Folder opening device location

Joined
Oct 8, 1998
Messages
5,403
Well, I dont know if I am going to start a problem here, but....

Anyway, a thread is going over at KForums, and since I can't post over there, I thought I would quote the thread and reply over here.......

Folder opening device location---

Joel McNamara posted "Something that hasn't been discussed much is the location of opening devices (hole, stud, disk) on folder blades. I've always wondered why some folders (particularly pivot down, which I prefer) are quicker to open than others.

Doing some measurements, I found there seems to a relationship between where the device is positioned on the blade and ultimate speed.

While practice can definitely enhance quickness, I think much has to do with the ergonomics involved with economy of motion - where your thumb needs to move during the process of drawing and opening the knife.

I found an optimal range of placement, comparing different Spyderco folders, when drawing from the front pants pocket. Surprisingly, a half a centimeter makes a fair amount of difference.

My guess is some formula might be derived for the best position based on thumb length. I haven't played with any pivot up folders, but suspect there might also be some economy of motion issues with the pinch grip draw and deploy.

You can probably tell it's a slow day. If anything else, looking at opener placement is
an interesting exercise, and gives you a reason to pull out your entire folder collection."

Joe Talmadge replied "Hey, I'll buy that. I think one of the reasons I like pivot-down carry, besides the fact that I don't have to pinch-grip, is the fact that I can stretch my thumb out comfortably to get to the opening device. With pivot up, all your fingers start close to the pivot, and as a result non-optimally close to the opening device. So there's always a bit more scrinching with my thumb on pivot-up draw.

I hadn't thought about it much, but that is part of the reason I find pivot-up draw a bit more awkward." jat@cup.hp.com

Steve Harvey replied "Generally, the closer the opener is to the pivot the faster will be the opening. The thumb has a shorter arc to travel, and the opener will be in a more mechanically efficient position, re the moment arm to the pivot, when the knife is closed.

Help me out with this, DC! "

madpoet replied "Moving the opener closer to the pivot will make it work faster, unless you get to the point where you lose so much leverage that you can't overcome the ball detente, pivot tension, or in some cases, the backspring on a mid or back lock with a blade opening button, etc.

Joe T mentioned a Mullin folder in another post that has a backspring and a blade button. The one I had was a bit stiff, and opening seemed to be hindered in part because of the closeness of the button to the pivot, but also because of how deep the small button was buried up against the finger cutout in the handle scale.

Moving the blade opener further out on the blade will increase the leverage, but make your thumb describe a longer arc opening the blade. Its a fine line, since I personally like the blade button/disc as close to the pivot as possible to get it out of the way of as much of the cutting length of the blade.

I tried once replacing the guard on an old Al Mar Gameskeeper with a small blade button, but it was so close to the pivot I couldnt' get enough leverage to move the blade easily.
Attaching a small 'lever' that moved the button about 1/4" forward on the blade made a world of difference in how it opened."

This is what I wanted to contribute------

The device being closer to the pivot does help. And pivot-up carry also seems to include an extra move, since with the pivot-down your hand is already wrapped around the knife.

Another consideration is the Microtechs and Microtch derivatives where there is no stop pin, and the thumb stud fills that role against the bolster, in that case, hopefully the engineering has put the stud in an optimal position.

I think the type of device affects performance as well. With different devices you can apply different amounts of force and with holes the device is bigger allowing for minute adjustments in angle and such. Where a stud allows only a certain vector.

In addition to overcoming tension caused be various springs and detents, blades with greater width change the dynamic.

The device I would like to see is an elliptical (eye) shaped device, given my experience with blade holes and my observations of the thumb, it seems to me that the ellips would give a low profile/high utility shape."



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Marion David Poff fka Eye, one can msg me at mdpoff@hotmail.com

Patiently waiting for the Spyderco SpydeRench, Lum Chinese Chopper Folder, Rolling Lock, Benchmade M2 Axis, M2 Axis AFCK, M2 Pinnacle and the REKAT Escalator and Pat Crawford Design.

"The victorious Warrior wins first and then goes to war, while the defeated Warrior goes to war and then seeks to win" Sun-Tzu














 
Joined
Oct 2, 1998
Messages
438
Well, the things you mentioned are right I think. Opening device placement closer to the handle produces a smaller length arc to travel through. And then of course, too close isn't good either, cause then there isn't enough leverage to easily overcome the detent or lockback spring or whatever. However, I don't think you can "make a formula" like you can for calculating perspective ratios. Because everyone's thumb/general hand mechanics aren't the same. And, as you said, the smallest variation can make a difference on the action of the knife. I suppose the best knife makers can do is 'play the odds', that is, make placements for 'average' hands. Or, make different knives with different configurations. Aw heck, get a fixed blade
smile.gif

 

SB

Joined
Oct 4, 1998
Messages
637
*Frasier mode on*

"Oh for Pete's sake just snap that thing open!"
biggrin.gif


*Frasier mode off*

BTW, why can't you post over there? If you wish, email me instead.

[This message has been edited by SB (edited 10 December 1998).]
 
Joined
Oct 7, 1998
Messages
1,838
Eye; you little weasel, you are not trying to compete with me for the 'most forums banned from' status are you??
smile.gif
Walt
 
Joined
Oct 14, 1998
Messages
89
Walt:

I sincerely doubt that anyone would accept the fool's errand of trying to oust you from your amazing lead in "number of forums banned from" status. Yours is the stuff that legends are made of
wink.gif


Humorous regards--Shades
 
Joined
Oct 8, 1998
Messages
5,403
I do not know for certain why I am banned.

I have e-mailed Earl and got no reply.

But I surmise it is because I said some strong things to one of the moderators.

I miss it every now and again, but usually the content wanders over here. That is if the content was not already over here.

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Marion David Poff fka Eye, one can msg me at mdpoff@hotmail.com

Patiently waiting for the Spyderco SpydeRench, Lum Chinese Chopper Folder, Rolling Lock, Benchmade M2 Axis, M2 Axis AFCK, M2 Pinnacle and the REKAT Escalator and Pat Crawford Design.

"The victorious Warrior wins first and then goes to war, while the defeated Warrior goes to war and then seeks to win" Sun-Tzu














 
Joined
Oct 8, 1998
Messages
5,403
Walt, no I can't compete with you, you are like a plank owner of the banned...

SB, who knows, I may take you up on that.

MDP
 
Joined
Oct 7, 1998
Messages
1,838
MDF; I apologize for the 'little weasel' remark. It is just that you posted the very day that Mad Dog told me I could post on KFC again. I regret my hasty reaction; upon reflection I realized that it wouldn't take much to get banned again, so my fears were groundless.

I do think you should clarify your decision on this, however, as there is a certain cachet to being banned from KFC. Further, if you are indeed banned, and see where the posters over there are hopelessly confused, simply e-mail one of them. Check their tests of survival knife, where they were floundering, until I sent Sid Post a cogent, definitive answer, which he posted, crediting me.

Once again I apologize for the remarks I made, and will try to conduct myself with more restraint in the future. Walt Plank owner, KFC BANNED.
 
Joined
Oct 8, 1998
Messages
5,403
Don't apologize, I cherish that 'little weasel' remark, in fact take your apology back, I can be a little weasel sometimes, even though most of the time I would best be described as an "enraged wolverine".

Yeah, I have been doing my best to contribute through e-mail.

One generous soul was going to go to bat for me with Earl, but this is probably for the best, my iconoclastic tendencies tend to make me a guerilla.

Anyway, what do you think of an elliptical shaped hole opener??????

Skip restraint, I like the raw you.

Walt Welch, among the eggshell walking, formerly a stomper....... GOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOD LUCK

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Marion David Poff fka Eye, one can msg me at mdpoff@hotmail.com

Patiently waiting for the Spyderco SpydeRench, Lum Chinese Chopper Folder, Rolling Lock, Benchmade M2 Axis, M2 Axis AFCK, M2 Pinnacle and the REKAT Escalator and Pat Crawford Design.

"The victorious Warrior wins first and then goes to war, while the defeated Warrior goes to war and then seeks to win" Sun-Tzu














 
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