Does bracing need to be quarter sawn?

[Daniel_M]

I am currently laying out my timber for my first acoustic build and was hoping that you can provide some advice on what needs to be quarter sawn. I am using bunya top and bracing, my question is should the bunya bracing be quarter sawn? Also, should the neck block also be quarter sawn? The reason that I ask is that all the books that I am reading says that they should be, but my pieces of wood have the grain running in what can only be described as a quarter of a circle. It looks like it was taken from the centre of the tree. Sorry if my descriptions are technically correct. Thanks in advance for all your help.
Daniel

[DarwinStrings]

Quarter sawn is what you want, can you cleave or saw the billet into quarter sawn pieces?

Jim

Life is good when you are amongst the wood

[Daniel_M]

Thanks Jim, i might be able to get away with it, I don't think I will know until I start cutting. I guess I was a little more surprised than anything, given that I purchased the timber for this purpose and all the timber I purchased previously has been perfectly quartered. Thanks again Jim.

[Mark McLean]

Hi Daniel
Yep, you want your bracing to stay nice and straight. All wood will swell and shrink with inevitable changes in humidity. Quarter sawn wood will tend to do that only in one dimension, whereas wood with a curve in the line of the grain will be inclined to bend, skew or twist. If it is a brace glued to a plate it will change the shape of the plate.

In the recent hot weather that we had here in Sydney I watched carefully the small stack of tonewood that I have in my (non-humidified) workshop. It all coped fairly well, except one set of blackheart sassafras which cupped pretty badly. The sassafras is slab-sawn, with a curved grain running in and out of the cut surface (which makes the figure look better). All of the other sets that I had (mahogany, sprue of various types, bunya, bubinga, rosewood) are quarter sawn and stayed nice and flat despite drying and then rehumidifying.

Bracing is important - use quartered stuff.

Mark

[liam_fnq]

If I purchased it as "bracewood" and I got it and it wasn't nice, even, straight grain and either perfectly flat or quartersawn I'd be sending it back.

[kiwigeo]

An interesting question. On the lute I'm currently building the grain in the bracing runs parallel to the top. This would have come about mainly because the old builders used top offcuts for bracing.



Cheers Martin

[Daniel_M]

Thanks all for your advice, I will post pictures. To be honest the grain is all over the place with the bracing and the curvature on the neck block is bordering on 90 degrees. I just wanted to make sure first as the timber was purchased from a well known supply house and don't want to tread on any toes. Thanks again

[Kim]

With brace wood you only need one split face. Once established just rip it in reference to 'that' face on a TS or BS and it will be just fine. It may be OK for the yanks to get all pedantic about splitting half by half each individual brace from a billet 'split' from sap wood, but you are in AU and spruce trees don't grow here. If you wish to follow Billy Bob Cumpiano's method to the tee, then I hope ur credit card is gold because you will destroy much perfectly good wood before you make a single guitar. The truth of the matter is that it simply does not matter as long as the wood follows the quarter established from a 'single' split face before it is put to the saw.

Cheers

Kim

[DarwinStrings]

Technically Martin your lute braces are quarter sawn and making braces with the grain the other way makes them back sawn unless they are lower than they are wide then they become quarter sawn again. So if you want to follow Billy's method then you want your bracing to be back sawn and not quarter sawn. A bit confusing ain't it.

Jim

Edit. Nice tip with the tape on the paring chisel Martin, that will save me being annoyed when I make that little slip at the end from now on.

[pat foster]

How are all you folks doin'? Been awhile.

Another reason to go quarter-sawn is that it's less prone to splitting out at the tapers Flat-sawn would split more easily between the grain lines, I believe.

Yep, good tip on the tape when carving brace ends! I've also been looking for a shallow gouge for the ends, but tape is cheaper.

Pat

[charangohabsburg]

Another reason to go quarter-sawn is that it's less prone to splitting out at the tapers Flat-sawn would split more easily between the grain lines, I believe.

I made the experience that vertical grained braces with runout are more prone to split than horizontally grained braces where no runout is guaranteed (in the direction that matters with braces). But the tapers of horizontally grained braces are a bit trickier to carve though.

Horizontally grained braces are a little bit stiffer than those with vertical grain, but it's not much, something virtually nothing: Two years ago, in a series of measurements I have measured differences between 1.5% - 13%. If we can /could get aware of those nuances at all we could compensate that bit leaving the brace a little bit higher and keeping it a bit slimmer if one was worried about weight. 10% difference is really not that much as it sounds when thinking for example of the difference between a 13 mm and a 14 mm tall brace. Keeping the width equal the latter one will be 25% stiffer stiffer than the 13mm brace.

[Kim]

Most repairs I have undertaken on guitars that had popped or split braces have, IMHO, been caused by the ends of the braces being left too high. IMO the ends of braces should be tucked into the linings, or carved down to 'nothing' at the ends where they meet the top. If they are tucked, they have support in the instance of impact, if they are carved down to nothing, they are able to flex in the instance of an impact. If they are left with any height at the ends, stress risers are formed and in an impact situation the brace can either survive unharmed, sheer along the grain, or the most likely outcome is that glue joint will fail at its end and the brace will pop.

Cheers

Kim