Prepping For Closure
With all three body parts ready for assembly (#1), I made sure to sign my work on the underside of the Soundboard first, before I forgot (#2). I also decided to seal the inside of the body before closing it up (#3).
I sealed the body and Soundboard after I attached the back to the sides. (It’s out of sequence because I only took photos of prepping the Soundboard). Prepping the back is exactly the same process.
Regarding interior sealing: Amongst Luthiers there is some debate over sealing the inside. I am for sealing because it makes sense to have a moisture barrier and not raw wood. Also one of my favorite builders, Jeff Jewitt, is in the pro-sealing camp and if it’s good enough for him, well… you know the rest. I sealed it with CrystaLac It's “Knot” Shellac, mostly because it is what I had on hand. When sealing the Soundboard it’s important to be sure to not to add sealer where the glue joint is going to be.
Fitting and Gluing the Soundboard and Back
To fit the Soundboard/Back it first must be lined up accurately with the sides. Once I did this, I taped it down to alleviate movement. I marked the Soundboard and sides where the sides and braces meet (#4). Using the marks on the sides exterior I then transferred them to the inner kerfing by lining the marks up with a ruler (#5).
I trimmed the brace ends to the correct length with a chisel (#6 and #7). That length equaled the distance from the outer marked lines minus the 2mm thickness of the sides. To cut the notch where the ends of the braces are inset to the kerfing, I used my rotary tool with a straight bit and depth gauge (#8). Afterward I cleaned up those notches with a chisel.
I attached the Back first because it can be seen easiest through the sound hole when the guitar is complete. Being able to clean up any glue squeeze-out is essential. When attaching the Soundboard it’s not quite as critical, since you cannot see the majority of it. With either though, care must be taken with the amount of glue you are using. Nobody likes a sloppy glue job.
I only took a photo of clamping the back (#9). I used the clamps I had on hand instead of buying or making speciality clamps for this procedure. The throats of my clamps were just barely long enough to fit over the mold but I managed to make it work.
Side Trimming
With the Soundboard and back attached the overhang needs to be trimmed off. (Photo #10 and #11 shows the Back trimmed but Soundboard not trimmed.) I used a handheld router and straight flush bit for trimming. It’s important to use a very sharp bit and to be careful in the areas where you're cutting against the grain. Those areas have the potential for tear out.
Since a binding channel has to be cut into the edges there’s no need to worry about the router not being squared to the sides for this trimming. It does however, become important when cutting the binding channel.
Side Sanding
Remember the slight warpage I mentioned when I wrote about bending the sides? With the edges trimmed the sides can now be fully sanded flat as much as possible. There several ways to accomplish this, the two most common are using a cabinet scraper or a rolling-pin style sander. I don’t particularly like scraping wood so, I opted for this rolling-pin sander.
Side note: The actual spindle tool part of this sander is fine but the rubber sanding drums are slightly lumpy, which is not ideal for their application. The drums are the same dimensions of the drums for my table top spindle sander so I used those instead.
To sand the sides, I checked the flatness with a straight edge (#12) then marked the uneven spots (lightly) with a pencil (#13) and repeated the process as needed. Once finished, I achieved a reasonable amount of flatness (#14 and #15), although it was not perfectly flat in some areas. I doubt anyone would ever notice these areas without checking them with a straight edge.
Oops…
It is important to note; it would be quite easy to sand through the sides (remember they’re only 2mm thick). I say this as a word of warning because I did just that. I accidentally sanded through a spot which unbeknownst to me was an area where the maple either had a massive ripple (I hadn’t seen) or had a defect. In an attempt to sand it out, I almost sanded through instead. I caught it before it went completely through the Maple but not soon enough for it to not be paper thin. The darker color of the Mahogany body was noticeable underneath. I did my best to repair it both inside and outside. The repair is okay and mostly blends in. I’m purposely not posting a closeup photo of it. I’d rather not point out the flaw, which in photos is probably not immediately noticeable
This mistake felt like a gut punch and made me rethink the project. I seriously considered scrapping the body and starting over. After much contemplation, I decide to forge ahead keeping in mind this entire build will have many mistakes and flaws and that’s okay. However, I still am not happy about it.
Only one more step to go before the body is complete and that is a big one: Binding.