Tuesday, May 22, 2012

Gluing up a guitar neck blank

ebony, maple, walnut, maple, cocobolo, maple, walnut, maple, ebony
Guitars are the reason I'm interested in woodworking. Building them is also very intimidating for me. I've built 2 in the past, neither from scratch. I've been designing, working, and mostly procrastinating towards the next two for the last two years.

Chalk demistifies planing dark woods. The high spots are gone.
Fortunately, my other projects have increased my basic skill level, and made these guitars a little less scary.

Even though this is not the goal, these ebony shavings really are beatiful.
The reason I first got into building guitars is because I wanted to own crazy ones that couldn't be purchased. The first one I built included two pickups that each covered only 3 strings. My next one was an electric baritone fretless 7-string from Warmoth parts. And this time I wanted a short-scale, 7-string, neck-through acoustic body guitar on a stick. No wonder building them is intimidating. If that didn't make sense, just keep following the blog and it will become clear at some point.

tape lets you open the layers like a book, but one continuous strip didn't leave expanding gorilla glue anywhere to escape.
Anyway, I thought it might be wise to also build something more simple and mainstream. So I'm also working on a normal-scale 6-string version of the same design. Since I didn't want to use truss rods, I looked up young's modulus on a bunch of wood species to figure out how to make a very stiff neck. I already glued up a neck blank for the 6-stringer out of hickory, with some walnut veneer.

spread the layers
Hickory is kind of a sleeper. It's much harder and stiffer than just about any other North-American hardwood, but not extremely expensive or flashy. Yesterday, I finally swallowed my fear and glued up the other neck blank. This one, for the over-the-top 7-string version, is made from cocobolo (center) and ebony (sides) with walnut and maple veneer layers. This kind of combination of exotics would probably look awful and be ridiculously costly in furniture, but for a guitar, I find it to be neither. Guitars are supposed to be weird.

The Ebony pieces I had were still a little rought from when I hand-ripped them, so I jointed them. A freshly honed 50-degree iron in my bevel-up-jointer did the trick. Very thin shavings were necessary to keep it moving at a reasonable pace through this dense stuff. After the planing, I aligned the wood, taped the flat side, opened it like a book, and temporarily removed the veneer. Taping along one edge is a great way to save time in face gluing, and I needed all the time savings I could get. In retrospect, I should have used several strips across the layers instead of one lengthwise. I used gorilla glue, which expands. Leaving the glue nowhere to escape on one side meant it kept trying to push the veneer out the other side.

wiped off some color
Supposedly cocobolo isn't very good at accepting glue, and I wouldn't be surprised if the same is true of the ebony, as dense as it is. I tried something I read about and wiped the faces down with acetone to remove oils from the surface. It also wiped off some of the color.

Next up, more procrastination. But just a little. I was about to glue up 9 layers of wood in one session. That means spreading glue on 18 surfaces and getting everything aligned accurately, and doing it all really fast. I'm not really sure what the open time is for gorilla glue, but I don't think it's a lot. So I paused and asked myself if this is really what I wanted to do. Maybe it would be safer to break it up into a couple of gluing sessions? I decided to just go for it. What the heck, you only live once.
the right glue spreader is KEY.

I misted the surfaces with water, because apparently that makes gorilla glue work better. Then I got my glue spreader and started working fast.

spreading glue like the wind.
As I went, the veneer started escaping, being pushed by the expanding glue. Eventually I had to get my hands messy, rip some tape off the back and start clamping in a hurry before the veneer moved again. Then I thought about how I wanted the glue lines to look (not full of bubbles), and applied every clamp I possibly could.

my first look at the results
A couple hours later, after the glue was dry but not petrified, I returned to clean up the excess foam and take a look at the results. Getting it all off took some effort, but luckily the glue lines were tight and invisible. Once I hacked off the large chunks with a knife, I used a block plane and a chisel to clean it up a little more.

It was all worth it. Well, maybe not the procrastination.
This part made it all worthwile. Seeing shavings with veneer stripes included was incredibly satisfying.

I think you can expect to see more on this project in the near future. This little success has got me jazzed about the project. Also, since I had the idea to build these guitars a couple of years ago, I've gotten a lot more comfortable with things like sawing to a line. Now that I imagine the next step, cutting off a piece to use for the headstock, I realize I'm not even too scared to do it. Hooray!

Step-by-step drawings
Speaking of procrastination and being too scared to work, one positive thing did come out it. While I was having trouble imagining the order of operations for building the neck, I solved the problem by drawing out the steps. Drawing helps me think and it's probably underrated. I'm talking pencil and paper, by the way. It's graph paper for me.

2X each: bridges, neck blanks, fingerboard blanks

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