CRKT's Failed

S

scanpro

Joined
Oct 3, 1998
Messages
30
I bought a CRKT M16-13 and decided to try a test of the liner lock. I opened the knife and wraped a towel around my hand and TAPPED the back of the blade on my bench. The lock failed and the blade closed! I didn't even hit it hard. So now I wonderd about my CRKT Apache Guess What, same thing happened! I guess I will not be buying anymore CRKT's. My new favorite knife is a Ken Onion Kershaw speed safe the black out version anyway.

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On any CRKT knife whose lock should release in the manner as described, it is covered under warranty and should be returned to the company for replacement.

Having only been involved with the Mirage project and not the other two discussed, I can only speak from personal experience with my own design. I would highly recommend you repeat the test with a Mirage and see what, or more correctly, what doesn't happen as far as the security of the lock. Try it and see.

Kit's 16's are fine knives, built with the same ruggedness as others in the line. I would expect your replacement knives to perform up to speed once this matter has been resolved.

Jim Hammond
 
Jim,

You must have run into this problem when fine-tuning the Mirages. In your experience, what is usually the cause of an unreliable liner lock in production knives? Is it the angle ground at blade tang? The length of channel that creates the split liner? Something else?

Joe
 
Wow, that's a first. I've handled five or six of CRKT's M-16 models and they were all rock solid. Like Mr. Hammond suggests, send them in to the warranty department or take them back to the store they came from.

Have you adjusted the pivot screws?

Jon

PS - CRKT's M16-14 and the Wharncliff Gray Ghost Mirage (model 7832) are the next two on my list!
smile.gif
 
To Scanpro:

If this lock failure happened to a no name brand, knock off type knive I would agree; Don't buy knives from these companies. You have however put down good money on knives from a reputable name brand company with good customer service. Simply contact CRKT direct or the dealer you purchased from and they should remedy the sitution. A liner lock is a precise hand fitted mechanism and therefore is one of the most difficult mechanisms to make on a production basis. As a result a poorly fitted liner lock can slip through in the final QC inspection. Although it is unfortunate the lock failed both knives, I would say this is a rare occurance. CRKT may be a competitor, however I consider their liner lock knives to be well engineered and well made. Before you blacklist CRKT products give them the opportunity to repair or replace the knives in question.


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Sincerely,
Outdoor Edge Cutlery Corp.

David Bloch,
President

Visit our new web site at http://www.outdooredge.com

 
Thank's for the replies I'm going to do as Mr Bloch suggests and contact CRKT.
Thanks again,
Jim
 
I have all 3 versions of the M16's and all 3 have passed with flying colors repeatedly with the spine pressure test and the AT Barr test.

I have full confidence in the series.....

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~Greg~


 
I recently bought a Mirage Gray Ghost.
Fully 5/16" of the handle end of the blade
is flat - unsharpened. I read a glowing
review of the Mirage in the May issue of
Tactical Knives which prompted my purchase.
The author described the extended cutting
area in the ricasso region of the blade
which other knife-makers do not utilize.
My vendor told me his other models of the
Mirage display the same flat blade surface.
I would really appreciate Mr. Hammond's
comments.

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shivey
 
My first M16-04 had this same problem.(horribly failed the spine whack test).
I returned it and BAM! new knife, no problemo!
NO more problem.
Work with'em.
They want you to be happy with their product.

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If it's stupid but works, then it isn't stupid.




[This message has been edited by misque (edited 08 September 1999).]
 
Shivey,

Thanks for sharing your question. The area of taper in a blade bevel from the ricasso (blade flat) to the area of the cutting edge is the plunge. The radius and taper of the plunge corresponds to the amount of arc found in the grind from its aft point on the ricasso until it turns into the spine of the grind. The greater the flow of the arc in the grind line, the longer and greater the radius is in the plunge.

The numbers for the Mirage state a blade length equal to the useable cutting edge; it does not say the entire visible blade's lower edge is sharpened. The undercut shape of the handle allows the blade to have a cutting edge farther back in regards to relative lengths than designs which have a ricasso area extending in front of a more upright handle face.

I did not want my grind lines hidden under the handle. However, in doing so, the grind/plunge combination could have been moved back to the point that more of the "flat" area you described could have been used as a sharpenable area of the bevels. Brought back far enough, the visible grind line would have been a straight line meeting the handle and the full lower flat of the blade profile back to the radius could be a sharp edge.

My design choice was to maintain visible exposure of the blade grind, have a flowing grind rather than a squared and upright grind in order to correspond better with the overall flow of the design, and allow for as much cutting edge as possible toward the rear. Holding these design parameters and limits, the unedged portion you described was the absolute minimum unused area that would remain given my design constraints. As I said, it could have been back more or eliminated altogether, but the compromise to achieve that went against my choices for the design. However, as pointed out, it is unusual to have a useable cutting length equal to the indicated blade length, and this is what this design combination produced and what is often mentioned about the knife.

That's an involved answer but I hope it helps somewhat in explaining the causes and effects found in the design.

Jim
 
Joe,

Regarding lockup issues, the locking surface interface is often the culprit for premature release. However, there are so many subtle variables leading up to this one factor that it's not usually just that simple a solution. Once there is a constant that works well with all the other facets of the lock's function (spring thickness, slot length, arm tension, bend angle, minimal reflex, lock angles, contact surface finishes and geometry, etc.) then where the rubber meets the road will usually be the point of failure--or not.

Jim
 
Thank you, Jim Hammond, for some real insight
into a world-famous knife-maker's
sophisticated thought. You've solved the
only problem I had with the Mirage. My
knife's lock-up is very secure, no blade
play. I carried the knife all of last week
and used it for everything from slicing
apples to feed to my goats to cutting
hornets' nests from the rafters in my barn
loft. At the end of the week, I simply
touched it to my old Case XX steel and it
returned to factory sharp. And when I
passed it around at my gun-club, it's
design fetched a number of compliments.
I'm printing out your reply in case any
of my fellow knife-nuts ask about that
flat spot on the blade. Again, thanks.
 
I had liner problems with the CRKT I purchased by mail. I discovered accidentaly that if I gripped the handel in an edge down manner the liner moved enough to release the blade. I felt I couldn't trust it and gave it away. As for contacting the maker I felt the replacement would pretty much be the same. I agree with george talmadge. I am a police officer and have had malfunctions with hand guns in the past and felt the same about them as I do the CRKT; I can not trust it to not fail even if allegidly repaired.
 
So much in designing is balance and compromise. The greater the access for a liner lock's spring for closure, the easier it is to unlock under a high stress or heavy load situation. This is not a malfunction but, unfortunately, the nature of the beast.

On my custom liner locks, the locking spring arm is recessed .020" back from the frame of the handle. Both handle profiles match on each side with no cutout notch for access to the spring for disengagement. When the handle is tightly gripped and torqued, the meat of the fingers is gripping the frame and not the spring arm, keeping the knife from unlocking. An internal tapered access arc is ground into the handle opposite the liner to allow greater access to the liner to unlock the knife when you're ready, but in no way compromises its safety during use. I've never worried about coming in first for speed of closure.

On the CRKT folder projects I have and am now working on, spring exposure has been kept to an absolute minimum for this very reason. However, on the production knives, this area remains a place of balance and compromise--maximum safety verses ease of closure.

Jim Hammond
 
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