Need Advice How to Reduce Neck Thickness

I'm working on a Warmoth neck for a friend. He wants me to thin the contour down from the existing .98 at the first fret to around .85 - .88 at the first.

The existing contour is .98 at 1 to . 98 at 12"

Removing material from the existing .98 to around .88 is nearly 1/8"! It's huge. I can't figure out the proper way to do this without creating a noticeable trench in the neck, and possibly altering the C profile.

I can't even figure out the best way to remove material without negatively affecting the entire profile. Can I use a palm sander and work quickly around the neck? I created the pictured neck profile sanding block, but being the lazy guy I am, this will take way too long for my tastes.

Any suggestions from folks that have done this succesfully is much appreciated.

http://dl.dropbox.com/u/58200902/GUITAR%20PICS/neck%20countour%20sanding%20block.JPG

There are a dozen ways, depending on whether you like metal or sandpaper, slow or fast, hand or power. And depending on your comfort and experience with various tools.

It's easy to take off too much; I'd use a cabinet scraper, POSSIBLY following a spokeshave. The spokeshave is unlikely to need more than about two passes; it would be a time-saver in this situation. Bear in mind that the scraper would only work if you know how to draw the burr and use the tool itself.

Others may well chime in with techniques more to your liking.

I'd do it systematically. Any other way would be prone to failure.

(my best advice would be to get warmoth to make one with the correct size!)

First and foremost - do all you can to find out where Warmoth puts their trussrods allows the reshape. Should be fine, but if you hit the rod cavity all bets are off.

1. Using calipers to measure and a tool that removes the same quantity each pass (spokeshave, surform etc), reduce the thickness of the neck from the headstock junction to the heel junction in a flat plane. You now have a neck with a big flat section on the back corresponding to the thicknesses you require.

2. You now have a neck that's the right thickness - now the task is akin to crowning a leveled fret. Use a pencil to mark the center of the back of the neck. Rule two lines about 1/8" apart and fill in the middle writing "DO NOT REMOVE!"

3. Take the corners off the edges of the flat keeping each side symetrical. When you get close to the final profile, switch to 80grit sandpaper in the "shoeshine" technique.

4. Step up the grits, ending at 400.

Be aware that it will be tempting to finish when you get to a D shape. Using a profile measuring tool, take and record the original profile so it can be copied exactly.

I use

Contour Gauge - profile
Digital Calipers - depth
Ferriers Rasp - removing material.

Then sand through the grits up to 400

I use a disk sander to do it. Once I get in the ballpark size wise, I put the neck on the guitar and string it up. I then go slow with a disk sander and then switch to hand sanding. I keep playing and sanding until it feels right to me. I don't worry about the numbers, I do it all based on feel.