A quick question on PM2 Bushing System

ijha

ijha

Joined
Jun 12, 2009
Messages
81
Dear Spyderco users, I have a quick question about the bushing system in PM2.

Today, my PM2 arrived and had chance to play around with it. I tightened the pivot and found out that the blade doesn't move at all. I mean, it is not like Sebenza 21 which also has the same bushing system.

As far as I know, the beauty of the bushing system is that the blade keeps a constant tension regardless of the tightness of the pivot. Am I wrong?

Thank you for your comments in advance.

Best,
 
ijha said:
As far as I know, the beauty of the bushing system is that the blade keeps a constant tension regardless of the tightness of the pivot. Am I wrong?
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I believe this only holds true if the pivot is machined to very precise tolerances — something Chris Reeve achieves, but which Spyderco does not (and which is reflected in the price).
 
Blade and Flame said:
I believe this only holds true if the pivot is machined to very precise tolerances — something Chris Reeve achieves, but which Spyderco does not (and which is reflected in the price).
Click to expand...

Thanks a lot for the quick reply. if so, what.s the reason Spyderco decided to use the bushing system on this specific model?
 
It is more of a "barrel pivot" than a bushing. It allows you to adjust the tension on either side, which many find necessary to obtain the "sweet spot".
 
Officer's Match said:
It is more of a "barrel pivot" than a bushing. It allows you to adjust the tension on either side, which many find necessary to obtain the "sweet spot".
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That makes sense. Thanks a lot. I should have gone through all the threads regarding this topic but I couldn't help asking out of curiosity. Thanks again. Now, it's time to find out what the barrel pivot is. ^^
 
But wait!

I just ran into a youtube video that shows the PM2 disassembling. The bushing of the PM2 just looks like the bushing in my sebenza. Now I'm confused again :o
 
ijha said:
But wait!

I just ran into a youtube video that shows the PM2 disassembling. The bushing of the PM2 just looks like the bushing in my sebenza. Now I'm confused again :o
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The CRK bushing is a free floating piece, so a normal pivot pin fits perfectly in the bushing which fits perfectly in the hole in the tang of the blade. The PM2's stepped pivot is one piece, pivot and 'bushing', so its not really a bushing at all but a stepped pivot.
 
kniferbro said:
The CRK bushing is a free floating piece, so a normal pivot pin fits perfectly in the bushing which fits perfectly in the hole in the tang of the blade. The PM2's stepped pivot is one piece, pivot and 'bushing', so its not really a bushing at all but a stepped pivot.
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Got it. hmmm I'm slightly disappointed. The main reason that I bought this is the bushing system. But other than that, I can say I am very satisfied.
 
ijha said:
Got it. hmmm I'm slightly disappointed. The main reason that I bought this is the bushing system. But other than that, I can say I am very satisfied.
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It basically achieves the same effect, so I wouldn't be too disappointed. It's just CRK tolerances are tighter than Spyderco.
 
I wouldn't count it out just yet. When I got my pm2 it was stiff, I loosened it and had blade play.. Then I used it and after a whole bunch of openings and closings, it has a spot where there is no play and a VERY smooth play. as smooth as any of the crk's I have handled. Maybe take some time to break it in. hopefully you will enjoy it
 
Thanks for the cheering comments. One more quick question. Do you think I need to loc-tite the pivot? I know it came in the loc-tited condition. Since I twisted pivot by adjunction tightness, it now got loose I guess. Do I need to loc-tite again?
 
ijha said:
Got it. hmmm I'm slightly disappointed. The main reason that I bought this is the bushing system. But other than that, I can say I am very satisfied.
Click to expand...

It's really a stepped pivot, not at all a bushing system in the most precise meaning of the term. In the end, it's all a question of the tolerances, and (I mean this in a friendly way) it's unrealistic to expect a $100 knife to achieve the same tolerances as a $400 knife.
 
I would loc tite it. I had a screw fall out of the handle scales (it had some loc tite from the factory and I thought it would be fine). Just a very small amount of blue should do it.

Like others have said, you just need to mess with it. There is a sweet spot, it's not like the Sebenza's bushing. You may have to loosen it a little on both sides, but make small adjustments, check blade play at full open, check to see if the scales have any play, and find the spot where it swings free but there is very little blade play.

I actually went to buy a Sebenza last weekend. I drove 100 miles, checked out the Sebenza; then I saw a S35VN PM2, and it had better action than the Sebenza orany of my other Spydercos. I ended up coming home with it, and the Sebenza stayed at the knife shop. The PM2 really is awesome when it's optimized, but it will make you hate it if it's too tight or too loose.
 
ijha said:
Dear Spyderco users, I have a quick question about the bushing system in PM2.

Today, my PM2 arrived and had chance to play around with it. I tightened the pivot and found out that the blade doesn't move at all. I mean, it is not like Sebenza 21 which also has the same bushing system.

As far as I know, the beauty of the bushing system is that the blade keeps a constant tension regardless of the tightness of the pivot. Am I wrong?

Thank you for your comments in advance.

Best,
Click to expand...

Let me say this, of all the PM2 models I own (over 20 currently, as it is one of the knives I collect). The pivot screws on every one of them is tightened down as much as can be and the blade moves freely. There is also no slop, no play, no lock rock, nothing. Blades are centered on all of them, etc. I know there are some pieces out there that are not this way, so it seems the tolerances vary from one to the other. For the 2 dozen examples i own, there is no "sweet spot" other than tightened all the way down. Backing up either pivot screw results in wiggle room.

CQI is constant quality improvement. Small changes made to models over time in order to improve the function of a knife in an area that was once found lacking to some degree. This is also why in some cases, a reblading of a common knife is not really feasible. It's sort of like a give and take.
 
I wish I could say the same. I've actually yet to have a PM2 that could be tightened down and still swing freely upon lock release.
 
Officer's Match said:
I wish I could say the same. I've actually yet to have a PM2 that could be tightened down and still swing freely upon lock release.
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I've probably got ~20 of these and fortunately none have lateral play on the pivot when fully tightened, all of them lock up tight if the pivot screws are tightened. It's not a big deal.
 
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