Blade play is good in a lockback?

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bk400

Joined
Nov 1, 2005
Messages
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Someone mentioned a thread from one of the forums where Sal Glesser said that blade play is actually good in a lockback because it allows the lock to function even if debris gets stuck in the mechanism.

Can anyone find this thread? I can't seem to be able to find it anywhere.

Separately, does Sal's statement hold water at all? I don't know enough about knives to be able to say one way or the other....

Thanks, all.
 
I'm not an expert but that doesn't sound right. My spyderco chinook II is a lock back with no blade play and operates pefectly. I think debris is an easy thing to avoid and is a more simple solution, but even at times with debris my knife still worked.
 
I'm sure someone will chime in with the thread, but Sal has actually expressed that idea in many threads. I'm not sure I'd call it "good" so much as "expected." The way that the lock is actually put together, you're going to get some play- usually up-and-down-, but it doesn't diminish the strength of the lock mechanism. ALL the lockbacks I've had exhibit this, and NONE of them have ever given me any reason to doubt them. I'd say that his explanation holds water, after all he's been making them for a LONG time.

-Anthony
 
That would be my instinct as well. But I'm fairly certain that I read another member's post that stated that Sal thought that a little blade play was actually good. Perhaps I was seeing things, then.

Separately, it's interesting because I have a mini Manix that started to develop vertical blade play after some fairly light use (breaking down a few cardboard boxes). I doubt the lock would fail at this point, but the blade play is a bit disconcerting. I also have developed blade play in both Tasman Salts and all three of my Delicas with relatively normal use as well. Just wondering if it's all part of the design.
 
destroythealter said:
I think debris is an easy thing to avoid and is a more simple solution, but even at times with debris my knife still worked.
Click to expand...

Debris is an easy thing to avoid if all you do with your knives is cut a few boxes and open the mail, but it is a problem if you actually use the knife.

All lockbacks will show some blade play under pressure. Most Spydercos I've handed were so tight that you really had to work at it to get some blade play.

I think you're right about Sal having mentioned that, or something similiar. The ideal situation is for the lock bar to go below the blade tang when locked open. But then things aren't lined up right and people will think it's defective when in fact it's stronger. You don't want the lock bar to be higher than the blade tang in the open position because that means the lock bar is sitting poorly on the tang and could fail. If a little bit of dirt or whatever gets between the point where the lockbar makes contact with the blade you'll see this happen.

So a little bit of play allowing the blade to move higher over the lock bar will create a stronger lock, assuming that the play isn't so severe that it moves past the point of optimal contact as well.

In essence, going past the point of optimal contact is a good thing, but not going far enough is bad. So that little bit of play that lets the blade go farther that it should is actually creating a stronger lock.
 
I remember sal saying that a small amount of of vertical movement is normal and expected in a lockback design.
 
Psychopomp, your comments make sense. Thanks for the replies, everyone. It's interesting because all of my knives, even axis locks, get some vertical play after reasonable use.
 
Psychopomp said:
Debris is an easy thing to avoid if all you do with your knives is cut a few boxes and open the mail, but it is a problem if you actually use the knife.
Click to expand...

"but even at times with debris my knife still worked"

...I clean my knives
 
bk400 said:
It's interesting because all of my knives, even axis locks, get some vertical play after reasonable use.
Click to expand...
Even your axis locks??? Not mine......
 
Maybe this thread can be moved to the Spyderco forum so Sal can elaberate.I ca'nt believe Sal would make such a statement.I've got many Spyderco's and none of them came with any blade play.Even my old plastic clip Endura has none after over a dozen yrs.of use.Maybe people have different definitions of blade play.Mine is if you hold the handle and use the other hand to move the blade up & down then side to side.If there is any loose movement then you have blade play.Its very common to have blade play on liner locks that have a lot of use,especially vertical movement.
 
ROBB said:
Maybe people have different definitions of blade play.Mine is if you hold the handle and use the other hand to move the blade up & down then side to side.If there is any loose movement then you have blade play.
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Yes, indeed, there are different definitions.

Many knifes don´t play even if you move the blade with strength.

I can´t say how much pressure i use but if the blade moves easy, let´s say at first touch, it surely has play. The rest belongs to personal impressions. I check knifes same way in a manner that fits to the knife.

Just my 5000A would show slight movement if pressed hard enough, there against non of my other BM axis folders has any play.
 
I guess what I meant to say in my earlier post was not actually blade "play" but rather a movement when applying a heavier force. I can feel the movement but there is actually no blade "play", I can't wiggle the blade either up and down or sideways.
 
When spyderco started cutting back on their warranty service all of sudden Spyderco started saying a little play in a lockback is part of the design. Then they started to say a little play was a good thing.

The real story is not one of my older spydercos have any play. I haven't bought any new ones since the warranty changes.

The real story is no other manufacturer makes the same claim. Benchmade, Buck, SOG all expect their lockbacks to perform w/o play. Even my cheap Pakistani Bullet lockback has no play.
 
A couple of my Spydercos have vertical play. Non of my Benchmades do.

I don't like blade play.

That's why I consider my Spydercos as beaters and my Benchmades as my fine knives.

"Blade play is good".
Riiiiiight.
 
My Byrd lockbacks are tight, my Golden Colo. lockbacks have the dreaded vertical play.:confused: Shouldn't it be vice versa.:thumbdn: :confused:
 
Sure would think so redhawk44p. Quality problems with spyderco and the change in their warranty is one of the reasons I haven't bought a spyderco folding knife for two years.
 
Wow. Some interesting responses. I don't know how to move the thread to the Spyderco forum to get Sal's response (not sure if he'd respond even if someone does). Perhaps a Moderator or someone who can move a thread could help out here...

My definition of blade play is when I hold the handle and the end of the blade nearest the tip and apply a vertical "shake" (vertical meaning in the direction the pivot naturally rotates). I apply both edge to spine and spine to edge pressure. On both the Spyderco lockbacks and the Benchmade Axis locks, I can feel the blade play (clicking feeling) more than I can see it. I've found that I can introduce play in both types of knives.

I personally prefer the Spyderco lockbacks over the Axis locks, but I'm very, very curious now after reading this thread to hear Sal's response to some of the warranty comments...
 
I remember Sal saying something to the effect that in their testing at Spyderco the lockbacks with a slight amount of vertical movement did better than the ones that locked up solid with no movement. I don't recall him saying why. He just stated his observations. Apparently the ones that did give just a little bit were able to take more force before defeating and it happened enough to be noticed.

Personally I don't like any movement in my lockbacks at all but I have several that do move within what is deemed acceptable tolerances. I've come to accept movement in liner and frame locks but lockbacks like the Buck 110 spoiled me years ago. Even still I have many production and custom made lock backs since the lock back is my favorite lock and many of them do move just a tad from play somewhere in their make up but usually the lock bar moves with the blade. In other words the mating of the blade and lock bar is solid and the movement is from some other factor. Usually this is from the pivot pin or the lock bar pin or a combo of both not being as tight or as close in the tolerances as maybe they could be to match up to the hole drilled in the body/liners.

I see discrepencies many times with pivot pins I buy to make my own folders. Using a digital caliper you can see that although all in say a ten pack are 3/16" diameter with 1/4" heads that when you get down to it some are slightly larger and some slightly smaller than one another. There have been times after drilling the hole in the blade with a 3/16 drill that one 3/16 pivot pin would slide right in nice and easy and another from the same pack would not go in at all.

In FRN folders (fiberglass reinforced nylon) I've seen many from all makers using that material that the pivot hole becomes oval shaped or oblong over time and use which is enough to allow some movement. Usually the quick cure for this is to take out the pin from the factory and simply replace it with a new adjustable pivot in the next bigger size. In most cases the knives lock up solid again like when new.

I would imagine that even though G10 and Micarta are both a step up from FRN that given enough time and hard use the ones made without liners of steel or titanium would eventually succumb to the same forces as the FRN ones I've seen. I have yet to see evidence of it in my shop for a repair though.
STR
 
Thanks, STR. Interesting points. I can also understand why there has to be at least some minor some blade play in a lockback because notch in the lockbar that contacts the blade tang travels in an upward "arc" when the user releases the lock, while that same part of the lockbar must mate at a right angle to the blade tang when it is engaged. If there is no play, then the lockbar has to release at a right angle also (i.e., straight up), but this is not possible given that the lockbar is fixed in length.
 
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