I’ve discussed this briefly in past posts but I think it’s a subject that could use some further investigation.
Or this for making a saddle slot in the bridge.
For my purposes, these are mostly used for router applications. In this case I use an 1/8″ down cut spiral bit with a fence attached to a plunge router.
Templates are usually attached to the object. This humbucker template is a good example
This is used with a plunge router as well but with a pattern makers bit. This has a bearing of the same size as the cutter and it’s on the top of the cutter or where the shaft meets the cutter. I always use the largest cutter because the smaller bearings are very fragile. In the case of the humbucker I use the bigger bit to “hog” out the majority and use the smaller bit just to clean up the corners.
This template is used to cut the heel on a neck.
I use a massive 3/4″ pattern bit for this.
As an aside, I always use the best bits I can. My choice lately has been Amana. The better the bit the less chance of blowing out chunks of precious wood. This goes for the router as well. The more horsepower, the less likely to bog down.
Lastly, the Fixture: A fixture differs from a jig in that it is usually the work that is attached to the fixture. An example would be this shooting board
In this case the “board” is attached to my bench and the back or top is clamped to the fixture to joint them for gluing. Notice one of my favorite tools, my Lie-Nielson 24″ joiner plane!
A couple more, my homemade side bender and vacuum table
As you can see, most of these jigs, templates and fixtures are pretty simple to make and use. Some of the other things I use these for are profiling necks, fingerboards, profiling solid bodies, forms for sides etc, cutting fret slots… the lists goes on. While you can buy some of them, body and pickup templates, I encourage you to make your own especially if you’re on a budget. A little 1/4″ MDF goes a long way and it’s cheap.