Cross-post of a little piece I wrote for Bladeforums.

[Spoonrobot]

I wrote this for the guys over at bladeforums since most of them seem like drive-by hobbyists who don't look close enough. I'm curious what you guys think, I have never seen this mentioned anywhere so I'm wondering if I got the names right or if there is more to the system.

This post excludes the Juice and Squirt series, the Crunch, and the Micra. It includes every other Leatherman tool model.

Hello, I have been a multitool hobbyist for years and have noticed a particular behavior in regard to Leatherman tools. There seems to be some confusion about how exactly most full-size Leatherman tools operate in relation to the tension of the plier pivots and the handles.

This is an issue I had never really thought about until recently, having seen it dismissed numerous times as the mysterious "pivot tension." This phrase and explanation of how Leatherman tools works is incorrect, most recently rearing it's ill-informed head during a recent thread about the Leatherman Core. It is thought that the interplay between the tightness of the pivot pins and the plier pivot hole is the reason the pliers on Leatherman tools remain open and useable. It was suggested that due to plastic handle inserts on the Core the useable life of the tool was reduced because the plastic would wear much more quickly than steel due to friction/rubbing of the steel plier pivots against said inserts. Of course, this is not true, the Core will live a long and healthy life no matter how much plastic wears away from the liners.

 It is my intent to explain exactly how they actually work.

First we must begin with the overall system. Leatherman tools unfold in a "butterfly manner." Grip the handles and rotate them outward and the force required to swing the handles increases until they "lock" into place and allow the pliers to be used in a manner similar to a full-size tool. It was long thought by many that the increasing force was caused by the pivot pin tightness and that as the pivot pins loosened the tool would become loose and eventually the handles would swing freely, reducing the useability of the pliers greatly. Upon disassembly of a PST and a Blast it was noted that the pivot pin tension has no effect on the effort required to open the tool and even with only the barrel bolt inserted the Blast would open in the regular manner.

Upon closer inspection it is noted that there are increasing friction ramps around the pivot holes of the pliers. Seen from the side below, note how the thickness of the ramps increase as they move from the outside of the pivot hole towards the plier joint. This ramp is the essential means of holding open the pliers on Leatherman tools. Note how the thickness increases as you move along the ramp from point 1 to point 2. (All of the following pictures are from the Leatherman Blast.)

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Here is another view showing the effect the ramp has on the handles. Note the wear spot at point 2.

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On most tools a small protrustion (point 1) can been seen on the back of the handle when the pliers are opened. This is most obvious on the Leatherman Core, pictured below.

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Now, this system has always been in use but the friction ramp varies by model and year. The original PST uses the same system but the increasing thickness of the ramp is hard to see and and the ramp itself is actually built into the area around the pivot hole and is hard to discern. Below are some of the different variations. All current tools use the same pointed ramp as seen on the Kick, apparently this is the current level of refinement found by Leatherman engineers and allows the simple blade locking mechanism seen on the Wave, Charge and Surge to work.

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So there is the explanation. Leatherman tools are held open by a friction ramp around the plier pivot pin hole, not by tension of the pivot pins. An interesting little system that works well.

Note No.1: This system is also implemented on some Bear MGC tools. There is no ramp on the Bear tools but the plier pivot area is not entirely rounded and features a flat spot that serves as a friction ramp. This is actually most similar to the PST ramp.

The Bear Jaws is on the right, the friction spot is labeled point 1. Sidebar: Not the differeing thickness of the Leatherman Kick handle (on the left, point 2) and the Bear Jaws (point 3). This thickness causes the Bear Jaws to be significantly harder to open but much more resistant to jamming. It may cause more wear than the Kick but may be more sturdy.
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[prime77]

Really interesting stuff Spoonrobot. I'm glad you posted here. I don't frequent bladeforums.

[Grant Lamontagne]

Soon you'll be writing stuff for here then copying at BF!

Hey, a guy can dream, can't he?

Def

[Spoonrobot]

Soon you'll be writing stuff for here then copying at BF!

Hey, a guy can dream, can't he?

Def

This place is my main posting forum because it is a really solid collection of light to heavy hobbyists and has the best technical information anywhere. Don't worry about missing too much in the future!

I had to post this piece over there because sometimes they are so clueless of the stuff we take forgranted. I don't expect to get a lot of replies but the more people see it the better.

I really feel like I exposed a multi-tool King Tut. Did anyone else know about this?

[prime77]

Before this post I never really realized the little tabs as a friction ramp.  I think it's interesting the way LM implemented a safety feature on the Charge, Wave and Surge models where the ramp moves a little tab that locks the two outside blades from opening up when you flip the pliers open with one hand.

[Spoonrobot]

I think it's interesting the way LM implemented a safety feature on the Charge, Wave and Surge models where the ramp moves a little tab that locks the two outside blades from opening up when you flip the pliers open with one hand.

Exactly! It's an idea that is wonderfully implemented; it is out of the way, peforms it's job well and is an important safety feature for a modern tool.

[NeitherExtreme]

Good write-up! 

Did anyone else know about this?

A while ago I had figured this out looking at my Charge. I like understanding how every part works (the nerd part of me). It is easy to see with the Kick/Charge/etc type pliar heads, but once I realized what was happening I could see it on the other models as well. It's kinda like a slipjoint, but with the spring- just friction.

[J-sews]

Great stuff Spoon! Nothing gets the ol' gray matter churned up better than tearing something apart and then having to put it back together! I took a Charge completely apart last week, then it took me three tries to get it back assembled correctly.    A person learns a bunch from doing that though.

[Grant Lamontagne]

It's one of those things that I have often looked at and filed away for further inspection when time permits, but never got around to.  The little ramps have caught my attention on many occasions.  I'm glad to finally have some detailed pics and a serious explanation for them!  Once we have a section on the main site for this kind of stuff I think I am going to have to post it there if you don't mind.

Def

[I'm Still Bison]

Spoon..2 thumbs way up !! I was reading the exchange going on BF...GOOD JOB! You got  two of BFs heavy hitters impressed.