small blades can flex?

H

holdanedge

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Sep 16, 2002
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i am now worried about my beloved bm770. if i grab the handle at the end and grab the tip of the blade with my other hand i can wiggle the blade back and forth. if the blade is in the closed position i can wiggle the very tip only all the way from one side of the handle to the other. about 1/4". as far as i can tell the pivot is not loose in the liners. so, can this small blade actually flex with very little pressure applied to it? if it does i am ok with that. i just hope it is not the pivot that is loose, since that is not exactly a quality i look for in a good knife! if i try to move this assembly by grabbing the thumb studs and rocking back and forth there is no play. that is why i do not think it is the pivot. plus i cannot visibly see the pivot move. is the pivot loose and i just cannot notice it, or can this little blade indeed flex? the torx on the pivot is pretty darn tight. so if it is the pivot the knife is shot. i do not want to send this back because it was a very limited edition that came complete with a titanium gift box. plus, i paid quite a bit more than a regular 770 goes for. if they replaced it with plain 770(that will probably have the same problem) that would suck! what do you experts think?



thank you,
holdanedge.
 
If you are grabbing the knife by the tip when it is open, then you will probably be able to wiggle the blade back and forth because the blade is acting like a lever. When you grab the blade down by the studs, you are shortening the length of the lever, so you are not exerting as much force on the pivot. Try grabbing the spine about an inch out from the pivot and see if you can induce blade wobble with gentle pressure. If not, I wouldn't worry about it. You might want to tighten the pivot as well. If this doesn't work, contact Benchmade and see what they say.
--Josh
 
i would have to agree with Josh Feltman, althogh some small blades "can flex",such as my fixed blade greco dangler, but on a folder i dont think they are designed to flex much...
 
thank you. this is a shame, as i doubt benchmade will be able to replace this one.



holdanedge.
 
Holdanedge,

Tighten the pivot screw. You will find this will most likely take away most of the blade play. You must realise that there is some type of washer between the blade and the liner to allow the blade to pivot smoothly. The looser the pivot screw, the less pressure these washers are exerting on the sides of the blade. This allows the blade to wiggle some, especially if you wiggle from the tip. Remember, it is like a fulcrum, the farther away from the pivot you exert pressure, the easier it is to move something. Your power is multiplied a lot at the end of the blade. If you tighten the pivot too much, the blade will be difficult to open. I would suggest some quality lube on the pivot washers. This will allow you to tighten the pivot screw a bit more and still open the blade smoothly. Hope this helps.

Mike
 
ok, i talked to benchmade and they said to send it back. of course they agreed that i would not get another limited prod. unit. that is bs. so since i am so anal i brought the knife to my buddy that works at a very fancy metal fabrication shop. he tightened the pivot for me. well, i can't flick it anymore but at least i can open it. now, to prove to me it is not moving much he used some fancy contraptions. he applied 26 psi of force to the tip of the blade spine with some magnetic device. then he aimed some sort of laser measurement machine at the pivot area. he said he would not apply more than 26 pounds of pressure to the tip because the blade would snap. anyways, he showed me that under that much pressure the pivot moved less than 1/20th. of 1mm. is that acceptable? he said it has to move a little or it would not open. it is after all a mechanical connection. the only thing that sucks is that i cannot flick it. i suppose if you loosened any knives pivot so you could flick it there would be play. even on a sebenza. am i right? maybe i need better oil. i have rem oil. i can get tuff oil. is that good? militec is not to be found here.




thank you,
holdanedge.
 
holdanedge-- I wouldn't worry about it too much-- that sounds like a pretty small amount of movement. The real question, though, is whether or not it is acceptable to you, since it is your knife. On my Benchmade 942, I find that there is a balance between ease of opening and blade play. The looser you adjust the pivot, the easier it is to open the knife. It also makes for more blade play. Why not get yourself a set of torx drivers and play around with the pivot adjustment a little bit until you have it where you like it.
--Josh
 
I think that you are making a mountain out of a mole hill. Most production folders have a minute degree of side to side movement (even some customs do). In fact, there are only 3 that I have owned that absolutely did not even with the blade "flickable". The other thing is that you are talking about a 770, a gent knife not designed for hard work. I really doubt that side to side play, that isn't obvious is of any pertinence. As far as being acceptable, that's up to you, sounds pretty solid to me.
Take a deep breath and enjoy your benchmade! :),
Matt
 
hi
this happened to my MOD trident after about 2 months (you know how it is, new knife, itchy fingers)
i did what was described, tighten the pivot pin
the knife store i went to mentioned using locktite thread locker to stop the pivot pin from coming loose
you might want to consider doing that
 
thank you all. i am just unrealistic. that is why these knives have torx adjustments i guess. if i set it so the blade just drops out, of course there will be play. i think any knife would have play when that loose. now that i tightened mine i can not visably see it move. i guess it is a compromise for what one wants from the knife. the very nature of the design would suggest that if i back the torx screw all the way out there will be movement. at least it locks up solid. no up and down movement at all. what gets me is that i paid almost enough to get an umfaan for this knife. it was one of a few that bm made a "mistake" on, that was not to leave the factory. but, somehow this guy got them and charges an arm and a leg for them. he has one left that wiggles even more but the pivot is loose on that one also. i figured this knife was a little more unique so i was willing to pay more for it. anyways, there are plenty of stores that sell the regular 770bc1 for $150-$210. so please don't comment on my paying too much i had my reasons. but, for what i paid i wanted it to be perfect. actually it is now pretty comparable to my seb. i can't see either move. the seb is also tight. i bet if the seb was all loose it would move too. what do you guys think? oh, just wanted to mention the "mistake" on these knives was not about the pivot. it has to do with the finishing. i don't think it is ruined and not supposed to be sold as bm said. i think it is cooler this way. and hopefully worth something, to me at least. i do not sell/trade my knives. if i pull on the tip while it is in the closed position REALLY hard the tip will rock from one side to the other, i still can not see or feal the pivot move. so i think now i AM bending the blade. when it is open i would have to manhandle it to see it move. i mean like jab it with all my might into a stump and then use my entire body weight to lean on it. i am not this stupid, i will not do that trick just to see if my blade moves and end up breaking it. i was just pointing out how solid it seems to be.

i think the bottom line is, i would be most happy with some good oil. i cannot get militec, is tuff oil good enough?

nonetheless, it seems adequate for opening boxes and bagels. which is all i wan't to use it for.

ok, sorry i carried on so much about this subject. i am done complaining now :).

thank you,
holdanedge.
 
As far as lube, I've had gool luck with Tri-Flow, which should be available at Wal-Mart, etc. It has telfon in it, and seems to work really well.
--Josh
 
is that stuff simalar to teflon rem-oil from remington? if the tri-flow is better what department in walmart has this? by the guns?

hey, while were on the subject, is the tri-flow good to wipe my blade too?



thank you,
holdanedge.
 
I think tri-flow is usually with the bicycles-- if Wal-mart doesn't carry it, check the local bike shops. I don't know if it is similar to rem-oil-- I've never used rem-oil. I have used tri-flow to wipe down blades, but I usually use mineral oil instead because it is nontoxic.
--Josh
 
i am surprised you guys have mentioned these products. in the past, around here folks only swore by militec-1 and some said tuff was OK.
i now have to agree, i am going to use mineral oil on my blade. i am a self proclaimed foodie and vegatrian. i use my little knives to cut all my foodstuffs, so ingesting teflon or other chemicals may not be a great idea! the whole idea for me is to eat healthy, not poison myself! i just hope that long term exposure to mineral oil does not ruin my bc1 or TIcoat blades!



thank you,
holdanedge.
 
i realized last night that if i pull REAL hard on the tip of the blade when it is open, not only will the blade flex but the handles will bend apart causing the pivot to loosen! i probably should't do that again :). it is not a very robust knife, it is not intended to be. i don't want to send it back and get in return something lesser than what i paid for. now that it is tightened, as long as i do not manhandle it it performs fine. a little umfaan is probably stronger. i asked about that once before. but, i like this knife better than an umfaan so i am keeping this one. that's all.



thank you,
holdanedge.
 
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