Hold on to your checkbooks, this got long on me...
There're degrees of "necessary," really. You could build a bass with sharp rocks if you really wanted to. I've seen some that look like people might actually be doing that.
I'm probably going to repeat what's already available on the net or in books, but, what the hell, teaching is learning.
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There are several tasks you need to accomplish, and a host of options for each task.
Straight cuts - This would include sizing of blanks, neck tapers, fingerboard sizing, etc.
The table saw is the preferred tool for straight cuts. Options range from $100 benchtop models (do NOT even think of getting one... You'll fight it more than use it) to thousands of dollars in commerical level saws. Good options are the DeWalt and Jet contractors saws with the motor on the inside. They're still in the $900 range. Ryobi makes a decent contractor's saw, too. If you want to get serious about other woodworking, too, consider the table saw your most important purchase and don't skimp. Somewhere out there, there's a Powermatic with my name on it... sigh.
But if you're only going to do luthiery, you don't really require one. You can do straight cuts on a bandsaw with a fence, or with handsaws. There's more cleanup involved, but you can do it.
Curved cuts - shaping the body and headstock.
The bandsaw is great for this. A 14" will give you enough power and clearance to handle this task, and allow you to experiment with resawing tops and things later on.
Without a band saw, you can use a handheld jigsaw. Note you'll be cutting thick, hard, well grained wood in a lot of cases, so you'll want some power. You'll also need a way to clean up the cuts, since jigsaws tend to leave a lot of saw marks. Cut outside the line and plane, shave or route to the line. You can use a variety of tensioned handsaws for this as well. Expect to sweat.
Shaping - shaving the neck, belly cuts, carving.
Hand tools excel here. The spokeshave is a good place to start for neck shaping. It removes wood quickly, but is controllable. Surforms work well, too. Then rasps, files, and chisels come in. You could get a surform, a combination rasp and a 4-chisel set for perhaps $30. Don't forget to calculate the cost of sharpening stones, etc. These tools MUST be sharp at all times.
Cavity creation - neck pocket, control cavity, pickup cavities.
The router and a set of decent bits is the tool here. A 1 1/2 HP plunge router is the minimum, and you can find good price bits at
www.mlcswoodworking.com
By hand, you could rough these out with an auger and clean up with chisels. The router is sooo much nicer, though.
Hole making - tuning machines, controls, ruining expensive hardwood with mismeasuring.
You can get by with a handheld electric drill, but for the really solid fit-n-finish you expect to see on a musical instrument, the drill press is unsurpassed. Plus you can use a drill press for drum sanding, which brings up the next task...
Smoothing - surfacing, sanding, leveling.
If you're doing a multi-piece neck (counting the fingerboard) you're going to need to create perfectly flat surfaces on wood. That's called surfacing. The electric jointer is the preferred tool there, but it can be done with appropriate hand planes and practice. I wouldn't recommend an electric hand planer.
For sanding, you'll need a full complement of sandpaper, and some sanding blocks or scrap wood.
Levelling is the act of making two surfaces the same height. You do it for inlays, bindings, anytime you have an imperfect glue-up. You can do it with planes or chisels, but I really like cabinet scrapers. They're cheap, easy to maintain, and easy to use.
Gluing - making things stick together.
You'll need glues and clamps. Lots of clamps. People will start giving you clamps for Christmas. And you'll thank them and mean it.
Finishing - protecting the wood.
Spray finishes require some method to atomize liquid. HVLP sprayers are great, but expensive. I'd start with pre-canned lacquer or use the Preval system of charged canisters. Reranch is a good source for preloaded cans. Home Depot sells Preval. I use a 15 gallon air compressor and a hobby airbrush. Slow, but functional.
Wipe on finishes don't require much in the way of tools and are relatively easy to apply.
Specialty tasks - fretting, nut filing, fretboard radiusing, etc., etc.
www.stewmac.com has a range of tools for this and can point you in the direction of what you need. Minimally, you'll want some specialty files for fret and nut work, and sanding blocks for the fretboard radius. It's easy to go overboard on the specialty tools. The good thing about every category except this one is that the tools you'll buy are usable in all types of woodcrafting.
Information - learning the process and techniques
You'll minimally want to get a book on making an electric guitar. Melvyn Hiscock's "Make Your Own Electric Guitar" is a good one to start with. There are several good ones, and even some videos. Plus, there's the internet.
Miscellaneous - everything else.
Screwdrivers, razor knives, nippers, pliers, feeler gauges, squares, cloths, rulers, pencils, band-aids.
That'll do it. So, consider several hundred in handtools to a couple thousand in power tools to be your range. Good luck!!
