KOA / Western Red Cedar Acoustic Guitar

I’m an ameteur / hobby builder and I started in 2003. I’ve built about 10 guitars in the last 7 years when I can carve out the time (pun intended). I’m currently working on 4 guitars and enjoy the time I spend on this hobby. So I thought it would be a good idea to show some construction photos of how I construct a guitar. I don’t have all the steps here but you get the idea. I’ve also had to insert photos from several different guitars showing the steps, I haven’t been able to find some of the shots I thought I had.

This is a Custom Concert sized guitar with the following specifications.

Flamed KOA back and sides
Flamed KOA bevel and edge binding
FLamed KOA rosette inlay
Western Red Cedar Soundboard
Laminated Mahogany/Maple/Rosewood neck
Below is a picture of the KOA sides being bent in the side bending jig. The sides are around .85 thick and have been squirted with water, then wrapped in tin foil, then sandwiched between a stainless steel slat and a heating element and another metal slat. That whole bunch gets worked around the bending forms via the screw at the top and the two spring loaded guides. The heating blanket takes the wood to around 300 degrees depending on the wood type.

Next is to glue the end blocks of Mahogany to support the Dovetail joint at the end of the neck and the rear tail end block. After that I install the kerf linings to give support and a glue surface for the back and soundboard. I also installed side support strips to give some cross grain support to the rim.

Looks like I don’t have a picture of the back bracing being glued to the back plate. I used laminated bracing of Sitka Spruce with Mahogany strips in the center. Here is a picture of the back already glued to the finished rim. Note the end of each brace is cut into the kerf linings and KOA sides for additional support. Its tricky business to get these lined up and cut perfectly, but it turned out nice on this one. You will also notice the inlay of “Magic Beans” on the Mahogany neck block. The guy I built this for sings a song about this, so I surprised him with this inside the guitar.

I’m not finding all the photos I thought I had for this guitar, so I’ve inserted the next 4 photos of a different guitar below showing these next steps.

Here how I glue up the bracing via a “Go Bar Deck” I use spring loaded 1/2” PVC tubes and a 3/8” dowel to apply pressure for glue ups. I should also note that the round sanding disc under the back is a radius dish that will give the top and back of the guitar a dome shape. I use 30’ for the top and 15’ for the back. All the braces are sanded on this dish before glue up so they conform to the shape of the dish and hold the top and back at their appropriate radius.

Here is a shot of the sanding of the back of the soundboard bracing.

And a couple of how I glue up the back and soundboard to the side rim of the guitar. I also forgot to mention the rosette which is a signature spot for any builder. This area is a nice place for details, this time I did a natural feeling rosette of KOA. This is done before I install the bracing so I can level it properly with a scraper.

Now that the body is in one piece its time for the edge binding. I’ve got a laminate trimmer setup that holds the trimmer vertically perpendicular to the side of the guitar and rides up and down via some drawer slides. I then clamp the body into a sled that can slide around under the trimmer. Below is a shot after the binding channels are cut. This is the “grand junction of binding” as there are 3 pieces of binding (plus 3 additional pieces of purfling trim) that all come together at this point. Notice the sled below holding the guitar body. Time for alot of fitting and more fitting to get the binding just right. All the binding is held in place with heavy masking tape during the glue up with titebond glue. Again a different guitar photo here…sorry.

Once the binding is completed and scraped flush the next step on the list is to get the bevel veneer installed. I had to make a pattern using masking tape, then transfer to a piece of KOA. Then bend it, bevel the edges and fit it into the bevel pocket. I think this took all day if I recall…pretty time consuming bit here. In the photo below you can see the thin black/maple/black purfling strip is already in place using CA glue. The KOA has to fit very tightly into that pocket or gaps will show.

Next the attention is turned to the neck. I laminate Mahogany/Maple/Indian Rosewood/Maple/Mahogany to form a neck blank then cut the profile out.

Building the neck is a complicated process in itself. If I don’t do it in the correct order I’ve found that I don’t have any reference points for alignment on later steps. So here are the bullet point steps in the neck once I’ve cut the rough profile of the neck blank.
-True up the angle cut for the peg head using the disc sander
-Glue the peghead veneer over the peghead
-Drill 6 holes in the peghead for the tuner using a drilling template
-Router the peghead shape using a template that fits into the 6 holes for the tuners
-Router out a center channel for a metal truss rod to support the force exerted by the string tension
-Router the dovetail joint using a special jig and template
-Center line the preshaped finger board of ebony onto the neck
-Pin the fingerboard via copper wire nails inserted through the fret slots, hidden by the frets ultimately
-Router the width of the neck to match the fingerboard width using the fingerboard as the template
-Shape the back of the neck using spoke shave, rasp, chisel, sandpaper, depth template
-Shape the base of the neck
-Cut the dovetail joint pocket in the neck block of the guitar
-Fit the neck to the correct neck angle from the guitar – This is very important to the ultimate playability of the guitar
WHEW! That all takes about a day….or two and looks like this when completed. (again a different guitar from the KOA guitar I started with)
Note the 4 small pins that are indexing the fingerboard to the neck you can see 2 stacked on top of each other on either side of the truss rod channel

Now that I’m in the home stretch its time for glue up of the fingerboard to the neck, and the neck to the body. Then its off to finishing. Here again, finishing is a lengthy process and takes about a month to complete the process. Mostly due to curing times for the lacquer. Here is the process again in bullet points.
-Sand all sanding marks out to 220 grit, then to 320 grit
-Seal the guitar with a sanding sealer wash coat
-Apply pore filler, sand, more pre filler, sand until its completely filled. EVERYWHERE! These show up all through the finishing process if I don’t get them now.
-Apply 2 thin coats of a thicker mix of lacquer, wait 5 minutes between coats
-Apply 2 more coats after an hour
-Wait 2 days
-Apply 4 more coats (thicker mix), wait 2 days
-Wet sand to level the finish
-Apply 4 more coats (thicker mix), wait 2 days
-Wet sand to level the finish
-Apply 4 more coats (thicker mix), wait 2 days
-Wet sand to level and inspect for any unfilled pores, drop fill as needed
-Apply 4 coats of finish mix lacquer, wait 2 weeks
-Wet sand 600, 1500, 2400, 4000, 8000 to an almost polished finish
-Buff and wax on the buffing wheel

Now I can finally install the bridge, frets and tuners. Then set it up for appropriate adjustments on the truss rod, bridge height and bone nut height for playability.

AHH Done. All told its usually about 6 months of work evenings and weekends when I can find the time. I’m estimating about 150-200 hours of total time. But I’m definately shaving that time down by doing more than 1 guitar at a time.

-- Philip, Minnesota, www.langguitars.com