Acoustic Guitar Construction

I'm building a 13" lower bout, ladder-braced parlor for a good friend of mine; sapele back and sides and sitka top. The Washburn 1930's parlor is my basic model, but that one is only 12" and I did not have a mold that small; however, I was able to adapt a mold from the Martin 00-12, and by making it smaller, the dimensions are just right.
I'll start posting some pics tomorrow to bore some of you, and really bore the rest. :-)

Just yesterday morning I was looking at a reprinting of a 1897 Sears & Roebuck cataloge and in there was a Washburn Parlor guitar with gut strings, of the highest quality materials, for $22. Shipping was like $.25.

The cheapest guitar for sale in was $3.95 with a case.

Kevin

The best part of that - it's WITH A CASE!! :-) That is too good...

I ended up purchasing some plans for the 1930 Washburn from Michael Collins. He draws up some very nice plans; I also have a set for his gypsy guitar.
The plans come with details for x-brace as well as ladder-braces; my friend likes that 1930's blues sound so of course we'll go with the ladders.
I'm going to modify a couple of things - I want to use some a-braces instead of the 'popsicle' stick for the upper bout, for soundhole protection and greater stability. I will also be laminating the sides for strength and crack resistance, and perhaps do solid linings as well. Also, I really do not see the need for all those back braces; John How builds some killer ladder braced parlors and he uses 3 back braces only. I'll probably do that.
40' top radius, 15' back. Not sure about the slotted headstock yet. C-shaped 12 fret mahogany neck with a truss rod and m&t bolt-on. Bound soundhole instead of a rosette - most of the instruments of this kind in that time period had really simple appointments, though I will be making wood bindings and not using plastic.
The mold I modified will be used in the vacuum bag for laminating/bending the sides, and for bending the linings (also laminated) and the bindings (you guessed it).

This is going to be fun to watch being built

Kevin

I hope so! :-)

When I looked at Michael's drawings it was evident to me why ladder braced guitars have a reputation for volume. There are only two braces in the money area of the top, compared to 7 for the X-braced. Given the same amount of string energy input, the lighter top is less encumbered to pump air and the reduction in braces permits it to move more rather than use a lot of it to overcome resistance to motion. Further, the X-brace scheme seems to lock out movement around the sides which might inhibit the long amplitude movements required for bass. Locking out the sides appears to reduce the area of the sweet spot to a fraction of that retained on the ladder-braced design.

It is not so evident why ladder bracing favors treble - or if it does. To really get a take on that, perhaps you should build both versions and compare?

Your A-brace makes sense. Triangles are stable, rectangles are not. Upper bout stability will allow for a closer action without fear of buzzing in the short run and help address neck lift in the future, all without adding weight.

Laminating the sides makes them more durable, as well as more rigid. In theory, rigid sides force string energy to discharge by moving the plates, which in turn are the most efficient for moving the aid.

This looks like a very good plan. One based in traditions that are known to work, but also incorporates sensible contemporary thinking that can advance the traditional approach a little further.