Action differences 9xx Osbornes vs. 5xx Pardues

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Feb 16, 2010
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I've noticed that the 940, 943 Osbornes have a very free moving blade with practically no resistance on the tang between partially open and locked. Unlock the open knife and the blade free falls. Of course this can be diminished by tightening the pivot screw, but generally speaking, in their sweet spot, this is how the 940/943 seems to me.

In contrast, with my 551 Griptilian (just arrived today - woo hoo!), even with a loosened pivot screw, there is an ever-so-slight resistance on the tang in this knife than with the 9xx Osbornes.

Is this an anomaly with my 551 or characteristic of the 5xx Pardues?

I did notice in my 551 a very slight, fine line indentation on the lock engagement surface of the tang, which I could just barely feel against the axis lock when opening and closing the blade. So I removed the blade and washers and reduced the tang engagement edge just enough to remove the tiny indentation with 900 grit, then polished with 1500 grit, followed by polishing with Flitz on a buff pad driven by my Dremel. (Your basic "Fluff & Buff" as often done with gun parts). I also buffed the phosphor washers and tang flats & lock engagement edge with the 1500 grit, followed by Flitz on the Dremel-driven buff wheel. Then a little FP-10 lube at reassembly. Result is a SUPER smooth action! But still the blade doesn't seem quite capable of having the same total-free-fall looseness that is characteristic of the 9xx Osbornes.

Is this pretty much characteristic of these different designs? Just curious what your experience with this has been.

I love my super smooth 551 now, but just wondering why it doesn't have the same totally loose (shall we say, floppy?) action that my 943 has. There is a significant price difference between the knives, of course. Would that indicate that the pivot elements of the 9xx line are given more polishing effort than the economy priced Griptilian? Or is the primary differentiation in price due to S30V vs. 154CM and aluminum scales on the 940/943 vs. polymer on the 551?
 
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i have always heard that the 9xxs were incredibly smooth knives...i havent ever heard that about grips...
 
Look at the price differance.

Price difference noted.

I'm just trying to determine what the mechanical difference is that accounts for the action difference. Different degree of polishing the phosphor bronze washers? Different degree of polishing the liners? Different degree of polishing the tang? All of the above? Something else? Just trying to sort it out.
 
Price difference noted.

I'm just trying to determine what the mechanical difference is that accounts for the action difference. Different degree of polishing the phosphor bronze washers? Different degree of polishing the liners? Different degree of polishing the tang? All of the above? Something else? Just trying to sort it out.

If memory serves me well I believe the 940's are just more balanced.(i also believe they weigh less).
 
My 551 is exactly how you described, I can loosen the pivot to the point where there is a significant amount of blade play and the blade still doesn't free fall when the lock is pulled (in the horizontal position), but my 556 has no blade play and it will fall all the way closed when doing the same thing with it, I always thought that maybe it was just the 551 that i got, I have a 550 on its way though, hopefully it will work like my 556!
 
My 551 is exactly how you described, I can loosen the pivot to the point where there is a significant amount of blade play and the blade still doesn't free fall when the lock is pulled (in the horizontal position), but my 556 has no blade play and it will fall all the way closed when doing the same thing with it, I always thought that maybe it was just the 551 that i got, I have a 550 on its way though, hopefully it will work like my 556!

I'm not an expert in the knife but maybe the 551 has a bigger detent = no free fall when the knife is closed.
 
I'm not an expert in the knife but maybe the 551 has a bigger detent = no free fall when the knife is closed.

no, the knife is open and the blade falls shut when the lock is pulled, or if its closed the blade falls open when the lock is pulled.
 
I'm not an expert in the knife but maybe the 551 has a bigger detent = no free fall when the knife is closed.

No, I primarily meant free fall from open when the lock is pulled back. But my 943 drops free from either position when the lock is pulled back. 551 won't do it from either position.
 
Part of it is the weight of the blade on the 940. The 940 and 943 are my smoothest axis locks.
 
my 943 has an exceptionally smooth action, but so does my 552M2-600. I'd give the nod to the 943.
 
Part of it is the weight of the blade on the 940. The 940 and 943 are my smoothest axis locks.

The weight of the blade on the 551 easily exceeds the weight of the blades on the 940/943. By that account, all else being equal, the blade on the 551 should drop more readily.

One factor I noticed is that the spring on the axis lock on the 943 feels lighter than on the 551. But that wouldn't account for the ease with which the 943 blade drops when the lock is released.

Since the only contact the blade has with the knife after you pull the lock back is the phosphor bushings and the pivot hole shaft (whatever that's called?) I'm thinking it must be a difference in the finish/polish/size of the phosphor bronze bushings and/or liners and/or blade tangs where they all interact at the pivot.
 
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