Just what is Jack Knife?

[kootenay joe]

"Stoutness" is the deciding factor when size could go either way. In general a Jack is over 3 1/2" and a Pen knife under 3 1/2". So what about a 3 1/2" knife with a blade at either end ? Well, if 'stout' like a Canoe, then Jack knife, if more slender, less 'robust' like a Senator then it is a Pen knife.
Because knives come in so many patterns no one definition can cover all. I mentioned 'robust' because just using size and blade placement leaves too many knives not clearly in either Jack or Pen groupings. Take into account how 'robust' a knife is and many in the uncertain group can then be put into either Jack or Pen groupings.
What is "robust" ? A judgement call for sure, so think of intended use: gent going to office, or city park to eat apple on lunch break (you get the idea) = Pen knife; worker going to work on land, factory, etc = Jack knife.
My examples are hokey but the idea is a Jack is built to allow for some force to be applied when cutting, but less so for a Pen knife.
A good thread might be "Jack or Pen ?" in which you post a knife which could possibly be in either group and get the opinion of other AAPK'ers.
Good idea ?
kj

[LongBlade]

Interesting discussion.... I do agree there are 3 major categories - Jacks, pen and multi-blade. Overall I think Levine did a good job in categorizing knives without making it unwieldy though I sometimes don't necessarily agree with his take on certain patterns in terms of attributes..

To me jack knives are one of the major categories under which many knife patterns may be relevant or more accurately actually fall under that heading. I would say they do not need to be stout or large - and also jack knives can be single or double bladed. Boys knives are jack knives and many are just +/- 3". Blades may also not be necessarily pivoting on the same end. Double-End jacks are a good example and have the blades not off the same end but indeed are under the jack knife category. In a sense this is like taxonomy with major categories or families and many subspecies. Finally perhaps the definition is somewhat related to functional utility as well though that may also cloud the definition to a degree - KJ just noted that right above this post....

Just my 2 cents and opinion...

[Paladin]

Historically and traditionally we have relied on Levine. Why not do that now?

From BRL IV, page 167:
"Jack Knives are relatively plain sturdy knives. Standard jack knives are single ended: they have their blade or blades hinged at one end. There are also a few styles of stout double-ended jack knives."

Ray

[FRJ]

and a Toothpick is clearly not stout.[/quote]

It seems all my Case knives named jack knife are more of a workhorse than others
( eg Eisenhower, pen, toothpick) Bob[/quote]

I think the Toothpick, while not necessarily stout, could be a real workhorse and thus fall under the heading of "Jack knife"
As in " I've cleaned a boatload of Jack Rabbits with that thing".

[kootenay joe]

I used the word "stout" because it is what BRL used. I interpret "stout" here as used more in Britain, to mean sturdy, solid, not flimsy. "Stout" can also mean getting towards fat, but that is not the intended meaning when describing a knife as "stout".
A single spring knife with steel handles would be slender while still being 'stout', i.e. stoutly built.
kj

[Tsar Bomba]

I find myself largely in agreement with the prevailing wisdom and definitions in this thread so far. A couple thoughts:

I never did really consider the "stoutness" of a knife to be a factor in its naming but you folks make a good point that most jacks are big, sturdy knives. The grey area comes when I start thinking about the medium-length, smaller-bladed knives pivoting on one end, such as the SR62087 I carried all week long. It's 2 7/8" long on the nose and it has a Turkish-style clip instead of the typical standard clip or spear, but I still think of it as a small jack knife. What do you folks think?

1980 Case SR62087

It drives me nuts to see moose/improved muskrat style knives/large 2-blade cigars referred to as "Texas jacks" or "equal-end jacks". A Texas jack is exactly what I think of when I see knives like the OP's avatar photo, and an "equal-end jack" is basically like the #54 Big Jack I carried most of this week. So what would we call something like the Queen NKCA cigar (around 4 1/4", 2-spring spear+pen, a good pile of knife)? A "cigar jack"? A "large pen"? Maybe just a "cigar"? These are the edge cases which make questions like this interesting.

1982 Case 6292

1981 Queen NKCA club knife

2017 GEC 54 Big Jack

I see single-blade serpentine jacks (my preferred nomenclature) referred to all the time as "stockman" or "single-blade stockman" (and knives I'd consider a serpentine pen "half-stockman"). I prefer to reserve that name for the multiblades we know as stock knives.

Oh, and re: English jacks -- aren't the Schrade 2OT and the like considered "English jacks"? That's a two-blade clip+pen configuration but "English jack" is the only name I've ever really heard used. Plus it looks so much like other knives by GEC and Queen branded "English Jacks". Perhaps I'm way off the mark on this one...

Any other grey areas you folks can think of that have given you pause in the past?

Edit: To add some pics and fix some errors.

[Mumbleypeg]

I find myself largely in agreement with the general tone of the thread and its definitions. A couple thoughts:

I never did really consider the "stoutness" of a knife to be a factor in its naming but you folks make a good point that most jacks are big, sturdy knives. The grey area comes when I start thinking about the medium-length, smaller-bladed knives pivoting on one end, such as the SR62087 I carried all week long. It's 2 7/8" long on the nose and it has a Turkish-style clip instead of the typical standard clip or spear, but I still think of it as a small jack knife. What do you folks think?

38729624354_270ec926bd_k.jpg
It drives me nuts to see moose/improved muskrat style knives/large 2-blade cigars referred to as "Texas jacks" or "equal-end jacks". A Texas jack is exactly what I think of when I see knives like the OP's avatar photo, and an "equal-end jack" is basically like the #54 Big Jack I carried most of this week. So what would we call something like the Queen NKCA cigar (around 4", 2-spring spear+pen, a good pile of knife)? A "cigar jack"? A "large pen"? Maybe just a "cigar"? These are the edge cases which make questions like this interesting.

I see single-blade serpentine jacks (my preferred nomenclature) referred to all the time as "stockman" or "single-blade stockman" (and knives I'd consider a serpentine pen "half-stockman"). I prefer to reserve that name for the multiblades we know as stock knives.

Oh, and re: English jacks -- isn't the Schrade 2OT and the like considered "English jacks"? That's a two-blade clip+pen configuration but "English jack" is the only name I've ever really heard used. Plus it looks so much like other knives by GEC and Queen branded "English Jacks". Perhaps I'm way off the mark on this one...

Any other grey areas you folks can think of that have given you pause in the past?

Your post is a pretty good affirmation of why we collectors need someone like Bernard Levine to keep us straight on definitions. Levine is widely acknowledged as a foremost authority and has authored several books on the subject. But folks still have their own differing opinions. And eBay is a virtual cesspool of misinformation!

For the average person definitions from Websters, Wikipedia, or other generic resources are adequate. For knife enthusiasts, we need more detailed information, more differentiation, and definition of subtle differences that are a "don't care" for others. And that is what Levine has provided.

Ken

[kootenay joe]

I see single-blade serpentine jacks (my preferred nomenclature) referred to all the time as "stockman" or "single-blade stockman" (and knives I'd consider a serpentine pen "half-stockman"). I prefer to reserve that name for the multiblades we know as stock knives.

The single blade version is still referred to as a "Stock" knife because it has the Stockman frame.
All of the knives shown 2 posts above are Jack knives. A 2 spring knife with blades at the same end is still a Jack even if under 3 1/2"; i.e. the definition of Jack or Pen is 'soft', not hard and fast. For example a 4 blade Senator has 2 springs & 4 blades yet is still considered a Pen knife because it is a dressy pattern not a hard work knife.
Many knives do not have all the criteria of a Pen or a Jack so you must decide which features are the dominant ones & then name it accordingly.
kj

[Old Hunter]

Thank the Lord I still have my eyes - call a knife anything you want (or call it what an inspired e-bayer labels it, or call it what a great cutlery company marketing department labels it). I can still look at the knife and label it as I see it (with spirited guidance from the pundits here and from the heavenly inspired works of Mr. Levine)! OH

[Paladin]

Thank the Lord I still have my eyes - call a knife anything you want (or call it what an inspired e-bayer labels it, or call it what a great cutlery company marketing department labels it). I can still look at the knife and label it as I see it (with spirited guidance from the pundits here and from the heavenly inspired works of Mr. Levine)! OH

Amen, OH!

Ray

[Tsar Bomba]

Question of the day for this thread:

Would you call this a jack, a single-blade stockman, or both?

[FRJ]

I'd call it a serpentine jack.

[jerryd6818]

I'd call it a serpentine jack.

+1

[tongueriver]

I'd call it a serpentine jack.

+1

X2

[Old Hunter]

Yep, that's a Jackknife! OH

[kootenay joe]

It is a Jack knife based on size & intended use even though it is a single spring knife. Then if you want a more specific name within the very large Jack category, it is as stated above, commonly referred to as a Serpentine Jack. It could also be called a Single blade Stock knife.
If you don't have "Levine's Guide to Knives" 4th Ed. get one on the secondary market. This book has greatly enhanced the satisfaction & enjoyment i get from my knives. Before 'LG4' i had a huge pile of knives. After reading LG4 my knives became more like individuals with a name, history & lineage.
kj

[FRJ]

What feature of the knife in question evokes the term Stock or Stockman?

[tongueriver]

What feature of the knife in question evokes the term Stock or Stockman?

I am assuming the serpentine frame calls up that title with some folk, but not me. Meanwhile, I found this on Ebay this morning; I found it vaguely amusing and vaguely disturbing. Ah, well... don't sweat the small stuff.

[FRJ]

Which takes us back to our first posts and the common use of the term "jack knife". (no mention of the word "stock")

At least they didn't leave the blades open for display.

[kootenay joe]

"Stock" knife because it is the same frame as used to build a Premium Stockman knife ("Premium = full size, serpentine).
kj

[Edgewise]

If you think this topic is fun, just wait till someone starts a topic called " Just what is a Bowie Knife"?
Not me! I don't want that responsibility.
btw, who was Jack again?
As good a way as any of determining what a jack knife is is to have each AAPK member post a single picture of a "jack knife" and see what comes up the most. After all, language usage evolves and yesterday's jack knife is not necessarily today's jack knife.

[TwoFlowersLuggage]

I take a more practical approach - if there is a picture in the ad, then I don't care what you call it - I just know what I like...

[Old Hunter]

These are Jack Knives, and classified by the manufacture as such. Both are built on Stockman frames (47 pattern - Premium frame, and 75 pattern - large frame), but each only has one Clip blade. OH

[Steve Warden]

Been reading with interest, always trying to learn.

I'm a simple guy - if the blade(s) fold into the handle and is carried in my pocket, it's a pocket knife, or just knife. Most people I interact with during the course of my days have no clue of the various patterns, nor do they care.
Now when I go to a knife show, or making a post here, I'll get more specific with the pattern.

It's your knife. Call it what you want.

[Tsar Bomba]

With all the pictures and the various viewpoints on knife terminology, this is a very enjoyable thread!I It has inspired me to go digging through my pile looking for interesting variations on the venerable jack knife. I rediscovered this ~4 1/8" Delrin-handled Kabar single-blade jack which I believe was made by Camillus (although I am nowhere near sure of it):

The interesting thing about this knife is that it might not have started out life as a single-blade. For one, the notch on the pile side handle makes no sense on this knife as there is nothing to open on that side. Furthermore, if you inspect the blade closely you will see that it isn't crinked but it appears to be asymmetrically ground to sit on a single spring with another blade pivoting from the opposite end. However, the blade well at the non-pivot end is rounded and does not make any room for a blade on that side.

Could this knife be a reassembled large double-ender or even stockman with a low-rider spey blade/punch? Unlike my confirmed Camillus-made Kabar knives, there is no model number on either side of the blade (perhaps further evidence that this was once a multi-blade). Since Kabar wasn't making knives in Union at the time this knife was manufactured, I have to assume it's a contract knife. In my mind, it would be weird for a cutler to send contract knives out the door with blades ground in this fashion and notches where none needed to be...

Any other "curious jacks" showing up amongst your piles, AAPK?