Hatcher High Figure Koa Penelope Sisters - Steel String and a Nylon Crossover
 

In February 2011, my wife and I took a couple weeks in Hawaii. It was very inspirational to see where the woods I have the privilege to work with come from.

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Here is a picture of a beautiful old Koa tree we discovered during our adventures.

http://farm8.staticflickr.com/7162/6...939ff3a1_z.jpg

Since that wonderful vacation I came across this gorgeous Koa board.

http://farm8.staticflickr.com/7156/6...65d4bebf_z.jpg

Here is a closer view.

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Even really close, it is hard to believe that this is a flat surface!

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This board is 42" long, 5"-10" wide, and 2" thick. The first order of business was to get it resawed to see what it would yield.

http://farm8.staticflickr.com/7154/6...c9e96ce6_z.jpg

I won't pretend that I resawed it myself. I have a decent 14" bandsaw but with all that figure and 10" width, I didn't want to risk it, so I sent it out to Dave at Borson Precision Resaw. I got back 12 great boards and 1 extra for faceplates etc! From each board I can get two back halves or two side halves. That's enough for six guitars!
The board still needed some drying when I got it. The pictures above do not have Naptha or anything on them though. Cut down thin they will dry much faster. The process for drying these is called "stickering" because you use "sticks" to open up the cuts so you get even airflow and control warping and cracking. By spacing the sticks both above and below the boards they can dry evenly and with pressure you can prevent warps and cracks. I covered it with plastic to start out. This slows the initial drying some and helps slow the shrinkage. This also reduces cracks.

http://farm8.staticflickr.com/7019/6...d695bb47_z.jpg

This set of wood gives me the rare opportunity to build book matched guitars. I am going to build two of my Penelope models, but with a twist,
one of them will be a nylon crossover. I will build them side by side on this thread so we can compare and contrast the processes and result.
While the Koa dries I'll get everything together for this project.

Thanks. I hope you enjoy the ride!

Oh boy! Thanks for sharing Mark; I cannot wait to follow this thread.

Happy New Year everyone.

Those are great pics -- and that Koa is stunning, to say the least!

Thanks for your comments.

Here is a link to my Penelope page on my website: http://www.hatcherguitars.com/models/penelope/

The Penelope on this link has a Western Red Cedar top and a cutaway. I am going to use Swiss Spruce and no cutaway on the guitars I'm building on this thread.
I am also changing up the trim and will have my sculpted headstock on the steel string. The crossover will have a whole new head design that I'm testing out now.

Right on Dude.

Thanks for sharing the photos.

Solo

Hey Mark - Still intend to make it down to your shop since I'm just up Rt 9 from you. What was the outcome with the beautiful cocobolo you had up a couple months ago....?

Regards,
Robert

Happy New Year!
 

Hello Solo and Robert

The Cocobolo guitar is still coming along. I'm French Polishing the neck and am waiting to get the body back with the back and sides finished with polyester. That should be soon and I'll be posting the finishing steps and set up. Then it will be going on a road trip. I still can take names for anyone interested. http://www.acousticguitarforum.com/f...d.php?t=227187
I moved and am now up the road from you in Milltown. I welcome you to come up and see the shop etc. I'd suggest you come up in 3-4 weeks as I will probably have that Cocobolo guitar back then, the shop will be more set up, and I'll be further along with these Koa sisters

Drying the Koa
 

After a week the plastic comes off and I can start to circulate the air a bit.

http://farm8.staticflickr.com/7031/6...bbf06b6b_z.jpg

From there it's just a matter of waiting until it reaches my target moisture level.

http://farm8.staticflickr.com/7152/6...2ca2983a_z.jpg

Hi Mark,

your Koa is wonderful!
Is 7% moisture your target for this wood?
and, btw, happy new year ;)

Q.

Hello Q

Yes. 7% is fine. It will be stable from here, so I can now start to cut the slices down to the back and side blanks. To get the backs and sides for this project I'm cutting four of these:

http://farm8.staticflickr.com/7164/6...c61e6933_z.jpg

And four of these for the sides:

http://farm8.staticflickr.com/7035/6...ba8a29a4_z.jpg

I can use the end cut for headstock laminates etc.
So from this I'll get enough for four guitars or two pair of book matched sisters. I'm picking the best pair for the Penelope sisters:

http://farm8.staticflickr.com/7015/6...385f5fcd_z.jpg

Time to select the woods. The figure in the Koa really varies from light to dark. I think having the Ebony black fretboard will help set that off especially contrasting against a very pale Swiss Spruce top. I'm using Cocobolo for the binding, tuner buttons, top crossgrain purfling, and bridge which I think will suggest the red in the Koa. Black and Maple purfling all around will help tie it all together. Here is a pic of the raw woods:

http://farm8.staticflickr.com/7157/6...7647869a_z.jpg

Thanks for viewing

Wow, gorgeous woods! I will look forward to watching this thread and seeing how these guitars develop.

Fliss

Hi Fliss,

Thanks for commenting. One of the best things about building guitars is that you get to work with such great materials!

Mark,

Fascinating... and beautiful! Thanks for sharing these pictures.

Top Wood Selection
 

I'm using Swiss Spruce for both guitars partly because I think the look is right but mostly because I think it's a wonderful pairing with Koa and this model guitar whether it is nylon or steel stringed. This wood is very light, stiff, and responsive to a light touch but certainly holds up very well to a little harder playing.
I went through all of my sets to find a closely matched pair. Both sets came in very light at about 5.7 grams per cubic inch. I also compared how stiff they were, both with and against the grain. Finally, I did the more subjective tap testing for tone and sustain.
The reason I'm going through all this trouble is to make as many things as close as I can on both guitars. There will be many more differences than nylon vs. steel strings when finished, but where I can, I'm going to start them off as close to the same as possible. In the end, I want to show what this guitar sounds like as a steel string and as a nylon crossover.

Here's a close up of the top wood, I'd tried to catch the silking in this photo even though this is dry and roughly sanded:

http://farm8.staticflickr.com/7151/6...6d760c94_z.jpg

Gluing up the first top:

http://farm8.staticflickr.com/7168/6...cdc556fb_z.jpg

Thanks for viewing!

Here are a couple more pics of cutting out and comparing the profiles;

http://farm8.staticflickr.com/7153/6...eed6c200_z.jpg

http://farm8.staticflickr.com/7141/6...99a8039e_z.jpg

Thanks

Dang, that's some nice koa there Mark!

Rossette
 

Hello,

I've been spending a lot of time looking at classic guitars as I am doing my research for this nylon crossover. What I've learned is that a classical guitar typically has a smaller soundhole than a similarly sized steel string. What I've found is steel string models, no matter the body size, tend to have same size holes. After experimenting I find my Penelope does sound better with more of an "optimized" hole to fit it's size. Now that I've got that settled I can make the rosettes and they are both are going to be the same size.

I'm going with segmented Koa with black white black purfling. The fretboard will be Ebony so I think it would look good to darken the Koa rosette and a little fire takes care of that.

http://farm8.staticflickr.com/7004/6...d2d76b8a_z.jpg

http://farm8.staticflickr.com/7142/6...7fc5c049_z.jpg

Thanks for viewing.

Wow cool - did I read your post correctly that you burned the Koa to make that darkened effect?

Another question. In your prior post, it looks like you did rough cuts around your top and back shapes. How do you then get perfect edges down to size? Just sanding?

Thanks. Yes, I just burned it a bit to darken it. I'll do the same thing around the edge of the Koa headplate. This torching certainly isn't anything new on my part, Bashkin immediately comes to mind, he has been doing this to wonderful effect for a while now.
As far as cutting the tops and bottoms down to size, this is typically done after they are glued down to the sides. From there you run a flush cut router bit around. Actually, there are a few tricks in doing that. Check in on the building section before trying it at home!

uf, it's gonna be very sexy body :p funny, i've just been reading a book about Hawai, there's one whole chapter about plants and a lot of about koa trees (no mention about the use for music instruments :). there are some pictures of koa with bizzare multiple trunks of which i would never say that they could be used for guitars... is it hard to find koa tress with a trunk(s) suitable for guitars?

Thanks Ivan,

Koa wood has been used for musical instruments (along with many other things) for quite a while. I think gnarled and twisted trees make more interesting pictures and that's probably why those pictures were chosen for your book (as well as the picture I posted) Koa trees usually grow pretty straight. Here are some young ones in a stand along the road;

http://farm8.staticflickr.com/7016/6...bd93965c_z.jpg


Koa trees grow fast and huge. They have been over harvested though, and grazing farm animals tend to kill them by eating the bark off. Luckily, there is a strong movement in Hawaii to replant the trees and, as I said, they grow fast.

By the way, I checked out your You-Tube link. Your a fabulous guitar player!
Thanks for putting that up.

Mark, looks like we have some great builds to follow here. Your other build thread had some great work and pics to help someone like me to learn alittle about approach and methods of work, thanks for sharing this.

As a long time woodworker I know what you mean by not wanting to resaw that koa and let someone who does it better do it, sometimes hard for us to admit someone else can do it better.

What a great piece of wood, almost seems like sacrilege to put a saw blade to it. But someone had to have the courage to do it, now it will serve a higher purpose, other than just looking fantastic! OMG what a hunk of wood.

Bruce,

Thanks for your comments Bruce,

I see you've just signed up to the forum-Welcome! There are a lot of great builds that get displayed here.
Your right about sending the board out to someone else. It was such a great piece and I just didn't want to risk not getting a maximum yield. My only regret is I didn't have it sent from Hawaii to California where it was resawed. It would have saved 6,000 miles of travel if I didn't have it come to me in NJ first! I guess I couldn't wait to see it.

Hi Everyone,

Time to post some more pictures. These next three are gluing and shaping the back graft. This cross grain strip reinforces the seam where the two back plates
are joined:

http://farm8.staticflickr.com/7032/6...6df17213_z.jpg

http://farm8.staticflickr.com/7017/6...6c9856a8_z.jpg

http://farm8.staticflickr.com/7021/6...6bb9ae3a_z.jpg

Here is a picture of the two tops. So far they are as identical as I can make them:

http://farm8.staticflickr.com/7020/6...5556ccc4_z.jpg

The bracing for the crossover is an area that has to be a lot different. The X bracing for a steel string guitar helps bring out the base from the steel strings. A nylon string guitar is braced in such a way as to bring out the high end because nylon strings tend more to the base side.

http://farm8.staticflickr.com/7022/6...66c2011a_z.jpg

Thanks for viewing!

Very nice work... look forward to hearing about it.

Brace Stock Quality
 

I'd like to talk a little about braces. Next to the soundboard the bracing is one of the things that can really effect the sound and responsiveness of a guitar.
The quality of the brace wood is very important as well as the cut and orientation of the grain. Braces that have the grain running true to the length of the brace are best. They are stronger, less likely to crack, and ultimately help the guitar sound better. That is why I take the time to split out my brace stock. By splitting the wood you are sure to eliminate the grain run out you may get otherwise.

http://farm8.staticflickr.com/7160/6...14448eca_z.jpg

Before there were sawmills in America boards were split from logs. Even after sawmills were available the tradition of splitting wood out was still used when the job called for maximum strength and reliability, especially when things needed to be kept light, like wagon wheel spokes or chair rails. "Riven" wood has been the name for quality and strength. It is also one of those traditions still carried on in the shop of a good handbuilder.

http://farm8.staticflickr.com/7002/6...7ab1a368_z.jpg

Splitting wood is usually done with a splitting froe. The froe is dull, but not blunt. It's size is appropriate to the job at hand, whether it's wood for boards, archery bows, or wagon spokes. This tool is small for things like splitting bamboo for fly rods or spruce for guitar bracing.

http://farm8.staticflickr.com/7004/6...923c1283_z.jpg

So, next time you take a tour of a guitar factory and are feeling a little cocky, ask them where they keep the splitting froes!

Thanks for following my build.

More on Braces
 

Hello,

Let's stay on braces a little longer.

http://farm8.staticflickr.com/7033/6...55f942f5_z.jpg

I have some unique brace designs that I feel add to the sound of my guitars.
First would be the profile. I believe this profile gives me the best brace to soundboard adhesion surface area and also provides more resistance to the twisting forces you get when using lattice bracing.

http://farm8.staticflickr.com/7160/6...998ff90b_z.jpg

I use a pretty complex mitre joint where braces cross. This eliminates the extra weight of having a box type joint. I also eliminates the hard spots you get from over-built joints. Again, this helps in voicing the guitar and getting predictable results from lattice bracing.

http://farm8.staticflickr.com/7144/6...21b1e9cb_z.jpg

Finally, none of this is of any help unless the time is taken to be sure that we have tight fit.

http://farm8.staticflickr.com/7162/6...553e40aa_z.jpg

http://farm8.staticflickr.com/7163/6...a52f09f8_z.jpg

The brace height is determined during the voicing proccess and each joint is then finally capped for additional strength.

Thank you for viewing. Comments are welcome.

Hi Mark,
I take it the lattice bracing is for the steel-string top, as your schematic for the nylon-string shows a fan-brace pattern. Or is this your back bracing?

Drew

Nice, clean workmanship Mark. And lovely Koa...wow.

Steve