Dreamer Easy in the Chair that Really Fits You

All of the braces are  exactly 1/4" thick.  The X-brace will be exactly 0.600" tall at the joint.  Above, I am using my scraper plane to make the braces planed perfectly smooth - no rough spots to collect dust.  Also, I can creep up on the thickness easily.  Below, I am sanding one of the X-braces to a radius of 28'.  The top will have a slight dome, one that is flatter than the 16' radius of the back.  The dome makes the instrument stronger (think of the arch shape) and thus, better able to cope with changes in humidity and temperature.  The top won't cave in on the first humid day.  Stronger also means I can build lighter.  And lighter is louder and more responsive.

Now, classic guitars do not have an X-brace.  And since the classic guitar has lighter strings (nylon vs. steel) they are built with more delicate braces so as to be as efficient as possible.  It's all about using the power of the strings to drive the top - evenly across the frequency range of the instrument.  The lighter the braces are, the more the top can move, and thus move air.  However, if the braces are too light, the top cannot withstand the pull of the strings. 

 The above is something only I do, as far as I can tell.  Sanding always produces a curved surface.  After I sand in the radius, I take a short plane (a block plane is short enough to follow the curve) and make the gluing surface perfectly square and flat from side to side.  I want the entire brace to glue to the soundboard, not just some of it.

Here is the X-brace joint.  Perfect.  No wiggle.  This might be the most important joint on the whole instrument.  It is believed that the integrity of this joint dictates how sound propagates across the sound board.