How (Not) to Flatten a Piece of Wood

I want to glue the fretboard to the neck, but I want the neck to be very flat and true first.  The fact is, however, this board is not flat.  The fiberglass/epoxy layers are probably more compressed in some places than others, the basswood probably wasn't exactly 1/16" thick everywhere - this is how it goes.

Near the start of this in a post entitled "Disaster...Or Victory?", you can see that I set up my laminate on a sheet of 1/4" plate glass.  This very typical and common type of glass is sometimes called float glass for its habit of being created on a pond of molten tin.  Molten tin!  So it's generally considered pretty flat.  The idea was, lay the laminate up on a perfectly flat sheet, weight it down against that sheet, and you get a board with at least one perfectly flat face!

Well that didn't work out so good.  Somehow it didn't happen, some entity or phenomenon got between my float glass and my laminate, and it just didn't work out that way.  So I have to flatten this board.  I'm naive so I figured I could just rub the board against some sandpaper affixed to that very same piece of glass, and make it flat.  But only the actual neck part - the headstock is going to get rebated away anyhow.  First mistake:  I should have taken the headstock down first by sawing, to get it out of the way.

For a while I had the glass on a carpet and pushed down on the board, as I rubbed it around in circles.  I drew in pencil on the board to see where I was taking off material - where the high spots were.  After about 40 minutes at 120 grit, I did get to a point where the sandpaper had cleaned up the whole board, but all was not perfect.  There was still a low spot in the middle of the neck!  I hypothesize that by pushing down on the piece, I flexed it into contact with the glass, thus taking more off the part directly under my hand.  In some strange way, the high parts escaped.  Perhaps, also, the glass was flexing into the carpet.  One thing I did right:  I constantly swept the sandpaper and the board clean to prevent little piles of dust from glomming onto the paper, forcing the wood up over it.  Here's the board with pencil writing on it:

But it was much better than before, clearly.  I was still hopeful.  Time to adjust my attack.  This time I placed the glass on a long level and gave it some new sandpaper, still 120 grit.  And - here's my innovation - I didn't press down on the board, I just pushed it gently from either end, back and forth.  And I checked it with a straight edge regularly.  And lo! it got even better.  But all was still not perfect, in fact I had a totally new problem:

I don't know if you can see it here, but the left side is thicker than the right.  The top may be flat, but the whole thing is canted over.  My cheap but cool digital micrometer is AWOL due to a battery condition right now, so I can't tell you exactly how much.  1/3 of a millimeter?  Something like that.  Is this a problem?  Well, two things:

1. The damn thing's still not straight enough.  I want it about as perfect as possible, because if the fretboard goes on flat then in theory I will have to spend less time leveling the frets.
2. I don't want it tilted over.  That irritates me.  I'm building a simple guitar, not some fancy ergonomic thing.

I still have enough wood to stop and figure out what to do.  Fender neck blanks are sold 13/16" thick, and this one is about 15/16".  The only trick is I don't want to stop on an epoxy/glass layer, or partway through one, as that'll force me to change my choice of glue from Titebond to epoxy.  Big deal?  Dunno.  And I'm not sure many machines will be happy cutting through a nasty layer of garbage like that.

In any case, I'm reaching out for help here while I've still got room to move.  I'll post more when I get the guidance I need.  You'd be surprised how hard it is to find answers to this on the internet.  You're either supposed to use a giant plane with ninja woodworking technique, or you're supposed to have an electric thickness planer.  Even to use the planer, I'd have to prop up the other side of the board (which is even worse than this one) artfully in a facsimile of a flat surface to give the planer something to push against.  I suspect I'm going to end up with a belt sander and a sanding frame, or some homemade router rig set up on a table saw table.

I have discovered this:  the concept of flatness is a human one.  It is a state known only to water on the calmest of days.  It's a strange place to be, knowing exactly what I think I want in a very geometric way, and being unable to arrive at that configuration.

I am a monkey.

The Trudginger I Go, the Receedinger the Mountain

I got a free band saw, but I think I have to modify it extensively to cut this wood-composite laminate I've created.  This is a good time to reflect on the meaning of Building Things Backwards, and the process of acquiring "knowledge".  Here I am, just trying to build a guitar.  Yes, I got tricky with materials, but it doesn't affect the overall process.  My process so far:

1. I got involved with composites
     A.  I built a heat box to cure composites
           i)  I had to struggle with foam and reflective bubble wrap
           ii) I had to build a heater out of lights
           iii) I had to test it for temperature range and stability
     B.  I layered the composite
           i) I attempted to use weights to compress the stack slightly
                 a) I discovered the need for a clamping jig
           ii) I discovered the practical need for a temperature controller
2.  I had to cut this laminate
     A. I tried a table saw with a plywood blade
     B. I tried a router
     C. I tried a hacksaw
     D. I tried a band saw
          i) I tried a cheap, stock wood-cutting blade
          ii) I will try a bi-metal metal-cutting blade
          iii) I will try to slow down the band saw speed so as not to overheat the plastic in the laminate
               a) I will explore gearing down with pulleys
                     1. I will diagram the entire machine
                     2. I will discover what arrangement of pulleys will fit in the machine
                     3. I will learn the mathematics of pulleys
                          I) I will create more metal framing to support the new pulleys and jackshaft
                               i) I will explore making the pulley tension adjustable so the machine isn't intractable
                               ii) I will explore making the machine operate in both new and old configurations
               b) I will explore using a DC treadmill motor
                     1. I will search the internet
                     2. I will search tag sales
                          I) I will learn to identify motor size by treadmill model
                          II) I will have to bring home a treadmill
                          III) I will have to dismantle a treadmill, preserving the parts I need

Maybe I'm not saying this well, or maybe I'm saying something too pointlessly obvious.  My point, however, is that every time I hit a wall I have to dig backward in a tangentially-related discipline. Each time I do, I am going back in time to follow the tracks of other people who visualized these problems very clearly decades and centuries before I was born.  "Band saw" to me means more than just a free saw that I have to recondition and tune up:  it now means blueprints and engineering and pulley ratios and keyed shafts and pillow blocks and jackshafts.  "Band saw", on a bad day when you have to cut something very strange, could be construed to mean, "All of engineering and physics."

I am constantly amazed by this process of blockage, regression, elaboration and breakthrough.  I don't know if I'm getting closer to building a guitar, or farther. There is a part of me that is always discouraged at this process; that is also the part of me that would have settled for rediscovering fire after each lightning strike, rather than learning how create fire.

I am a monkey.