Silly Question about Jigs - --

[MHaseltine]

Last Saturday I was at an auction and was looking at the tools which happened to be inside . Another person was also broswing. The owner had made a number of wodden jigs for his table saw ranging from a miter sled to a tennoning jig. Just to make conversation with the other person, I stated that the owner and been rather prolific and had a lot of jigs to go with the saw. The person gave me that knowing look and said "their fixtures - you need to be careful and not call fixtures jigs" Well, my response was I'm a bit of a newbie at his (which is true) but everything I have read and heard refers to these things as jigs - fixtures is a new way of naming these things"

Well, my silly question is, "Are these jigs or fixtures?"

Michael

[Swingman]

My bet is that in the machine shop, and in the machinist' world, the difference is probably more pronounced/important/politically correct than it is in woodworking.

There is, at least semantically, a difference. To paraphrase, precisely, one of my old books: "A jig is a device used to maintain mechanically the correct positional relationship between a piece of work and the tool or between parts of work during assembly, and a fixture is a device for supporting work during machining."

Then again, I/it could be all wet.

[DJ Delorie]

Maybe the difference is more subtle: "A jig is a device for holding the wood relative to the tool, and a fixture is a jig used by people who think they know the difference."

IMHO, if it moves, it can't be a FIXture, because it's not fixed in place.

OTOH, if it doesn't dance, can it be a jig?

Ok, I'll quit now. Here's my excuse for bad puns (warning - lots of photos on this page):

(note the snow in the last few pictures - sigh)

I used a lot of jigs building that. They danced out of my hands a few times.

[Bob Gramza]

That makes the figs then.

: > Well, my silly question is, "Are these jigs or fixtures?" : >

: > Michael : :

[Pounds on Wood]

His "knowing look" probably had more to do with the racial connotation that jig carries. Pretty silly to my way of thinking, in this day and time. In my experience the "knowing look" is usually accompanied by a snicker or SEG, and usually comes from a racist. Flames welcomed.

[Jay Windley]

Basic difference: a fixture holds/guides the stock; a jig holds/guides the tool.

A fixture is a device used to hold stock in place while you work on it. A vise, by this definition, is a sort of universal fixture. Assignment #1, first week of class: design a fixture for a brake disc. Classical solution: first square the stock, then use a generic square fixture to hold the stock while you drill the radial hole pattern, then make a fixture with the same hole pattern and bolt the stock to it while you machine the profile (grooves/holes, circular outline, etc.). And yes, this is metalworking, not woodworking, but the definition ought still to apply.

A jig may be a fixture in that to do its job it must also secure the workpiece. But the primary role of the jig is to guide the tool, whether or not it also secures the stock. In the modern manufacturing world where you can have CNC machinery the notion of a jig is somewhat outdated. You just tell the tool where to go, and how fast, and it happens. In our world, where we have generalized hand-controlled tools, jigs take the form of pocket-hole devices, router templates, guide rails, etc. that constrain the motion of the tool to the path we wish it to follow.

A pocket-hole jig is an example of a jig that doesn't also need to be a fixture. You fasten the jig to the workpiece and it guides the tool, but the stock can be held any way necessary or comfortable. Some dovetail jigs also function as fixtures because they hold the stock in place (since you'll have both hands on the router) as well as guide the router through a profile.

"Fixture" would be the proper term associated with holding stock for use in a table saw. Many CNC systems also work by moving the stock, so "fixturing" need not be interpreted as "holding the workpiece stationary" but rather by holding the workpiece firm in a certain coordinate system of the tool. If a tool works by moving a platform -- with workpiece attached -- along a path relative to a stationary cutting bit, then a "fixture" would ensure that the workpiece does not move relative to the platform.

--Jay

[Swingman]

My book said basically the same thing, only a hell of a lot less windley.

[James D Kountz]

This sounds to me like one of those freaking irritating know it all type of people who feel they MUST correct everyone all the time so everyone else will talk like they do. Their way is correct, everyone else is wrong. These idiots really gripe my ass ya know? Its not like the creep didn't know what you were talking about, he just had to correct you anyway. Its some sort of compulsive thing I guess. Jig, fixture who cares? I would have known fully well what you were speaking of if I had been the other guy, therefore no correction from me would have been necessary at all.

Jim

[MHaseltine]

Thank you all for the information - I really hadn't heard the use of the word "fixture" before but then I am a newbie and haven't worked in a production shop.

Again a geniune thanks Michael

[George M. Kazaka]

Been making sawdust for 48 years and never heard of anything but jigs and I didn't read a book to get this info. Have never heard another woodworker call them anything else either But when you really come down to it does it really matter what you call them ??? Doohickey sounds good, so does thingamafrig Geez I hope I haven't insulted anyone here

[Andy Dingley]

People like that are why auctioneers carry gavels.

[Jay Windley]

I really don't, prior post nothwithstanding. None of my mechanical engineering and machinist colleagues care. They all use "jig" and "fixture" interchangeably ("jig" mostly).

I know the difference, but I don't often respect the difference. Especially with the kind of tooling I deal with, the differences aren't usually important. The original poster asked if he had been looking at "jigs" or "fixtures". Well, if you *really* have to know the difference, there's a way to tell, and I used to have to teach this so I know the difference.

But the guy who's saying, "You need to be careful and not call jigs fixtures," is vastly overstating the issue. If you said something like that around our manufacturers they'd laugh and accuse you of being some sort of Tool Nazi.

If you want to call a jig a fixture, or a fixture a jig, or call it all "tooling" (which I do a lot), or point to it and call it a "thinga-ma-bob", you'll probably find me doing it right alongside you.

--Jay

[CW]

[CW]

You have the correct definition. BTW, most machinists don't know the difference either.

[CW]

Sounds like someone who is wrong a lot and gets tired of being reminded of it.

[Fly-by-Night CC]

My wife works at the corporate HQ for a hi-tech computer company here in Oregon. That thingie between the buildings with the ducks swimming in and geese milling around it, with the trees overhanging, with the cat-tails and lilypads, and croaking frogs is NOT a pond, but a...

"water feature ".

[Juergen Hannappel]

So a "sharpening jig" would really be a "sharpening fixture", since it holds the stock (i.e. the blade to be sharpened) and not the tool (the sharpening stone)?

[SwampBug]

Changint it from old "pond" to the new "water feature" lets the contractor mark-up at least 40% right off the bat!

[Swingman]

[Hylourgos]

CW,

I'm not certain but I'll give it a shot. In the same vein as California's recent attempt to remove hurtful and politically incorrect language (e.g., slave, as in "slave-cylinder"--gotta laugh at that one) from all areas of public discourse, POW imagines that the other WW's "knowing look" was the product of his own (racist) politically correct ideology, stemming from his understanding of the word jig as a racial derogatory (shortened form of "jigaboo"). A kinder judgment of the other WW might see him as trying to be (overly) sensitive, but I guess it depends where you stand on the "politically correct" issue.

Jig has been a common term among rednecks for a long time. See a brief explanation of it, and other such, at: