Side to side blade play?

Wowbagger said:
This Spyderco Para 2 in Cammo and S30V DLC coated steel has zero play an pivots so fast and light I can not imagine having a knife that does any better.
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This Benchmade 710, which is a more expensive version of this model being a limited edition in M390 steel ( I simply love the handle shape and this steel alloy) . . . well . . . the pivot sucks so bad. It has play, when the knife is room temp or cooler and it swings free, when I carry the knife in my pocket it warms up to body temp and even with a trace of play it doesn't pivot nearly as well as it should . . . if I put it in the refrigerator . . . the materials go right back to pivoting freely.
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THE PARA 2'S ARE JUST FLAT-OUT GREAT KNIVES. FEW (MY SLYSZ BOWIE?) CAN APPROACH THEIR QUALITY.

THE 710'S ARE VERY NICE FOLDERS...HAD SIX OR MORE, INCLUDING M390. FACTORY LITERATURE (OWNERS MANUAL) CLEARLY STATES (SMALL PRINT) THAT THIS KOOL KNIFE BE CARRIED IN THE POCKET IN A BAGGIE WITH CRUSHED ICE.
 
Many of my knives have a tiny bit of lateral play. I don't have an issue if you have to really force it to move, and the lock itself doesn't rock. It's more of a nitpicky issue if it's just a smidge of play, but if the blade rattles it can induce failure. I'd rather have free dropping with a hint of play than stiff with no play.
 
T Todd21969 I don't think he was saying the % lockup affects side to side play, but instead pointing out that the lock itself on a really late lockup on a knife might fail (by slipping completely past the blade) when the blade is moving side to side a lot. That's the way I understood it anyway.
 
Lipripper Lipripper If the locking liner travels all the way to the other liner, even if it's possible to slip off the tang, the knife won't close. The whole locking tab will be in the way.

At least on any liner lock I've ever owned. Pre-Fiskars Gerber, Old USA made Kershaws, ZT, Spyderco, Emerson,etc. And I'm sure a few other makers I've forgotten about.
 
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Not being able to tune out blade play is unacceptable to me in this hobby. Even a hard time tuning out blade play gives me pause. If I didn't care, I'd stick to buying cheapo fleamarket knives. Besides materials, build quality and fit and finish are what justify this expensive hobby to me.
 
T Todd21969 No, the blade probably wouldn't close. It would certainly be an annoying issue to have with any knife though, and I personally would find it unacceptable :)
 
Todd21969 said:
Please explain how lockup % of a liner lock affects side to side blade play.
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I've had a cheap knife with blade play and late lockup, and if you moved the blade the lock bar could travel all the way across.
This is just the worst case scenario with a piece of junk though.
 
Hickory n steel said:
I've had a cheap knife with blade play and late lockup, and if you moved the blade the lock bar could travel all the way across.
This is just the worst case scenario with a piece of junk though.
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And it closed and cut you? Slipped completely of the tang and jammed the knife open? What's the worst case scenario?
 
Todd21969 said:
And it closed and cut you? Slipped completely of the tang and jammed the knife open? What's the worst case scenario?
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Yep jammed open, but it had already lost two body screws so I threw it away instead of trying to get the lock bar uniammed.
 
Todd21969 said:
And it closed and cut you? Slipped completely of the tang and jammed the knife open? What's the worst case scenario?
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If you were doing something that put stress on the lock, like pulling it out of a stiff medium that the blade is wedged in (hard food, rubber, cardboard, wood, etc) or turning with the knife in hand and accidentally hitting a solid object, then it could possibly close inadvertently. It seems like it only takes a small change in the angles of the engaging surfaces to make most locks fail, and this doesn't appear to be an uncommon event among people who get serious cuts.
 
Hickory n steel said:
Yep jammed open, but it had already lost two body screws so I threw it away instead of trying to get the lock bar uniammed.
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Ok. So the liner lock had nothing to do with the side to side play, and wasn't at fault. You were using a (broken) knife with missing parts.

Thank you for the explanation.
 
marrenmiller said:
If you were doing something that put stress on the lock, like pulling it out of a stiff medium that the blade is wedged in (hard food, rubber, cardboard, wood, etc) or turning with the knife in hand and accidentally hitting a solid object, then it could possibly close inadvertently. It seems like it only takes a small change in the angles of the engaging surfaces to make most locks fail, and this doesn't appear to be an uncommon event among people who get serious cuts.
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Yes, this I know. But this wasn't about lock slippage towards the lock side.
 
Todd21969 said:
Ok. So the liner lock had nothing to do with the side to side play, and wasn't at fault. You were using a (broken) knife with missing parts.

Thank you for the explanation.
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Sort of but Not exactly.


Basically the blade play which was not caused by the lockbar made all the difference, blade play normally effects very little and this was kind of a perfect storm situation.
 
Todd21969 said:
Yes, this I know. But this wasn't about lock slippage towards the lock side.
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Right, but you asked what the consequences we're, and it seemed like you're inferring there aren't any if it slips towards the show side. Which is usually true, but a bit disengenuous because in that scenario it could also easily slip the other way.
 
marrenmiller said:
Right, but you asked what the consequences we're, and it seemed like you're inferring there aren't any if it slips towards the show side. Which is usually true, but a bit disengenuous because in that scenario it could also easily slip the other way.
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For a liner lock, with late lockup (touching the opposite liner), to slip all the way to the lock side and disengage from blade play?

I suppose it could happen. Though I wouldn't say easily.

That would have to have a whole lot of play. Or a very loose wide bodied knife with a thin tang and thin lock tab.

Though in this specific scenario it did slip off on the opposite side.
 
Todd21969 said:
For a liner lock, with late lockup (touching the opposite liner), to slip all the way to the lock side and disengage from blade play?

I suppose it could happen. Though I wouldn't say easily.

That would have to have a whole lot of play. Or a very loose wide bodied knife with a thin tang and thin lock tab.

Though in this specific scenario it did slip off on the opposite side.
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Well, I have heard that liner locks/frame locks depend on a 7-10 degree engagement angle. If it was right at the edge of that anyway, and you deflected a loose blade... who knows. I don't think it's likely to occur but then again I don't tend to put any force on frame/liner locks. Also, I'm not saying a knife with the liner already touching the other side, but a normal liner lock with normal engagement. I'm assuming it slips open rather than closed because that's usually what I've seen failing liner locks do.

It may only slip closed if you forced the blade sideways while you had a load applied against the lock. However, I think that might be easily possible if you pull a stuck knife out of something very stiff.
 
dkb45 said:
Many of my knives have a tiny bit of lateral play. I don't have an issue if you have to really force it to move, and the lock itself doesn't rock. It's more of a nitpicky issue if it's just a smidge of play, but if the blade rattles it can induce failure. I'd rather have free dropping with a hint of play than stiff with no play.
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I m the opposite. I d rather have a folder with no side to side play that doesn t fall shut freely. If I get a knife with a small amount of side to side play that has the blade fall freely on closing, I ll tighten the pivot to allow a smooth opening and closing with finger pressure, but has no play whatsoever. I personally don t see the benefit of a free falling blade on closure. Just as with a slight bit of play, there is no functional problem with a non free falling blade. More of an aesthetic preference. Which I don t share.
Of my several dozen knives, I ve been able to adjust all side to side play out of all my knives with the exception of two different Chinese knives I got as complimentary benefits from membership renewals.
I have had a problem with back and forth lock rock which cannot be adjusted away on three or four knives. I don t like that either.
 
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marrenmiller said:
Well, I have heard that liner locks/frame locks depend on a 7-10 degree engagement angle. If it was right at the edge of that anyway, and you deflected a loose blade... who knows. I don't think it's likely to occur but then again I don't tend to put any force on frame/liner locks. Also, I'm not saying a knife with the liner already touching the other side, but a normal liner lock with normal engagement. I'm assuming it slips open rather than closed because that's usually what I've seen failing liner locks do.

It may only slip closed if you forced the blade sideways while you had a load applied against the lock. However, I think that might be easily possible if you pull a stuck knife out of something very stiff.
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This discussion got me really curious.
So, the only late lockup liner lock I own is my Emerson. Like that is a suprise :)

To induce side to side play I took out the pivot bolt and washers. With the blade held in place by the bolt sleeve and lock I tried to get the lock tab to slide off either side. No dice,and I torqued hard. The body spread a bit but the lock didn't slip.

Doesn't prove much. But satisfied my curiosity.

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