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View Full Version : OTF blades run on rails?



Chippychap
05-15-2011, 09:20 AM
Hi Guys, at the top end of the market, Microtech et al I would expect absolutely no slop in the extended blade.
I've seen the schematics and the Youtube vids but do the blades run in a channel?
Some of the blades have a fuller-type groove but they don't extend the full length of the blade so I guess that ain't it.
The blade seems to run up against one of the scales so that would help secure the blade.
How do they get it rock solid?

Peter Killgore
12-21-2012, 12:28 AM
To put it bluntly they don't get it rock solid. I own a Microtech Ultratech and have handled a few other Microtechs as well as the Benchmade Infidel. The Microtech has FAR less slop in the blade when extended than the Benchmade (and it's significantly cheaper). Still, even it has some wobble to it. It is minimal though and doesn't detract from the performance of the knife. When it comes to a locking mechanism, I don't know how the Microtech works. The slot that the blade ejects through is very precisely machined so there's not a lot or room for it to wiggle. I've seen some OTFs taken apart (and have even taken a cheap one apart myself) and they all have some kind of spring mechanism that kicks in under the tang to secure the blade. Some kick in from the edge/back of the blade. Others kick in from the flat side. I would imagine that a tapered slot and a tapered blade would ensure a lockup that is as tight as possible. That's just my speculation though... The fuller type groove you're referring to is what's known as a bloodrail. Its purpose is to keep the blade from sticking when it is used to stab. That's what I've always been told at least. I hope this was helpful to you!

Peter

rhinoknives
12-25-2012, 06:06 AM
The fuller type groove you're referring to is what's known as a bloodrail. Its purpose is to keep the blade from sticking when it is used to stab. That's what I've always been told at least. I hope this was helpful to you!
Peter

Peter,
The blood groove or rail theory as you call it is one of the biggest Myth's in Knives & Swords!
It is called a fuller and the purpose is to add strength & lighten the blade by giving more surface area in the same amount of blade. Think of how a piece of I beam steel is stronger & lighter than a solid bar of steel. Some auto OTF designs may use it as a guide? But there is no documented proof ever that stabbing into live muscle will make the muscle spasm and tighten down on the knife etc..

I also had been indoctrinated with this Blood Groove BS and when I got into knife making I learned that the true name is a fuller and its about making the blade stronger & Lighter.

Cheers!
Laurence

www.rhinoknives.com

ElementFe
09-19-2013, 10:45 PM
Brilliant- of course that's what it is!
I don't know if "stronger" is the most precise word, though- I think it's obvious that it would make the blade stiffer, at least.
And the name comes from the tool, I believe- in blacksmithing a Fuller enlarges a section by spreading it in one direction (making it more full, as the old timers might say), depending on the orientation of the Fuller relative to the work piece.

Gary Miller
09-19-2013, 11:48 PM
all otf knives are like a ak47 if you take the wiggles out it won't work. fullers have nothing to do with draining blood. if we don't get away from all this tacktal blood and guts crap when talking about knives were going to end up with more stuipd knife law, we have plenty already

rhinoknives
09-19-2013, 11:58 PM
Stronger equates to stiffer? The important part that I didn't write in there for some reason is that the blade would be stronger/stiffer than one of the same weight since the fuller adds in surface area. That has been my experience from knife making anyway?

We would need to do a cross section load bearing test of two blades of the same weight and one with a fuller, one not, to get a true test on this? I am always open to new proven scientific data. I am only married to my wife, so to speak. LOL

ARCustomKnives
09-20-2013, 03:16 AM
Peter,
The blood groove or rail theory as you call it is one of the biggest Myth's in Knives & Swords!
It is called a fuller and the purpose is to add strength & lighten the blade by giving more surface area in the same amount of blade. Think of how a piece of I beam steel is stronger & lighter than a solid bar of steel. Some auto OTF designs may use it as a guide? But there is no documented proof ever that stabbing into live muscle will make the muscle spasm and tighten down on the knife etc..

I also had been indoctrinated with this Blood Groove BS and when I got into knife making I learned that the true name is a fuller and its about making the blade stronger & Lighter.

Cheers!
Laurence

www.rhinoknives.com

I'm not sure it necessarily adds strength, it just lightens the blade.

If you have an I-beam vs a solid bar of steel with the same outer dimensions, the solid bar will always be stronger, BUT it will be significantly heavier.

Now, if you scale that solid bar down such that it is the same weight as the I-beam, then the I-beam will be much stronger, but only because it is much bigger.

LiamLynch
09-20-2013, 08:38 AM
Hi Guys, at the top end of the market, Microtech et al I would expect absolutely no slop in the extended blade.
I've seen the schematics and the Youtube vids but do the blades run in a channel?
Some of the blades have a fuller-type groove but they don't extend the full length of the blade so I guess that ain't it.
The blade seems to run up against one of the scales so that would help secure the blade.
How do they get it rock solid?


None of this matters to you anyway because you aren't allowed them because they are far too scary. You could have an OTF bottle opener if you wanted. I think it is '68 they were banned here.

I'm not trying to be rude, just go and not get arrested, it makes it tougher for everyone here.