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ts
06-30-2007, 2:22 AM
I was thinking about this while I was using my knife today...

You guys know how in medieval swords and some knives they have a cut out? (There is a common misconception that that is for the blood to drain out) But in reality the reason why that is there is to lighten the weight and strengthen the blade.

Thinking of a stamped AK receiver there is a dimple on it - is that to strengthen the receiver?

On a milled receiver why is that cutout there - to strengthen the receiver and to lessen weight?

Just curious,
Tony

Sal
06-30-2007, 2:37 AM
on the stamped one the dimples are to make the inside of the magwell narrow enough to hold the mag steady side to side.

on the milled receivers its just to make it lighter.

aplinker
06-30-2007, 2:59 AM
I was thinking about this while I was using my knife today...

You guys know how in medieval swords and some knives they have a cut out? (There is a common misconception that that is for the blood to drain out) But in reality the reason why that is there is to lighten the weight and strengthen the blade.

Thinking of a stamped AK receiver there is a dimple on it - is that to strengthen the receiver?

On a milled receiver why is that cutout there - to strengthen the receiver and to lessen weight?

Just curious,
Tony

Fullers don't actually make a blade stronger, just stronger for an equivalent weight. Having it filled in would still be stronger, but it would weigh more. Having the same dimensions and weight without a fuller would make it thinner everywhere.

ts
06-30-2007, 3:23 AM
Fullers don't actually make a blade stronger, just stronger for an equivalent weight. Having it filled in would still be stronger, but it would weigh more. Having the same dimensions and weight without a fuller would make it thinner everywhere.

You sure about that? I was under the impression it gave the blade less bending ability. And in my mind that would make the blade stronger since it would not bend and break. I might be wrong though.

xenophobe
06-30-2007, 4:26 AM
No it does not make a blade stronger, just as fluting does not make a barrel stronger. It makes the blade lighter.

on the stamped one the dimples are to make the inside of the magwell narrow enough to hold the mag steady side to side.

on the milled receivers its just to make it lighter.

^what he said.

socalguns
06-30-2007, 4:43 AM
The word is STIFFER :)


The basic design principle is that bending causes more stress in material near the edge or back of the blade than material in the middle, due to leverage. The diagram at left shows stress distribution in an ideal blade with a rectangular section, with only a small amount of shear stress present at the neutral axis. Fullers remove material from near this neutral axis, which is closer to the blade's spine if only one edge is sharpened (see photo above). This yields stiffer blades of a given weight, or lighter blades of a given stiffness. The same principle is taken to an extreme in the I-shaped cross sections of most steel beams. Some even contend that this concept was borrowed into architecture from weapons design [1].

aplinker
06-30-2007, 10:37 AM
The word is STIFFER :)

This yields stiffer blades of a given weight, or lighter blades of a given stiffness. The same principle is taken to an extreme in the I-shaped cross sections of most steel beams.

Careful where you point that big stiffer there.

Anyways, the words "a given weight" make that exactly what I said. You can make a better light blade with a fuller, but if you filled in that spot (if you didn't care about weight) it would be stronger.

Lateralus
06-30-2007, 11:13 AM
the dimples are for the mag, the center support is for strength.

Most people believe fluting strengthens a barrel. The best thing to remember is this: There is NO WAY to remove material and make something stronger. But a clever engineer can MOVE material around...

correct me if im wrong, but i heard the main advantage of fluting is to increase surface area so it dissipates heat faster.

ts
06-30-2007, 12:34 PM
the dimples are for the mag, the center support is for strength.

Most people believe fluting strengthens a barrel. The best thing to remember is this: There is NO WAY to remove material and make something stronger. But a clever engineer can MOVE material around...

correct me if im wrong, but i heard the main advantage of fluting is to increase surface area so it dissipates heat faster.

why would u need to dissipates heat heat on a blade?

jumbopanda
06-30-2007, 2:10 PM
why would u need to dissipates heat heat on a blade?

You don't, he's talking about barrels.

ts
06-30-2007, 6:50 PM
You don't, he's talking about barrels.

Okay - but I do believe you guys might be mistaken. If you take a flat sheet of metal and try to bend it, it would be much harder to bend if it had dimples in it. Am I not correct?

The cut on a blade does lessen weight but I would think because of the angular cuts of the metal it would give it less bending capability, same concept as simpling a sheet of metal.

I can be very mistaken - let's think about it scientifically.

socalguns
07-01-2007, 3:41 AM
yes, harder to bend -- no one is arguing it isn't.
As for fluting, fluting is done to reduce weight,
all they do is reduce the diameter of the
barrel towards the muzzle.
surface area is less than before, not more.

saki302
07-01-2007, 6:34 AM
TS- you're missing the concept with the bent sheet metal example. If you had a solid hunk of steel the same thickness of the dimpled sheet metal, it would be stiffer still.

A grooved blade will be stiffer than a non-grooved blade of the SAME WEIGHT. But as another poster stted, there is NO WAY to make ANY material stronger/stiffr by removing metal. Period. Defies the laws of physics there.

A fluted barrel will be stiffer than another barrel of EQUIVALENT WEIGHT, and will have better cooling than a non-fluted barrel (more surface area).

i suspect most blades with grooves are done because it looks cool' haha! The old long bayonets were grooved mainly to reduce weight- they're still heavy with the groove!

-Dave