Fitting the Acoustic Guitar Top
Source: Guitar Building Articles: The Guitar Sides, The Guitar Top
Tools and materials Required:
Japanese Pull Saws
Fine Dovetail Saw
Wood Chisels
Square File
Sandpaper 180, 120 Grit
Large Rubber Bands
The Top Installation Process:
First of all, make sure your Top Plate is ready to go. The braces should be glued on the top, shaped and sanded. The bridge plate should be attached to the top and sanded. The rosette should be in installed as well as the rosette reinforcement strip installed beneath the rosette.
Put your sides in the inside form, top side facing up. Put in your Side Spreader Jacks and make sure the sides are tightly following the form. Place the Top Plate on the sides, and line up the center of the top to the center-line of the sides perfectly. Put a half a dozen or so large rubber bands over the top to hold it firmly in place so top braces are resting on the sides of the guitar. Double-check your alignment.
Visually Inspect Your Work:
Do a visual inspection around the guitar to make sure everything is exactly lined up. Now take a sharp pencil and trace the perimeter of the sides onto the scallop portion of the braces. Be sure to be accurate with this and place this mark directly next to the guitar side.
First Method of Brace Attachment – Brace Extend Through Sides:
There are two major ways to connect your bracing to the sides of the guitar. The typical Acoustical Guitar method is to saw a channel directly through the sides of the guitar and let the braces run through this channel. This would apply to both the standard kerfed lining or the separate block style of lining.
You start by carefully marking the brace locations on the guitar sides during the top fitting process as listed above. You should use a very sharp pencil or a marking knife for this. Lift off the top and measure the depth of each brace where it intersects the side.
Saw the brace outlines out with a fine dovetail saw or a Japanese Pull Saw. I cut down to within about 1/16″ of an inch. Now take a small pliers and crack these pieces out very carefully.
Take a square coarse file and cut the channels down to your depth marking for each brace.
Precautions: Make sure the depth of your braces + the thickness of the top do not exceed the depth or your binding around the instrument. This means that the brace needs to be very thin when penetrating the guitar side.
Dry Fit The Top:
Now is the time to see how accurate your were. Place the top on the sides. It should fall right into place with very little pressure. Your channels should not be really tight but they should not be sloppy either. It should feel like you are place a plastic lid on a can.
If you run into too much resistance. Inspect your work to find the problem areas and adjust as necessary. The top should lay perfectly flat on the sides with no gap.
Now trace the side profile onto the bottom of the top plate. Remove the top and carefully band saw the outline to within 1/16″ of the line – closer if you are careful. Sand the rest of the way to the line or just a bit beyond the line.
Second Method Of Cutting Bracing To Guitar Sides
Source: Guitar Building Articles: The Guitar Sides, The Guitar Top
Second Method of Brace Attachment:
The second way of attachment of the braces to the sides is typically used for Classical Guitars, but I have used this method for the higher end Acoustic Guitars as well.
Mark The Braces: Mark the brace location on the top of the sides (and lining if lining is already attached). Take the top off and measure in from the marks on the braces the exact thickness of the side wood. Cut the braces to the proper length and angle with a fine dovetail saw or a Japanese Pull Saw.
Reshape The Braces If Necessary:
Now compare the cut-to-length braces to your bracing diagram on your Guitar Plans. If you need to do some reshaping on the scalloped ends, now is the time to do this. The braces should all basically be about the same depth where they join the sides that shows on your bracing plan.
If you have linings installed, transfer the brace depth to the linings. Take a fine saw and cut the lining down the the depth mark without cutting through the side wood. This means you will only be partially sawing through the lining and will need to chip the rest out with a 1/4″ chisel. Clean all of these channels and remove all traces of the lining from the sides.
Dry Fit The Top:
Now is the time to see how accurate your were. Place the top on the sides. It should fall right into place with very little pressure. Your channels should not be really tight but they should not be sloppy either. It should feel like you are place a plastic lid on a can.
If you run into too much resistance. Inspect your work to find the problem areas and adjust as necessary. The top should line perfectly flat on the sides with no gap.
If you have not trimmed the top plate to your tracing mark, now is the time to do so. Refit the top to check it once more.
Tags: fitting the acoustic top, fitting the guitar top plate, Guitar Building Articles, guitar plans, how to build a guitar
