Stretch 2 lock rock?

[Big John]

I recently got a Stretch 2 in k390 and it has substantially more lock rock (front back play) than any model from Golden I've owned (Golden backlock is the only one I have experience with). It's not a big deal, it's just far from rock solid. Is this typical? How do the backlocks compare between the 3 main manufacturing plants?

It also has the most uneven sharpening job I've seen on a Spyderco, also one of the least sharp out of the box. This doesn't bother me at all though, I love sharpening k390. And all in all, it's a great price for what I received. Just curious about what others have experienced.

In contrast, my micarta Shaman which arrived on the same day, is one of the most perfect models I've ever received, minus negligible lock rock (both are rock solid from side to side).

[capt.carl]

I've handled 2 police k390's and both had some lock rock (including the one i own) so does my k390 delica 4, although less than the police im suspecting because of the shorter blade. it shouldn't be an issue. I have noticed that my taiwan chaparral locks up tight, they definitely have better tolerances. Yes, my delica k390 had a VERY uneven bevel, but at least it was thin.

[Soanso McMasters]

Mine has it

[jegred2]

The Seki lockback models tend to have lockrock, I have an Endura and Endela and the Endura has some play.

[Doc Dan]

The only sure way to get rid of lock rock on a back lock is to put in a stop pin, as on the Chaparral, and on the Triad Lock. The Triad Lock is simply a back lock with a stop pin added. The Chaparral has a stop pin in the tang.

It is the nature of the lock, but it certainly does not affect strength as a back lock is far stronger than a liner or frame lock, and probably a ball bearing lock unless the spring is made extremely difficult to use.

[VooDooChild]

Your problem is the Golden backlocks are really really really good.

The seki lockbacks usually have a tiny amount of lock rock. The best thing you can do is just ignore it. Its something to do with that type of backlock design, for whatever reason there is that tiny bit of play.

I can promise you the lock is fine and will hold up. I have done plenty of hard cutting with one of my enduras with lockrock and nothing happens.

[ChrisinHove]

It’s just “character”!

[Big John]

Thanks for the feedback!

I am not concerned at all with the lock failing.

[Brock O Lee]

My K390 Stretch is surpisingly solid.

[elena86]

The fact that most “encourage” the existence of this(inacceptable IMO) lock rock as being “normal” or “inherent” and that it doesn’t affect the strenght of the lock, probably delayed “ad calendas” the implementation of an internal stop pin. It’s sad to say at least.

[VooDooChild]

The fact that most “encourage” the existence of this(inacceptable IMO) lock rock as being “normal” or “inherent” and that it doesn’t affect the strenght of the lock, probably delayed “ad calendas” the implementation of an internal stop pin. It’s sad to say at least.

Accepting that a design is a certain way isnt encouraging anything.

But I will encourage it right now. Does a backlock need more components if it makes it more expensive or more complex? I think there is something to be said for simplicity.

Also an internal stop pin like on the chaparral does nothing for the strength of the lock.

If stop pins are the way the designs end up going then I will probably be fine with it. So long as the locks for the salts dont have any corrosion issues. Where I would potentially get upset is if I had to now pay significantly more for a redesigned lock that only solves a, functionally speaking, non-issue.

Edit.
Although I cant imagine implementing new designs with stop pins would drive up cost that much...

[elena86]

The fact that most “encourage” the existence of this(inacceptable IMO) lock rock as being “normal” or “inherent” and that it doesn’t affect the strenght of the lock, probably delayed “ad calendas” the implementation of an internal stop pin. It’s sad to say at least.

Accepting that a design is a certain way isnt encouraging anything.

But I will encourage it right now. Does a backlock need more components if it makes it more expensive or more complex? I think there is something to be said for simplicity.

Also an internal stop pin like on the chaparral does nothing for the strength of the lock.

If stop pins are the way the designs end up going then I will probably be fine with it. So long as the locks for the salts dont have any corrosion issues. Where I would potentially get upset is if I had to now pay significantly more for a redesigned lock that only solves a, functionally speaking, non-issue.

I am a 62 aged retired mechanical engineer so I understand a thing or two about design, tolerances and functionality. So you are saying that functionally speaking that lock rock(which by the way, has the tendency to increase and might eventually “encourage” the lock to fail) is a non issue ?! Really ?!

[VooDooChild]

...
I am a 62 aged retired mechanical engineer so I understand a thing or two about design, tolerances and functionality. So you are saying that functionally speaking that lock rock(which by the way, has the tendency to increase and might eventually make the lock to fail) is a non issue ?! Really ?!

Thats news to me since I havent heard that. Sure if it does get worse and causes the lock to fail as you stated, then thats a huge issue.

If it doesnt get worse then its a non-issue. Because if the design and use isnt causing wear, then its within tolerance, which you know all about.

Edit.
From a design standpoint I understand the dislike for lock rock.
But I would like to see the evidence against it.

There are millions(?) of well used lockback knives with lock rock that still have appropriately working locks. I would say that is evidence that, yes, it is functionally a non-issue.

[JRinFL]

This will seem like "stirring the pot", but that is not my intent. I would like to see one or more of the old lock back knives with heavy use that have had the locks fail due to lock rock and not due to a snapped spring. I know we have members here who have some of the earliest Spydercos and other brand knives with lots of years of use on them. Let's see some of these, please.

For the engineers amongst us: At what point in a design is good enough actually good enough?

[JSumm]

I think there must be higher tolerances in Seki backlocks vs Golden. I only have 2 Golden backlocks, so my perspective is small. Seki lock rock I would say is typical to some degree. Although I have a couple of examples with negligible to zero lock rock. My 2 Golden examples seem rock solid. Only 2 of my Sekis can I notice in use. More of an annoyance than anything. Just a trade off I guess. Thinner blade stock and designs I prefer out of Seki override any annoyance it may or may not be.

[ChrisinHove]

When you consider that the extreme lock movement of the Siren was declared to be safe, I have no fears regarding the safety of any of my Seki lockbacks with their tiny amounts of movement.

Is it a desirable feature? No. Does it warrant an over-engineered and costly solution? No. Are there alternatives if it offends. Yes.

[FK]

I have a large collection of Seki knives with back lock design. All are excellent with no rock lock, not the slightest. If you really force a large amount of pressure on the blade spine, a slight amount of movement may be detected in a few knives. Presently have several K390 Stretch 2, Endura and Delica,,,, all are solid with no a trace of lock rock.
The only Spyderco knives I have had with lock rock were early Native models from Golden. Had three with unacceptable lock rock movement with slight pressure on the blade. Gave up on the Native models, probably unfairly as they have been improved over the years of produciton.

Regards,
FK

[Manixguy@1994]

My Stretch 2 K390 is solid . MG2

[apollo]

I guess i am very lucky because not 1 of my lockback spyders has any form of bladeplay let alone something as worse as lock rock.
But i do want to mention that the US lockbacks are overal have better fit and finish on the lock parts then the seki ones. Many of the seki ones are not flush with the handle and are even a bit to crispy on the edges.

[R100]

I have quite a few Seki lockbacks and they all have some degree of lock rock. I think whether a particular example is good or bad comes down to luck but my K390 and ZDP-189 Stretch 2s are the best I own. I also got lucky with my Stretch XL which is extremely solid. The really woeful ones I have are an Endela and a Caly 3.5. They are so bad I don't use them but that is just personal preference not because I think they might fail.

Dan