Hopefully this will help contextualize what "a little" and what "more" lock rock is. "More" is subjective of course; I'd call it a lot, but others might not even notice it.
Nice setup. Now that we have data, everyone just needs to agree upon what is good and what is bad.
After viewing your setup, I can see what you're talking about. I'm sitting here with three knives, and I can feel the play in the same way that you're measuring. Interestingly, if I open the lock, I can feel fore/aft movement on the blade. There's a little slop at the pivot. So some of the "lock rock" is actually play at the pivot. A thousandth at the pivot is going to translate to a whole lot of angular movement at the end of the blade. Again, the question is whether it is good to have a pivot and a lock with zero clearance. I don't know what's easily achievable and if the resulting mechanism would be reliable in a dirty environment.
Thank you for doing this. Now, (particularly if you do a bunch of these tests) everyone can see for themselves that there are no special back-locks that are perfectly rigid. There never has been a back-lock that didn't have some blade movement, and there never will be. If there were such a knife, the blade pivot would be frozen in place and the lock bar wouldn't move either. All back locks have movement inherent in the design, the only question is, how tight are the tolerances.
The movement you're measuring is different from the movement mentioned in the first release of the Siren (where the lock was slipping). That sort of lock movement on a brand-new knife was a very slight error (around .001") within the angles of the lock that has since been resolved, but it is also the sort of thing that could happen over a long enough period of time and hard use, or abusive working conditions. Wear on the lock faces (blade and lock bar) as well as wear on the blade pivot and the lock bar pivot will all add to the movement of the blade and/or the lock junction over time.
I hope you do more tests. I personally think the Native is the best overall mid back lock design ever produced, for a variety of reasons. I would expect the tolerances to be the same as the Manix, but still curious what the actual numbers are. Do you have a Native you can test?
:spyder: Spyderco fan and collector since 1991. :spyder:
Father of 2, nature explorer, custom knife maker.
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This post is going slightly OT here, but some of the worst lock rock on back lock knives I've ever owned were in knives made in the USA by a company whose name rhymes with "truck."
So lock rock in back lock knives is definitely not something that is unique to Seki-made knives.
Interestingly, if I open the lock, I can feel fore/aft movement on the blade. There's a little slop at the pivot. So some of the "lock rock" is actually play at the pivot. A thousandth at the pivot is going to translate to a whole lot of angular movement at the end of the blade. Again, the question is whether it is good to have a pivot and a lock with zero clearance. I don't know what's easily achievable and if the resulting mechanism would be reliable in a dirty environment.
I seem to be noticing the same thing with the movement in mine, it actually seems to be at the pivot, which makes me question whether it even is the fault of the lock after all, at least in my particular knife. Some knives locking mechanisms actually seem to reduce movement to a degree, which does make them cleverly designed, but I'm not sure that the lock design is actually causing it on mine.
There definitely is a question of whether you want the tolerances too tight in some instances. When the U.S. military was still using the 1911, they specifically allowed some slop in the slide to frame interface so that it would not jam up when introduced to dirt. My gunsmithing instructors always say that you want some over travel in a trigger so that a piece of grit can't stop the sear from engaging. That said I'm not sure to what components that concept would apply to a lock back knife. I think more than likely the objectionable part of tightening tolerances would be the cost increases associated.
This post is going slightly OT here, but some of the worst lock rock on back lock knives I've ever owned were in knives made in the USA by a company whose name rhymes with "truck."
So lock rock in back lock knives is definitely not something that is unique to Seki-made knives.
Ha! I do not, can you believe it? The legendary Native, and I don't own one.
This sort of testing is not something I'd want to do on a regular basis. It's not a pleasant test because the tester has to be very careful not to "clamp over space," which is dangerous (to the knife not the human). Sure, one could make custom spacers, but I didn't get that far into it. I tried to clamp toward the backspacer. I used the minimum clamping torque I could. Both knives survived. Hopefully the procedure is repeatable by anyone who wants to test their own knives, but be careful about "clamping over space" if you do, folks.
I suspect a lot of forumites have not run into a Spyderco with lots of rock and wonder "What's the big deal"? Most of my Spyderco back locks are pretty tight, and I'm guessing that might be the case for the majority of forumites, too.
Steel novice who self-identifies as a steel expert. Proud M.N.O.S.D. member 0003. Spydie Steels: 4V, 15V, 20CV, AEB-L, AUS6, Cru-Wear, HAP40, K294, K390, M4, Magnacut, S110V, S30V, S35VN, S45VN, SPY27, SRS13, T15, VG10, XHP, ZWear, ZDP189
With all due respect, lock rock, side to side play, lock slippage, can and will eventually result in failing. I value my fingers and my hands so I will not trust any of members with a faulty lock in any fashion. There are reports of this happening and people needing serious surgery. Cars fail in accidents and testing because of improper design, engineering, mechanics, etc. Tools as well, among many other items out there. If you're not bothered by it in daily use, that's your prerogative. Me on the other hand, I won't take any chances.
Studiousworkman, this is not about who is right or wrong and I don´t mean to annoy you - I am just still genuinely interested and waiting (could be I am missing or not be aware of something):
- Can you give any examples or proof that "Seki lock rock" "will eventually result in failing"?
Despite the FRN Sekis are so popular and so many out there, I am not aware of any accounts, not even of Spyderco backlocks failing in general (and if this happened I personally still heavily doubt that "lock rock" could be the reason)
- Do you really think (honest question!) that Spyderco would give one of their most popular, best selling and established for a long time now lines (the FRN Sekis) a "faulty lock" that has the tendency (or a higher tendency than the other locktypes) of "failing" and endangering the users?
- Especially when one thinks of how long it often takes till a model finally hits the market cause they want to get exactly those essential things right first?
- And when thinking of their constant cqi process IF anything turns out not to be good?
- Consider that for example the Endura or Delica come in their 4th iterations yet - don´t you think Spyderco would have fixed any real problems or safety issues yet, if their had been such?
Last edited by Wartstein on Wed Nov 29, 2023 6:25 am, edited 1 time in total.
Top three going by pocket-time (update March 24):
- EDC: Endura thin red line ffg combo edge (VG10); Wayne Goddard PE (4V), Endela SE (VG10)
-Mountains/outdoors: Pac.Salt 1 SE (H1), Salt 2 SE (LC200N), and also Wayne Goddard PE (4V)
I think a quick and easy reply to the OP's question is that the knives have lock rock because the blades and lockbars are mass produced separately, then matched together later. I'm guessing that the knife being able to lock up is more important than whether there is a perceptible amount of lock rock.
It's been a while since I've handled a Native, but don't they have a slightly thicker lockbar than the Seki models? I'm sure the wider surface area may help keep the perceptible amount of lock movement down.
I don't like having lock rock in a knife, but it's something I can deal with as long as it isn't excessive. I'm still confused as to how someone could think it's a safety issue though. Last I checked, knives are supposed to be used edge first, which pushes the blade upward away from your fingers. Of course, it could be that I've been using my knives wrong all these years.
Chris
Haves: Lava, Delica 4 Sante Fe Stoneworks, Spy-DK x2,
PaloArt wrote:
Now as for the reply to the original post - I have newly acquired K390 Delica, lock rock was very pronounced but since I bought it from abroad, I didn`t want to go through all the hustle with returning. Disassembled the knife and tried to pull out, by approximately two millimeters, lock spring, closer to the pivot, away from the handle butt (if that makes sense). Now that lock rock is miniscule, still there, but not bothering that much - try it and let us know if that helped perhaps?
Interesting, I wonder if I could have inadvertently done as you described when I disassembled my Endura. I am very curious now to know what component or components actually contribute to the amount of lock rock at this point. It seems from what I could tell, most if not all of the movement in mine was at the pivot, but it is difficult to tell if anything else could be moving.
It seems like it would be pretty cool to get a stop pin in Seki models, it always sounded like an efficient and effective solution, but I assume that would require a new version of all the modified knives, and would require new tooling etc, etc, which all adds up to costs costumers would have to pay for, and I'm not sure that it would actually boost sales. That all makes it a potentially difficult sell, especially when so many people seem quite satisfied with it in it's current state.
That said it seems like to me there is not much that can be improved mechanically at this point (ergos are a different story), except for maybe adding a stop pin. So logically from a CQI perspective, this seems like the way to go. If it solved what instances of lock rock we see now, it would be very difficult to fault the knife mechanically and it will have achieved about as close to perfection as I imagine you can get in it's given price bracket, even if the price did rise a little.
There are various things, as per my uneducated opinion, causing lock rock. Observed on my ZDP Endura, for example, that the "play" comes from main pivot hole being bigger than the pivot itself - when pressing on cork surface with the blade, I can feel pivot move. In my Delica, pivot hole is perfect but the lock rock seems to be more in the pin holding the lock bar and in FRN knobs on the backspacer, sometimes it might be as well inconsistency in notch and lug where lug might be too small\shallow... From my experience the best backlocks I own are Chap and Native 5 whereas Chap is without any blade play or lock rock and Native has very minimal lock rock... Now retired Delica 4 VG10 developed lock rock of 2mm movement which I found bothersome and unsafe to use, mind you that Delica was old, bought it when Gen4 FFG was issued by Spyderco and the blade got shorter by 1cm from all the use and sharpening... gave it away to someone who said they will try to experiment with it.
There is Modder from Czech Republic, who mods Seki models so they don`t have lock rock, of course new set of scales is made in the process but this shows it is doable.
As bothersome as it might be to me, it doesn`t prevent me from buying new Seki models... I just know that after some time, that piece needs to be replaced eventually or will send it for some spa time to person who can create new set of scales.
After reading this thread I checked all of mine out of curiosity. Definitely not scientific, just more of could I "perceive" lock rock or not. I have 4 Golden, none with perceivable lock rock I have 12 Seki, 6 have no perceivable lock rock and 6 do. Only one would I consider bothersome (Stretch 2 K390) but not enough to make me feel unsafe using the knife, just more of an annoyance.
I think the biggest point of contention in this thread is that there’s no agreed upon definition for “Lock Rock.” That phrase is being used much too vaguely. Through reading this thread, it would seem that any movement beyond fixed blade stiff, can be called “lock rock.” Even if it’s user induced and being forced to happen through applying excessive pressure on the blade.
Is there a difference between “lock rock” and “forced lock movement?”
I believe there is.
I had a Pacific Salt 2 with, what I would have considered to be, “lock rock.” When the blade was open, just shaking the knife was enough to cause blade movement. It still locked up without failing but the “lock rock” was easily detectable.
Currently, every single one of my Spyderco backlocks does not do that. I have to force the locks to move. Meaning if I put their blades on a solid surface and lean on the knife to try and force the lockbar to move, then yes, the lockbar might move but for me it feels naive to call that “Lock Rock.”
I think I have found this in a couple of mine, the Endura 4 and Endela, but not in the Delica 4, Atlantic Salt, nor Pacific Salt 2. The Native 5 is fine also as is the Native Chief. In my case, with those two, the Endura 4 and Endela, it is definitely a 'forced' event. I made sure to not have any pressure on the lock itself while testing. Just trying to shake the blade, neither has any movement at all. But, if I place the handle on a surface where the blade hangs over empty space, I can press down the tip of the blade very slightly. In this case, I can force the opening of a fraction of a mm gap between the blade and the lock bar. Possibly due to the longer lever/blade length, it takes slightly less effort to do this on the Endura 4 than the Endela.
Edit: Just to clarify, I have not been able to achieve/force any other type of blade movement than that described here. And, as this movement is opposite that of any normal usage blade pressures, I have absolutely zero worries about it.
I think the biggest point of contention in this thread is that there’s no agreed upon definition for “Lock Rock.” That phrase is being used much too vaguely. Through reading this thread, it would seem that any movement beyond fixed blade stiff, can be called “lock rock.” Even if it’s user induced and being forced to happen through applying excessive pressure on the blade.
Is there a difference between “lock rock” and “forced lock movement?”
I believe there is.
I had a Pacific Salt 2 with, what I would have considered to be, “lock rock.” When the blade was open, just shaking the knife was enough to cause blade movement. It still locked up without failing but the “lock rock” was easily detectable.
Currently, every single one of my Spyderco backlocks does not do that. I have to force the locks to move. Meaning if I put their blades on a solid surface and lean on the knife to try and force the lockbar to move, then yes, the lockbar might move but for me it feels naive to call that “Lock Rock.”
There's also no agreed upon definition of excessive pressure.
For example in this video where I made my C95 lock audibly click, I was using just hand pressure on a chest high shelf.
Is it possible to apply "excessive pressure" with just one hand? Or do we need to use two hands or lean our body into it?
Should a knife as rugged as the C95 be expected to have zero lock movement if one applies a few pounds of pressure to the edge?
At what point should the line be drawn between lock rock and "forced" lock movement?
To me, if a lock of any sort shows any type of vertical movement under any normal conditions, there's lock rock. I define "normal conditions" as the knife is in good working order and is being used for a regular knife task with reasonable levels of care.
I know this is a Pandora's box can of worms topic, so I usually avoid it, but self control isn't always my strong suit. I am leaving much of the topic alone, but only want to add, I definitely have Spyderco back locks that have no discernible lock rock. Sure, you could press harder, crank harder, whatever, but really, it's just not there. So, not all do. Some do, and I get why it bothers people.
vivi wrote:“At what point should the line be drawn between lock rock and "forced" lock movement?”
I was thinking about this while I did my indicator dial test, above. I was thinking it would be nice to use a scale to make the pull. Attaching the scale to the edge (or the block) for a pull was frankly more engineering than I was up for, so I didn't. However I did casually notice the amount of effort it took to make the pull on both knives.
The Caly took (overall) "less" effort to take up the rock slack--it was pretty easy. On the Manix (overall) it required somewhat "more" effort. Then there was also that inflection point, for both knives, where causing the rock to occur went from "easy" to "firm," as noted. I thought the "easy" part of the pull was more informative, because that would be more likely to show up in daily use. Being it was only .005" on the Manix, it's understandable it wouldn't be noticed, unless specifically looking for it. (I had never noticed rock in that Manix until I prepared to test it.)
That "easy" to "firm" pull transition makes me think that overall slack/tolerance in the lock mechanism is being taken up in two distinct areas. For instance (just a guess) it may be that the "easy" part of the pull takes up slop in the blade pivot, and then the final "firm" part also gets a bit of slack out of the lock bar pivot. Or some other two-step process like that. But there were clearly two distinct areas of slack take-up on both knives, the first requiring little pressure, and the second requiring more, with the second giving up very little additional.
Because I was concerned about the knives slipping under considerable pressure, I didn't pull back "hard" on either of them. Just moderate finger and wrist pressure. I never put my weight into it. But without a scale it's difficult to say what's "easy" or "firm" or "hard."
On the basis of just those two (and here I show myself to be a rotten scientist, making a guess based on n=2), I would guess that knives with small blade movement/rock would be correlated with larger effort, and larger blade movement with smaller effort. Ie, an inverse correlation. Just a hypothesis.
Steel novice who self-identifies as a steel expert. Proud M.N.O.S.D. member 0003. Spydie Steels: 4V, 15V, 20CV, AEB-L, AUS6, Cru-Wear, HAP40, K294, K390, M4, Magnacut, S110V, S30V, S35VN, S45VN, SPY27, SRS13, T15, VG10, XHP, ZWear, ZDP189
