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Nope, steel string. Strong enough for mediums at least.
Though I'd love to hear any suggestions on how I could improve the bracing design.
Cheers

I would put them either side of the truss rod (if any) starting just below the nut going all the way through to the end of the fingerboard extension. To reduce the weight of the headblock, you could use a normal L shaped block as you would do on a double-tenon neck joint, then put some carbon rods from the top of the headblock to the waist, like so:
http://www.anzlf.com/phpBB2/userpix/65_P8310209_3.jpg
If you still want the bolt to be adjustable from the outside, you could insert a hollow carbon rod as a compression block with the bolt running through the middle.
Actually, looking at it again, that might be what you have drawn already. I'm not familiar with the Brunner neck joint.

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"I am always doing that which I cannot do, in order that I may learn how to do it."
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We keep posting over each other! I'm no expert on bracing, but you can look at some of the info about Ervin Somogyi out there. Here's a good one, again on the ANZLF: http://www.anzlf.com/phpBB2/userpix/65_P8310209_3.jpg (Scroll down to the picture). I've used variations of this pattern on both the guitars I've built. On my quinto, I used 3 fan braces instead of the lower lattice bracing and you could probably do the same on your travel guitar. Just keep it really light - all the plans I've seen are massively overbraced. The x on my OM was 6mm wide, finger braces 4mm and lattice 3mm. Top was about 2.6mm. It sounds amazing (to me )and has hardly bellied at all in 6 months.

_________________
"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

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Haha Didn't happen this time as I was cooking up a steak! Very nice it was too.

The rods in that pic really are very appealing. I'll have to do some reading about them. I also think most of the plans seem over-braced. I built my dad's L-00 to much the same specs you did your OM. definitely seems lightly built, so I hope it holds up as well as yours.

With the slightly smaller body on this one, I'm thinking of building lighter still. Not too much though, as you can see in the following pic, the body is only slightly smaller than a full size OM, and much bigger than the Baby, so hopefully this won't suffer from "small body syndrome" in the way the Baby does.

The neck reinforcement sounds like a great idea, as does the extra support for the headblock... I'm tempted to say I'd leave such complexities for a follow up "Mark II", and more or less treat this one as a prototype. A

That's very intriguing! On the original Brunner, the bolt just passes straight through an oversized hole in the headblock, through to the neck and into the barrel nut/cross dowel, much like Cumpiano's neck.

I'm not sure I totally understand your suggestion. A hollow carbon rod for the bolt sounds good, but how would it work as a compression block?

Sorry, ignore that idea, I wasn't looking at the picture properly.

_________________
"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

Cool. Please let me know if you think of anything else!
I'm tentatively pleased that, so far, no-one has laughed the idea off entirely.

Ok, here's what I got, combining your idea with a smaller neck block and carbon rods. I think it would be less work than that massive headblock and be lighter too. (Easier to see in 3D)

_________________
"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

Cor blimey, you don't do things by half measures do you! That's fantastic, thanks so much for the input!

Honestly, I've not done much reading about installing the CF rods, so I shall have to start. I'm sure I'll be able to manage it with a bit of effort It's too good an idea to not do! Saves a lot of weight on my routed headblock.

I just wonder if the rear CF rods will support the force bearing down through the set screws? What about another CF rod from under the fretboard extension down the the back? Or a Spanish heel of sorts to put the rod between?

It only takes 5 mins in Sketchup! Forgot about the downforce in the middle. If you switch the waist ends of the rods around (top to bottom), it should be able to cope - the force would go straight into the sides in the lower bout at roughly 40°. Most of the load is in a straight line which get taken by the end of the headblock. You might want to strengthen that somehow, possibly like on the video I posted before: http://www.youtube.com/watch?feature=pl ... njZmPyugUQ

_________________
"I am always doing that which I cannot do, in order that I may learn how to do it."
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I thought that after I posted, that should be fine.

Whole thing is a definite improvement on mine, thanks again... There's still weeks till I start building. Here's hoping the design keeps getting better and better in that time!

As for reinforcing the back of the neck pocket, Brunner screw a brass plate there, is that the sort of thing you mean? There could even be grub screws there for fine tuning intonation, though it could only ever be for tiny adjustments if I have (as I must) a tight fit. Thanks to the chamfered edge on the end grain of the neck, even adjusting from a really low action to a high action only changes the string length by 0.3mm at the most (the through-bolt will obviously need a bit of "wiggle-room" in order to line up wit the neck's cross dowel.)

It does seem like the CF rods would be easier to install when building in an outside mold, which I wasn't planning to do. Hopefully that isn't a problem.

Nick

I think the neck should be supported against string tension at the pivot point (like the carbon fiber bar in the video), not the back of the neck pocket. With it that way, adjusting the neck angle will change where the neck contacts the supporting area of the block. It can be done that way, but it seems to me that it would be much more difficult to construct accurately enough to be satisfactory. Maybe I'll do a sketch...

edit: an outside mold is the way to go

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

Thanks for the advice, Rodger! I need all the help I can get

The two I've built so far have both been without an outside mold, so maybe it is time I used one. There is something that appeals to me about building free-form though.

I'd love to see a sketch if you get the time
I'm just pleased my drawing hasn't been laughed at! Yet... In fact, I'd love to hear from anyone who hates it!

Cheers,
Nick

There is something appealing about building free form, I did my first 3 or 4 that way. Then I entered a Challenge, I believe it was on MIMF, and the first thing that the two builders for which I have great respect did was to build an outside mold, as if that was a necessary step. After doing several with a mold, it may not be necessary, but it sure is easier!

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

I can see how it would be! If I have to use a form, so be it... No biggie really.
As long as the neck joint works out (and I'm cautiously optimistic that it will) I think this is going to be a fun build!