Acoustic Guitar Construction

As we go through this -- it will help you with future projects if you go and forth to the articles to get a feel why the question and measurements are pertinent

First thing we need is a picture with a combination square set to the edge of the sound hole, place the square on the rim at the neck block and measure the gap between the square and the sound board -- with that I can figure the slope angle of the top under the finger-board extension.

Gap at the rim edge is 3/16, gap at the first ring of the rosette is 1/32

Dave - Thanks for the encouragement! I'm keeping my fingers crossed.

The measurement of this gap needs to be very, very, very, precise -- perhaps, you may need a helper to make sure the square is pushed perfectly flat against the rim and then measure that gap to within 1/64th of an inch. In mm is ok too

We'll also need the thickness of your fingerboard in the center including the fret. and the thickness of you bridge in the center.

You are a victim of the Stew Mac assembly system I've seen a lot of these many do not ever get finished!! I can pretty much tell you at this point already, that no amount of "whittling away at the neck heel" is going to remedy the problem.

Also a picture from the side with a straight edge pushed down on the finger-board extension area (perhaps a helper again) and a measurement to the bottom of the straight edge at the bridge position on the sound-board

I hope you and those following the thread are getting the idea of why we need these variables.

What process did you use to sand the top edge of the rim?

Ugh, I hope this is one of the ones that does get completed, I got the kit as a 50th birthday present so I'm really hoping I can at least strum open chords on it.

I used a radiused 25' sanding bar mounted/centered on a pipe and mimicked the dish approach.

The first picture is of the gap that I stated was 3/16, it appears to be 5mm. I may not be clear on the other requested measurements but here goes. The fingerboard is 18" in length so halfway is between the 7th & 8th frets, with my micrometer that measurement is 6.11mm, on the 8th fret it's 7.44mm. The bridge thickness is 10.7mm. The 2nd & 3rd picutres are what I think you asked for.

Thanks, Dave

Well -- trying to establish this slope and mating surfaces with a 25' dish/bar, that explains a lot -seems like more bad info off the internet, our forum is seeing lot of that the last few days.

Again , this is a very precise mathematical stack of dimensions. Its true the factories have a flossing operation for their dove tail joints to clean up the look of the mating surfaces, but they are not determining slope angle and neck set complimentary angle -- just detailing.

Here's more explanation of the math requirements and the tool to make it happen
http://www.kennethmichaelguitars.com/rimslopeMM.html

Your sound board slope is more then two times what it should be -- at this point it looks like a tapered shim under the fingerboard extension may be required -- not to worry its done all the time, there's one pro here in Michigan that does this to many of his guitars -- if done correctly it looks perfect.

The question regarding the fingerboard, we are looking for the thickness of the FB at the apex of the contour (which is usually 16") so across the width at the center of the 12th fret would be a good place.


Now we need to figure your neck heel cheek angle -- a picture fingerboard plane on a flat surface, square up against the cheek --- dimension of the gap -- height of the heel

Also -- will the neck drop into the mortise deep enough for the finger-board plane to be flush with the surface of the sound-board?