened like that. I run micro bevels at 20, it never thickens to 0.2 mm wide. The small 1095 paring knife I generally work the entire bevel when I sharpen and rarely need more than the finest stone. I just raise the blade a little and hone so the edge bleeds gradually from about 3 to 6 after working the primary for awhile. You can't tell by looking at it that there is a distinct bevel, you don't see one under mag either, but if measure the curvature carefully you can see it shift. If I do some drastic like cut sod or similar, I'll work the blade flat to a burr and then resharpen.
-Cliff
kel_aa said:
Yes for some knives, my small Sebenza is sharpened like that. I run micro bevels at 20, it never thickens to 0.2 mm wide. The small 1095 paring knife I generally work the entire bevel when I sharpen and rarely need more than the finest stone. I just raise the blade a little and hone so the edge bleeds gradually from about 3 to 6 after working the primary for awhile. You can't tell by looking at it that there is a distinct bevel, you don't see one under mag either, but if measure the curvature carefully you can see it shift. If I do some drastic like cut sod or similar, I'll work the blade flat to a burr and then resharpen.
-Cliff