Acoustic Guitar Construction

I finally pulled the trigger on a small CNC machine, a Genmitsu PROVerXL 4030 V2. I had always feared the CAD part of it so I tried the free trial of vcarve and drew out a Gore style bridge and simulated the tool paths.





Using just 2.5D there is some limits in terms of 3D profiles. In this case sloping the block top to bottom. Instead I etch some lines and finish up by hand. To test the process I cut out a bridge in poplar practicing a bit before I carve the rosewood.

That's very cool. Your machine is much bigger/better than mine.
I should really spend some time learning to use mine to make parts like that.
I have V Carve but haven't dug into it yet.
Looks like you caught on to it pretty quick.

Little by little I still been gather and fabricating what I need to build the guitar.



I using epoxy I laminated the previously bent strips and split them to form the two sets of falcate braces.









I finally did some real routes with the CNC. I designed a three ring rosette as a nod to a Martin 00.



Still new to CAD I ran a test run on a square of spruce I had from a previously ruined top.



With the CNC running I joined a couple scraps of Koa to use as a wood ring.









Cut out the ring



Test the test run.



Run the toolpath on the real top and make the rosette.



I used some seal lac and alcohol to seal the channels.



I installed all of the rings and flooded with ultra thin CA.





I leveled the rings I will still need to clean it up a bit.

Little by little I am making progress. A bunch of my work (play) is hidden while I play in the CAD software. I worked out the straight string contemporary headstock that incorporates a client supplied inlay. I will use my cnc to cutout the headstock when the time comes.



I used my Fox bender to bend a set of profiled sides. No issues; I thicknessed the sides to .080" and bent them at around 285F. I sprayed the cutaway side with Supersoft II and let it sit wrapped for about 8 hours.





I am using the CNC router to make templates for the build. In the picture below I made a bridge hole template where the leading edge of the template is the leading edge of the saddle. The falcate braced top need the bridge peg holes drilled before bracing. The template will really help place the holes relative to the saddle location.



On the fun side, I have a vectorized version of my logo. I etched it with my CNC router, filled it with black CA and sanded it back.

Very cool. You're having fun with the CNC.

With the sides bent I used titebond to glue on the tail and neck block. The tail block is straight forward with the sides trimmed to size on the bandsaw and the belt sander.





I have always struggled clamping clamping the heel block to the cutaway sides. This time it finally hit me that there is no need to glue both sides on at once.
So I first glued the cutaway aligned and glued on the cutaway side.





After a couple of hours I glued on the non cutaway side.





Before profiling the sides I used the square top side to evenly place the sides in the molds and then marking a couple of lines to help me realign the sides in the mold after the top and bottom are profiled.



Starting on the back sides I used a plane to remove most of the excess. The sides were profiled but tall. I marked the sides down a few millimeters and used a plane to take them down to the lines.



Then I used a 10' radius board to clean up the sides to the 10' profiles.



Leaving the rims on the 10' radius board I used a 32' radius board for the top profile.



In the picture above notice that I do most of the sanding on the lower bout. I lower the lower bout to create the correct angle for the neck angle. Most builders profiled the entire top and work on the upper bout to create the correct angle. I instead get most of the angle by dropping the lower bout.

I any case I profile the rims until an unbrace top held on the rims show that I have the right angle.

First is too low needs more work



After a bit more work the 3 mm bit shows me I am close.



Once the top is braced I play with the profile more to make the fit perfect.

On the CAD front I figured out how to profile the wings with the trapezoid block shape.

Sure I am a bit distracted playing with my CNC but I am doing some useful work. The bridge pins need to be located and drilled early on a falcate braced steel string acoustic. The primary falcate braces need to go between bridge pins (I suppose I could go pin less!). So to make the placement easy I made a hole guide where the leading edge of the guide is the leading edge of the saddle at the high E location. This guide makes it really easy to locate, center and square the hole guide.



The drilled holes are used to index the, in this case a hard maple, bridge plate also cut with the CNC. The bridge plate is 1.5 mm with a laminated CF weave between it and the top. While Gore's process is to put the CF tow for the primary falcate braces down at the same time as the bridge plate I have found it is too stressful to do the plate and the falcate braces at the same time. So I installed the plate by itself. When I epoxy the falcate braces down I will run the CF tow over the plate under the falcate brace.



Not to waste the epoxy I mixed I made a laminated bridge blank, from top: 3 mm Brz rosewood, CF weave, 8 mm Brz rosewood.





Bridge plate epoxied on top



While waiting for the epoxy to cure I carved a test bridge from a rosewood blank I had. I will use this for a non falcate guitar in the future.







Happy with the bridge I carved one with the laminated blank





Moving back to the top I put in the rebates for the bridge plate in the primary falcate braces. I used a razor saw for depth and just carefully used a chisel clear the rebate.







Finally today I epoxied on the falcate braces. Sorry no in process pictures as I always have epoxy on my fingers. So a picture getting ready. Mise en place!