8 String Falcate Braced Nylon String Crossover Blog:
April 13th 2018
Sorry It has been a while but I spent two weeks in Chicago helping my mom in rehab from a stroke and then spent about a month in Thailand and Laos. I have been making some progress on this guitar. I managed to finish the rims today.
As this is a new body shape for me I need to layout the heel block. This guitar will have a bolt on bolt off neck so it has the heel block extension as well. As the rims are already sized for the wide neck I used the rims as a template for the block.
I shaped it on the bandsaw and the beltsander
A few clamps to glue it in place
I also installed an end block
I sanded the top to a 40' radius (I have previously used a 32' but I do not want to pre tension the top as much). The back is radiused to a 10' radius. Crazily this time I ended up using the band saw to cut about a quarter inch off of the installed heel block as I made the sides a bit too tall. I managed to get away with it.
I used reverse kerfed linings for the top
Once installed I marked where I wanted the side braces and notched the kerfed lining to accept them
I tried something new for me. I made the side braces the same height as the kerfed linings. Then instead of installing and notching the back linings. I installed the side braces and filled in the AST A4 linings.
Tomorrow I will make the falcate braces for the top.
April 19th 2018
With the back and rims complete it is a good time to brace the top. As this top is braced with laminated fiber carbon reinforced falcate braces it takes a couple of day as I need to allow the epoxy to cure in between steps.
I had to really look for some tall enough bracing for the main falcate braces I needed brace stock at least 1" so that I could laminate and form a brace wide enough for two braces and rip it when finished. Most the brace stock I could buy was .75-.8". I did find a supplier that sent spit portions of the log. Plenty tall enough and nicely quartered.
I ripped a bunch of 1.7 mm strips, bent them on a form and laminate them on my falcate brace forms.
I use wax as a release on the form.
Once cured I rip them on a band saw and clean them up on a flat radius dish (the back side of a radius dish)
I use my [url=http://www.luthiersfriend.com/aOtter/Otter.html]Ken Pickou "The Otter"[/url] routing table to grove the braces just deep enough to inlay the carbon fiber. As there were three laminates and my bit was close to 1.7 mm I used a scrap bit of the laminate strips to offset the fence. My depth is a tad deep so I route and then sand them a bit to they are just the correct depth.
As I need to handle the top a bunch I cut out a 5 mill cover for the top. I also tape over the hole I used to route the rosette and most of the way doe the sound hole.
In my quest to be clean, I work with my gobar deck on my bench with plenty of light. Before gluing down the falcate braces I get everything ready. I use a small brush to apply the epoxy and I wipe my gloved hands between all of the steps.
April 12th 2018
Nearly finished with the top. I epoxied on the remaining straight braces all with carbon fiber underneath. I had notched the narrower braces for the CF tow but did not worry about the wider sound hole braces. I probably could have included these braces in my last glue up but it gets a bit crazy with that many go bars .
The following morning I profiled the braces using mostly a plane for the falcate braces and a chisel for the smaller braces. The main falcate braces are 10 mm and the secondary falcates are 8 mm. I will probably end up with a top resonances between 180 and 190 Hz. I brace a classical for between 190 and 200 Hz. I want to help the bass out a bit as this guitar as two extra bass strings.
To fit the transverse brace over the falcate and sound hole braces. I carefully position and clamp the transfer braces to the braced top. I use a scalpel to accurately notch the location of the sound hole and falcate brace on the transverse brace. Taking the transverse brace to my parrot vise I position the brace at just the right height in the vise and use a razor saw to cut the out the edges of the rebate and a chisel to clear the waste. This method allowed me to fit the brace in one go.
The final glue up involved epoxying a CF two on each of the braces and epoxying down the transverse brace.
I am trying something a little different with the transverse brace. Usually I have radiused brace flattened in the area under the fretboard and glued using a specially shape caul. Given that this top has a large radius 40' I went with a non radiused transverse brace with the 40' radius dish as the caul. I am sure that resulting radius under the transverse brace will be much larger and easy to work with as I fit the neck and fretboard.
May 10th 2018
I have started to close the box on this guitar. To get to this point I had to profile the tops upper transverse brace, fit the top and the back to the rims including routing out pockets for all of the transverse braces, one on the top and three on the back.
To fit the top and back to the rims I place the plate on the correct radius dish and use a scalpel to mark out where the braces intersect with the linings. I use a straight edge across the notches I create with the scalpel and use a pencil to market out the pocket for the brace. Also not in the first picture I misplace the transverse brace a bit leaving a gap between the block extension and transverse brace. I extended the block extension with a strip of mahogany. You can see it in later pictures.
I trimmed the ends on the braces to fit in the pockets. Sorry about the dearth of pictures, in a bunch of my other builds; I route each pocket to the depth of the actual brace using the brace to set the depth of the a pneumatic pencil mill grinder.
I wanted to install the end wedge before I closed the box. This meant I needed to finalize the binding scheme. The bocote is so figured I wanted to frame it in black bindings. Given that the horn on a Venetian cutaway has such a tight radius I decided to bend the binding first to assure I will have a match to the ebony end wedge I wanted to install. On a previous guitar I did successfully after breaking about 10 ebony bindings bend the ebony bindings to the shape. However earlier this year I bought some [url=https://www.rocklite.co.uk/]ROCKLITEŽ Ebano[/url] bindings from LMI. This stuff looks and acts like wood. Luckily I found that it bends more like East Indian Rosewood then like Ebony. Its structure seems to be a lot like wood so it can be over bent with the top fibres ripping. I Usually bend my bindings on the fox style side bender with the sides. I have had trouble though getting the bindings out of the side bender without cracking them. Also it is hard to get the binding bent tight to the shape as there is always spring back. By hand I can over bend so that the spring back is to shape. I bend two bindings at a time taped together purfling to purfling.
On to the end wedge
I cut out an extra long end wedge out of a scrap of ebony I had. My plan is to have the ebony with a maple purfling to match the bindings. I marked the rims deep using a scalpel and completed the cut with a razor saw. I then chisel the waste to the end block.
Once the channel is cut I clamped in the wedge with the purflings, tapped it tight with a hammer and flooded the clamped wedge with thin CA.
I used a plane and then a scraper to take the wedge flush
Ready to move on and start to close the box, back first. With the back clamped on the blocks I slowly inspected the entire joint, making sure the box closed without issue. I found that a couple of the pockets were not deep enough, so I fixed them with a chisel.
Once the back fit I put a bead of glue on the tims and the blocks and clamped the back on the rims with the rims sitting in the tops radius dish. The rims are still clamped in the mold to assure that everything stays square. I had enough clamps so I did not bother with a gluing caul.
While preparing to glue on the top I thought it best to finally finish the sound hole. It is mostly routed. I also bevel the sound hole patch, so the top does not look twice as thick when view in the sound hole edge. As part of the beveling the sound hole waste dropped out.
Also before moving on I marked out the true profile on the top and cut closer to that profile on a band saw. I also cleaned up the back on the bandsaw. When I trim the top and back with a flush cut bit I want to start within the diameter of the router bit.
Today I will clean up the inside of the body while the guitar is open and glue on the top.
I finished closing the box. I cleaned up the top, checked the fit to the rims. I used a spiral flush cut bit to trim the excess on the back, and finally I glued on the top. I ran out of cam clamps and add a few violin clamps to make sure that I had relatively consistent pressure.
May 21th 2018
I finished the body last week including installing the bindings and purflings. I hate binding a guitar. I am getting better but dang if I do not get something I have to deal with later. In this case there were a couple of places where I chipped out the sides on the bottom of the binding channel. Nothing that I could not fix, but still ...
I do learn on each guitar. On this guitar I decided not route until the rims were basically finished sanded. There is nothing worse than sanding out a low spot with in the rims and figuring how to do it without thinning the binding. I used a cabinet scraper and sanding blocks until the rims were properly leveled. As part of leveling near the end I wiped down the guitar with a wash of shellac and level sanded it off. The low spots do not hide an they remain shiny
Not shown is these pictures, I routed the channels using my Blues Creek [url=http://www.bluescreekguitars.com/shop/index.php?main_page=product_info&cPath=43&products_id=140]Fleishman Binding Machine[/url]
I hand finished the binding channel where the cutaway meets the neck. I use my fancy [url=http://www.leevalley.com/en/wood/page.aspx?p=70837&cat=1,43314&ap=1]Karl Holtey Design Purfling Cutter[/url]. The first picture I am just setting up the tool for the size channel I need.
I used a chisel to clear the waste.
I used titebond hide glue and only did one half of one side at a time. not shown in the picture I had to cut to miter cut the cutaway binding a the neck
Without the purfling the back went in without issue as well.
I prepared the short bit of binding for the neck to body transition and installed it as well.