Technically what is a "jack"?

T

thedaver8

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May 22, 2013
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Maybe this is just a minor thing that makes no difference in the long run, but I've been curious for some time as what is defined as a "jack" as far as knife patterns. With GEC especially, but maybe it's a more universal term? What are your thoughts on the subject and what's your favorite "jack"?
 
I'm the least qualified person I know to respond, but that won't stop me. Seems to me that a Jack has 2 blades that pivot at the same end of the knife. But maybe there is more to it than that.
 
Some definitions of 'jack knife' simply define it as any folding knife. I think the most common accepted definition is a folding knife on which all blades (usually one or sometimes two) pivot from one end of the handle only. This presumably would exclude patterns like the muskrat, moose, stockman, whittler or any others with blades pivoting from both ends.


David
 
Generally speaking, a two blade knife with both blades at the same end is known as jack knife. and generally speaking, a two blade knife with the blades at opposite ends is known as a pen knife. Just my opinion. Not meant for argument.
 
I too believe that a Jack Knife has a main (spear or clip) blade and a secondary (usually a pen) blade on the pivot end. Although I've seen single-bladed knives called a jack knife and even some knives with a blade on each end called a jack knife, I don't see them as Jack Knives.
 
I think of it as a two bladed knife with pivot on one end, but I have heard a equal end jack which had one blade pivot on each end.

I am NOT and expert.
 
The term "jack" orginally meant "short", I believe. A "jack rafter" is a short rafter. In Georgia, when I was a child playing football, the coaches used the term "jack leg" to call your attention to underperformance in some area, and that was meant to refer to what I also learned to call a "short arm".

Farther back, a "jack" was a laborer, either someone in a trade--like a lumberjack--or someone who did odd jobs. It could even refer to a sailor.

So, with no reflection on the actual configuration of the knife, I think it's plausible to think the original meaning had connotations of shortness (as compared to a belt knife) and a hard worker.
 
In Levine's Guide to Knives and their Values, 4th Edition, Bernard Levine offers this definition:

"JACK KNIFE" is a general term for the simplest form of folding knife. The standard jack knife is single-ended. Its blade or blades are hinged at one end of the handle. There are also a few large heavy-duty double-end jack knife patterns. Double-end jack knives have a large blade in each end.

Small knives with blades pivoted at both ends are called "pen knives." Tiny single-ended knives with just a short pen blade are called "quill knives." Although they are constructed like jack knives, quill knives were the original pen-sharpening knives, so they too are classed as pen knives.
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While I believe post #3 to be correct, I think its just a term used loosely today to cover
most pocketknives weather Moose, stockman, whittler no matter how many blades or where
they pivot from.
Ken.
 
Sounds like those who know a lot more about knives than I do are saying that almost any folding knife can be called a jack knife, therefore, there is no definite definition of the term.
 
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It could be that the "double end jackknives" are called that because each blade has its own spring, unlike pen knives where at least one of the springs (sometimes the only one) is used by two blades.
 
I've always thought that the name 'Jack' was linked to the heavy folding knives carried by British sailors ('Jack Tar's) in the 19th Century. While noting that the term 'Jack' can be, and is, applied to heavier single-bladed knives, what are essentially stout pen-knives, and other patterns, for me the definition has always been a two-bladed knife, with both blades at one end, as stated above.
 
A "Jack" is a devious type of Fellow, located in the U.K, found lurking around open stalls, sifting through small trinket boxes looking for old knives.
 
NeilB said:
Farther back, a "jack" was a laborer, either someone in a trade--like a lumberjack--or someone who did odd jobs.
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As in the expression 'Jack of all trades, but master of none'* :)

Though, I think the term might be closer to just a humble worker, more what we'd think of today as being semi-skilled.

I'm sure someone very learned and knowledgeable will be along in just a minute :D



* - There's some discussion about the etymology of this phrase here, though I'm afraid it adds little or nothing in terms of the original question.
 
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NeilB said:
The term "jack" orginally meant "short", I believe. A "jack rafter" is a short rafter. In Georgia, when I was a child playing football, the coaches used the term "jack leg" to call your attention to underperformance in some area, and that was meant to refer to what I also learned to call a "short arm".
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I found this http://http://www.wordorigins.org/index.php/site/jackleg_jackknife/ (not neccesarily authoratative, but of interest):

Jackleg is a U.S. southern slang adjective meaning unskilled or unqualified. The term almost certainly comes from jackleg knife (jackknife) and was probably originally used as jackleg carpenter, a carpenter with only the most basic set of tools.

The term dates to at least 1837. From the 4 March issue of Spirit of the Times from that year:

He is no more to be compared to Osceola than a jack-leg lawyer to Cicero.
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Wide variety in what can be a jack knife; in my mind the classic Jack will have two traditional style blades hinged on one end. This one is a John Primble and exemplifies the style to my way of thinking. OH

Primble_Jack_knife_11-17-2012.jpg
 
In Bricklayers lingo,the term "Jack" means one brick stacked directly over the other.
 
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