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Sad Day for a BM Owner
- Thread starter Petunia D. Feeble
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Tried it ten different ways on my Spyderco Szabo, which I know is not a Benchmade. (Including looseningnbody screws) Szabo-10, Me-0.
Only thing I can think of is that the Szabo's pivot has a screw on each side of the pivot. I was loosening both way back out, torquing the blade and then tried tightening the presentation side first, then the clip side. No luck. Tried opposite, no luck. Blade is still scraping the clip side.
Only thing I can think of is that the Szabo's pivot has a screw on each side of the pivot. I was loosening both way back out, torquing the blade and then tried tightening the presentation side first, then the clip side. No luck. Tried opposite, no luck. Blade is still scraping the clip side.
ChazzyP
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It hadn't occurred to me not to loosen the body screws first and I edited my pictorial post of the process to emphasize that one should do so. I suppose Jimmy's right that it's not necessary, particularly if the knife is clamped in a vise, but it strikes me that it's still more effective and requires less force applied with the body screws loosened. With the body screws un-loosened, one needs to overcome the friction at those connections while trying to shift the axis of the pivot.
As a methodology, clamping the blade in a vise also eliminates any bending of the blade that would need to be overcome to apply the force more directly to the pivot axis. Clamping and loosening the screws just strikes me as a requiring less stress and providing greater ease and control. Of course a certain amount of trial and error is still required.
ChazzyP
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One should be loosening and retightening the body screws not the pivot screws. The latter aren't cranked down hard (otherwise the knife wouldn't pivot) and should still shift at their normal position.
I'm not familiar with the Szabo, though. Does it have a bushing pivot? That might make shifting the axis more difficult there.
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But Jimmy said to loosen the pivot screws and infact that I didn't even have to loosen the body screws.
What you are saying is that I just loosen the pivot screws a tiny bit, loosen the body screws all the way till they are about to fall out and try torquing the blade this way?
What you are saying is that I just loosen the pivot screws a tiny bit, loosen the body screws all the way till they are about to fall out and try torquing the blade this way?
ChazzyP
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I just quickly re-read the thread, and Jimmy didn't mention loosening any screws. Most methods for centering blades that I've encountered involve leaving the pivot screws alone and loosening the body screws. I would suggest loosening the body screws just enough to take the tension off them. Leave the pivot alone.
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Loosening the pivot screws would defeat the point entirely. You're trying to get the pivot to shift between the scales, permanently. If the pivot's loose then it'll wiggle back and forth with no permanent affect.
You don't need to loosen the body screws, it just seemed to make the process easier for me.
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It may not work for everything. It does nothing for my Kershaw Link, but I know why it sits off center.
The hole through the blade for the pivot is too big. That combined with the lockbar tension forces it off center. You can compensate with pivot tension, but then the action blows. Just a flaw in the manufacturing for this one. New blade or thicker pivot are all that could fix it properly.
It's a cheap knife though, no big deal. Locks up solid and isn't rubbing so I'm ok with it.
The hole through the blade for the pivot is too big. That combined with the lockbar tension forces it off center. You can compensate with pivot tension, but then the action blows. Just a flaw in the manufacturing for this one. New blade or thicker pivot are all that could fix it properly.
It's a cheap knife though, no big deal. Locks up solid and isn't rubbing so I'm ok with it.
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Yeah do not loosen the pivot screw(s). I guess slightly backing out (not removing) a handle screw could help things shift a bit more on a stubborn knife but it usually isn't necessary. I do like the idea of using a vise for the reasons stated (mainly safety).
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Depends on why its offcenter. If it got pulled offcenter because you were torqueing the blade then yes it will last until you torgue it hard again. If it is just offcenter for no reason then no it will not last and it will eventually find its way back to where it was before.
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It's shifting the pivot. Think of it like a bridge between the two scales. You want it to be perfectly level, otherwise the slight angle of the pivot will translate down the blade, getting closer and closer to the scale as you near the tip of the blade.
If the pivot's square then the blade should be square.
ChazzyP
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The blade can't be off-center for no reason--clearly there are causes the ill alignment. I should think that if re-orienting the pivot axis will bring the blade back to center, then it should last unless the tolerances of one or more elements coincide fully toward the same directional error, causing normal use and side-to-side stress to eventually return the blade to its off-centered resting point.
If the methodology for correction is achieved without loosening and retightening the body screws--essentially an extreme
prying action--then it would make sense that using one's knife as a pry-bar could cause the blade to become uncentered again.
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Maybe that wasn't exactly the best wording. There is always a reason it will be off center. I was meaning if it were off center due to something other than being put together improperly or being pulled off center. Some reason other than something you can figure out. In my experience and I have a pretty good bit of it. The blade will be ever so slightly misground causing the knife to be off center if everything else is right. I have seen this with knives I have swapped the blades on. One knife might not center to save its life and if it does it just goes back. Try a new blade (from the same model obviously) and it centers up perfectly and stays there. Only thing changed was the blade. If that is the cause you are basically screwed unless you get a blade swap.
ChazzyP
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Point taken, and I don't think we necessarily disagree.
I had a 940-1 that had a crooked blade. I had read that BM had some difficulty with their S90V blades deforming when heat-treated and that certainly seemed to be the case with mine. Before understanding that one could use an open blade for leverage to re-center a knife I was able to improve the blade position by loosening the body screws, wedging the blade over, and re-tightening. It was better, though not quite centered, and did not move back to its original position.
Perhaps using the additional leverage in the open-blade technique I might have been able to get it even better if not entirely centered. That being the case, and applying the point I made regarding coincidence of tolerance limits in #36 above, the amount of "shiftability" of the pivot axis combined with a crooked blade might then be at their limit of correction in the same direction. If so, applying side-to-side pressure in use (prying, which is something I really never do with a knife) could certainly cause the blade to return to an uncentered position. (Re-reading before posting, I should also note that there is a fair amount of lateral force exerted on a knife during certain hard-cutting tasks that doesn't constitute prying per se but certainly could cause the blade to re-shift.)
A knife that keeps going back may indeed be beyond user correction and needs to go back to get made right.
ChazzyP
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That's not it at all. The pivot screws have nothing to do with it--they just hold everything together there. The screw or screws thread into the pivot shaft--the blade's axle, if you will--that runs through the liners (or handle slabs) on each side and through the hole in the blade. What you're doing is taking advantage of the ever-so-slight difference in size between the holes in the liners/slabs and and the pivot shaft to effect a very slight change in angle between the axis of that shaft and the handle sides.
Think of the blade and pivot axis as a T. Draw a downward line parallel to the blade from each end of the T's top and you have a diagram of a perfectly centered knife. The angles between the outside lines and the T's top are moveable and the connection of the T itself is rigid. Keeping the two outsides parallel, move one upward and see how quickly long body of the T swings toward the upwardly moving side.
In round numbers, my 710's blade is 4.5" long from its pivot's center and the pivot shaft is slightly over a quarter inch long outside-to-outside of the liners. At less than 1/16" off-center at the tip the blade touches the liners. At that extreme the pivot axis would be less than 0.795 degree out of square to the body of the knife. To bring that axis back to square requires a forward/rearward shift in relation of the two liners of about three-and-a-half thousandths inch outside-to-outside and about half that inside-to-inside. Doesn't take much movement at all, just the right amount of leverage to effect.