RustyIron wrote: ↑Fri Jun 26, 2020 5:56 pm
Michael Janich wrote: ↑Fri Jun 26, 2020 7:10 am
The Native 5 has a true concentric pivot. That means the radius from the pivot pin to the arc of the profile of the tang remains the same throughout the arc. That means there is constant, consistent pressure on the tang throughout the opening arc.
Hey, Mike.
Maybe I don't completely understand what you're saying, or could it be that the rule doesn't hold true along the whole Native 5 line?
I'm not super knowledgeable with back locks or even proper knife nomenclature, but I'll try to describe what I'm seeing. I have a Native 5 G10 REX 45 and a Native 5 LW REX 45. When playing with them to figure out how to best operate a back lock, I noticed that if I casually push the lock in, the blade falls to about 90 degrees. Push a little more, if falls further. Push less, it doesn't fall as far.
To examine closer, I closed the blade a bit, and noted the position of the back lock. As I slowly rotate the blade more closed, the back lock depresses just a little more. It seemed clear to me that the curve of the tang is not circular with the pivot as the center. Not being a knife designer, I'd never considered this, but concluded that the increasing radius was sheer genius. After all, the user might not want to have the blade fall down upon his fingers. What better way to limit this than to increase the radius?
Are we talking about two different things? Did the guys in the shop pull a switcheroo?
Dear Rusty Iron:
The blades of all back locks have a flat or slightly concave section at the "bottom" of the ricasso, on the edge side of the blade. Traditionally, the forward portion of this flat section--where the shoulders of the bevels begin--is the "kick," which keeps the edge from contacting the lock bar and spring on the inside of the handle and dulling the edge. When the blade is closed, the spring pressure of the "lug" of the lock bar against this flat section acts as the "self-close" that keeps the blade closed.
As you open the blade, you work against the spring pressure and raise the front of the lock bar. Typically, when you get to about 45 degrees of the opening arc, the spring pressure disappears because the lug of the locking bar is now contacting the radius of the tang. At this point, the self-close action no longer snaps the blade closed and, in most cases, the protrusion of the front of the lock bar above the back of the handle is at its highest point.
If you open most back locks to this point and take careful note of the height of the front of the lock bar, you'll find that as you slowly continue to open the blade, the front of the lock bar will lower gradually, achieving its lowest point just before the lock engages. That's because the radius of the tang gradually decreases. The dimensional change isn't much, but it lightens the force of the opening arc as the blade opens.
If you do the same thing on a Native 5, you'll see that, once the front of the lock bar rises to its highest point, it stays there through most of the blade's opening arc and dips later. It's a subtle difference, but it means that the spring pressure applied to the radius of the tang is more constant throughout the blade's opening arc. As such, the Native 5 feels different when it is opened one handed than most other back locks. Open a Native 5 and an Endura side by side and you'll feel the difference.
The only reason I mention all this is that the OP described a "grinding" of the blade of his knife during its opening arc. I'm not sure what his experience is with other back locks, so I wanted to make sure he understood the difference in feel of the Native 5's consistent spring pressure.
I hope this helps.
Stay safe,
Mike
Spyderco : Resilience, Tenacious, Persistence, Manix 2 G10, Para 3 G10, Para 3 LW, Paramilitary 2, 