Can you really eliminate blade play?

S

samphire

Joined
Sep 10, 2005
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I would propose this:

Vertical play I think yes.It can be brought below the threshold of perception because the blade is in a locked position, thoroughly immobilised.

However, lateral play I believe can be minimised - any sloppiness can be taken out - but a small amount of play must remain with any moving part. Otherwise, almost by definition, it will no longer be a moving part.

I think the differences in knives that people say have some lateral play and those that haven't actually lie in their owners ability to perceive very small amounts of movement. Some of us are very acute sensors of this, others less so.

So, what do you think?
 
DaveH said:
pivot bushing would help minimize play of both kinds. :p :rolleyes: :rolleyes:
Click to expand...

Hmmm... sounds like a good idea, may want to mention that to someone.;)
 
I have some which I definitely can't tell, and I tend to notice every little detail. Still, I would bet it's just beyond my human abilities to notice. Most knives do have noticable left/right play.

There will always be some amount of flexibility in materials, even with hardened steel if we are talking about absolute reality on a molecular level. But I am not so sure a knife couldn't exist that were exactly the right size with the blade vs. the handle vs. the pivot pin. Couldn't two things be "touching" as we know it and have no pressure, or at least not enough pressure to prevent rotation?

What I think is impossible is making such a knife in any quantity. One knife could be perfect by chance, but there is always some level of error involved. Linerlocks might be able to do it because there is all of that wedging together involved. A liner lock with a loose pivot pin can still be solid up/down-wise when open, and if you look at the blade thickness in relation to the liner, it holds tight in all directions if designed well. The problem is there is a lot of leverage involved in the left-right play, and the liner is designed to bend (by necessity). It just wouldn't work out.

But again, I have seen things "perfect" beyond my ability to tell. Even simple lockbacks can be good. I have 2 Delicas that are "perfect," though with a lot of use they will wear out and get looser. But the point is, a cheaply designed pivot can be made closer to perfect than we can notice, so the fact that nothing is ever perfect on a molecular level is not an excuse for anything we CAN see.
 
samphire, good question(s) let's look at some examples. (let me say, these are just my opinions)

1- Cliff would say, there are many different styles of locks and therefore many different characteristics of each design.
2- For clairity, two types of blade play: horizonal (side to side) and lateral (up and down).
3- with liner locks, (as with any knife with an adjustable pivot) horizonal play can be minimized with simply tightening the pivot screw. Lateral play can be adjusted with the strength of the lock bar. The more preload on the bar, the more resistance for lateral blade play. (a good example: a CRKT with the Lawks system. Engage the Lawks and push the lock bar back to the Lawks. The blade will have some lateral play)
4- Spyderco's compression lock would fall under the same as liner locks
5- Axis locks, horizonal play agian with the pivot screw and lateral play will (should) be automaticly adjusted with the force of the omega springs against the lock bar.
6- lockbacks, again horizonal play with pivot screw and lateral play will be mostly non-adjustable with the design of said lock. They often have a slight bit of play.

These are the big four.

To further answer your questions. 1-I agree that you have to have some of both types of play in order for the lock to work. Although this would lean more to horizonal play than lateral play.
2- To each his/her own, your opinion of acceptable blade play will vary from the next.
3- My own brother doesn't care if the blade moves 1/4". (exaggeration) This amount of blade play would send me straight into convulsions!

I'm not sure I've helped, but here it is. :D Of all my knives, my Benchmades come as close to "zero" for me.
But Spyderco is in my pocket(s) 85-90 % of the time.
 
Sebenzas have no lateral blade play. I wish my BM's would do that, and still allow me to flick the blade open. If I tighten the pivot screw to stop lateral play, they become very difficult to open. Sebenzas have the design down pat. I guess it's the pivot bushing as mentioned above.

Mike
 
Yeah… my Sebenza is the only folder I have where I can’t perceive any side-to-side play. I think that’s probably due to a combination of the several factors: the pivot bushing, large diameter washers, and an almost perfect fit.
 
cerulean said:
Yeah… my Sebenza is the only folder I have where I can’t perceive any side-to-side play. I think that’s probably due to a combination of the several factors: the pivot bushing, large diameter washers, and an almost perfect fit.
Click to expand...
Does it have any vertical play?
 
ElectricZombie said:
Does it have any vertical play?
Click to expand...

Nope! The lock-up is completely rock solid. :thumbup:

The only problem I can envision with a Sebenza is that the washers may wear down after a lot of use, causing some blade wobble that can’t be eliminated by tightening the pivot screw. IIRC, Darrel Ralph posted somewhere once to explain that that’s why he doesn’t like to use pivot bushings in his knives. (Not sure it was him though, as I can’t search for the thread.)

You don’t see many complaints about that in the CRK forum, and it would probably take several years for the washers to wear to the point where you would notice any play, so I don’t know if that’s really an issue. Also, I guess it would be easy enough just to replace the washers if the blade ever got too loose.
 
The bushing solution sounds like it works well. I was thinking an oversize pivot, a la Strider knives, might be a good route also.

Do Strider owners find this to be the case?
 
IMO, owning one and handling 3 other Strider knives, the larger pivot does NOT help with blade play. I think the only thing that matter is accuracy and precision in construction.
 
DaveH has it right. The quality of the construction is what counts. I have all different folding knives with locks as varied. It is the construction of the individual knife (as well as overall design) that determines bladeplay. I have paid good money for knives that were a total disappointment and ended up selling them. Spyderco's stay with me time and again.
 
cerulean said:
Also, I guess it would be easy enough just to replace the washers if the blade ever got too loose.
Click to expand...

Sanding down the pivot bushing might also work, but not as good an option since you would not be able to replace the washers with new ones and have it fit correctly.
 
Yeah, I also have two sebenzas and can detect no play from any position, lateral or sidewise. You guys are correct in saying a well executed design will virtually eliminate blade play.
 
cerulean said:
Nope! The lock-up is completely rock solid. :thumbup:
Click to expand...
Excellent. I've been thinking about buying a Sebenza because I'm tired of having knives with blade play.
 
I have several knives in which I can detect no blade-play at all:

Benchmade 880 Darkstar (liner-lock)
Browning Ice Storm (liner-lock)
Spyderco Toad (liner-lock)
Gerber GamePro (frame-lock)
Kershaw Ken Onion Leek (frame-lock)
Buck 112 (lockback)

The only conclusion I can make is that some knives have tighter tolerances than other knives, and a knife with no blade-play can be produced without bushings.

The real question is: does a very slight amount of blade-play matter?
My old Schrade LB7 served me very well for many years, as did my Spyderco Delica, and they both have blade-play.
It did'nt seem to affect their performance in the least.

Allen.
 
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