Slipjoint pull scale

[xceptnl]

Can someone please point me to a resource to learn more about the pull numbers (scale) for traditional slipjoints. Thanks in advance for helping out a NOOB.

 

[black mamba]

In general, a 10 is practically unopenable, a 1 nearly flops open, and a 5 is what the average Swiss Army Knife is for the main blade. Most people seem to prefer something from 5-6 with some preferring a stouter 7-ish. 8 gets to be awfully firm and 9 is a nail breaker. Some people do like softer pulls, but 3 and below are pretty frowned upon.

 

[sitflyer]

http://www.bladeforums.com/forums/s...raditional-Pull-Scale?p=11294981#post11294981
as you will discover by reading the linked thread, this can be a very difficult criteria to nail down, as each persons own interpretation of such a tactile thing can vary wildly...still, Confucius37's scale made sense to me anyways.

Another member sent me a message remarking that he liked the pull scale I put on my sale thread. I thought I'd put it out there for everyone to see here and get some opinions/suggestions.

The values on the scale are just what made sense to me, so everyone's scale could be different, but maybe we can come up with something that most people can agree on? The one thing I did try to do was make sure 10 and 1 included the most extreme cases as most everyone can relate to a knife being impossible to open without tools and one that simply does not stay closed at all.

The Scale:

10 - unable to open by hand
9 - able to open but breaking a nail likely
8 - able to open but very stiff, tough for edc use
7 - firm pull, edc range
6 - ideal edc range
5 - nice for secondary blades, tad light for a main blade
4 - starting to get too light for use
3 - maybe acceptable on very old knives
2 - barely closes
1 - does not stay closed

 

[knarfeng]

There is no official posted scale.

Jeff's answer is about what I keep in mind. We set an SAK pull as the midpoint and compare to it. Like everything else about the SAK, the opening pulls are very uniform and make a good "middle of the road" benchmark for effort needed to open. Plus, almost everyone has an SAK, so everyone has a standard in their possession.

So
1 means just enough pressure that the blade does not flop open on its own.
5 means about the same as an SAK main blade.
10 means the average fella can't open it with a fingernail.

Any numbers in between those are an interpolation.
(I know that the concept of interpolating is hard for the digital generation to figure out, but those of us who remember slide rules and meters with dials all remember how to interpolate between numbers.)

 

[Bigfattyt]

I like 8-9 (when new). I find all of my folders seem go get a bit easier over time. Maybe it is just that they smooth out. What I consider a nice 8, many consider unopenable. I handed my friend, a 6'6" former swat officer a knife I consider a 6-7 and he handed it back with a torn nail, and called it un-openable. I opened it with my pinky for him.


No one is going to feel the same about the pull on any given knife.

 

[rma100]

Just a little off topic with my apologies. The act of opening a slipjoint knife also has a lot to do with technique. I have no problem opening any knife I've ever handled, and there have been many. I, too, have easily opened knives that others needed some type of tool to open. I can not readily describe this technique. Physics has a lot to do with it. A short, thick blade such as a GEC 26 will be harder to open than a long thin blade such as a GEC 92. To a certain degree, the spring must match the thickness of the blade. Placement of the nail knick or pull on a blade will also affect the pull strength necessary to cam the blade. I.E., placement of leverage. Some famous person once said " I could move the Earth with a lever that was long enough. I think that TECHNIQUE can somewhat help to minimize the effects of construction when opening a slipjoint. In short, one persons 10 could be a 7 to me because of technique.

 

[jomarti]

Not to get too far off the op's question but will continued use make an 8 pull lesson over time? My GEC 73 pattern is tough and I attribute that to thickness and temper of the back spring so I wonder if using and/or opening the blade to "1/4 or 3/4 cock" will reduce the pull.

 

[rma100]

It will, as many others have posted before, a thorough cleaning of the pivot joint will also help.

 

[xceptnl]

Thank you to all for the replies. I hear the terminology frequently in this corner of BF and wanted to educate myself. I don't have very thick fingernails and often that are cracked or split so a lighter pull works better for me. The alternative to this is a stronger pull (which I would prefer) with an easy pull cutout or a wharncliffe blade that protrudes from the handle to allow a pinch opening. Thank you again guys!

 

[pmew]

In short, one persons 10 could be a 7 to me because of technique.

Very true, I have watched people struggle in the past and then succeed following a "no, try holding it here" prompt.