Zero Tolerance 0550 differences

A

av8or2

Joined
Apr 12, 2012
Messages
55
This post should not be viewed as complaining only observations...I am very pleased with the quality of KAI/ZT products.

Just acquired my second ZT 0550 and noticed some manufacturing differences.

1. The lock bar slot is much wider on the SN 2539 (on left in photo below) than that on the SN 2053 (on right)...refer to photo. SN 2053 looks like might have been wire EDMed or lasered vs. milled on the SN2539.

2. Next the lock-up on the SN2539 is much later and only fully seats when pressure is applied...lock-bar actually "floats" until side pressure is applied to "seat" it against back of blade. Will contact KAI/ZT Customer Service to discuss next steps. Refter to second photo (SN2539 on left, SN2053 on right).

3. One other difference noted is the depth of the pivot bolt on the SN 2053 it is seated much deeper in handle than that of SN 2539.


IMG_1849.jpg


IMG_1850.jpg
 
my lock bar gap on my SN 0193 is wide like the one on the left in the first pic. as far as the lock up on mine its like a F%$#@ng tank no floating moving or anything of the sort, and feels as smooth as my 0560-0561. detent is awesome. and my pivot screw seats flush..kinda weird that they have lil in consistencies, but I'm happy, my is buttery smooth all around. just give them some time to break in.
 
I bet if u call zero tolerance's warranty department and tell them about it they would say send it in, they may replace the titanam side
 
Yea, my other 0550 (knife on right above and my 0560) lock up like bank vaults. Imagine they will want me to send it in...only problem is that I'm going to Alaska to present it to a USCG airman next week. Will see what they say.
Still love these knives and know the outcome will be good...KAI/ZT customer service rocks.
 
Last edited:
My 550's serial number is in the mid-0850s. It resembles your serial number 2053.

I've seen pics of serial numbers less than mine, in the 250-310 range, that resemble the wider cut of your 2539.

So, it appears that there's some sort of manufacturing change that switches, back and forth, between the two types, more than once, over the production run.

Hopefully, someone can tell us why.
 
Last edited:
i have the 0551 and it had the wider cut out. it had a sticky lock and developed severe lock rock so i sent it in for repair. it came back with the thinner cut out, it locks up like a bank vault and is super smooth to disengage. it honestly feels like a completely different knife. they have obviously made some tweaks to the design and im glad they did, im very impressed with the quality and customer service!
 
Jimmer5 answered it in one of the 560 threads (assuming the history is the same between them). Searching will confirm it, but from memory, they started off with milling it, then switched to laser but had trouble with the slag at the end of the cut, and have now switched back to milling it.
 
Still, what's the reason for the change between thin and thick cuts? And why switch back and forth?

Where one might be seen as an improvement in the design, why change back, and then change again?
 
If I can recall correctly, the changes in the way the lock is cut is laser ve waterjet. Also, the numbers on the blade are not stamped in order by which they are made. There are further changes wheree the lockbar cutout is now on the outside. Attempting to trqdk changes based on serila numbers would lead one to inaccurate theories.
 
UPDATE:
Just talked with KAI/ZT warranty department ... 0550 will be all better soon ... exactly like you would expect ... incredible customer service. Thanks KAI/ZT !!!
 
I have 550's two as well. (I'd have more if I could... just waiting on the latest version) One with the wider cutout and one with the narrow. Just sent the one with the narrow cutout to KAI for repair with the narrow cutout in as it had a very late lockup, a detent so strong you couldn't open it with one hand, and some lock rock. The one with the wider cutout is exactly the opposite! very early lockup (25-30%), super smooth and like a tank!

Here's a link where I asked a few months ago about the differences in the cutouts with Thomas' response: http://www.bladeforums.com/forums/showthread.php/958866-ZT-0550-Lockbar-Cutout-Question
 
FYI
Just like everyone has stated in the past ... KAI/ZT Customer service is fantastic ... got my 0550 back and it works just perfect ... THANKS KAI/ZT !!
 
You must log in or register to reply here.
Back
Top