Seb 31 - Different type of blade play and how to fix it.

[Kryme]

You'll find this behavior on almost every folder out there. I have about a dozen around me, Microtechs, CRKs, Spydercos, Hinderers, ProTechs, ZTs... all have it. It's nothing unusual, if there's zero spacing between the pivot and blade it would be easy for it to get stuck when the pivot gets gunked up, lubricant dries up, or even heat. It's just how folders be, unless the pivot itself is a bearing I don't see how you could pull off zero play, and even bearings have play built into them for the aforementioned reasons.

 

[J. Doyle]

Sounds like pivot play: the hole in the blade is a tiny bit too wide relative to the pivot (bushing in this case). Doesn't do any harm and can't be fixed, short of using a slightly wider bushing, or replacing the blade with one that has a smaller hole. My 31 has this, too, but I don't notice in normal use. Can only be felt by pushing/pulling on the blade while it's in between open and closed.

It absolutely can be fixed. It just takes skill and know-how.

But it isn't worth fixing because it isn't a problem

 

[Blade Lab]

You'll find this behavior on almost every folder out there. I have about a dozen around me, Microtechs, CRKs, Spydercos, Hinderers, ProTechs, ZTs... all have it. It's nothing unusual, if there's zero spacing between the pivot and blade it would be easy for it to get stuck when the pivot gets gunked up, lubricant dries up, or even heat. It's just how folders be, unless the pivot itself is a bearing I don't see how you could pull off zero play, and even bearings have play built into them for the aforementioned reasons.

I agree it's common, but it definitely isn't universal. Oz, Koenig, AB, CKF, Shiro, SPK... virtually undetectable pivot play. It's a precision thing.

 

[TheOne45]

I cannot imagine how extra expensive folders would be if every pivot needed to hand selected and fitted to avoid lash and still operate as a pivot with just the right action.

For the price they ask those pivots and blade holes could be made in close tolerances so no need to ''hand select'' them. It's not a ''rocket fly to the moon'' science to make a guide bushing and guide bolt in close tolerances these days. I'm talking about hole/shaft tolerance in H7/g6 range which are common tolerances and easily achieved. You would feet no play with such tolerances and the knife would open and close without a problem.
But it's a lot cheaper to just say some space is ''normal and needed'' for the operation of the knife. This doesn't lower the price of those knives...as I wrote...make it cheaper, charge the same and make more profit.
Just to add; this is my personal opinion about premium price and what you should get for such price. Like my Audi would have some play in steering wheel and someone would do his best to convince me this is normal for operation. After all; it's not one of those Polski Fiat 126. They got a play (not just in steering wheel) after a month of driving.

By the way; anyone here own a Rockstead folder. I wonder how much play those knives have.

 

[SharpBits]

I'll leave this to people who know more about precision assembly than I do. However, some of the examples listed above are knives that cost significantly more than a Sebenza, which I guess partially proves my point. Except for the AB PJ, which seems like an excellent value in this group of knives.

 

[Bill DeShivs]

It doesn't matter if the blade falls out, lands on the floor and jumps back into the knife in the open position- as long as it's secure when open and closed.
There are different methods for designing knives. They don't all work like you are imagining.