Well first of all you've gotta understand that a neck tapers in width from the headstock to the body joint. Which means, just making a sanding block with the right profile doesn't guarantee results.
First of all, you're looking to thin the neck. That means, controlled removal of material, as far down as you want without cutting too deep. The first thing you better have, is a set of calipers to get the accurate measurements of your neck from the back's thickest point to the fretboard's highest point. Then, decide how far down you want to sand. For example, if you measure your neck at, say, 1-1/4" or 1.25", and you wanna take off a sixteenth, or .0625", then you set your calipers to 1-3/16" or 1.1875". Then you know that once you're thin enough, those calipers should slip over the neck all the way. And by sliding that calipers up and down the neck, you can see if it's deep enough from head to body.
Since you're just flattening the neck, you'd be fine to start with foam sanding blocks, which are soft and flexible. They'll keep from creating a flat spot on the back of the neck like a solid sanding block would, and will create a natural beveled contour with the sides of the neck. You'll probably not even sand more than 1" wide in the thickest spot, for a very small removal of wood.
Go buy some coarse 60 grit, medium 120, and fine 200 grit sanding foam blocks, and start with the 60 grit. Fast removal of material until you're close to getting your calipers to fitting over the neck. Then to medium, getting closer and paying attention that you're not creating waves. Then fine to get ready for a finishing coat.
To watch for high spots and low spots, sand with strokes all the way up and down. DO NOT DO SHORT AREAS! Full strokes for the full length of the neck. Get yourself a good quality metal ruler (drafting supplies will work nicely) to lay on the back of the neck. Then look at it sideways to see if you have gaps or if the ruler rocks back and forth like a see-saw.
To get really careful, get carbon paper. Lay the carbon paper, black side down, and rub your metal ruler up and down to "rub" the high spots. Where you see black, you sand back. Once you get marks alll the way up and down the back of the neck, you're done!
Then test to fit. If it's not thinned enough for you to play comfortably, start again. Set your calipers another 1/16" narrower, and get back to work. I guarantee that an 1/8" will make a very significant difference in feel. But, you don't want to cut it all at once, cuz you CAN'T GO BACK. Once you sand too deep, you're screwed.
Hope this helps.
) that's just a wee bit too thick for me. I'm not looking to do a heavy reshaping. I just want to shave the thickness down a tad. What's the easiest way to do this?
