bunya pine thickness

[xray]

hey team, just recovering from watching the dismal performance from melbourne storm in the G.F. im actually still considering trying my luck as a professional league player because apparently you don't have to be that good to play. (Sorry any melbourne fans)

Anyway to be serious about the real reason for the post, im a little confused with my next soundboard im using and tuning. Its bunya pine and i have got it down to about 2.5mm and it had okay tap at 4mm in its original form, but when i took it right down i have noticed the tap tone has significantly changed and lost alot of resonance (seemingly). am i going mad or is this a normal thing with bunya. It certainly wasn't the case with king billy pine, that thing rang like a bell when thicknessed down!
anyway please help because its doing my head in.

[kiwigeo]

4mm is a bit too thick for a top.....2.5mm is average thickness for my sitka, englemann and Lutz tops.

I wouldnt get too obsessed with the tap tone of the wood.....I think you'll find that once you get the bracing on the tap tone will change quite significantly. Then after the top gets glued onto the sides.....it'll change again.

My best advice...bite the bullet, brace up the top and get on with the business of guitar building.

[xray]

Hi mate thanks for the quick reply. 4mm is the thickness i got the board at. i have taken it down to about three and go from there with tapping and shaving. i am very particular about tuning the soundboard prior to bracing, however i havn't come across a soundboard that has behaved like this one yet. i have heard that the tone will improve with bracing and moreso when the back and sides are incorporated. just sounds odd now thats all. thanks for the help. Anyone else had any experience with bunya?

[Allen]

I haven't used Bunya, but with Australian Red Cedar, the top sounds like cardboard until it's braced. Then the whole game changes, and your back to shaving braces and listening to the ring.

I too would have taken it down to at least 3 mm before I started to test the stiffness with each pass through the drum sander.

My advice, if when you flex it, you are in the ball park of how stiff you like your tops, then go ahead and brace it. You're never going to know until you dive in and try it.

Let us know what your impressions are after some braces are on.

[kiwigeo]

Ive got some Bunya in my shop and to tell the truth I cant say Im in love with the stuff...not as much as Im in love with the Lutz, Englemann and Red Spruce sitting on my shelves. The Bunya just doesnt have the stiffness and ring that the other woods have.

[Richard]

The one bunya pine topped guitar I've got at the moment is about 2.8mm. Turned out to be a very loud instrument. I've taken it down to 2.5mm before no worries.

Every piece of wood is different so you'll have to find a thickness that suits what you're building, though I wouldn't be worried for a second about 2.5mm.

[kiwigeo]

When working a top to final thickness I judge when Im there by flexing it. You soon get to feel when the top is at optimum thickness by how it feels when you flex it. I use the same test for sides and backs.

[graham mcdonald]

2.5mm should be fine, but go on the feel of it's flexibility. It is not going to be the same as a spruce as an unbraced plate, and it might well not behave the same with braces glued on. If you have some idea where the resonances were on a spruce soundboard of the same size that made a good guitar, aim for resonances around the same for the bunya, whatever size the braces end up. I do think you are being over particular about tapping an unbraced soundboard. The important thing at that stage is the flex across, and to a lesser extent, along the grain. The cross grain stiffness will be established by how thick it is (as well as the nature of that piece of wood), the longitudinal stiffness is more a factor of the wood species. It is what you do with the bracing that is going to control the stiffness, which is all you are trying to do anyway. It is working out just how stiff and in what ways that is the elusive thing we are all trying to work out. And then there is the whole thing that the resonances of a free plate can have little to do with how it works once it has been glued to the sides and becomes part of a box...

Bunya can make a decent guitar soundboard, but it is somewhat unknown territory. It tends to be a bit heavier than spruce and probably not as stiff across the grain. Two factors worth keeping in mind when considering the bracing. Good luck

graham

[xray]

thankyou for the advice, i feel a little more comfortable about playing around now and i will go ahead and start shaving more off to reach the 2.5mm mark and brace and afterwards tune from there.