Just built a sweet tenoning jig, really just right angle plywood bracket clamped to my large crosscut sled. Takes a little attention to adjust, but for the time (1/2 hour) is really cheaper than a manufactured jig and safer than shopmade jig for ripping tenons against a fence. My new motto is to use the sled whenever possible. Really my fingers are 8″ away from the blade at all times! More like driving a car than cutting wood. Really not sure how long it will survive without modification, though.
Antyway it got me thinking, while cutting dozens of saddle joints tonight . . . What is the main difference between a jig and a fixture? Is it permanence, or self-containment? Is it the intention to reuse the setup? I thought this would be an interesting conversation. In plumbing or electrical work a fixture is intended to be used for a number of years; in carpentry and woodworking a jig can be a spur of the moment setup which may be forgotten the next day. Both are a type of guide. The two terms definately overlap in woodworking. Any other thoughts? Have I answereed my own question? I want to sound as smart as possible about this in the future.
Brian
Replies
In my shop, a jig is something that I use quite frequently, while a fixture is a jig that I've used once and hung on the wall out of the way...
A jig forms a guide for the tool(s) used in a machining operation.
A fixture secures a workpiece for a machining operation.
................................................
You can't wait for inspiration. You have to go after it with a club. Jack London
Very Interesting. Did you get that from a specific source or is it common knowledge? Seems like it still may be hard too define in some cases . . . oftentimes the workpiece is being held and the machine guided in some way by the same contraption. E.g., my crosscut sled? Sure temporary setup vs. permantent helping hand have nothing to do with it? Still curious.Brian
Brian-"Still curious."You can probably satisfy your curiosity more easily by reading some of the thousands of items a Google search turns up. The terminology arose in the machine tool industry. As applied to woodworking, the consensus seems to be that a fixture is fixed to the machine to guide the workpiece (e.g., a rip fence) and a jig is attached to the workpiece to guide the machine (e.g.,a dovetail jig). What you choose to call your crosscut sled won't leave this forum.Don
A jig guides a moving cutter, or tool, relative to the work piece.
A fixture, guides the work piece relative to a fixed cutter or tool.
Dovetail jigs, are jigs. A cross cut sled is a fixture. My Woodrat, is both.
This is getting confusing
d
I don't think this is getting as confusing as Dusty does. But he probably has his mind on actual work, as I should. There does seem to be a concensus, which you have supported, that jigs relate to portable or hand held tools and fixtures relate to stationary tools. This is something that I never would have thought of, or really thought to be significant, so am glad to have learned something and will begin to throw the terms around immediately. Brian
I forgot to mention that fixtures also are used to align pieces, i.e. the Kreg tables with the clamps for constructing face frames are fixtures. As are the 90-degree blocks used to hold parts perpendicular when gluing.
My Dad designed fixtures for assembling the wings and tail surfaces onto the fuselage of aircraft, during WW-II, and the early fifties. Some of those were huge, and capable of linear motion, and rotation in all three dimensions.
A lot of the confusion of the terms in woodworking, comes from the magazines most of us learned woodworking from. I learned the difference from my Dad, and a few years working in a union machine shop, as a "pre-apprentice".
On that basis, I am a fixture and my wife is a jig.
Well, life is heck, then you die....
Brian,
No doubt you will soon be improving the clamping mechanism- in fact you may make another JIG with several improvements-what about angle adjust ? (;)
A fixture realtes to machinists stuff in my mind-same as Don Green's. And then there are light fixtures with bulbs or tubes....
I like Dgreen's definition. Your tenoning jig really is a jig. If you've attached a toggle clamp to it to hold the work in place, it's also a fixture.
Chris @ www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Have studied this one ad nauseum, wrote a book about them. Present definition so vague that it becomes an argument for the hell of it.
Much better to use that time making & using jigs rather than defining such.
Right on !
Now I love a good discussion and even when tempers flare there can be meaningful exchanges . But some seem to get caught up more in the process then the destination or end result so to speak .
What bevel angle for my plane blade ? mdf or Baltic Birch for my jigs ? You know you can make a jig to get the job done or you can take some time and make a jig/fixture that is bullet proof and will hold up for 77 years but who cares and what difference does it make in the real world ?
As an example a simple taper jig dosen't seem to exist any more , we each learn our own ways and out of necessity we get used to doing with what we have to do with .
end of rant
regards dusty
A jig is a guide.. a fixture is a glide.
This forum post is now archived. Commenting has been disabled