Vertical play and hard use?

[pinnah]

What causes vertical play on Buck lock back under hard use and does it get worse over time?

I've been using my Buck knives harder in the past few years, especially with respect to cutting brush and small limbs on my property and in making wood shavings for camp fires. A big part of this has been my more recent exposure to Opinel knives, whose lock mechanism seems pretty impervious to any hard use I've dished out. But I've noticed some of my Bucks developing some vertical movement under this sort of hard use.

Typical "hard use" entails push cutting through a branch or sapling. Sometimes I use a bend and slice method. Other times I just use a slicing push type of cut. In most situations, it's with a good deal of force.

I typically keep my thumb on the back of the knife, near the joint. When doing this with my Bucks, I can feel the lock bar move during peak force. Obviously, there is no danger of the knife folding, but something is moving. I don't understand what exactly is happening and am concerned of the play getting worse.

Here's a nice picture of the Buck locking mechanism laid bare to see. (Thanks Robotech!)

Judging from this picture, there appears to be a slight angle to the vertical interface between the lock bar and the blade. My conjecture is that with enough upward force on the blade, there is enough force on the front face of the lock bar that the lock bar is momentarily moved up just a bit.

Alternatively, the movement I'm feeling in my thumb might be explained in some movement in either the blade pivot or the lock bar pivot.

Or maybe a bit of all of the above?

The real question here is whether or not I'm killing my Bucks using them this hard? I'm fearing that this sort of hard work is deforming the front vertical face of the lock bar and that, over time, this will lead to even more vertical play in the blade.

Any thoughts and guidance?

 

[RAZORBLADES]

I've had some recent 110's I bought from CAbelas with a huge amount of blade play,and theyw ere new.I have never seen a old version 2 dot 110 with any type of problems,and i've held and used a lot of them.I don't trust the locks on any of them no matter how tight they are,they are still a folder and i grab a fixed blade for tough jobs.

 

[sitflyer]

The lockbar and blade ride on a 1/8" brass (blade) and steel (lockbar) pin. The blade on the older ones had a steel bushing between the blade and pin, on the newer ones it is a bronze or brass bushing. All of these parts move and over time develope some wear. Under hard cutting forces like you describe a lot of pressure is put on a relatively small area. Both the lockbar/rocker pin, and the blade bushing/pivot pin are under under a lot of pressure, so wear would understandably increase. The other area of wear is the lock face and blade cutout for it. If one repeatedly "partially" depresses the lockbar and then closes the knife with the lock riding over the edge of the cutout, that edge will become less sharp...and over enough time a lock failure could become possible...best to fully depress the lockbar and hold it while rotating the blade closed.
Lint in the cutout for the lock engagement could cause the lock to not fully seat...which could cause some play.I routinely check for lint in this area of all of my lockbacks.
These knives are classified as folding hunters because they were designed to cut meat.

 

[dmattaponi]

These knives are classified as folding hunters because they were designed to cut meat.

I think that about nails it. I can't imagine choosing a Buck folder to cut small limbs/saplings, when machete, small saw, etc., would be so much more effective. My Bucks are for slicing up game animals, and things of that sort.

 

[pinnah]

I think that about nails it. I can't imagine choosing a Buck folder to cut small limbs/saplings, when machete, small saw, etc., would be so much more effective. My Bucks are for slicing up game animals, and things of that sort.

I have all of those tools in my barn. Also have a lopper and several hand clippers. I should have clarified that the sapling/limb size I'm talking about is up to about finger thick -- roughly the size for which I would reach for hand clippers if I had somebody following me around with all my tools.

Yesterday was a perfect example. I was knocking back several bushes (including a nasty quince) and was using hedge shears. One of the bushes was harboring a junk maple sapling that was finger thick and maybe 5" as it was seeking sun at the top of the hedge. A machete would have been of no use and even a folding saw would have been hard to use there. Clippers would have been perfect but would have required a walk back to the barn.

Two quick cuts with my pocket knife had the maple cut out.

These knives are classified as folding hunters because they were designed to cut meat.

Sigh. I guess I have to accept that if I'm doing work that is vaguely similar to farm work (in a very lightweight, weekend warrior way) that I would be better served using a knife whose original design and use was as a farmers utility tool - namely the Opinel. They do this sort of cutting and handle dirt and junk in their joints better. I wouldn't want to try to wash blood out of an Opinel though.

Bucks for hunting.
Opinels for hard yard/woods work.

 

[sitflyer]

The folders will do this kind of work, and many have used them for years for hard cutting, but the play that you described is likely to develop over time...
If I read correctly you can feel a little a little rise in the lockbar when cutting hard, I would suspect that the blade pin has a little wear ring on it creating enough play that the joint between the blade recess and lockbar can move together. I've seen this in some rough use knives I have torn down and re pinned, or re bladed.
I guess what I should have said is that if you use them hard, they will wear and loosen up a bit... Nothing to be too concerned about, but if it's unacceptable to have this happen, then choose another tool. Not bashing, just sayin' is all.

 

[BG42EDGE]

I'd rely on a Two-Dot or Three-Dot 110 for the toughest work.

Have you tried them?

:thumbup:

 

[pinnah]

Yes, I have a 2 dot 110 and a 2 dot 112. The 110 has no play and the 112 has very, very little. The 112 had more (got it used) and Buck repinned the lockbar to save the 440C blade. They did say that it would have some play due to some damage on the blade at the lock notch.

(My Buck 500 has no play but I don't hammer on that knife.)

The knives that have developed vertical play are all newer knives: Ecolite 112 (modified), Bucklite Max 482 and Bucklite Max 486.

I suspect that Sitflyer is on the right track with his comments on the bushings (newer ones are brass or bronze instead of steel). The newer knives open more smoothly but have more play.

I suspect that Buck will sell more knives owing to a smoother pivot than they'll loose from yahoos like me pushing the knife too hard. I've seen it more times than I can count where a design choice is made to help make a sale, even if there are downstream problems. First noticed when buying heavy hiking boots. The Merrill Wilderness fit wonderfully out of the box but I was warned that they would fall apart quickly. They did. As the cobbler said later, nice boot once it's been rebuilt.

I'll just use other knives for hard yard work. Good to have options.

 

[st8yd]

I acquired a used one that had some vertical play and found that the lockbar just behind where it locks into the blade was bent.
Proper positioning of the knife and use of a punch I fixed it without having to take it apart.