A few thoughts on lockback fit/finish

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DesertChris

Joined
Sep 8, 2013
Messages
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This has come up a few times recently.....

So I had been thinking about it, and pulled.out the spare 501 parts I have laying around from a previous blade swap project.
I intend to make a handle for these parts at some point in the near future.

Anyway, the difference in where the end of the lockbar sits, higher or lower when closed or open, looks like a matter of the distance between where the lockbar tab sits on the tang in both positions.

Specifically:
1) The distance from the center point of the pivot hole to the point at the bottom of the tab where it fits into the notch on the tang when the knife is opened.
2) The distance from the center point of the pivot hole to the bottom of the tab where it rests on the tang when the knife is closed.

Those 2 distances must be equal for the end of the lockbar to be in the same exact location when the knife is opened or closed.

If the tab sits closer on the tang than it does in the notch, then the end of the lockbar will be higher in the closed position than it is in the open position.

If the tab sits farther on the tang than it does in the notch, then the end of the lockbar will be lower in the closed position than it is in the opened position.

Both scenarios could be fixed by removing material from the lockbar tab, or the tang, in the appropriate locations for each scenario, but that would be a pain in the rear end ;)

Here are some photos of the guts etc....







These particular parts are matched well, the difference between open and closed is a small fraction of a millimeter.





The tiny bit of lockbar end riding higher can be seen if the knife is held just right, to get some glare on the metal.

 
Since most often people mentioning lockbars that are not perfect seem to be concerned about the lockbar end riding high in the open position.

Here is a solution.

Tap out the blade pivot pin.
Rotate the lockbar through the handle.



The tab and notch are both "V" shaped.
Remove a tiny bit of material on both sides of the tab so it sits a tiny bit lower in the notch.
A buffing wheel and compound might even work well.
Do very small amounts and check the knife while temporarily reassembled.




Afterwards, when satisfied, put the blade and pivot pin back in.... peen the pivot, sand, buff etc....
And now it will be perfect :)
 
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I went to a seminar where a world-class lockback folder maker was teaching a while back. From what I remember, it was a little more complicated than that. I believe that in the open position, you ideally want the lock bar to be wedged in the slot on the blade, but not touching the bottom. Has something to do with better lockup.
 
knifeleather said:
I went to a seminar where a world-class lockback folder maker was teaching a while back. From what I remember, it was a little more complicated than that. I believe that in the open position, you ideally want the lock bar to be wedged in the slot on the blade, but not touching the bottom. Has something to do with better lockup.
Click to expand...

In the photo above, in the first post, you can see there is a good sized gap there.
What you are saying makes perfect sense. If the tab bottomed out, it could result in blade play.
But there is also a big enough gap to allow for a little adjustment too :)
 
Looks like you got it! I think that's exactly how they fit the lock, working the sides of the tab. (sorry, I didn't see your immediately previous post...)
 
knifeleather said:
Looks like you got it! I think that's exactly how they fit the lock, working the sides of the tab. (sorry, I didn't see your immediately previous post...)
Click to expand...

Hahaha, no worries.
I just figured it was a worthy topic, since it has been brought up a few times recently :)
 
So DessertCrhis,

This is great for the aspiring knife mechanics.

But what about for us simple users?

What could be offered to Buck to help them produce better, more durable lock up and alignment out of the factory?
 
pinnah said:
So DessertCrhis,

This is great for the aspiring knife mechanics.

But what about for us simple users?

What could be offered to Buck to help them produce better, more durable lock up and alignment out of the factory?
Click to expand...

All of my Buck lockbacks lock up solidly, with no blade play.
So for me personally, that is not an issue. Other people may not have the same experience with theirs.

The riding high end of the lockbar when closed could quite possible fix itself by opening and closing it enough times to "break in" the parts.....
That could take quite a while, but would seem likely over time.
Perhaps a blob of.polishing compound squeezed into the tang notch area, then engaging and disengaging the lock alot, might buff it out enough to remedy the situation of high lockbar end in the closed position.

My favorite and easiest solution is to simply open the knife, cut stuff, close the knife, and put it back in the pocket.
The Lockbar end height has no bearing on the function, so can be easily ignored :)

What could be offered to Buck? I prefer to just offer my patronage by purchasing their knives.
In my opinion the knives work perfectly for cutting things, and that is why I buy them.
 
I think you may have a hard time smoothing this spot out; :)



I watched a repair video where the guy ground the lock bar even with the liners and vise versa and it turned out well.
 
Stumps said:
I think you may have a hard time smoothing this spot out; :)



I watched a repair video where the guy ground the lock bar even with the liners and vise versa and it turned out well.
Click to expand...

Hahaha!! Good one Mark!
That handle is definately done for, but makes a great place to store those parts until I make a new handle :)

I sanded everything flush on this one, in the opened position.
Closed it has a very minute of the lockbar end higher, but it is very minute.





I think no matter how much I sand it flush, one position or the other would always be minutely higher than the other.
 
So for the lockbar end riding lower in the closed position than it does in the opened position....
Removing a small amount of material from the bottom of the lockbar tab, or the tang where it rests, would even things out
But messing with the tab or the tang could open a can of worms with the detente and where the kick hits the lockbar etc.
The kick might have to be sanded down too, and then the blade might ride lower in the blade well....

I would avoid messing with this aspect personally.....

 
DesertChris said:


I think no matter how much I sand it flush, one position or the other would always be minutely higher than the other.
Click to expand...

Mine is the same way. I think it looks great and I didn't want to push it further and mess it up so I quit while I was ahead.
 
DesertChris said:
Hahaha!! Good one Mark!
That handle is definately done for, but makes a great place to store those parts until I make a new handle :)

I sanded everything flush on this one, in the opened position.
Closed it has a very minute of the lockbar end higher, but it is very minute.





I think no matter how much I sand it flush, one position or the other would always be minutely higher than the other.
Click to expand...

Am I looking at it wrong because it looks the same to me in the open position as well as the closed. (lock bar riding high on the thumb press side on both)


I am certainly no engineer. I have to play with things to see how they work. Can't work stuff out like this just in my mind most of the time. :)

The video I was referring to was on a slip joint, so I can see how that would have been easier to flush up.
 
Stumps said:
Am I looking at it wrong because it looks the same to me in the open position as well as the closed. (lock bar riding high on the thumb press side on both)


I am certainly no engineer. I have to play with things to see how they work. Can't work stuff out like this just in my mind most of the time. :)

The video I was referring to was on a slip joint, so I can see how that would have been easier to flush up.
Click to expand...

The difference is definately very tiny. But you can feel it with your fingernail...:D
I sanded it flush with the knife open, so it is definately not sticking up while open :)

When I took the 2013 501 and 2013 484 and turned them into the second knife pictured, I checked the parts, and the 484 blade matched up better with the 501 lockbar, and those went into the 501 frame.

Likewise, the 501 blade and 484 lockbar matched better, so those will be put into a handle I someday will make.

Here is a 501 exhibiting the higher lockbar end when closed.
But flush when opened



 
DesertChris said:
The difference is definately very tiny. But you can feel it with

When I took the 2013 501 and 2013 484 and turned them into the second knife pictured, I checked the parts, and the 484 blade matched up better with the 501 lockbar, and those went into the 501 frame.

Likewise, the 501 blade and 484 lockbar matched better, so those will be put into a handle I someday will make.

Here is a 501 exhibiting the higher lockbar end when closed.
But flush when opened

Click to expand...

That's flush compared to what mine used to look like before I took a belt sander to it.
 
I tend to notice when a lock bar isn't flush more in pictures than I do when I'm using a knife.

I had one knife apart and there had been so much force applied to the locking end of the lock bar that it was bent a little. I straightened it out with light taps on the anvil and it was perfect again when I put it back together.

I'll have to get one of my 110's out with the bullet proof glass and watch closely to try and see what you are talking about.
 
Stumps said:
I tend to notice when a lock bar isn't flush more in pictures than I do when I'm using a knife.

I had one knife apart and there had been so much force applied to the locking end of the lock bar that it was bent a little. I straightened it out with light taps on the anvil and it was perfect again when I put it back together.

I'll have to get one of my 110's out with the bullet proof glass and watch closely to try and see what you are talking about.
Click to expand...

I completely agree..... I also think it is irelevant to the functioning of the knife, if the lockbar sticks up.


I wish I had one of those bulletproof glass ones!!
But then again, I would probably use it.....:p
 
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