TI framelocks, what makes for a perfect durable lockup?

[REK Knives]

Has anyone thought about... A titanium insert instead of a steel one? Even if it wore eventually you could just pop another in

 

[kuraki]

Has anyone thought about... A titanium insert instead of a steel one? Even if it wore eventually you could just pop another in

The first time I saw one I thought they were just a way for a production company to machine 1,000 at nominal, 1,000 at +.001", 1,000 at +.002, etc so during assembly they could just throw in whatever length required for the current tolerance stack

 

[marrenmiller]

You should call them up and offer your services, you'd be doing us all a favor. What is the proper geometry on the tang and lock bar?

Sure shiny, I'll play.

Assuming a dry steel on steel interface, you'd need about 8.5 degrees or less relative to the lockbar contact to have the lock function without slipping. This can be estimated using a static analysis of a ramped surface, where:

Force_reaction = force_applied * cos(tang_angle) & Force_friction = Force_reaction * friction_coefficient_static -> tang_angle = inv.tan(friction_coefficient_static).

Generally, the dry steel on steel friction coefficient is observed to be 0.15 as per experimental measurements. This gives a maximum tang angle relative to the lockbar of 8.5 degrees before slipping occurs; ideally you'd want less than this. This is generally in line with the usual recommendations of 7 to 8 degrees. At the very least this is a great starting point, and can be fine tweaked as needed depending on the specifics of your system.

Feel free to vehemently disagree with all of this as per usual; I have you on ignore anyway.

 

[shinyedges]

Sure shiny, I'll play.

Assuming a dry steel on steel interface, you'd need about 8.5 degrees or less relative to the lockbar contact to have the lock function without slipping. This can be estimated using a static analysis of a ramped surface, where:

Force_reaction = force_applied * cos(tang_angle) & Force_friction = Force_reaction * friction_coefficient_static -> tang_angle = inv.tan(friction_coefficient_static).

Generally, the dry steel on steel friction coefficient is observed to be 0.15 as per experimental measurements. This gives a maximum tang angle relative to the lockbar of 8.5 degrees before slipping occurs; ideally you'd want less than this. This is generally in line with the usual recommendations of 7 to 8 degrees. At the very least this is a great starting point, and can be fine tweaked as needed depending on the specifics of your system.

Feel free to vehemently disagree with all of this as per usual; I have you on ignore anyway.

Wow! A one year expert who has the secret some of the largest knife manufacturers need! Please contact ZT and educate them!

Bummer you don't have enough self control to utilize the ignore function without clicking to show what it (the ignored content) says and responding

I love the brand new experts who don't do squat. Armchair quarterbacks sound like they have the answers 100% of the time, but let's not forget they don't make squat and are contributing hot air in their livong rooms.

 

[Spey]

ribeyemediumrare,

I read your OP and would say you have asked a lot of good questions. I plan to come back and read the thread as I am sure it will be entertaining (but I don't have the stomach for it now), but will make a recommendation for you to research as I did years ago beginning with ...

1) Find a copy of Michael Walkers (father of liner-lock) original descriptions and diagrams related to liner lock geometry (and study them for your questions). I believe you will find this also applies to frame-lock questions you have asked.

Hint: you are not going to find this info on Wikipedia, etc. You will need to search a little deeper, and will learn along the way ;-)

It is my belief many of the knife-makers of the past decades ignored a few simple principals of his original design (and my references below to geometry), and this lead to much of the issues we have seen in the past 10-15 years or so.

2) Others may have commented on this already ..., also research information related to the triangulation (as applies to distribution of force) between the lockbar contact, stop-pin, and the pivot. Ideal geometric configuration would be equilateral triangle, or a wide isosolices triangle, or as close to as possible. If you have ANY doubt about this ..., look up strongest geometric shapes as they relate to forces (pyramids still appear to be a good illustration of long lost knowledge related to triangles ;-)

3) Then consider wear surfaces involved, dissimilar metals and how they relate to each other over time and use of a design based on their desired function. There are always Band-Aids to solve design deficiencies. Better to design better to start, than to rely on things like carbidizing, etc.

4) Then inspect the wear surfaces (under magnification) of some of your existing liner/frame-lock folders (lock-bar face & tange contacts, stop-pinc contacts). Learn to know what to look for by previous example. An example to get started for you below.

Researched in that order, I believe you will find answers to many of your questions.

Here are a couple pic's of same knife (new knife with relatively few opening engagements), photo taken same day, to give you an idea of what to look for when attempting to diagnose an issue, or learn to understand what the naked eye may not see (same goes for sharpening).

This model is what I would consider a fairly well designed knife (geometry of lock design), but it had some machining related issues during production that QC did not catch. Interesting this model was know to have initial stick that sometimes would "break in" or wear-in" over time. Under heavy spine pressure loading I noted a small amount of lock slip on this one too.

What you might, or might not, see with naked eye (lockbar tange contact). Also, note the nice even stop-pin contact patch along top of tange):

Under a little magnification (lockbar tange contact patch pretty fugly):

Hopefully something helpful here to you.
Regards,