You are simply wrong Hluth, or perhaps you bought some other wood???. I explain why below.
I have used New Guinea rosewood necks on
most of the 455 instruments (35 guitars a year over 13 years while i was there) we made at Gilet guitars in Sydney Australia since 2003 (not to mention the- ill say 100- student guitars we helped build).
We never had any neck issues and we used it for 12 string guitars, which have about 250 Lb of string tension (with light strings- see below for link) to a tenor ukes 40ish Lbs!!!
So, i think you have something other then what we are working with as neck deformation is
just not possible for a uke when using
Pterocarpus indices, aka, Narra & New Guinea Rosewood. (it should smell like roses when you cut it.)
Check out these stats which show Narra outperforming in all fields except weight but a previous post of mine shows the weight difference is actually very little (30 grams or so) with a uke neck.
Narra- aka New Guinea Rosewood
Common Name(s): Narra, Amboyna (burl)
Scientific Name: Pterocarpus indicus
Average Dried Weight: 41 lbs/ft3 (655 kg/m3)
Specific Gravity (Basic, 12% MC): .54, .66
Janka Hardness: 1,260 lbf (5,620 N)
Modulus of Rupture: 13,970 lbf/in2 (96.3 MPa)
Elastic Modulus: 1,724,000 lbf/in2 (11.89 GPa)
Crushing Strength: 8,270 lbf/in2 (57.0 MPa)
Shrinkage: Radial: 2.8%, Tangential: 4.0%, Volumetric: 6.9%, T/R Ratio: 1.4
http://www.wood-database.com/lumber-identification/hardwoods/narra/
Honduran Mahogany
Scientific Name: Swietenia macrophylla
Average Dried Weight: 37 lbs/ft3 (590 kg/m3)
Specific Gravity (Basic, 12% MC): .52, .59
Janka Hardness: 900 lbf (4,020 N)
Modulus of Rupture: 11,710 lbf/in2 (80.8 MPa)
Elastic Modulus: 1,458,000 lbf/in2 (10.06 GPa)
Crushing Strength: 6,760 lbf/in2 (46.6 MPa)
Shrinkage: Radial: 2.9%, Tangential: 4.3%, Volumetric: 7.5%, T/R Ratio: 1.5
http://www.wood-database.com/lumber-identification/hardwoods/honduran-mahogany/
Spanish Cedar
Scientific Name: Cedrela odorata
Average Dried Weight: 29 lbs/ft3 (470 kg/m3)
Specific Gravity (Basic, 12% MC): .38, .47
Janka Hardness: 600 lbf (2,670 N)
Modulus of Rupture: 10,260 lbf/in2 (70.8 MPa)
Elastic Modulus: 1,323,000 lbf/in2 (9.12 GPa)
Crushing Strength: 5,860 lbf/in2 (40.4 MPa)
Shrinkage: Radial: 4.1%, Tangential: 6.2%, Volumetric: 10.2%, T/R Ratio: 1.5
http://daddario.com/DADProductDetai...=EJ38_12_String_Phosphor_Bronze__Light__10_47