Jig/Fixture

1. How Woodworkers Define Jig

2. Jig, Fixture, Guide, Template, Pattern, Form

3. Definitions from General Dictionaries

4. R J Decristoforo: Master Among Jig Makers

5. In Metal Working, Jigs Are Given Great Emphasis

6. In Woodworking Writing, the Concern for "Defining" Jig is Not Pronounced

7. Jigs An Example of "Bottom-Up" Nature of Woodworking

Sources

1. How Woodworkers Define Jig/Fixture

"A jig is a device that holds the work and guides the tool...; while a "fixture simply holds the part as it is being worked" For the woodworker, a jig is an on-the-spot device created to make the cutting or shaping of a part the wood in a project either more safe, more efficient, more accurate, more rapid, or any of a multitude of other reasons.

"Jigs are getting a lot of attention these days, to the point of being commercialized" R J De Cristoforo The Ultimate Jig Book. Cincinnatti: Popular Woodworking Books, 1999, pages [6-7] See Sources

More than any other tool or technique in the woodshop, jigs and fixtures demonstrate the "bottom-up" aspect of woodworking; that is, it is a truth that the majority of woodworking devices created result from woodworkers solving a problem on the the floors of their shops: It could have been seeing that a single-edged chisel would be made more efficient by having a series of edges, and thus the first multi-toothed hand saw was conceived. Or, that by filing a profiled-edge on a plane's iron, and creating a decorative molding. And a multitude of other ideas about doing a woodworking operation more effieciently, more safely, etc. Jigs are devices which are laid over the object to be manufactured to act as a guide to the tool being used to shape it. They are used in order to produce identical dimensions in repetition work. Source: R A Salaman; Dictionary of Woodworking Tools, ca. 1700-1970, and Tools of Allied Trades Newtown, CT, U.S.A. : Taunton Press, 1975; rev ed.1990.

For early historical development, these topics covered in W L Goodman's The History of Woodworking Tools London: Bell, 1964. See also Sources section at the end of this page. I have discussed the evolution of the woodworker's cutting edge in greater detail in Appendix 8.)

2. Jig, Fixture, Guide, Template, Pattern, Form

After circulating this larger draft -- on jigs/fixtures -- to a circle of friends, I received the response directly below from Charlie Belden, a woodworker friend (and webmaster) who lives in Silicon Valley, California. He agrees that Jig and Fixture have a conceptual linkage, but in addition, he claims that guide, template, pattern and form also share a piece of the same concept, if I may put it in such terms.

I agree with Charlie, but -- at the moment -- hesitate at any attempt to combine into a single entry a discussion of all five of these terms. Instead, as a sort of mental reminder, I choose to set the five terms out, and think about how they should be treated. Thoughts from readers about these matters are welcome.

Jig: a device which positions two or more objects to a location in space such that degrees of freedom of movement of the objects relative positions are limited to movement along, or rotation about, a single axis. Fixture: a device which secures a single object to a location in space relative to a specific reference plane and/or point by limiting at least four of its possible six degrees of movement in space (the possible six degrees of freedom of movement being movement along the x, y and z axis and rotation about said axis). Guide: as in "a drilling/boring guide", which -- in fact -- may be more of a very specialized Template. Template: an object, real or virtual, whose outline, or a specific portion of its outline, is followed directly or indirectly by a material removal tool. Pattern: an object, real or virtual, with a specific set of dimensions in 2-D or 3-D, used as a reference for reproducing one or more of that object's dimensions by whatever means, either exactly or at any scale. The means of actually creating the reproduction may or may not have direct phyisical contact with the PATTERN during the material removal operation, unlike a template which always requires contact with the wood removal tool. Form: a device to which one or more object or set of objects is/are made to conform in order to create a specific surface shape.

JIGS AND FIXTURES Broadly speaking, a jig or fixture is any device that guides drills or other tools so as to produce work that is interchangeable within the tolerances set by manufacturing requirements. The same terms are also used for devices or frames that hold pieces in their proper position while being welded, or otherwise joined together. We are, however, most interested in devices for holding work during various machining operations, and jigs and fixtures of this class will receive the greatest attention. A distinguishing definition for jigs and fixtures that seems to be generally accepted is about as follows: A jig is a work-holding, device which is not fastened to the machine on which it is used. A fixture is also a work-holding device but one that is bolted or otherwise fastened to the machine. The jig, for example may be moved around on the table of a drill press to bring each bushing under the drill spindle. A fixture, on the other hand, is fastened to the table or base of a machine, and either the tool is moved to the point of operation, as in the case of a radial drill; or the table is moved under the cutting tools, as in a milling machine. This definition, however, has not been offically standardized Source: Fred H Colvin, Jigs and Fixtures: A Reference Book, Showing Many Types of Jigs and Fixtures in Actual Use, and Suggestions for Various Cases. 1913, page 1 (I checked the text of subsequent editions, 1922 and 1938, and found the definitions unchanged.)

3. Definitions from General Dictionaries

The New Standard Dictionary (1952) defines jig/fixture as, [A fixture is] any device, constituting an essential element of a machine, which holds in position either the work or the tool acting on the work. A fixture in serving its purpose is generally dependent upon the action of the machine of which it is a part, while the jig is not. Webster's International Dictionary, 2nd Edition Unabridged, (1952) defines: Jig; A contrivance fastened to or enclosing a piece of work, and having hard steel surfaces to guide a tool, as a drill, or to form a shield or template to work to, as in tiling. Webster's International also has this to say about fixture: "(a) A device for supporting the work, during machining, without guiding the cutting tools. (b) A similar device, for holding parts in correct position during assembly or testing."

Adapted from the Oxford English Dictionary, this next definition, I think, betrays the lexicographer's lack of experience in using jigs; in other words, an "outsider" seeking to capture a sense that doesn't need to be "defined" by the "insider":

A label loosely applied in different trades to mechanical contrivances and simple machines for performing acts or processes, some of which arise directly from uses of "jig" as a verb; in still other instances, the sense is little more than 'dodge', 'device', 'contrivance'. Every manufacturing trade employs aids of the above kinds which may vary greatly from workshop to workshop. Examples of those used for making Planes will be found under Plane Maker. A selection of templets used by toolmakers are illustrated above.

Selections from the "Sixth" meaning in Oxford English Dictionary:

1849 U.S. Congress 31st 1st Session. House Executive Document. Report No. 5. III. 479; also United States congressional serial set By United States Government Printing Office Published by U.S. G.P.O., 1850 v. 551. "Assay and analysis of the washed metals from the jigs at the Boston and Pittsburg Company's mine". 1874 ; Edward Henry Knight, Knight's American Mechanical Dictionary: A Description of Tools, Instruments ... 1876, Volume 2, page 1214: Jig. I. A handy tool. The name is applied to various devices, and in many trades small and simple machines are called jigs. In the armorer's set of tools we find cited, Drilling-jig. Filing-jig. Milling-jig. Shaving-jig. Tapping-jig. (Knight's "dictionary" is (1) more of an encyclopedia, since it consists of 5 volumes, with extensive entries, and (2) full of generally good quality black-and-white illustrations.) 1881 William Wellington Greener, The Gun and its Development: With Notes on Shooting London: Cassell, 1881, page 481. By means of jigs, callipers, and other tools the exact size of the stock and its angle with the barrel is obtained.

4. R J De Cristoforo: Master Among Jig Makers

On the left is an example of De Cristoforo's flowing imagination in this jig/fixture for the lowly bench-top drill press. The book is The Drill Press Book, Blue Ridge,PA: Tab Books, 1991. but it is the book's subtitle that grabs more attention: "Including 80 Jigs and Accessories That You Can Build" The box below contains a fragment of R J Decristoforo's Introduction to one of at least two books that he dedicated to "jigs".

The "Bottom-Up" Nature of Jigs

The "bottom-up" nature of jigs -- they start out in homeshops but after patenting, end up on the floor of woodworking stores or in catalogs of woodworking tool distributors -- is illustrated in the highlighted text from one of De Cristoforo's other books on jigs,

:

A jig is an accessory that's custom made. It might be a quick assembly to solve a one-time chore but, more often, it becomes as permanently useful as the tool on which it was designed to be used. Many times, the project enables you to extend the applications of a tool beyond its basic functions. Simple or complex, jigs are a bridge to more competent woodworking.... Jigs work in various ways .... Some jigs are designed out of downright necessity.... In the final analysis, a jig must be a practical accessory, fun and reasonably easy to produce. But it must be carefully made.... Source: R J Decristoforo The Ultimate Jig Book. Cincinnatti: Popular Woodworking Books, 1999, pages [6-7] (On the left, above, for example, is a "jig" I use to accurately cut sides for picture frames. This jpg shows the frame being made out of weathered barn wood. The device holds the workpiece at a 30degree cant. Read more here.

5. In Metal Working, Jigs Are Given Great Emphasis ...

In 1943 Donaldson and LaCain used this:

A jig is a device for insuring that a hole to be drilled, tapped, or reamed in a machine part will be machined in the proper place. The term "jig" should be used only for devices to be used while drilling, reaming, or tapping holes, as defined above. If the operation includes machining operations like milling, planing, shapiig and so on, the term fixture should be used. Source: Cyril Donaldson and George H. LeCane, Tool Design, New York: Harper and Brothers, 1943, page 253.

Girardot and Karash, co-chairmen for writing in Tool Engineers' Handbook on the subject of "jigs" supply this definition:

"Jigs physically limit and control (guide) the path of a cutting tool. Fixtures do not guide the tool but allow it to find its own path." Source: E H. Girardot and J. I. Karash, "Jigs and Fixtures", Engineers' Handbook New York: McGraw-Hill Book Company, Inc., 1949, page 1541.

In the 1947 book, Jig and Fixture Design, Ewald L. Witzel et al explain the difference between the two as follows:

A jig is a special device which holds, or supports, or is placed on a part to be machined. It is a production tool so made that it not only locates and holds the workpiece, but it also guides the cutting tool as the operation is performed. Jigs are usually fitted with hardened steel bushings for guiding drills or other cutting tools. A fixture is a production tool used to locate accurately and to hold securely one or more work-pieces so that the required machining operations can be performed. A fixture should be securely fastened to the table or the machine upon which the work is done. Though used largely on milling machines, fixtures are also designed and used to hold. work for various operations on most of the standard machine tools. The main purpose of a fixture is to locate the work quickly and accurately, support it properly, and hold it securely. Source: Ewald L. Witzel et al, Jig and Fixture Design Albany, NY: Delmar, 1947, page 6.

6... While in Woodworking Writing, the Concern for "Defining" Jig is Not as Pronounced

In woodworking, according to Kansas State Teachers College master's student, James R'Leigh Bell -- as late as 1955, nothing can be found in books that attempts "to define or clarify what is meant by either of the words 'jig' or 'fixture' as these terms are used in woodworking literature."

(Bell's thesis is, incidentally, the only account that I have been able to locate on the issue of "jigs in woodworking".)

To get around this lack of definition, Bell seeks to derive a meaning of jig in a woodworking context by analyzing the usage of jig in woodworking literature.

In some instances, Bell found, the words are used interchangeably, as if they had the same meaning.

Bell's example is Milton Gunerman's 1950 How to Operate Your Power Tools.

With the aid of a fixture, for example, Gunerman illustrates the sanding the edges of circles and curves on a disk sander. Gunerman shows the fixture, and how to make it, but in the process of his explanation, he uses jig and fixture interchangeably.

Unlike the devices used in the metal industries the term "jig", in their shops, woodworkers often use it when they refer to aid for a hand tool. In the woodworking fields and/or the school woodshops, users of jigs understand the word "jig" means a device which is used to hold, guide, or direct the work, or the tool, for a hand or power machine. It is not fastened to the bench, the machine table, or fence, but may move and act with the operative part of the tool or machine. A fixture may also hold, guide or direct the work or tool. The fixture is fixed or fastened or held to the bench, the machine table, fence or stationary part. Either jigs or fixtures make it possible to do a given job better, faster, more economically or safer,. A jig or fixture is not a complete tool in itself but only becomes a part of a tool when it is performing one or more of the specified objectives stated herein. Sources: Milton Gunerman How to Operate Your Power Tools. (New York: The Home Craftsman Publishing Corp, 1950, pages 95, 116, 119; James R'Leigh Bell, Jigs and fixtures in the wood shop, Pittsburg: Kansas State Teachers College, 1953.

7. Jigs An Example of "Bottom-Up" Nature of Woodworking

Attentive readers will soon detect that -- as is well-know by woodworkers themselves -- , in large part, woodworking technology develops from the "bottom-up". The "bottom-up" issue in woodworking is a matter about which I have considered at length. Why? Because I think that "jig making" is an essential component of woodworking, a principle that can be proven by disassembling a woodworker's bench -- itself a "jig" into its component parts: Vise, Bench Dog, Bench Stop, Bench Hook, or Bench Screw, (or what R A Salaman calls "Bench Chops" -- for all of these "jigs", see R A Salaman, Dictionary of Woodworking Tools, 2d ed revised, New town, CT: Taunton Press, 1989).

Put simply, for me, the Workbench is itself a woodworker's "tool", and all of the apparatus that embellish workbenches today started out as jigs and/or fixtures. The Vise on a workbench, for example, because -- for many generations -- it has been an attached integral component of workbenches.

The same can be said about origin as jigs of the Sleds, the Miter Squares, the Table Slots, the Zero Clearance Inserts and multitude of other jig-like devices that comprise the standard gear for today's Table Saw. The Biesemeyer fence is an example of a "jig", and definitely falls under the rubric of "bottom up" development.

(And woodworkers -- who maybe can't afford the commerical biesemeyer, resort to their own ingenuity in making their own version of this device:

http://home.comcast.net/~jaswensen/machines/fence/fence.html

http://www.twistedknotwoodshop.com/tsquarefence.pdf )

As Wallace Kunkel points in How to Master the Radial Saw, historically, the Radial Arm Saw was designed as a production machine for use in lumber yards, and cabinet shops, for builders and similar users; however, because of its versatility and ease of operation, it is now found in many home workshops as well. Read more about the radial arm saw here

With (usually home-made) accessories and attachments, the Radial Arm Saw does Horizontal Mortising, Molding, Drilling, Sanding, Shaping, and several other operations that involve the use of circular cutting tools. Undoubtedly these accessories that are now part of a package that most buyers include with purchase of a RAS started out as jigs, developed by one individual woodworker with a problem that needed to be solved.

For the Radial Arm Saw, the sanding mode is interesting, in that, before the Performax Drum Sander appeared on the market, ? [name not known at the moment, but working on it] first developed this drum sander in a home shop operation -- I have memories of the ads in woodworking magazines in the late 1970s and early 1980s. An excellent example of the "bottom-up" nature -- as a "jig" developed in a woodworker's home shop -- i.e., the invention of power tools in the woodworking industry. First the Performax was patented as an attachment for the radial arm saw, and then, finally, actually organizing into the Performax Drum Sander Corporation as a manufacturing operation in its own right. (I'll post more details on the history of Performax later; the entry on WWW.OWWM.COM is sketchy: http://www.owwm.com/MfgIndex/detail.asp?ID=631)

Sources

Fred H Colvin, Jigs and Fixtures: A Reference Book, Showing Many Types of Jigs and Fixtures in Actual Use, and Suggestions for Various Cases. 1913; Cyril Donaldson and George H. LeCane, Tool Design, (New York: Harper and Brothers, 1943; Ewald L. Witzel et al, Jig and Fixture Design Albany, NY: Delmar, 1947; Milton Gunerman How to Operate Your Power Tools. (New York: The Home Craftsman Publishing Corp, 1950; James R'Leigh Bell, Jigs and fixtures in the wood shop, Pittsburg: Kansas State Teachers College, 1953; R A Salaman, Dictionary of Woodworking Tools, 2d ed revised, New town, CT: Taunton Press, 1989; Wallace Kunkel, How to Master the Radial Saw privately printed, 1997;R. J. Decristoforo, The Ultimate Woodshop Jig Book. Cincinnati: Popular Woodworking, 1999. R. J. Decristoforo,The Jigs & Fixtures Bible Cincinnatti Popular Woodworking Books, 2003