Zero Tolerance 350 stiff to open

P

pellidon

Joined
Nov 27, 2008
Messages
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I have tried lube and adjusting the pivot screw but the blade is hard to flip out. It takes a lot of finger pressure and after a few flips my finger is sore. I just got a newer one that has a relief milled in the lock bar. I have seen some old images of the knife without the relief. I am thinking it should go back to KAI for an upgrade. Am I correct?

350lock.jpg
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Did you take it apart and see if there's any gunk inside that could be slowing the blade?
 
The following is the musings of an engineering student. Grain of salt not included.

It might be the torsion bar. I've had two identical Speedsafe knives that had variable flipping pressures as well. I never figured it out, but my hypothesis is that something with the opening mechanism on one makes it tighter than the other. You might add some Vasoline or similar to the pocket that contains the torsion bar and then maybe switch torsion bars to see if you get the same effect.

Also, while you have them taken apart, maybe compare the lockbar deflection. Without the blade, they will move to their naturally bent position. Measure how much the lock distances itself from the vertical position and then you'll have a better idea if one is putting more pressure on the blade than the other. I don't expect it to make much of a difference though... In the end, every knife is different, even amongst the same models.
 
Are you saying the older style # 24xx is harder to open or the newer #64xx? And are you asking if you should send in the older style 24xx to get new locking side? My opinion is this:
There is nothing wrong with the older style at all. They just redesigned how they make the locking side. I have had a serial #0500 older style and a newer style 0360, 2 of them matching serials #0113. The only differences are that there is a detent in the newer 0350/0360's and there was not in the earlier styles, and the cutout you show above. The detent may be part of your problem. My early 0350 was easy to deploy, the newer 0360's are a touch harder to overcome with the detent. One of them is smooth the other is not. It happens with small variances here and there. If it's still too much after fiddling with it, give ZT's CS a call and see what can be done. They are very nice and easy to work with, and most importantly they want you to be happy with your knife.
 
They and I suspect the detent ball is pressing too hard against the hole. We worked through several tests to come to that.

We decided it's time to send it in.
 
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