Fixing Lock Rock in Seki FRN lockbacks

[Brock O Lee]

I've tried to ignore it and live with it, but it still annoys me.

I "fixed" it by picking other lock types for larger knives that I typically use for harder cutting.

So instead of Police or Endura, I pick Military or PM2.

[Brock O Lee]

I really like solid back lock on Chaparral, where internal stop pins on the blade run in channels in the liners to combine with the back lock to provide rock solid lockup.

[Doc Dan]

There is going to be lock rock to a small degree in back locks, especially mid back locks. The only back locks that I know of that have no lock rock are the Spyderco Chaparral and the Triad Lock, both of which have use a stop pin.

Not sure if it will always be there in a small amount because i never seen lock rock in any of my old Manixes or chinooks. Also have not seen it any of my natives yet.
Maybe its just an issue that happens in like 1 to 5 % of the pieces of a batch of knives?
If i am honest and i think about it harder i can not say i ever had a spydie with lock rock before. I do have one very lousy made buck lockback from when i first started collecting 20 years ago. Its so badly made i keep it as a memento on how much my taste in knives has improved

My Manix 2 back lock has zero lock rock (they need to bring this back and tell people to get over the minutely thicker blade). One Endura is rock solid but one has a very tiny bit, so tiny it would be noticed if you weren't looking for it. All of my other back lock Spydies have no lock rock. However, I have a couple of Benchmade made Lone Wolf back locks that have significant lock rock. The spring is so light the blades can be easily flicked open.

[Albatross]

It can be fixed by peening the lockbar, but this should not be considered an option. The likelihood of catastrophic damage to the hardened steel lockbar is too great and not worth it, besides, the eventual lock wear would cause the lock rock to return at some point anyway. I've fixed a couple backlocks by peening the lockbars, but also had one chip slightly.

[vivi]

This is a complaint I've never understood. Not saying it isn't legitimate, only that I don't understand. I can duplicate the phenomenon if I try, but I have never experienced it to a perceptible degree while actually cutting something. So I have to ask, and please, I'm not trying to single you out:
1) what are you cutting that requires so much force?
2) should you perhaps try a different cutting technique, e.g., slicing vs. push cutting?
3) is your knife as sharp as it needs to be? Using excessive force because your knife isn't sharp is hazardous.

1. Thin cardboard
2. Lock rock occurs on a push cut or slice
3. Reprofiled to 10dps and shaving sharp

My EDC is a gen 1 Pacific Salt and it only takes 100-200 grams of force on the edge to make the lock rock.

Does it bother me?

No.

But it does happen, and it isn't because I'm bearing down with all my weight. Every day to day cutting task I do makes the lock rock, aside from say cutting a thread.

I've never owned a Spyderco lockback that doesn't do this. Some require more force than others, but everything from my first run Pacific Salt, to my golden made Native Chiefs, to my Manix C95's to my kids Ladybug has some degree of lock rock.

I don't mind it at all, lockbacks are still my favorite, but it is there.

[cjk]

Some amount of rock seems kinda inherent to the backlock design. It doesn't only happen on Spyderco backlocks.

Some knives have lock rock out of the box. Some knives develop it noticeably after a lot of use. Some have it only minimally if at all.

My non-knifemaker observations are that the cause of lock rock can easily be a number of different things, but mostly tolerances and fit of this or that. Such as:

• Actual lock bar fitment into the tang of the blade.

• Tolerances and fit of the pivot hole in the blade and the pivot hardware

• Tolerances and fit of the pivot hole in the lock bar and the lock bar pivot hardware

• Tolerances and fit of the pivot holes in the liners.

• The need of the design to accommodate physical wear and still function.

Seems like 6 parts need to be near perfectly machined with reasonable enough tolerances to get near zero lock rock, but then the design still has to be able to wear and still work. The lock bar is also effectively the stop pin. When one cuts something, the blade pivot and lock bar pivot have to hold all that pressure. They have to be strong enough and also fit all the holes closely enough for there to be no movement there, but also fit loosely enough for the knife to be reasonably easy to open. Seems like there has to be just a little slop there for the mechanism to work at all.

[apollo]

There is going to be lock rock to a small degree in back locks, especially mid back locks. The only back locks that I know of that have no lock rock are the Spyderco Chaparral and the Triad Lock, both of which have use a stop pin.

Not sure if it will always be there in a small amount because i never seen lock rock in any of my old Manixes or chinooks. Also have not seen it any of my natives yet.
Maybe its just an issue that happens in like 1 to 5 % of the pieces of a batch of knives?
If i am honest and i think about it harder i can not say i ever had a spydie with lock rock before. I do have one very lousy made buck lockback from when i first started collecting 20 years ago. Its so badly made i keep it as a memento on how much my taste in knives has improved

My Manix 2 back lock has zero lock rock (they need to bring this back and tell people to get over the minutely thicker blade). One Endura is rock solid but one has a very tiny bit, so tiny it would be noticed if you weren't looking for it. All of my other back lock Spydies have no lock rock. However, I have a couple of Benchmade made Lone Wolf back locks that have significant lock rock. The spring is so light the blades can be easily flicked open.

Totally agree with you. And i love a blade with some extra stock. The old Manixes , Chinooks , the Shaman are all my favorites by far!

[JRinFL]

This is a mind over matter issue.

If you don't mind,
It doesn't matter.

I long ago stopped worrying about it on most back locks. However, I had one of the Sirens that had excessive lock movement and I had that one swapped with a CQI version.

Changing the lock, even just making it more like the US made ones, would basically mean a whole new knife. New molds, new blade cut out profile, new lock parts. It'll happen when and if they revamp the Seki FRN line up. It also assumes the Japanese makers are willing to change their processes.

[capt.carl]

The two police 4s in k390 I’ve handled had equally good amounts of up and down play. Still locks up solid but feels kinda weird when you wiggle it. Amazingly smooth action thoug.

My usa back locks (chief) and taiwan (chap) have been completely rock solid

[dsvirsky]

This is a mind over matter issue.

If you don't mind,
It doesn't matter.

That, I think, is the heart of the matter. If it bothers you, it's a problem. If it doesn't, it's not. Clearly, some people pay more attention to this sort of thing and I'm not one of them. I own a gen 1 Pacific Salt (PE) that I purchased shortly after the model was first released. Until just now, when I tested it after reading Vivi's post, I never noticed it has a small amount of vertical play caused by poor fitment between lockbar and tang. Will I pay any attention to it next time I cut something with the knife? Probably not. As long as lockup is solid, I'm good.

[electro-static]

Hey Everyone, Just an update I seem to have found a solution.

I installed an aftermarket flytanium backspacer for my endura 4 and that seems to have for the most part stopped the lock-rock issue. The action now feels more stiff so I will have to take another look.

[w3tnz]

Hey Everyone, Just an update I seem to have found a solution.

I installed an aftermarket flytanium backspacer for my endura 4 and that seems to have for the most part stopped the lock-rock issue. The action now feels more stiff so I will have to take another look.

I have also found replacing the FRN back spacer for a metal one makes a noticeable improvement to the action overall. Definitely stiffens up the spring and provides a more solid lock up.
Could be a realistic candidate for CQI on these models or at present an option for those to upgrade themselves.
Thanks for the heads up that they are back in stock btw, have been waiting for some Delica ones!

[PaloArt]

Lock rock on Seki models is much more pronounced than on the others (Taichung, Golden), that is fact. It is most definitely something I dislike on otherwise great models. Saying it is not issue, it is normal etc. is a moot point.

What causes lock rock? There are few things that might cause it but I would rather cover what causes it with Spyderco knives - bad tolerances in pivot holes especially D shaped pivot that is in some places little bit bigger (can feel pivot moving on my ZDP Endura when cutting through beef for example); plastic pin which is part of back spacer and holding the spring of the back lock; Back lock lever sitting too shallow in the notch and again inconsistent quality of the lever "dent" as it differed on few models I had in my hand and that I owned (Stretch, 3x Delica 4th gen, 3x Endura 4th gen).

What can be done? The only thing you can do right now with knife you probably own is spend some money on modification from someone who knows how to eliminate issues above. Currently I know of only one person from Europe doing this and most definitely there would need to be completely new set of scales. Guy has nick MydlinkaTM on insta and he is modder from Czech Republic

https://www.instagram.com/p/Cp18OeKtup5 ... BiNWFlZA==

I love my Spydercos but due to Lock Rock I limit usage of Seki models now for more serious cutting jobs and I enjoy my Chaparral and Native 5 for anything where I need precision not being compromised by lock rock (ocassional whittling, carving, outdoor activities).

[PaloArt]

Some amount of rock seems kinda inherent to the backlock design. It doesn't only happen on Spyderco backlocks.

Some knives have lock rock out of the box. Some knives develop it noticeably after a lot of use. Some have it only minimally if at all.

My non-knifemaker observations are that the cause of lock rock can easily be a number of different things, but mostly tolerances and fit of this or that. Such as:

• Actual lock bar fitment into the tang of the blade.

• Tolerances and fit of the pivot hole in the blade and the pivot hardware

• Tolerances and fit of the pivot hole in the lock bar and the lock bar pivot hardware

• Tolerances and fit of the pivot holes in the liners.

• The need of the design to accommodate physical wear and still function.

You covered exactly main issues with back lock design. Didn`t notice it before I made my post above this one. Chaparral is so far the only back lock knife I encountered without any sign of blade play or lock rock.

[R100]

Hey Everyone, Just an update I seem to have found a solution.

I installed an aftermarket flytanium backspacer for my endura 4 and that seems to have for the most part stopped the lock-rock issue. The action now feels more stiff so I will have to take another look.

I had a similar experience. I bought some micarta scales with carbon fibre back spacer from Etsy for my K390 Delica and the lock rock is almost completely gone.

Dan

[Ramonade]

There is going to be lock rock to a small degree in back locks, especially mid back locks. The only back locks that I know of that have no lock rock are the Spyderco Chaparral and the Triad Lock, both of which have use a stop pin.

Not sure if it will always be there in a small amount because i never seen lock rock in any of my old Manixes or chinooks. Also have not seen it any of my natives yet.
Maybe its just an issue that happens in like 1 to 5 % of the pieces of a batch of knives?
If i am honest and i think about it harder i can not say i ever had a spydie with lock rock before. I do have one very lousy made buck lockback from when i first started collecting 20 years ago. Its so badly made i keep it as a memento on how much my taste in knives has improved

I join apollo on that. I have 12 or 13 Natives and only the Native 1 has minor lock rock, the others have no perceptible lock rock, no matter how stupidly I try to move the blade vertically ! There must still be a tiny, tiny amount of lock rock otherwise it'd be a fixed blade, but for the Native and Chaparral it's just a joy. The S90V CF Siren is the same for me.

As far as Seki mid backlocks go, I only have 2 with annoying lock rock, the ZDP-189 Endura 4 and Delica 4. On the other side, I got a Byrd Hawkbill that is a total vault when other's samples aren't. So this kind of stuff will vary, that's how it is

[Bolster]

I've experienced a great deal of variability in Seki backlocks; some are solid and wonderful, others have been sent down the river due to excess rocking (by which I mean: blade rocks excessively even when NOT cutting--it rocks just with simple hand pressure on the spine of the knife).

The fact that there is so much variance in rock-ability (some backlocks have large amounts of it, some don't) is evidence it can and should be addressed at the factory, IMO.

How many seconds does it take for the QC person at the factory to grasp the knife in both hands, and simply check for excessive rocking?

[wrdwrght]

So here’s different question.

Did vertical blade-play in midlocks (which I, too, dislike) become an annoyance (to us AFIs) once the compression lock, the CBBL, the power lock, the stop lock (thanks Spyderco, for the Parata I just got at the OpFocus seconds sale), the Chaparral, etc. hit the market?

Context, after all, is everything.

Bad-mouthing Seki for this baked-in “flaw” is ironic since the “flaw” has afforded us all the acceptable stuff.

By the way, this “flaw” has denied no one a high-performance knife.

Moreover, is it realistic to retool Seki’s FRN models (lined and not) to make them perform like
Chaparrals, for example, given their obvious acceptability to non-AFIs, and even some AFIs.

Beware asking for Spydies to cost more, which retooling will surely cause.

…just some random thoughts while out on the road, looking for the America of my youth, and happily finding it.

[DavidNM]

I don’t have nearly the number of Spyderco knives as many here but it seems to me that it is a minor issue. I have an older Navigator II that has pretty bad lock rock but it never caused any issues in actual use. Never failed nor failed to performed. I have a fairly recent manufactured Delica and while I can still detect a small amount of lock rock it is really minor. Not a large sample size but Seki seems to have improved over the years and I don’t really see the problem. Fortunately Spyderco makes many knives with different lock design so if the lock rock bothers you then move onto a different lock design.

[capt.carl]

I just got another police k390 frn and this one has much less lock rock than my other one which has a substantial amount. Guess tolerances are decently variable