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Planning and Building a Jig

36K views 36 replies 19 participants last post by  Tangle 
#1 ·
Introduction

I grew up on a ranch, a place where you have to be able to do just about everything yourself. Plumber, mechanic, veterinarian, heavy equipment operator, you name it. Having been raised that way, I can't stand to pay anyone for anything I think I can do myself - my wife would say that is why nothing gets done around here!

I make a lot of my own jigs and fixtures. Some of them only get used once, some of them are used so much they almost never get put away. Either way, they are tools that allow me to work faster, safer, and more accurately.

Lots of people with more experience and expertise than me have written books and articles about jigs. A couple of my favorite books are by R.J. "Cris" DeCristoforo and Kerry Pierce, from whom I have gleaned a lot of great ideas. I have also recently become acquainted with the ideas of Niki Avrahami who is a regular contributor to LumberJocks.com and an expert on doing more with less. In fact, many of the members of LumberJocks.com have generously provided great ideas and suggestions that I have been able to incorporate into my designs for current and future jigs.

Most of the books and articles I have read about jigs have been project instructions - they told me how to build a jig to perform a specific function. Instead of giving a tutorial of how to make my favorite jigs, I'd like to discuss the process behind designing jigs and fixtures.
 
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#6 ·
Definitions

The story is told that after the Great Fire of 1666, the architect Sir Christopher Wren was commissioned to rebuild St. Paul's Cathedral in London.
Upon the completion of this huge undertaking, Queen Anne reviewed the work and is said to have declared that it was, "Awful, amusing, and wholly artificial." Wren was quite pleased to receive such a compliment from the Queen! The English language has a sneaky way of changing over time, and a lot of woodworking definitions have changed or been lost as the language changed. Many woodworkers can not explain the difference between a dado, a groove, a rabbet, and a fillister. "Mullion" and "muntin" have become virtually synonymous. Many professional woodworkers don't know the difference between a smoothing plane and a jack plane. I don't think the change of definitions is either good or bad - it just happens.


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"Jig" and "fixture" are two more words that have become virtually synonymous. Even though most of the books I have on the topic use both words in their title, none of them even make an attempt at explaining the difference, and Webster's definitions aren't very helpful, either, so we are stuck with my definitions. In my mind, a "jig" holds or guides a tool and a "fixture" holds or guides a workpiece. Unfortunately, these definitions fly in the face of many common uses (whoever heard of a "honing fixture"?), and there are any number of devices that hold and guide both the tool and the workpiece! I will abandon my definitions without hesitation if I think the "correct" usage might cause confusion or seem redundant. Generically, I tend to refer to jigs and fixtures as "jigs".
 
#18 ·
Safety



Workshop Safety
I can't overstate the importance of workshop safety. Don't wear loose clothing, jewelry, or hair. Your tools come with guards for a reason - use them! If you aren't sure the action you are about to take is safe, then assume it isn't and figure out a better way to do it. Keep your work area clean, especially underfoot. If you are using a tool - power tool or hand tool - wear eye protection. The best protection against injury is your brain - it may be soft and squishy but if you use it correctly, you can avoid all kinds of potential problems!


Jig and Fixture Safety
A jig should help you to work safer, so you should have safety in mind during every step of design and use. Think about where your hands will be in relation to the tool when planning your jig. Incorporate some sort of handle into your design so you will be less tempted to place your hands in an unsafe position.

If using a jig or fixture will require you to remove a guard from your tool, add some sort of replacement guard to your jig. A great material for guards is clear plastic - it is easy to find, easy to shape, easy to attach to wood, easy to machine and drill, and it won't block your view of the work. If you don't have some scrap plastic available, buy a small sheet of 1/8" or 3/16" acrylic or lexan. A little bit will go a long way. If you don't need to see through the guard, a scrap piece of wood will do.
 
#20 ·
Apology

This blog entry is an apology.

First: to those of you who are following this blog series, I'm sorry it has taken me so long to get to the next entry. It's almost ready and I'll try to post it soon. It's a masterful piece of literature that will have you begging for more. Okay, well I think it will be informative.

Second: to my wife, who graciously took the time to read and critique several of my posts and entries and informed me that women like to be called by their name, not just "my wife." Her name is Marianne. She's wonderful, and I'm lucky to be able to (occasionally) call her my wife!

Third: to everyone who read my last blog entry on safety. My wi… er, Marianne pointed out that the last entry sounded arrogant and impersonal, and that I don't always follow those safety rules myself. She gave a little tug on my sweatshirt hood drawstrings to illustrate her point. She's right, of course. My idea with this blog series is to share information, not to lecture. I think safety is very important, and since this topic is aimed at those who are newer to jig making, I think a safety reminder is important. So, from this point forward, I will try to keep entries on this topic friendly, and I will renew my commitment to safety in my shop (I put the guard back on my table saw).

In my defense (and with tongue in cheek) ...
First: It's the holidays and I'm busy - lay off!
Second: No one here knows your name is Marianne! They will have no idea who I'm talking about!
Third: So I sound pompous, do you think I want you to loose a finger?
 
#28 ·
SHOP BUILT VS. STORE BOUGHT

Some common kinds of jigs are available for sale at woodworking stores and even big-box retailers. Every time I see a jig for sale I think, "I could make that." I imagine most of us think that! If I see a jig for sale that seems like something I could make, I try to be realistic about whether it is worth the time and effort.

I'm a cheapskate, and I almost always build jigs out of scrap, so the expense to build is very low. If you enjoy building jigs, then even if it takes an hour or two away from a paying job, at least it makes for a nice change of pace. If a jig is just a plastic version of something you would make out of wood, then you should seriously consider just making it yourself.

On the other hand, there are some jigs for sale that would be really hard to match with a shop-made jig. Sometimes it really is worth it to just lay out the cash and buy a quality jig. If you could build something "close" but would have to leave out some features or capabilities, then you should seriously consider saving up and buying the jig.

There is a third option that falls into this category: paying someone to make a jig for you. There are limitless operations you can perform with your tools, but there aren't jigs on the market for all of those operations. You may require a level of precision from your jig that you can't produce, or it may need to be made from materials you don't have the ability to work. Having a jig built for you would be the most expensive of your options, but it is something to consider as a last resort. This may be a good time to make friends in other industries! I recently had a jig made for my shop, and I kept my costs down by trading labor with a friend who works with metal and plastics.
 
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