what are blood grooves for?

forging does displace & does not compress. this is getting back to that old 'edge packing' myth
 
Once again. This seems to come up over and over. Removing material does not make the structure stronger. A steel I-beam is stronger than a solid beam of the equivalent weight, but not as strong as a solid beam of the same external dimensions.

A fuller can be used to reduce the weight of a blade while retaining more strength than simply making the whole blade thinner or smaller.
 
Cynic2701 said:
Basically by removing material from the blade, it changes how forces act along the radial axis of the knife blade. Instead of having a large amount of the force concentrated at the center of that axis, the "blood groove" is supposed to remove enough steel from that center point to allow a degree of flexibility. As a result, the torsional forces acting on the knife are concentrated on the two, thicker, pieces of steel that are located further from the center of rotation.
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I get what you mean now. Weird how I didn't understand it in much simpler terms. And to anybody who wants to say something negative or insulting, I know physics pretty well. I don't know the formulas and all that useless (if you aren't going into a physics intensive field) stuff, but I understand the physics themselves.
 
DrFish said:
Once again. This seems to come up over and over. Removing material does not make the structure stronger. A steel I-beam is stronger than a solid beam of the equivalent weight, but not as strong as a solid beam of the same external dimensions.
Click to expand...

The above post should be a sticky.

"Removing material does not make the structure stronger."
 
Nothing mentioned will increase density. Metal being maleable and a wire edge (?) is just pushing material around, not compressing it and making it denser. A super ball isn't compressed either, it deforms then springs back to the original shape providing energy for the bounce. It's just a spring of sorts. Liquids and solids can't be compressed. That's why hydraulics work.
 
FlaMtnBkr said:
Nothing mentioned will increase density. Metal being maleable and a wire edge (?) is just pushing material around, not compressing it and making it denser. A super ball isn't compressed either, it deforms then springs back to the original shape providing energy for the bounce. It's just a spring of sorts. Liquids and solids can't be compressed. That's why hydraulics work.
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Had to prove you wrong. There is a solid that compresses. We call it ice. The Ice itself can be compressed, and when it melts it becomes more dense. Hence why ice floats in water.
 
Nope, that's not what happens.

Cold Kill said:
Had to prove you wrong. There is a solid that compresses. We call it ice. The Ice itself can be compressed, and when it melts it becomes more dense. Hence why ice floats in water.
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Steel does expand and contract according to temperature, and I wouldn't say that it's impossible to compress steel, we know that iron atoms can be moved closer together when dislocations form (also leaving spaces), but I've never heard of anyone being able to make steel more dense using pressure. It would take extraordinary amounts of energy to accomplish and any change would almost certainly be temporary (those atoms really like their space).
 
Thanks, that's good explanation.

Cynic2701 said:
Basically by removing material from the blade, it changes how forces act along the radial axis of the knife blade. Instead of having a large amount of the force concentrated at the center of that axis, the "blood groove" is supposed to remove enough steel from that center point to allow a degree of flexibility. As a result, the torsional forces acting on the knife are concentrated on the two, thicker, pieces of steel that are located further from the center of rotation.
Click to expand...
 
Cuts made on a rifle barrel are commonly called flutes. This reduces weight and increase strength buy increasing the surface area.
 
mossyhorn said:
Cuts made on a rifle barrel are commonly called flutes. This reduces weight and increase strength buy increasing the surface area.
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I'm not sure that last part makes sense. What type of strength are you talking about? Barrel stiffness? I don't think so.
 
That's a pretty good explanation, IMHO.

ono724 said:
I must of missed something, was there an explanation of it's function? :rolleyes:
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DrFish said:
Once again. This seems to come up over and over. Removing material does not make the structure stronger. A steel I-beam is stronger than a solid beam of the equivalent weight, but not as strong as a solid beam of the same external dimensions.

A fuller can be used to reduce the weight of a blade while retaining more strength than simply making the whole blade thinner or smaller.
Click to expand...
 
fluting a barrel reduces stiffness. Fluted barrels are stiffer than non-fluted. Sounds totally contradictory. But, a barrel needs to be a certain wall thickness to handle the pressures of shooting rounds. You don't take a regular barrel and cut grooves in it to reduce it below that minimum. You take a thicker walled barrel and mill the grooves to that thickness, not below it. The larger diameter ribbing means the fluted barrel is stiffer than the smaller diameter round barrel. But the barrel before fluting had more material and was stiffer.
 
ono724 said:
I must of missed something, was there an explanation of it's function? :rolleyes:
Click to expand...

...it was post #7 that first caught my attention; a bit early in the discussion, so I guess easy to miss...

puukkoman said:
As stated, the name "blood groove" is based on a myth. Anyone who believes it has obviously never used a knife to puncture an animal's body cavity. It makes no difference.
They are usually used to reduce weight while preserving strength (same physics principles behind the "I-beam"). In the case of the Pilot's Survival Knife made by Camillus and Ontario, the groove also has the added benefit of allowing the blade to turn during use, when the sawback is used for its intended role (sawing through aluminum aircraft skins). If there were no fuller in the blade, it would be much more difficult to rotate the blade to make curved cuts, while it's plunged into a rigid piece of metal.

Done and done.
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DrFish said:
Once again. This seems to come up over and over. Removing material does not make the structure stronger. A steel I-beam is stronger than a solid beam of the equivalent weight, but not as strong as a solid beam of the same external dimensions.
Click to expand...



Obviously worth quoting yet again.

Leadfoot
 
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