Downsides to Pivot Bushings? Why don't all knives use them?

I've been using and collecting folders for almost 60 years and never even once did I feel that a folder needed a bushing or really even a ball bearing . Maybe I just don't appreciate the finer things ? :rolleyes:
 
I own a Sebenza, and i'm a massive hardware/mechanical nut and over-obsess on how all these things work, I have to say there is a drawback to the bushing. Of all the Sebenzas i've handled, there is some side to side play when the lock bar is not engaged - now hear me out. If you open your Sebenza fully, let it rest against the stop pin, then disengage the lock, chances are you will feel a tiny bit of side to side play. I've felt it on all 5 Sebenzas i've owned/used, and it is not the normal small tolerance clearance that the pivot needs to get through the hole, it is proper side to side play because the washers are a bit too thin and aren't under 100% contact tension. Now, is it the end of the world? no. But it does (to me) contradict the extreme tolerance claims, but to be fair the washers are hand fit by humans and there in lies the issue. The washers in a perfect fit should be thick enough to be under enough tension in order to be smooth and still have no play - even when the lock bar is not engaged. So my point is, the negative aspect is that if the person fitting the washers at the CRK factory that day over-polishes them a bit making them that tiny tiny bit too thin, you will have that play - and you can never dial it out without extra precise machining of all the bushings on the knife to then compress the scales down further to contact the washers. Again, not a major issue of any kind, the knife will work well for a lifetime, but still, it's one small strike. On the other hand, if a non-bushing pivot knife wears some of the washer down a tiny bit over 5 years, i can adjust the pivot and dial it out in 3 seconds without sending it away to some factory to wait a month to get it back.
 
Mick_1KRR said:
If you open your Sebenza fully, let it rest against the stop pin, then disengage the lock, chances are you will feel a tiny bit of side to side play.
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That makes sense. I understand 100% what you are saying, although I cannot detect any such play in my Sebenza. If it is there, it is unperceptable. That said, you have hit on a key disadvantage to the bushing: the action is much less adjustable. With a bushing pivot, everythinf is meant to fit together properly and in one way--if that doesn't meet your fancy, there is little you can do about it. Sure, you can polish your washers, but that must be done carefully and eventually you will run into problems if you continue to polish or remove too much material. It doesn't have the same ease and range of adjustment as a standard pivot does.
 
Erik Norseman said:
That makes sense. I understand 100% what you are saying, although I cannot detect any such play in my Sebenza. If it is there, it is unperceptable. That said, you have hit on a key disadvantage to the bushing: the action is much less adjustable. With a bushing pivot, everythinf is meant to fit together properly and in one way--if that doesn't meet your fancy, there is little you can do about it. Sure, you can polish your washers, but that must be done carefully and eventually you will run into problems if you continue to polish or remove too much material. It doesn't have the same ease and range of adjustment as a standard pivot does.
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I'm very glad to hear your sebenza hasn't got the play like i described, the person fitting your washers did a good job :thumbsup:
 
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