Cross braced backs

Shane Neifer · **Posted:** Mon Sep 19, 2005 4:08 am

Can anyone show me some pictures of a cross braced back for an OM and also supply some dimensions and placing of the brace stock? Does this method add much weight when compared to typical ladder bracing?

Thanks

Shane

Dave White · **Posted:** Mon Sep 19, 2005 4:20 am

Shane,

Haven't made an OM - I don't exactly go with "conventional" shapes - but this is the X-ladder hybrid bracing that I do on my guitars now as is on a baritone I did recently:

No extra weight at all. I do it as it gives me more consistent doming length and widthwise. There are lots of different X braced back patterns - check out this thread on 13thfret forum:

Xbraced backs

LanceK · **Posted:** Mon Sep 19, 2005 4:24 am

Hello Shane,
The OLF Om plans and Sj plans come with layouts for both X and straight back bracing.
Although I have never done an X brace back, I would think that it would not add any appreciable weight, since its just a different orientation of two braces.

Alan Carruth · **Posted:** Mon Sep 19, 2005 4:34 am

It doesn't add any weight to speak of. For one thing, the braces weigh so little compared to the back itself that even if the X braces are longer they still won't add much.

I X-brace backs so that I can 'tune' them before gluing them to the sides. Even though the back doesn't contribute much to the tone, it does something, and I'll take all the tone I can get. I've never had much luck 'free' tuning ladder braced backs.

I've used bracing like Dave's. I've also used bracing that is more like the top's in some ways: cross braces in the upper bout and waist and an X below that. That's what I'm using now. I find it helps in my work to have the X crossing fairly low down on the back, but that's only what works for me. YMMV.

Michael Dale Payne · **Posted:** Mon Sep 19, 2005 5:08 am

The OLF OM x brace thatI desdigned adds no extra weight over std Martin OM back bracing. In fact it is a just a tiny bit lighter. I like the response I get from the x-brace. The OLF SJ plans also have a optional x brace pattern

My pattern is more lower bout orientated x pattern than the one Dave shows. It consist of the x brace, waist brace and upper transvers brace and naturaly seam graft.MichaelP38614.5914351852

Shane Neifer · **Posted:** Mon Sep 19, 2005 5:21 am

Thanks for the help all. Michael, do you happen to have a picture of your brace pattern and any dimensions of the members? I can buy the plan but I just want to explore cross braced backs as I want to build shapes of my own. So any info just on back bracing would be greatly appreciated!

Just thought I should mention that this current guitar is based on OM dimensions, although it is more 'rounded' at the top end than a traditional OM, that is the reason for asking specifically about an OM.

Thanks again

ShaneShane Neifer38614.6000578704

Michael Dale Payne · **Posted:** Mon Sep 19, 2005 5:44 am

Shane, I am going to decline giving out the dimension and instead refer you to the OLF library of plans. Only because the plans are there to help support this forum. If I had not donated the plans to help support the forum, I would be glad to share but it would not be fair to those that have paid for the plans or the forum for me to give them out free. Hope you understand. Let me suggest that you order a set or maybe the OLF SJ plans as well. I think you will find them to be well worth the money, and it is great way to help support the OLFMichaelP38614.6149421296

Shane Neifer · **Posted:** Mon Sep 19, 2005 6:21 am

I understand Michael, thanks. I am not trying to side step the forum, to the contrary, I support them every month and will continue to do so through my companies involvement with advertising and offer for the sponsorship program. I will consider the need to have the plans around or just experiment with what I can find. Thanks again.

Shane

Michael Dale Payne · **Posted:** Mon Sep 19, 2005 6:37 am

I will tell you that the upper rim/x-brace intersection is just short of the rim/waist brace intersection and the lower rim intersection is half way down the "lower" lower bout radius it is 89 deg x if I recall correctly. i think that is enough to it lay out to your liking

MichaelP38614.6537962963

Shane Neifer · **Posted:** Mon Sep 19, 2005 6:58 am

Thanks Michael, I do think that I have all that I need to proceed. I do appreciate your efforts and thanks again for the information.

Shane

Dave-SKG · **Posted:** Mon Sep 19, 2005 8:20 am

Shane,
As Al Carruth said It allows you to tune the back. In my humble opinion that's a real benefit. I actually think it is less weight. But I make my braces very thin ala Somogyi. Come to think of it all of these pics are pre - Somogyi training...now they are thiner and better!

These are some old shots:

THIS ONE IS A DOUBLE X:

THIS A COMBO:

Dave-SKG38614.7236226852

Michael Dale Payne · **Posted:** Mon Sep 19, 2005 8:34 am

Dave I believe the next experiment on back bracing I do will be a double x like your middle pic. Do you have any coments on this system i.e. structure or tone?

Mark Swanson · **Posted:** Mon Sep 19, 2005 8:47 am

Here's a picture of the way I've been doing it. Since this guitar, I put in two small braces going from the X center out to the furthest parts of the lower bout. I got a little sinking of the dome in that area in this first one.
I use the CF braces at the neck block, too. But I think one is enough.
I just took one of these guitars to a large festival, and the first question people would ask was about the Cf rods- they kept calling them "sound posts". <G> I got tired of explaining it!

Shane Neifer · **Posted:** Mon Sep 19, 2005 9:00 am

Hey Mark (and Dave W),

I am not up on the carbon fibre stuff. I am trying to see the beneifit of using the rods but it just escapes my simple mind. The whole guitar is somewhat of a torsion box, weak in each of it's elements but incredibly strong once put together. It seems, from the angles that the rods are positioned, that they are intended to distribute compression from the strings through the neck to spread that load over more of the guitar. But doesn't that huge glue surface area on the top of the head block, coupled with your top bracing pattern, offer enough resistance to that compressing force?

Mr. Bland, what dimension do you now use for your braces? I am going to try a cross braced back and I like that double cross look also. I just want to keep things light, alive and responsive (within reason <G>).

Thanks

Shane

Steve Kinnaird · **Posted:** Mon Sep 19, 2005 9:23 am

Yeah, Mark--tell us more about those sound posts.

Steve

Mark Swanson · **Posted:** Mon Sep 19, 2005 9:37 am

I heard about it from Rick Turner. Shane, you pretty much are seeing the forces on a guitar. Remember that the strings are trying to fold the guitar up. Sure, conventional bracing has been shown by time to work- BUT neck resets are common. Lots of guitars need neck resets, even though there is nothing visibly wrong, all of the glue joints are tight but the geometry of the guitar has changed and the neck angle is no longer right even though it was when it was first made. Something moved- what was it? In time and with string tension the wood itself has given in a bit. The back and sides can actually deform or chance shape slightly and this causes the neck block to come forward. So, putting in a couple of CF re-inforcements really stiffens up the back and sides, and takes any "folding up" stress from being shifted to the top.

Pwoolson · **Posted:** Mon Sep 19, 2005 9:43 am

I've posted this pic before but it's another example of an alternate bracing pattern on a back.

Dave White · **Posted:** Mon Sep 19, 2005 10:13 am

[QUOTE=Shane Neifer] Hey Mark (and Dave W),

I am not up on the carbon fibre stuff. I am trying to see the beneifit of using the rods but it just escapes my simple mind. The whole guitar is somewhat of a torsion box, weak in each of it's elements but incredibly strong once put together. It seems, from the angles that the rods are positioned, that they are intended to distribute compression from the strings through the neck to spread that load over more of the guitar. But doesn't that huge glue surface area on the top of the head block, coupled with your top bracing pattern, offer enough resistance to that compressing force?

[/QUOTE]

Shane - I got the idea as well from Rick Turner, Howard Klepper and Mike Doolin (although he uses a composite wood/carbon fibre butress brace system). My take is "similarish" to Mark's. The pull of the strings is pulling the neck's heel away at the bottom and pushing it in at the top. Over time this torsion force can slightly flatten the back to front arch in the back and move the neck angle even though the "geometry" of the box doesn't seem to have changed. The rods are there to help combat this force - the top rods will be in compression and the bottom ones in tension. I use 2 to "balance" these forces and the bottom ones are there to stop the flattening of the back arch in particular. Mark's system with the anchor on the bottom and the rod attached to the top of the neck block works, I suppose, on the principle that if the top of the block doesn't move then neither will the bottom, but I suppose the top of the block could stay put and the bottom arch still flatten.Better safe than sorry is my motto.

In my system they are not there to "spread" the strings load - I tie the top bracing into the neck block with an A frame and haven't made the neck block any smaller. They are a long term "insurance" for almost zero extra weight. The flattening of the arch is a long term effect and the tension/compression forces on the rods is, I suspect, not huge. I guess this as on one guitar two rods weren't properly glued in to the tie blocks and I was easily able to take them out and reglue with the strings on the guitar - no huge pressure deforming there.

Rick Turner makes his neck blocks very slim and has very little bracing on the top upper bout - in his case the rods may be taking more of a pressure bearing/distribution role.

Reminds me of my favourite Groucho Marx quote "Time wounds all heels" - this is the builder's paranoia too and what this is insurance for. It's a bit like Elephant traps I suppose - if the neck stays put for 20 yars it's working (I see no elephants!!)

Mark - is that a Mike Doolin style adjustable neck I see in the neck block in your photo. Tell me more, I'm thinking of trying this system out.Dave White38614.8042013889

Shane Neifer · **Posted:** Mon Sep 19, 2005 10:17 am

Paul,

Thanks for that Pic, that is the one that I was thinking of when I started to consider a cross braced back. Does the lower ladder brace bridge the cross and the seam grafts?

Mark,

It is as I thought for the carbon fibre. Next question is then has there been any evidence that these rods work and that they don't actually move the issues to another area of the guitar? It is interesting to see solutions to these issues and I am just interested in your opinion on this one. You use them so I guess you like them but I am just wondering about their 'track record'.

Continued thanks!

Shane

Pwoolson · **Posted:** Mon Sep 19, 2005 11:04 am

Shane, the lower ladder is all the way across. the "x" braces are mitered and butt up to it.

Official Luthiers Forum!

Cross braced backs

Who is online