Top Bracing Question on my 2nd guitar

[Paul Eisenbrey]

Hi folks,

With a lot of help from all of you in the forum, I got my first guitar finished -- it looks a mess, but it sounds good! For my second I thought that I'd do something normal rather than do my own design work, so I bought an 000 form from LMII.

The top is sitka spruce with a really nice bearclaw pattern. I've got it thicknessed to around 3mm, and the rosette made and installed. (I'll post pictures when I have enough posts on the new site to qualify. )

My question is about bracing. I am following Cupiano's book again, so normally I'd put two finger braces on each side and two long ones on the lower bout. But I found a nifty pictorial (http://instrumentmakers.net/LLcom/tutor ... intro.html) where he only uses one finger brace on each side, and a single long brace between the X struts.

Anyone out there tried this?

--Paul

[Bob Connor]

Yep. But on an 0 model - not a 000.

I have a couple of questions for you?

What is your reasoning behind wanting to do this?

What other steps were you going to take to ensure the structural integrity of your top?

Regards

[kiwigeo]

You could probably get away with one brace across the lower bout but the pay off is going a bit thicker to compensate for the reduction on bracing. A thicker lower bout in turn has a payoff in terms of ability of the top to vibrate freely.

I too would ask how one lower bout brace is going to give me an advantage over the conventional two braces.

As for all bracing.....its all about finding that fine balance between having enough bracing to prevent the top caving in and having too much bracing and supressing the tops ability to vibrate freely.

[Allen]

My recommendation is to go with the conventional bracing, as it's been tried and works. The subtleties you can get by how you shape that bracing. Where it's glued to the top, and the thickness of that top will give you enough variable to work with for years to come.

[Taffy Evans]

I reckon for early builds follow the plan, then later as you get more experience and understand better what you are hearing, and what parts contribute to tone and volume ect, try your own ideas. I have done bracing as you explained , but as Bob said, only on my smaller models. My first guitar was from a plan that was a Dread, but had no tone bars in the lower bout, just a cross brace behind the bridge between the two legs of the X. I copied this knowing that all I had read was different. But I learnt a lot from that, I have been playing this guitar for over 35 years and it still sounds great. One day i'll go back to that layout as I know how well it works.

[Mark McLean]

When I first saw this I figured that Cumpiano must be using that bracing for an 0-sized guitar. But if you look at that link it is an OM. I have also seen some others with just a single diagonal brace on OM and 000 sized tops (like in a nice article on Froggy Bottom Guitars in the latest Fretboard Journal). It is clearly possible to do it that way - but the brace would need to be heavier. Also, it might not be suitable for every soundboard. Perhaps good for a nice stiff piece of sitka, left a little thicker; a bad move on a thinner or floppier one; hopeless for a cedar top. Very experienced luthiers will assess the characteristics of individual tops and adapt the bracing to suit. That takes a lot more experience than I currently have - so better to stick to a standard formula.

The standard pattern came from CF Martin. In a factory setting like at Martin or Taylor they can't vary the production for each piece of soundboard timber so they come up with a standard layout that works for the majority. Undoubtedly, it errs on the side of over-bracing - that way they can be confident that not many of their instruments will fall apart in the hands of a customer, which would be bad for business. A lot of their instruments end up over-braced and sounding a bit dead - but the average customer doesn't know the difference and is just happy to have a guitar that looks shiny and has a famous name on the headstock.

So, what should a beginner luthier do? Like the others say, you are taking a risk to deviate too much from the middle of the road, design-wise. But as your experience increases you will want to be more versatile. If you feel like taking a risk at least make it a calculated one and know what the consequences might be. If it fails - at least you had fun and you learned stuff and nobody died from your mistake. And then you can learn how to remove a top and rebrace it, or find some other way to recover.

If you do stuff-up it is good to seek therapy here. I seriously under-braced my first guitar and pleaded for help on this forum. The suggestion of a Bridge Doctor rescued that guitar, and it sounds great now.
cheers
Mark

[Paul Eisenbrey]

Thanks guys, this is exactly the kind of advise I hoped for. I'll definately use a standard brace pattern on this one, and probably on the next 8 or 10 as well.

My thinking on this was a reaction to my first attempt. It actually sounds pretty good: nice lows, a good strong midrange, and a nice complex ring. But the high end is a little stifled for my taste. I'd like a bit more of the high overtones. So I am going lighter on the soundboard than the first. I left the first one at 4mm, and this one is down to 3mm.

Then I saw the Cumpiano pictorial and thought: well, if HE doesn't need two braces there, why should I? It will certainly make the top lighter.

Two things worried me, though. First, Cumpiano has about 35 years of experience on me, and probably knows what he's doing. It is likely that he compensated somehow for the single brace. Since the pictorial was not really a tutorial, he wasn't under any obligation to go into it. So I thought I'd ask you guys before committing to the plan.

Now the question is: to scallop or not to scallop?

--Paul

[Bob Connor]

If you want to get adventurous take the top to 2.75-2.8mm. That'd be about right for a 000 of medium stiffness.

I only leave the tops of 000's at around 3mm for Western Red Cedar or King billy tops

Scallop the lower legs of the X-brace a little and see how it ends up. You can always get a finger plane inside there to take a little more of after you've strung the guitar up (if you think it needs it)

[Paul Eisenbrey]

Hey again,

I brought the top down to 2.85mm. (I have to get a drum sander if I'm going to keep this up. It feels like I've been scraping on this top for days...)

I had no idea 0.15mm would make that much difference! The top was reasonably stiff when I started. Now the darn thing feels like I could roll it up like a scroll. The tap tone -- decent before -- now rings for around 5 seconds to my ears. And I've been playing rock n roll for 35 years. If this doesn't resonate, nothing will.

One brace between the X? No chance.

Thanks, guys, for the great advice!

--Paul

[Allen]

If you don't know what the cube rule is, then you need to do a bit of studying up. Very small amounts make an incredible amount of difference. Ervin's books and video's go into this a lot as well as a great many posts on various forums.

Have fun with it. You'll be amazed at what can be done with what appear to be insignificant modifications.

[Mark McLean]

Yep, if your last one was 4mm and this is <3 you are going to notice a difference. And it doesn't need to be the same thickness all over. The periphery below the waist can be thinner. Keep us posted with your progress.

[Kim]

Hey again,

I brought the top down to 2.85mm. (I have to get a drum sander if I'm going to keep this up. It feels like I've been scraping on this top for days...)

--Paul

STOP!!! WAIT!!! Put the wood back on!!! You've done the wrong thing!!






















Sorry Paul, just couldn't help meself

Enjoy the journey mate your doing well and in good company.

Cheers

Kim

[Paul Eisenbrey]

Nutz...

Kim may be right. I noticed that I'd gouged the top in a couple of places with the plane. Hardly noticeable, but one was right under a brace, which would have been a problem when I glued things in. So I got out the planes (mistake #1), and

Gouged it again.

Pulled the blade in a bit and (mistake #2)

Gouged it again.

Ran out of cuss words and found a thesaurus to help out.

I finally got everything flat and even. At 2.25mm. I don't think I'll be scalloping the braces on this one.

--Paul

[kiwigeo]

Nutz...

Kim may be right. I noticed that I'd gouged the top in a couple of places with the plane.

Have you checked top for runout direction? Normally a top will plane in one direction but will gouge/tear out in the opposite direction. Because a top is normally two book matched halves from the same billet the runout direction will be opposite on each half.

Sometimes the plane blade edge will gouge the wood. To reduce risk of this I work a slight curve into the cutting end of my plane blades and I also bevel off the corners of same.

When working a top with a plane make sure the plane is really sharp and I work the plane at an angle to grain rather than exactly with the grain. Another trick is to fit your plane with a toothed blade and do your rough working with this and then final working with a cabinet scraper.

Cheers Martin

[Paul Eisenbrey]

Thanks Martin!

I didn't know, but now I do. There is a lot about woodworking in general, and guitar making in particular, that I don't know yet. I got into this very late in life. A year and a half ago, to be exact.

Before this my experience with carpentry topped out at knocking a deck together out back. Two-by-fours don't appear to behave the same as 3mm spruce.

But I'm learning. My goal is, in ten years, to have put this skill together well enough to brag about it. Thanks for the support and information -- I'll post pictures when I've got the bracing on.

--Paul

[Lillian]

Paul, might I suggest that you grab one of those 2x4's and cut it in half so you have two pieces that at 1x4, or rather .75"x4. Joint the edges so that they can be glued up to give you a 1"x8"ish bookmatched piece. Now get to know your planes with this, or several of these. Start by getting the cut faces flat across the width. If you bookmatched them, you'll find that one side of the plate will cut better in one direction, while the other side is best from the other end of the board. Once you are happy with it being flat across the face, mark the sides at some nominal depth, like a half inch, then flip the plate over and thickness it down to the half inch mark you made along the sides, making sure that it is a half inch all the way around and flat across the face. Repeat until it's easy for you to do.

And while you are doing this, dig up the threads on sharpening your blades. That is a skill that you really have to master to avoid frustration and damaging the wood. You should never have to force an edge through wood. If you are forcing it, it either needs to be sharpened or you need to reevaluate your technique.

Kim, what was that thread you did about getting to know your tools? It was brilliant.

Just my 2 cents.