Difficulty "thumbing" blade open; I'm new to ZT

M

MaestroGustav

Joined
Dec 15, 2013
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23
Just got a new 620CF. It's equipped with the Emerson Wave and of course a thumb stud.

I have limited experience with blades in general; however, I've always been able to utilize the thumb stud to open a blade one-handed, left or right, with or without a small flip move.

This ZT has a real "bump" that holds it closed. I wore blisters in each thumb trying to get used to the geometry of this particular knife, and still have very limited success in getting it open.

For a newb, please tell me if there's something peculiar to ZTs, or this model, that make them harder to open this way-- or if it's just too new. Or if my technique is bad-- maybe there's a video somewhere? Thanks.
 
When opening with your thumb, make sure your index finger is not pressing on the lock bar. That will make it harder to open because that is right where the detent to keep it closed is.
 
I've not used the 0620, but thumb disks often take a slightly different technique to open effectively. try placing your thumb on the surface of the blade behind the disk, rather than on top of the disk itself. Then push out and up, the optimal angle varies on the knife. You can simply place your thumb behind the disk with your nail against the disk, stage a little pressure, and flick it open.

If all else fails and the detent doesn't break in, KAI should be able to fix it for you.
 
Yes, I should've said thumb DISC, not stud.

I've been trying to "follow" the arc of the opening. Pressing more "forward," in the direction toward the direction of the opened tip of the blade, is really helping.

The pivot is definitely not "rough," or stiff;very smooth. Just that first bump is harder than I'm used to.
 
How smoothly does the blade move once it is out of the detent? If you hold the lock bar away from the blade, does the blade swing easily? If not, the pivot is too tight. The pivot nut is 3/8". If you happen to have a Dremel tool, the included wrench is the same size.

If/when the pivot is adjusted correctly, open the blade 90°. Can you lightly shake the blade closed? If not, the lock bar may be applying too much pressure. To adjust that you would need to disassemble the knife, remove the lock bar over-travel/steel insert, and bend the lock bar back towards the handle a little bit.

If both of the above are fine, then the detent is just too strong. It may break in over time, but you could also send it to ZT and have them address it. My 0620CF is one of my smoothest opening knives, so what you are experiencing is not an intended attribute.
 
All of the advice above is good...As a general statement though, with most ZT's, give it a week to break in. After a couple hundred opens re-assess it. My experience is that there is some break-in involved with ZT's. You should have the thumb technique down by then too...

And don't lube it during break-in....
 
Draw an imaginary line from the pivot to the thumb stud, push the stud perpendicular to that line, this transfers the force most efficiently.
 
EChoil said:
All of the advice above is good...As a general statement though, with most ZT's, give it a week to break in. After a couple hundred opens re-assess it. My experience is that there is some break-in involved with ZT's. You should have the thumb technique down by then too...

And don't lube it during break-in....
Click to expand...

I agree my Zt blades usually take a little bit to break in, then they smooth out. My 0620 is getting smoother by the day.
 
+1 on the break in, and the geometry is a bit different on that one. You are probably used to putting more upward pressure on the stud causing it to "pop"....I found my 620 has more of an arc to travel in opening, and while it is very smooth, it doesn't jump open. I also found relaxing my hand went a long ways to making deployment more enjoyable if that makes any sense. Relaxing your hand muscles that have memory to other blades while operating the knife kind of lets the knife tell you how it moves.
 
Use the flipper...wait what?
Seriously, just open the knife in a smooth controlled motion. NO need to flick it open like you are trying to start a lawn mower.
 
I don't have a 0620 (yet), but with my CQC-5K and 6K, I did find the thumb discs had a different feel from thumb studs. It took a bit of getting used to. The detent on the 0620 might be a bit stronger on account of the heavier blade (versus the Kershaw models).

If you need to open it fast, just use the wave opening feature. ;)
 
i have the black version of this knife and i also have the same issue. the knife is completely impossible to open using my thumb due to the strength of the detent and also the framelock pushing against the blade. the knife waves open like a champ, but yeah manual opening is impossible, even after using lube and trying to open and close it a bunch of times to break it in.
 
I have an 0561. I've heard that they have various amounts of blade detent, mine seems to have a lot and I cannot open it with the thumb studs. I don't have any problem opening it with the flipper and when my finger pulls hard enough to overcome the detent, the blade opens pretty fast and has enough momentum to open all the way.
 
Update: I've mastered it with my left hand-- I'm a lefty, but probably more importantly, my fingers don't engage the frame lock.

Sadly, on my right hand due to so many tries, I've started to separate the flesh of my thumb from the fingernail. Hurts like hell! Rather be waterboarded. I'll tell you anything. And it's still not opening!

I'll have to give it a rest for a few days.

the wave requires slightly different angles than my original emerson, but it is working virtually 100 percent after just a couple dozen tries.
 
BetrayalSpree said:
Draw an imaginary line from the pivot to the thumb stud, push the stud perpendicular to that line, this transfers the force most efficiently.
Click to expand...

That angle doesn't work in my experience. I've been carrying the 0620CF daily for nearly two months now. This is the angle that works for me:

Image68.png
 
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