Watu lock stick (or lockstick)

[nightoil]

So it applies to the PM2 and Shaman as well. You diagnosed the same cause - locking depth.
And you managed to bend the lock bar the exact amount needed.
I didn't need to go that far but really interesting to hear that it worked for you!

Yes it seems like the issue is found in a wide variety of compression lock knives unfortunately. With such tight tolerances I guess it should be expected. Thankfully I have always been able to fix it one way or another. Sometimes it just needs some break-in, others need more invasive procedures. Usually it's relatively easy at least.

How much trial and error did it take you to get the lock bars bent the exact amount needed on your DLT PM2 and Shaman? As I said, I haven't tried that yet. I mean, if it could be got really accurate, I wouldn't have to mess with the L-side pivot screw at all.

It would be really interesting to know how they go about this in the factories. They've got to aim to get it right first time on thousands of knives.

It'd be fascinating to hear Sal's take. He will have been wrestling with the problem ever since... well, since whenever the first compression lock came out. Sadly, I don't imagine he's going to start creating a new can of worms for himself telling us how to take his knives apart and tweak them interiorly!

Took a few tries the first time, it was my last resort. Didn't want to fubar anything so I was extremely careful. The first time I reassembled it felt better, but still bad, so I disassembled twice more and kept going until it was all but barely gone. The rest disappeared with break-in. The shaman was much more simple, got it on the first try. Also seemed to help with the action significantly, as the shamans seem to have a small issue where the scale prevents the lockbar from moving over more, leading to a stiff closing. I've seen people dremel out scales for a similar effect

Well, that's very interesting. More or less as expected - difficult to get right in one go.

It may be that one doesn't want to over-bend the lock bar. I've got this idea in my head that repeated bending alters a metal's grain structure, progressively making it less springy. (Could be complete tosh - I'm not a metallurgist.)

My Watu situation is that the L-side pivot screw adjustment remains minimal to remove lock stick - barely 1/16 turn from tight. So I really don't need to bend the lock bar at the moment.

Yes, I can visualize the problem with the Shaman and the struggle to unlock. It's a pain (literally) having to fight with your fingers to get a knife to do what you want. The Watu's lock bar edge in the finger press area was too sharp for comfort. Had to grind it down to a rounded profile and then polish it to a "comfortable" shine.

curlyhairedboy's suggestion to lightly lubricate the stop pin's underside seems good since the lock bar tab's top face does have to slide along it during unlocking. Whereas lubricating the lock bar / tang interface doesn't help (or make any difference), as far as I can see. The interface is different - basically wedge-shaped or sloping, i.e. a friction hold.

This is possibly why locking depth matters. Keeping a microscopic gap between the faces prevents lock stick but maintains locking, without PERCEPTIBLE lock rock.

I actually use strong sewing thread as a thread locker - less messy than Loctite. You just lay a length of thread across the pivot screw hole, poke the center down into the hole, screw in the screw until the blade action is correct and nip off the thread ends. Allows for adjustment but not spontaneous loosening.

[JRinFL]

Yes it seems like the issue is found in a wide variety of compression lock knives unfortunately. With such tight tolerances I guess it should be expected. Thankfully I have always been able to fix it one way or another. Sometimes it just needs some break-in, others need more invasive procedures. Usually it's relatively easy at least.

How much trial and error did it take you to get the lock bars bent the exact amount needed on your DLT PM2 and Shaman? As I said, I haven't tried that yet. I mean, if it could be got really accurate, I wouldn't have to mess with the L-side pivot screw at all.

It would be really interesting to know how they go about this in the factories. They've got to aim to get it right first time on thousands of knives.

It'd be fascinating to hear Sal's take. He will have been wrestling with the problem ever since... well, since whenever the first compression lock came out. Sadly, I don't imagine he's going to start creating a new can of worms for himself telling us how to take his knives apart and tweak them interiorly!

Took a few tries the first time, it was my last resort. Didn't want to fubar anything so I was extremely careful. The first time I reassembled it felt better, but still bad, so I disassembled twice more and kept going until it was all but barely gone. The rest disappeared with break-in. The shaman was much more simple, got it on the first try. Also seemed to help with the action significantly, as the shamans seem to have a small issue where the scale prevents the lockbar from moving over more, leading to a stiff closing. I've seen people dremel out scales for a similar effect

Well, that's very interesting. More or less as expected - difficult to get right in one go.

It may be that one doesn't want to over-bend the lock bar. I've got this idea in my head that repeated bending alters a metal's grain structure, progressively making it less springy. (Could be complete tosh - I'm not a metallurgist.)

My Watu situation is that the L-side pivot screw adjustment remains minimal to remove lock stick - barely 1/16 turn from tight. So I really don't need to bend the lock bar at the moment.

Yes, I can visualize the problem with the Shaman and the struggle to unlock. It's a pain (literally) having to fight with your fingers to get a knife to do what you want. The Watu's lock bar edge in the finger press area was too sharp for comfort. Had to grind it down to a rounded profile and then polish it to a "comfortable" shine.

curlyhairedboy's suggestion to lightly lubricate the lock pin's underside seems good - the lock bar tab's top face does have to slide along the stop pin during unlocking. Whereas lubricating the lock bar / tang interface doesn't help (or make any difference), as far as I can see. The interface is different - basically wedge-shaped or sloping, i.e. a friction hold.

This is possibly why locking depth matters. Keeping a microscopic gap between the faces prevents lock stick but maintains locking, without PERCEPTIBLE lock rock.

I actually use strong sewing thread as a thread locker - less messy than Loctite. You just lay a length of thread across the pivot screw hole, poke the center down into the hole, screw in the screw until the blade action is correct and nip off the thread ends. Allows for adjustment but not spontaneous loosening.

Another solid tip! Thank you.

[nightoil]

Thanks again, JRinFL!

[nightoil]

I'm posting these photos to show the near-fatal damage I did to the lock bar and tang locking faces in trying to solve the lock stick problem (before realizing that it's locking depth that's the determining factor).

As I've already said, smoothing off and polishing the locking faces had NO beneficial effect in eradicating lock stick from this knife.

If anyone else is minded to remove metal from these parts, compare your unaltered part to these first.
On these, I definitely think I went too far (and for no gain).

Luckily, I just got away with it without writing off the knife, i.e. creating permanent lock rock.
In fact, the knife is running well now. Lock stick can be dialed in or out with the pivot screw alone.

Moral: be very wary about removing metal.
You may end up down a very sad rabbit hole!

[nightoil]

A well-made knife - easy to take apart and reassemble.
The pivot bushing adds smoothness and stability.
All screws on both sides thread into the pivot pin / standoffs.
All the latter have flats mating with D-holes in the R-side liner.
Pivot adjustments can be with either pivot screw.

For reference - the Watu dismantled:

[ChrisinHove]

Interesting thread. My Watu is a firm favourite. It’s quirky looks belie it’s qualities as a cutting tool.

I hadn’t realised it had a pivot bushing, but that explains it’s fantastic, albeit lightweight, action.

[nightoil]

ChrisinHove, quirky looks = a futuristic Delica, maybe?!

I know they divide opinion but I'm OK with the carbon fiber / G10 laminate scales. They do lean towards gentleman's rather than tactical - but they feel good in the hand and seem to wear well.

Specifically on why they went with laminate rather than full CF, Sal said (16 Jan 2020):
viewtopic.php?f=2&t=85773&start=20
"I guess we can listen to you complain about the CF laminate or the high price? Methinks the higher price is a bigger problem, so we go with the laminate."

Integral to the Watu from the start, the pivot bushing is part of Spyderco's CQI (continuous quality improvement) program, which includes not necessarily waiting for new model designations before implementation. So literally continuous. A forward-thinking and customer-oriented company, I would say.