Thread: chambered body - top thickness stability question

Hi Ray,

Ive seen photos of walnut used for backs and sides of acoustics braced using the normal ladder style. Ed Roman certainly likes the stuff http://www.edroman.com/customshop/wood/walnut.htm maybe you could ask him. He also mentions Rick Turner so a PM may be in order. It sure looks pretty.

Sebastiaan

I only have an opinion, nothing supported by actual construction...
Accoustics tops are < 3mm, so are the sides. And although they are braced, there are large areas that arent. Plus the top is soft wood. 3/16" is still a fair whack of timber.
For me, I would be inclined to support the f-hole by a plate rather than bracing (in the sense of accoustic bracing), you could make the plate so that it's hole was a little bigger than your f-hole so that it wasn't visible, leaving enough room around the cavity so that if there is any accoustic movement of the top it can still move like a diagphram.
It may only need to be a 1/16th of an inch.
Man, that sucks as an explanation, but you're not paying me by the hour (luckily)
Sweet build - I haven't seen anything but nice builds from you though...

I would consider running a couple of braces perpendicular to the grain of the top, especially either side of the f-hole. These are my thoughts as to why. An accoustic although thinner is consistently thin and any slight movement due to humidity etc would only exert a small amount of stress. The bracing on an accoustic is cross hatched (top), and perpendicular (back) and gives the boards strength accross the grain. With a solid body, due to it's thickness and direct connectivity, any slight movement (hopefully none, but it can happen) or internal stress may exert alot of pressure across the grain of your relatively thin top. Given the total length of the chamber (along the grain) this provides leverage for splitting across the grain. In addition, cutting a hole will concentrate the load ordinarily spread along the total length of the board to an even shorter length. Even just a couple of very thin braces across the grain would provide considerable additional strength and stability, I think. These are just theoretical thoughts, not based upon personal experience. i am just trying to throw some thoughts out there.

Am interested in other's thoughts,

Peter

Can anyone else see the budha (?!?) in the grain of the walnut? The top of his head is facing the left, big wavy grain is his shoulders...

I think I need to go to bed...

Yep, it's there allright, Mongrel.

Very nice so far, Ray. Walnut suits this one perfectly.
Be careful or you'll wear that bloody tele template of yours out !!!

Originally Posted by oz tradie

Be careful or you'll wear that bloody tele template of yours out !!!

When you're onto a good thing...

as i said earlier thats a photoshop mockup
the actual top has more of the figure you see in the top corners of the rear bouts - unfortunately buddha was a part of a knot formation which was lost in choosing the figuring - but its still a nice pair of tops and still another 2 tops in that board at least

more pics later

What did you decide to do Ray?

im still thinking
i'm considering cutting some more [thicker] tops now that i have a better understanding of resawing.

i had the board tight into a fence wth a feather edge so when the blade started to lead off the line i had nowhere to go hence the thin tops

after that i found out about a point fence which allows you to swing around the board to take account of the blade drift

a little more conceptual work [my euphemism for chair sitting and space gazing] i will have a good system worked out

got to have a look at the walnut i have left

how would the top look with a laminate under it, a contrasting stripe wood? Nice white maple or something darker? Wouldn't have to be thick, laminating makes things heaps stronger.

Originally Posted by mongrel

Can anyone else see the budha (?!?) in the grain of the walnut? The top of his head is facing the left, big wavy grain is his shoulders...

I think I need to go to bed...

....I'm fixated on the twat up near the neck pocket...

when the guitars together there will be a neck and a head sticking out of buddha's ****, buddha's giving birth, and it sounds like music!

crack a woodie?
This axe will have a complex. Sounds like it's lucky ol' buddha gone. Though you have a plethora of names for it now...

unfortunately or fortunately buddha wont be depicted with a neck protruding from his @rse - the knot complex that made the buddha image had a crack [hehehe] so i had to lose it - laminating is an option but now that the boards are joined i dont really want to tempt fate attempting to laminate them to another thin board

i have 2 choices
1st brace it and go ahead with the thin tops - i would aim then for a superlight body and cut as much weight out of the core as possible - the idea has a lot of merit as it will make a very resonant body giving a very alive feel if you get what i mean. the mahogany is quite dense so i doubt i will have neck divers

2nd would be to go back to bandsaw and cut more [thicker] tops out of the figured walnut left - the 2 tops i have made will be fine as a cap on a lightwieght solid body- i have plenty of very light sthn myrtle

the two tops turned out very nice actually and will look good on whatever project they end up on