Benchmade Lock Rock

steve itm

steve itm

Joined
Mar 9, 2014
Messages
236
benchmade 755 mpr.jpgI purchased a Benchmade 755 mpr back in 02/14/14 its only cut paper but yet i noticed it has lock rock..!!!! I've tried to adjust the stop pin which works until i tap the spine on the palm of my hand, and then it has it again...I have to admit im disappointed to say the least..This is my 1st benchmade and wasn't expecting to have this kind of problem. I emailed benchmade and asked what my options are ?? but haven't received an answer yet...Its just one of those deals that even if i send the knife to them im not sure if i'll ever trust it...Would benchmade replace a knife for a different model even if i didnt buy it directly from them...IF so what would be a good alternative...
 
Honestly If you like the knife I would just let them either fix it or replace it with this model. It doesnt matter what benchmade you get. You could run into a problem with any knife from any manufacturer.
 
I tried tightening the pivot and it will stop the lock rock but all's i have to do it tap it on the palm of my hand and its back....
 
It may be that the knife has yet to sufficiently break in. I've honestly never heard of tapping the spine being the cause or determining factor for lock rock. I'm not doubting you per se, but a lot of people don't really know what lock rock really is or how to properly identify it vs normal production model tolerances necessary for the moving parts to function.
Go to the Benchmade website, print up their warranty form. Fill it out, package the knife include the form and a letter from you to them explaining in great detail what the problem is and how you arrived at your conclusion. The more detail the better. Never assume anyone understand exactly what you are referring to, at least not when it comes to warranty repair. Remember, what appears out of the norm for you on one knife, may just be common place to them after handling hundreds and thousands in any given week.
 
steve itm said:
I tried tightening the pivot and it will stop the lock rock but all's i have to do it tap it on the palm of my hand and its back....
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Is it loosening after you tighten it? If so you always use blue loctite or permatex to keep the pivot from loosening.
 
I assumed lock rock was when the blade will move back and forth when in the locked position ???? I didnt cross my mind it would have anything to do with it breaking in...it doesn't loosen up after i tighten it ....I was a little worry it maybe because its a titanium lock with a M390 blade steel...when i tap the spine of the knife on the palm of my hand you can see the lock backing off ??? I can push it back in and the lock rock go's away but that just doesnt seem right to me...I tried my other 15 frame locks and none of them have the same problem...I email benchmade so im sure they will be in touch at some point
 
I had the same problem with my 755. I sent it back. They fixed it. It developed lock rock again so I sent it back and they fixed it again. I then sold it. My observations were that their lock geometry is the cause. It is very similar to the old Strider geometry. It is a secure lock, but the lock rock is inevitable. Its a shame because it is a cool knife.
 
2014-04-20_20-52-01_939.jpg I tried to take a picture...It looks like its engaging the blade in one small spot...johnnytoxin I think your right....that sucks !!!
 
The area of lock up looks great. It seems that the lock face on the blade is radiused which often results in lock slip later on.
 
One thing I always try with very mild rock is to adjust the lock bar over a little so it will lockup a little later (bend the arm). It has equal times of success versus causing more problem, and it can be easily undone, so the mechanically inclined could try it at little risk.
 
2014-04-22_07-59-51_830.jpg2014-04-20_20-52-01_939.jpgIt looks to me that it is a radius style cut on the lock face....and the lock bar on the 755 is notched...so i can't really adjust the lock bar over..johnnytoxin who replied to this thread said he sent his back to benchmade twice and finally just sold it...so im assuming they are probably just playing with the stop pin...still waiting for them to contact me.
 
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tokerblue said:
Just s FYI. The entire lockface is not supposed to touch the blade ramp.

http://emersonknives.com/blog/emerson-knife-anatomy/
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This is Ernest Emersons OPINION. There are many knife makers that do not abide by this"rule". Chris Reeve, Rick Hinderer, Spyderco, Kershaw/ZT, Jim Allen(3 Sisters Forge) etc.....I'm sure there are many more. The knives that use Emersons geometry always have more lock rock problems than those that have more of the lock surfaces in contact with each other. That's been my experience anyway.
 
Although the thread is to fix our buddys BM.

I dont care for Emersons at all. All I can say that every Sebenza that I have handled not owned ( a few dozen) , spyderco military, ZT 0550/0561 and strider have the same lock up. The sebenza may appear to make full contact but when you take every knife apart and look at the lock bar it is the front of the lock bar that wears and engages. Some contact more than others. If it were full contact it would have issues as soon as the stop pin begins to wear in even a little bit.
This is simply what I have noticed.


johnnytoxin said:
This is Ernest Emersons OPINION. There are many knife makers that do not abide by this"rule". Chris Reeve, Rick Hinderer, Spyderco, Kershaw/ZT, Jim Allen(3 Sisters Forge) etc.....I'm sure there are many more. The knives that use Emersons geometry always have more lock rock problems than those that have more of the lock surfaces in contact with each other. That's been my experience anyway.
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johnnytoxin said:
This is Ernest Emersons OPINION. There are many knife makers that do not abide by this"rule". Chris Reeve, Rick Hinderer, Spyderco, Kershaw/ZT, Jim Allen(3 Sisters Forge) etc.....I'm sure there are many more. The knives that use Emersons geometry always have more lock rock problems than those that have more of the lock surfaces in contact with each other. That's been my experience anyway.
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I've taken apart my Kershaw and ZT framelocks and they both use similar geometries. The lockface is not supposed to have full contact with the blade tang.
 
I need to clarify. I know no lock face makes FULL contact with the tang. Some make more contact than others, and its these that seem to have less problems. Also if you follow the Emerson link you will read the part where he says there must be an angle between the blade lock ramp and the face of the liner lock. Correct me if I'm wrong but I owned a sebenza for quite a while and it did not have this angle that Emerson speaks of. Neither does my TSF Beast. All knife makers have things they do slightly different than others. I like Emerson, but I won't take his way of doing things as the only way.
 
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I appreciate all the info, i really do...Thanks everybody. My issue is i have it in my head that the knife has problems and its not just mine !!! The knife is in the cabinet and i grabbed something else and even if Benchmade tries to fix it, I know it will probably go back in their and just sit...which sucks. Im sure they won't do it but im going to ask if they will exchange it for a different model...???? at this point i don't have anything to loose ...Thanks again
 
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