Gerber EZ-Out

I hate to bring this old subject back up but I have an update. I had my dad test his ez-out by wacking the back of the blade on the carpet using a 2 finger hold on the base of the handle. He took the knife back yesterday.

I also went to my local knife store and had them try on the one on display(ats-ez-out) and it failed. This failure rate cannot be a faulty batch since some are much older. I think this may be a design flaw. Hopefullly Gerber reads these posts. I'm even thinking of sendimg mine to gerber, but this is the only gerber folder I like. Maybe I'll start using it as a throwing knife.
 
FOOD FOR THOUGHT
I don't have one, but looked on the net. Seems to me that inertia is taking over. When you do a test like you have been talking about, sounds like either Gerber didn't anticipate the need for a stronger spring, or the test may be out of line. Seems to me that when the lock is properly engaged, the friction between the blade and the lock, in conjunction with the spring, is enough to keep the blade in battery. Was the test performed while a closing load was on the knife? It seems that the timing of the impact of the blade on the surface and the time inertia takes over, would have a lot to do with the closing of the knife. When would you have an occasion, in a real world situation, to put a negative pressure on a knife in such a manner as to allow the inertia of the lock to allow the the knife to close. Dunno, just thought I'd ask.
 
You might be right, since as I stated from the beginning, I cannot force mine, but when I wack the back edge as is suggested it fails. My other lockbacks don't. Does anybody has a better way of testing this type of lock without destroying the knife?
 
Zaine - appreciate the "real world" point of view. V - appreciate the post on the heat. Zaine - appreciate the response. The use of "reason" and "understanding by the members is part of what makes this such a pleasurable site. Thought to share some opinion.

1. The prime culprit of lock defeat in an otherwise "safe" knife (or permanent lock-up in a linerlock is debris collected in the mechanism. If you don't clean your teeth regularly, problems result. The same would be true of most moving parts. Keeping a knife clean should be rule #1.
2. The first time a lock defeats, it usually creates permanent damage to the tang lock interface. This makes it more susceptable to subsequent defeats. Similar to a heart attack. If this first defeat was the result of debris that you didn't clean out, the fault lies not with the factory. Tapping the back of the knife firmly on a book (so you don't damage the table) is a reasonable test. Be sure to hold the handle in such a manner, that if the lock defeats, it won't cut your hand.
3. 75% of lock strength is in the geometry of the lock interface. Even with good design & engineering, tolerances become important. The closer the tolerance, the higher the price. Something about "getting what you pay for" might fit here. If you are buying a "used" knife, perhaps lock defeat was the reason it was sold by the previous owner?
4. The problem of lock defeat enters the
"real" world on the "up" stroke preceding or following the "down/cut" stoke. eg: cutting off a piece of something while holding it on the edge of a table. Then lifting the knife to make a second cut, hitting the tip of the knife on the edge of the table. If the lock defeats on something as sharp as a Spyderco, the cut could be very inconvenient. Lifting the weight of your arm and the knife could generate an upward force of 10 or 15 lbs. Hitting the tip of a 4" knife puts the distance to the pivot pin at about 4.5" X 15 lbs + 67.5 "inch/lbs" of force. Reasonably (in my opinion) a 4" blade folding knife designed and built for general use should have a minimum of 150 "inch/lbs" of lock strength. Less blade length would require less lock strength. A knife that is designed to be used in Martial Bladecraft, with the back of the blade being used for grabbing or passing an adult arm and the resulting forces or two arms applied...deserves some real thought. Some thoughts to share. The more "we" (humankind) learn, the more control "we" can have over our lives.
sal
 
Mitchell --

You asked about the practicality of "negative pressure" (pressure against the spine towards the edge) on a blade. Sal gave a good answer, you cut down and then lift up for the next stroke. If you're carrying for defense, the thought to using the blade spine to pass, or of the blade spine getting hit by something, are reasonable things to worry about. Lastly, I recently heard from a guy who was cutting something and his knife got wedged into the material. He starting torquing and rocking the knife out. During this, pressure against the spine (plus torque) defeated the liner lock -- 10 stitches.

For a "gentleman's knife", or for just opening boxes, this kind of lock test isn't as important. But I think many of us use our knives harder than that, or at least can fathom the possibility of using our knives harder, and so demand better locks.

Joe
jat@cup.hp.com
 
Sal, good points, but I have some comments.

Starting with your point #3, where you say liner lock stability is a matter of tight tolerances, and you end up getting what you pay for. This is maybe my biggest disagreement. In my experience, the good factory manufacturers -- e.g., Spyderco, Benchmade -- are putting out better liner locks than even the best "tactical" folder makers. After being to many shows and handling a lot of liner locks, I really believe this to be true, and I'm not the only one who has noticed it. It's also why several of us -- a group that includes some people very experienced with testing knives -- rarely or never buy liner locks anymore.

Maybe that's why I also disagree with your point #1, about debris in the mechanism being the most common cause of liner lock failure. Maybe it's the most common cause of failure in Spyderco's liner locks, but it's definitely not the most common cause overall. The most common causes are mistakes by the maker. Often, the liner sticks up too high (or is too accessible through the cutout), so when you hold the knife firmly, the flesh of your hand sinks in around the lock and unlocks it slightly. The lock will simply disengage as soon as you put some pressure on the spine.

Also, problems in the liner/tang junction are still *way* too common -- when spine pressure is applied, the lock simply slips off. This problem can often be seen in the absence of any dirt. Sometimes, a tiny bit of dirt can cause this failure. But a knife with a clip on it is meant to be carried in a pocket. If it gets filthy, I agree that all bets are off. But if the knifemaker knows the knife is going to be carried in a pocket, he should make sure his lock can handle being put in a pocket for a couple hours. This isn't spun glass, this is a hard-use folder, and it is not unreasonable for me to expect a little robustness in the lock.

The real biggest problem in liner locks is that too many makers don't seem to bother testing their locks. If I'm going to buy a $400 "tactical" or "hard use" folder, I expect that the lock will hold up even if I hold the knife firmly (should be expected!), or if there's some pressure on the blade spine, or if I carry the knife for a few hours in a reasonably-clean pocket.

Joe
jat@cup.hp.com
 
Joe - good points. #1 was in reference to lockbacks. debris prventing the lock from completely engaging. Occasionally preventing a linerlock from disengaging. #3 was also in reference to lockbacks. Although linerlocks are critical in tolerance, the lockback interface between the back part of the lock-lever and the adjacent face is critical. The Gerber EZ out which was the topic of this thread is a lock back.

Spyderco lockbacks are precision ground at this interface. However the cost of a Spyderco Lockback is probably twice as much as the fine blanked and tumbled method used in high volume houses. Take some knives apart, get a 10-12 power lupe and study this junction. closer toloerances in the pins (both pivot and locking bar) also makes for a stronger lock. Sorry for the confusion.
sal
 
As a child growing up in Japan, my favorite past time was to whittle. I would make samurai swords with my pocket knife out of newly trimmed branches of my father's peach tree. It was quite a chore to whittle green saplings as they would grab the blade mercilessly and hold it in their sticky death grip. That was when I learned that the lock of a folder can be defeated at the time either when I tried to extract the blade or, more frequently, when I forced the cut with such force that the blade would snap back.

My word of caution: be careful with your ez-out when you are compelled to whittle out samurai swords!!

Slowjocrow
 
Sal, I saw a few references to liner locks sprinkled about, and confused the references.

Anyway, with regard to lockbacks, it turns out all 3 of my most-carried knives are lockbacks. I carry the Calypso Jr. as a gentleman's scalpel, an endura as my everyday beater, and a CS Vaquero Grande as my big night-carry knife (legal in CA, doncha know!).

I would love the EZ-Out if the lock was made better. Other than that, they've done a good job on the design.

Joe
jat@cup.hp.com
 
Interesting thread. I have used the E-Z out for about two years now - the same one. It has been nothing but reliable and has really had some abuse. Yes, if I try hard and whack it on something hard witht he back of the tip then the lock will fail - but I paid £23 (uk) for it and am happy with what I got for the money.

A question - It was mentioned here that the knife uses 425? Mine says "Gerber 450" on the riccasso. Is this usual?

Yoda

------------------
"No, try not. Do, or do not - there is no try"..... Yoda
 
Yoda... The steel of the Gerber E-Z-OUT is 425 stainless steel. The number engraved on many Gerber's and Buck's is not the blade material, but in fact the model number. Most Buck and Gerber's use 425 steel now, so unless it's clearly stated to be different, you can assume that it is 425.
As for my EZ-OUT... I still carry it. I like the design, even though the lock could be a little better. I think a major contributor to the locking problem is the material. 425 steel for some odd reason always has rounded edges. Looking at the little locking bar, I notice it too is slightly rounded at the corners, as is the the groove in the tang of the blade...
I had hope for the ats-34 version, hoping that there would be no rounded corners to fail the locking mechanism, but the people with ats-34 ones experienced the same problem. How disheartening.

 
I would would just like to add,that I have an gerber 450 ez-out, 1995 first production run. And I paid $45 for it being young and ignorant. But I've never had any problems w/it except w/maintaining sharpness. I've used it for many unintended purposes.
Now I'm no expert on knifes but trying to learn. Anyway mine has been perfect and I think it was worth the extra $15-20.
HHurdler_400@yahoo.com
 
I own a Gerber model #450 and have had no problem out of it. A friend and I just tried the test and it did not fail. My knife is my everyday carrier and is mostly used for opening boxes. My knife is well taken care of , it is cleaned and sharpened at least once a week. It has been a very good knife for me. I wish everyone else had as good of luck with their knife as I have with mine.

Jeffro Dog
 
I carry my EZ-Out 450 every day and I've never had any problem with it. It opens smooth and locks VERY solid. For me it's just perfect all_day_carry knife.
BTW, should I oil my EZ or not? I know there are some washers between blade and scales, but I have no idea what they are made of - maybe you know?
 
I got my "First Production Run--1995" in 1995 for $24 from the Cutlery Shoppe here in Boise. Not a bad knife for the price. No problem with the lock. Lately, I bought one for my son from the military PX for $21! BTW, the early blades, and those not made of ATS-34 were made of 440A, not 425.

Bruce Woodbury
 
Haha! Theres the other Yoda.. the one that kept me from joining without the numbers on the end of my name... wonder why he dont stop by no more.....
 
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