Bunya Query

[DaveW]

Hi
I have just been thicknessing (is that a word?) my first Bunya top.
And I dont have any experience with it at all and have noticed how floppy it has become ,across the grain it certainly isnt anything like Sitka or even Cedar stiffness wise,Ive taken it to about 2.7mm and it has quite a nice sound when I give it the "wobble board" test,but it seems very loose ,I realise it isnt sitka which is quite stiff but it almost feels like its going to split .
As I have no experience to go on is this normal for Bunya or have I taken it down to far ?
Dave

[Trevor Gore]

All the Bunya I've tested has been too crappy to use. There must be some good stuff around, but it has evaded me! It sounds like you have the sort of stuff I've tested.

[DaveW]

Yes probably
I was hoping that I was missing something but its structure is almost like a "wet tram ticket"
maybe I go with a sitka top which is a shame as I was hoping to have an all Aussie build ?
Dave

[P Bill]

Interesting observations. I've just started carving bunya for a tenor archtop and joined the offcuts for my first flattop. 20mm and 4mm atm. Both tap very bell like and I was concerned they might be too stiff. Bunya and Hoop are cousins and very hard for pines, going floppy is a surprise for me. I'm going to stay with it just to find out.

[nnickusa]

I made my first from Bunya, because that's what came in the "kit" of timbers my wife gave me for Christmas, and knowing nothing else, I followed Kinkade's recommendations for spruce, going 3mm in the middle and then to 2.5mm at the edges. Mine sounds quite good.

I did keep tapping as I was shaping the braces, and finally stuck my Snark on it, ending up with a G note on tapping. I have no idea if that's where it ought to be, but it sounded good to me, and I went with it...

I have no recollection of what it felt like at the time, tho, so i can't help there.....

The big Aussie makers use Bunya all the time, and some of them are nice sounding guitars.....for factory builds

[Kim]

I think a big part of the problem with Bunya is that most of the wood is coming from regrowth. Unless you happen to get lucky and stumble upon some old growth stuff sitting on private property, it will be difficult to find a board wide enough that is on the quarter and free of heart. Most Bunya I have seen wide enough to resaw a bookmatch from seem to run from heart through a few inches of quarter and then on to skew @ 45 degrees. Clearly these regrowth logs most of which are being logged from forest just north of Caboolture SEQ are not big enough yet to convert without fudging in some crappy stuff so they should probably be left to grow out for a while so the product does not end up with a negative reputation even when it is good to go...It won't take long either because Bunya is a fast grower so I will be holding judgment.

Cheers

Kim

[P Bill]

Yeah Kim this is old growth. I bought 12 boards from a chainsaw miller in 1995, 35mmx 400-450mm x 2.7. Most of it went to furniture. My verandah table is two of these boards. Only about 1/2 of each board is dead quartered.

Plantation Hoop is easily spotted by the brown marking in the grain , only on one side ( sap or heart ,can't remember ). It has been bred to grow fast. Genetically pure hoop, after a bit of oxidation, is golden both sides no brown lines. Same with Bunya.

[curly]

As far as Aussie soundboard options go Bunya looks really good by it's technical data . I agree with the previous posts that it rarely lives up to those statistics . Having processed a large amount of plantation Bunya I can verify that what is making it's way onto the market is pretty low grade . For a while I've resawn and dried Bunya from an unnamed source for a school and was flat out embarrased at what is being sold as sound soundboard material . This is a long way from split billet spruce to be sure .
As to the couple of old growth trees I have worked on , aside from being more colurful , along with the poo browns they also had red washes and sometimes almost a green streakiness . The real benefit of old trees is that you have larger , knot free sections from which to properly quarter your billets . Even then if it sounds good I can't say I'm a fan aesthetically .
Australia has a great diversity of hardwood species with tonewood potential , but unfortunately the truth of the matter is that our conifer flora is comparitively limited , proper soundboard trees are just plain difficult to come by . What little we did have is pretty thin on the ground out there now .

[Trevor Gore]

As far as Aussie soundboard options go Bunya looks really good by it's technical data . I agree with the previous posts that it rarely lives up to those statistics .

Bootle (Wood in Australia) quotes 13 GPa for long grain Young's modulus with a density of 460Kg/m^3. I measure typically 4-6 GPa at 480-520 kg/m^3. Typical sound radiation coefficient (just one measure of "goodness") is ~5.4 m^4/kg.s; typical Engelmann is ~14-15, i.e. simplistically, ~3 x better.

Why would you bother?

I would like to see Bootle's piece!

[jeffhigh]

4-6 GPa ugh
And the trees try to kill you too in cone season

[peter.coombe]

I carved a mandolin top from Bunya some years ago, soon after Maton started using it. It is heavy and quite stiff, but just does not sound right to me when I tap it. Not only that, but I found it really hard to cut the rosette channel (by hand as usual) and ended up giving up. There are easier ways to make a mandolin top. Looks ugly as well, so never used it. It is still sitting in the workshop and will probably stay there or get chucked eventually.

[Kim]

Regardless of the Bootle book's figures, or even tree size for that matter, Bunya's suitability a stringed instrument's soundboard is going to come down to the properties of the board at hand, and that is no different from any other candidate, some spruce makes the grade and some doesn't. Granted that compared to Englemann you would be hard pushed to find near as many Bunya tops per 100 that are worthy of your efforts. But as I suggested earlier I think a big part of that is the small log sizes that poor logging practices find acceptable to push on to the market..

To put it more plainly, even after we remove the wide variables within a species from the equation, we are not comparing apples with apples. North America has a long history of supplying wood to the musical instrument making industry and those at the business end see nothing out of the ordinary about being required to split billets from the round to service that market properly. To them its just part of the job and they understand its why they get to charge a premium. Try asking ur average Aussie sawyer to do that for you and see how you get on..Fuck you mate, I'm happy to charge you the premium for the 'tonewood' name but don't expect me to understand what it means!

Some do say that Bunya looks ugly. But that comes down to personal choice because there are others that actually 'like' the wider grain and even the peach and brown dirt discolourations claiming they make the top look like 'real' wood instead of the perfect 'geisha face' of clean white Englemann. Personally I don't mind the look on tyhe right instrument with a flat finish, it can look quite earthy. I will also add that one of the nicest sounding guitars I have played was a Maton, I think, Aussie series that was hanging in a guitar shop..yep, Bunya top. It was warm and clean, nothing brash about it at all but no shrinking violet either, it was just a nice sounding guitar..My point, fair go...and Bunya has not had one IMHO because we cut it down as soon as it will turn a buck and most of our sawyers don't seem to give two pinches of goat shit about anything but turning a buck right NOW!

Cheers

Kim

[Trevor Gore]

Just as a comparison, Bootle quotes Pinus Radiata as long grain Young's modulus 9-10 GPa, at a density of 480-500 Kg/m^3. I quote Bootle, because (still) not many people know how to measure the properties themselves, so look to references like this, unaware of the piece-to-piece variability. I have measured (Shed Guitar, and I'd say that was not the best radiata I've ever seen) 9 GPa with a density of 480 kg/m^3, much the same as Bootle, and both very obviously plantation timber samples. Sound radiation coefficient is 8.8 m^4/kg.s, getting on for twice that of the handful of pieces of Bunya I've measured.

So my experience is that you're much more likely to find decent radiata than decent Bunya, if you can stand the "bananas in pyjamas" look and multiple piece tops. And it doesn't sound too bad!

[DaveW]

Hi Guys,
since I was the one that first started this debate ,Im continuing with this build if nothing else to improve my knowledge base
I think it will be interesting to see if it sounds like my workbench( which I wont be surprised about) or if it actually sounds musical
if anyone is interested I will post my progress
Dave

[Nick]

Hi Guys,
since I was the one that first started this debate ,Im continuing with this build if nothing else to improve my knowledge base
I think it will be interesting to see if it sounds like my workbench( which I wont be surprised about) or if it actually sounds musical
if anyone is interested I will post my progress
Dave

Always interested Dave.

[DaveW]

Hi
well Ive been beavering away and I have a few picis
the top bracing is fairly heavy as this was how I thought it needed to be done due to the :floppiness" as discussed before ,it actually had quite a nice tap tone after bracing and I actually got to a point of "limited return" so left alone,this isnt atually the finished bracing as I decided I would try my hand at doing an arm bevel which actually ended up altering one of the X brace legs ,as Ive said before Im using this build as a bit of experimentation ,trying a few things that I havent tried before to build u my skills and memory bank so to speak
Dave

[Taffy Evans]

I remember having some sitka spruce years ago that was way too flexible, it would bend/flex like cardboard, but thoughtful brace positioning and carving brought about some nice sounding guitars. The customers thought so anyway.