Blade play - so what?

Blade wiggle may be subjective. Wiggle on a lockback like a $30 Buck 110 may be expected. I'd don't have the time, equipment or experience to quantify "wiggle". Tirod you may have some theoretically valid points but I think you are making this thing more complicated than it has to be. As a consumer, I decide how much blade play I will tolerate and I don't have to measure it. I go for higher end framelocks and I don't tolerate any bladeplay that I can perceive.;)
 
I don't have any specific caliper-measured "standard" at which to draw an accept-or-reject line, but in general I much prefer lesser blade play. The more force that has to be applied to the blade in order to notice the play, the better. Excessive side to side blade play will certainly cause faster and uneven wear, and that is something I'd definately like to avoid.
 
hardheart said:
Trying to portray this as a technical discussion when it is really just a fanboy response to the complaints of sloppy QC of Striders (which I have not experienced firsthand) is hilarious. Taking offense at being belittled when you are the one belittling everyone else who is a consumer and expressing their subjective opinion without providing you with hard numbers to argue for the adequate build quality of My Favorite Maker X is simply trollish behavior. Nobody has to assign a numerical standard, and no one has to agree with yours.
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I've read the whole thread thus far, and I don't see where he belittled or insulted anybody.

And again, here we have the Strider insults. When did tirod ever mention that this was a Strider thread?

:foot:
 
Of course all folding knives will have -some- play. If I can feel any play AT ALL (while in use or when I try to wiggle the blade with my hands), then it's too much. If you need advanced measuring equipment to detect the play then I couldn't care less ;)
 
knarfeng said:
Maybe we should look at what we mean when we say "zero blade play".

To me, "zero blade play" means that when I lock up the knife, I can't wiggle the blade in either vertical or horizontal planes using the amount of force I would normally use to cut.

Is there some movement? Undoubtedly so. As tirod3 points out, there has to be some clearance or the knife won't move. Can I feel the movement in a locked up position? I cannot. Not for most of my knives. Got a couple of Gerber EZ-outs that wiggle a bit if I work at it. Can't feel any movement in my Spydercos and Benchmades.

Just an aside. I would not expect the tolerances to change significantly over a change of 120F. The CTE of 400 series stainless is on the order of 7ppm/°F. So if the temp changed by 120°F, a 0.125" thick blade would change in thickness by 0.00000075". I don't think I could detect that with my bare hands.
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It means the knife blade doesn't wiggle when locked, or rattle when closed. That's the only definition practical to this thread. I understand the idea that one could put a 'well-made, strong locking' folder under a 'blade-play-o-meter' and detect a few tiny increments of movement, but I don't think that's what everyone is talking about.

The Benchmade Griptilian I bought for about 40 bucks is rock solid when locked. It does not wiggle when open, it does not rattle when closed. I expect the same out of any 'good' production knife.

That being said, I also own a two year old car, and keep it in nearly new condition. I expect it not to 'rattle' while driving, or 'wiggle' when I'm turning a corner. If it does begin to wiggle or rattle, I take it to the dealership immediately and have it fixed, most of the time under their warranty. :D Sorry for stealing that example from the original poster who mentioned cars, but it seems to fit.
 
punisher_nbi45 said:
I've read the whole thread thus far, and I don't see where he belittled or insulted anybody.

And again, here we have the Strider insults. When did tirod ever mention that this was a Strider thread?

:foot:
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He insinuates that anyone who complains about blade play or is unable/unwilling to fix it themselves as uninformed, emotional whiners who have no knowledge or understanding of basic mechanical functions. He also tries to compare tolerances in internal combustion motors to knife pivots, as some justification for the need of blade slop. True, there has to be at least a half inch of clearance between a compression ring and a cylinder wall, because there's no way you could have metal on metal contact for something that travels 100 miles an hour (depends on stroke and rpm, of course) with rapid combustion going on above it to not expand like the deficit. There also has to be significant clearance between lifters and camshaft lobes, because they spin twice as fast, and you definitely couldn't have spring tension applying force to any totally non-existent contact area (because there's clearances there) cause things would completely lock up on start-up. Oil? shoot, that's fine fer them fancy motors and such, but we don't use phosphor bronze or teflon for lubricity, no we rely on big open spaces between our parts to prevent accelerated wear from such high stress actions as opening a 3 inch blade. I sure as hell can't slide a book across a table, there's no clearance.

http://www.bladeforums.com/forums/showpost.php?p=4278259&postcount=28

There's the Strider/Sebenza thread comment, since you missed it.
 
tirod3 said:
Folding knives must have clearance at the pivot or they just won't open. Whether you notice or not is entirely subjective, and without measuring the amount in precise dimensions, you don't know what you're talking about.
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just so im clear on your reasoning here. there doesnt have to be 'clearance' for the parts to move. metal will move if touching metal. it would depend on how tight the pivot is.

eg, i can rub my fingers together, and there is no clearance between them. if i apply enough pressure, eventually i wont be able to move them.
 
on emerson folders, the pivot can easily be loosened or tightened. it can be tightened so there is no noticeable lateral play when locked open, but the bushings are still touching the blade and the scales, so is there clearance there? ie, space between the bushings and other parts?

if the pivot is tightened further, eventually the blade wont move, but that is from the lateral pressure applied by the scales via the screw.

tirod, maybe you could clarify for me.

i dont agree that with zero clearance the blade wont move, but im no physicist, so i may be totally wrong. then again, for practical purposes, 'zero' would mean not detectable by feel or eye, correct?
 
You also have to define to what precision. Zero to two decimal places, or something of the like. and of course, do you mean zero inches, centimeters, lightyears, etc. But I want full contact.
 
Gentlemen, I believe we are making progress :D

We have discovered that there is noticable blade play - an amount of play which draws itself to you attention on casual handling or normal use - and we all seem to agree this is unacceptable on anything over convenience store grade knives.

There is discernable blade play - an amount of play which can be felt with the hands if one is checking for it - which some find acceptable, some find acceptable only on lower end knives, and some find unacceptable.

And there is detectable play - an amount of play which will require measuring instruments and a specific test procedure to determine - which no one seems to care about, since it is too small for them to notice.

I understand these things to be subjective. I understand people will be upset if they are informed that their thousand dollar, hand fitted, custom built, precious to them folder has detectable blade play, even if it would require a runout micrometer and a special test procedure to detect it. I understand that people are reluctant to quantify their standards, simply because tolerences vary between people as surely as they vary between machine parts. What bothers one person may not even be discernable to another.

I may well be wrong, but I thought the original subject of this thread was an attempt to quantify that perception. If you say "this folder has too much play" what does that mean to me? Does it mean that holding the handle in one hand and the tip of the blade in the other, I could easily move the blade tip back and forth 1/4"? Or does it mean that you felt movement somewhere when you were cutting that oil drum in half? I know that sounds like I'm just being snotty, but I have been hanging around the boards long enough to have some idea of just how picky some people can be.

Okay, I'll go away now, and I promise not to post in any more threads on blade play. (Along with lock strength, which brand is better, trademark laws and a few others)
 
I'm not worried about minimal /indiscernable blade play . I get concerned if I feel a steady increase developing , my concern is then about lock integrity . What I'm looking for is two highly subjective gualities- solidness and smoothness .

Chris
 
I separated the discussion of blade play to a totally separate post to discuss an issue that many others have commented on - about many other brands that I also own and have experienced -Benchmade, Spyderco, Kershaw, Buck, etc. I constrain myself to discussing facts about brands I own to establish a minimum level of credibility - yes, I own a Strider SnG, and God knows why that engenders so much bias. I will reserve that for a separate post.

I'm impressed that some have credible knowledge about blade play, and some don't but know what they want in the classic American way - like art. Wouldn't have it otherwise for them, it keeps the market on it's toes.

As for those who responded to the less formal way I wrote my responses, I will do better in the future.
 
While we're on the subject (if it's not hijacking), I sent in my Large Manix to Spyderco because I noticed vertical play when I moved it with my hands or when I cut anything harder than cardboard. Anyone here who wouldn't have cared or sent it in?
 
From the posts I have read concerning the vertical play of the Manix, it seems to be normal for it to have a bit of vertical play, and even said to have it "built in" from Spyderco.
 
tirod3 said:
So what we see here is one informed response from an experienced technical viewpoint, and pretty much all the rest uninformed consumer opinion.
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I think it's more a matter of definitions.

For example,
If the question was:
"Blade play of one Angstrom Unit - what's the big deal?";

replies would be very different than
"Blade play - what's the big deal?"

___________________________________

IMO there's a generally accepted view of what constitutes reasonable or
unreasonable "blade play". Technicians, machinists and scientists among us can be satisfied with a blade that feels "rock solid" in its lockup.

A relative of mine, for instance, happens to be is one of the leading experts in the country on nuclear fusion technology.
But when, let's say, I'm over at his house and ask if the the coffee is "hot", he'll answer based on what's generally understood as "hot" coffee.
He doesn't answer, "Well, compared with temperatures generated by a stellarator, it's quite cold".
 
rifon2 said:
A relative of mine, for instance, happens to be is one of the leading experts in the country on nuclear fusion technology.
But when, let's say, I'm over at his house and ask if the the coffee is "hot", he'll answer based on what's generally understood as "hot" coffee.
He doesn't answer, "Well, compared with temperatures generated by a stellarator, it's quite cold".
Click to expand...

Right, because most people find it obnoxious.
 
While I don't expect anyone to measure bladeplay in angstroms, what has occurred has been a general acceptance of a vauge term - rock solid, or zero play, and it's interpretation in knife forums.

It has two elements - vertical and horizontal. Vertical is generally agreed to be potentially detrimental to secure lockup. Lockbacks can tolerate this better than liner locks because the notch and hook require a lot of movement to unlock. Horizontal play, ie side to side, is dependant on pivot style and assembly, and affects blade operation. A pivot tightened 1/8 turn too much can easily put so much pressure and friction on the blade that it will not pivot by forceful hand manipulation. At blade rocking against a liner lock ramp can walk the lock out of engagement and allow the blade to unexpectedly close. Vertical or horizontal play, or both, can cause this.

Therefore, lockbacks may show evidence of bladeplay and remain secure, and even be intentionally manufactured. Linerlocks are a different story - my experience is that any play at the ramp must not affect the ramp/lock engagement, especially knives with thin liners.

So, the big deal is how hot is hot. A cold reactor and a cup of cold coffee can be hundreds of degrees different, but a lockback with bladeplay is no big deal. It's usually not a functional issue, but a imprecise perception of quality control. The operation of a liner lock however,affected by a lot of diverse factors, must work in a much tighter functional window than a lockback. Ramp angle, liner lock thickness and length, scale flexibility, pivot bushing hardness, and vibration from impact can all affect secure lockup. Slop in the blade is not too welcome, and pivots should be kept as tight as the owner can stand it. It's a big deal, and points out why rigid designs work better - metal bushings, thick liner locks, stiff scales. When they're not right, they are hazardous.

As is a nuclear plant not operating correctly. Fortunately, knife meltdowns only leave obnoxious cuts.
 
I think the blade-play issue has alot to do with the UNOFFICIAL industry standards.
With out a doubt, most of the folks on this forum have handled more folders than the average Joe, and so, they have more comparative knowledge and experience.
Whether we are consciously aware of it or not, we are always comparing a new folder with ones that we have held and used in the past.
So when we find a folder with more movement in the pivot than we have experienced in other knives we determine that it has "blade-play", possibly due to looser tolerances or lesser craftsmanship.
Whether it functions properly or not is really not the point.
What matters is how it stacks up against the competition.
If I know, from personal experience, that Buck can make a lock-back with extremely little "blade-play", then why would I settle for a knife with more "blade-play" than the Buck?
I might find myself asking: If Buck can reduce most of the "blade-play", then why can't brand X?
And I might come to the conclusion that Buck must know something about locks and tolerances that brand X does not, or that brand X has sloppy quality control or lesser standards.

Does this ring true with anyone else here?
 
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