I have looked all over the web trying to find the radial and tangential movement of Osage orange. I have found it in charts but it just gives dashes where the numbers should be. Why is there no data?
Not a commercially important lumber species to invest the testing and measuring time, very likely.
Only get the volumetric shrinkage values.
You could do some measuring of pieces to get a close approximation in radial and tangential directions as the wood dries. Would need a way to weigh the samples and get accurate measurements.
Why do you care? Just curious.
Hi Jake,
I use to have that, can't find it? What you can do is take the "Volumetric" data, and work backwards to a similar pieces with the same data points and extrapolate. That should get you close.
Regards,
jay
I am cutting some for guitar backs and sides. The builder says everything must be quarter sawn for stability and stiffness. He said he built the back of a guitar out of flat sawn walnut once and in the summer months the back bows up because of seasonal movement. I compared the movement of "argentine Osage orange" which is related but a different species and flat sawn Argentine is more stable than quarter sawn walnut. Im sure even a small movement in guitar wood affects the tone so I was trying to get the numbers for maclura Pomifera. Maybe I could cut a green sample and mail it to you dodgy. ;D
Dang! I shoulda said "a special boring wood project" like you did all of us. I coulda kept ya guessing :D
'Maclura Pomifera
0%MC = 9.2
6%MC = 7.4
20%MC = 3.1
Note, the 7.4 by comparison would make it a relatively stable would compare to other hard woods.
http://www.fpl.fs.fed.us/documnts/TechSheets/HardwoodNA/pdf_files/maclureng.pdf
Guitar backs - Okay, I can definitely see your need for information on expected wood movement. Sometimes woodworkers will do ridiculous wood movement calculations for simple things like a jewelry box. In most instances, making a reasonable allowance for wood movement is all you need to do. Luthery is a different ballgame where small changes can make big differences.
Jay, I believe your measurements are for volume. I was wondering radially vs tangentially.
QuoteWhat you can do is take the "Volumetric" data, and work backwards to a similar pieces with the same data points and extrapolate.
My reply #4
They tend to be statistically proportional, so you use the number, say at 6% MC and do a comparative analysis. Wood Doc may even have the math for you to use, I would do the search but am really swamped with work at the moment. If these are going to be for electric guitars you should be fine just getting them to a stable MC, but that should be for the Luthier to hassle with, unless you are helping out. Good luck and let us know how it goes.
jay
They're for acoustic guitars. And I'll see if I can find the formulas.
acoustic guitars?
Jake,
What part?
Just think, Jake, you could be on the cutting edge of some new research!
Backs, sides, fingerboards, headpieces, and rosettes. Boy I got a lot of cuttin to do.
Generally, wood shrinks approximately twice as much tangentially as it does radially, generally.... Some woods don't quite follow this rule. If I remember, walnut is one that doesn't quite follow this rule which is why it is very easy to air dry without distortion. Without a percentage ratio to follow I don't know how you could extrapolate from the volumetric data unless you just assume it's a 2:1 ratio. You know what is said about assuming... ;D
i don't think wood is suitable for acoustic instruments if it is not quartersawn, regardless of species.
it is very difficult to bend sides that are not quartersawn, the grain wants to seperate at least it did back when I tried it a long time ago. The quartersawn stock I had was "bendable"
Jake what MC% range? Going from green to 12% or something?
V sh% from green to oven dry is 9.2%
Green Sp Gr is 0.76
From this all you can get is the fibre saturation point. But the Wood Handbook uses a benchmark of 30 % for fibre saturation point.
The figures on shrinkage are usually given for going from green to oven dry, so you have to use partial shrinkage calculation and you don't have the figures.
But anything I see published concerning the wood, says it is very stable once dried. And one source said there wasn't much difference between radial and tangential shrinkage in the species. So take it from there.
Hi Dan_Shade,
Over all, I have to agree with you about the cut of the wood for most acoustical instruments needing to be quarter saw, especially for the body work. I believe that you could have some leeway on other components being plain sawn. Another factor, especially with M. Pomifera is the density of the wood. If brought to a stable MC, and handled properly, and slowly, you could shape body work out of certain plain sawn wood. It will all depend on the cut and grain patterns of the pieces chosen.
Regards,
jay