Rift Sawn Neck

[Bmth Builder]

Will a rift sawn peice of wood be suitable for a neck? (with the rings lying at around 50 degrees)

It seems to be some where between regular slab sawn and quarter sawn in terms of neck quality? (at a guess that is)

Cheers

[Dudz]

How many times have people on this forum said only to use flat sawn or quarter sawn? Many times. Riff sawn will warp easily as to my understanding of it.

[fryovanni]

Wood shrinks at different rates in the in the radial(quarter) and tangential(flat), some woods more(say Madrone which has about 4 time as much tangential movement as radial) some woods less (say khaya which in service will have an almost even shrinkage rate * Tangential still being higher though). Now picture what will happen as that wood expands and contracts if the wood is oriented square to the freboard plane (even movement), and if quartered the slightest movement will be up and down, and the greatest would be to the sides of the fret board plane. Now skew that grain and visualize the change in dimension. This is why the "traditional" use of quartersawn wood is prefered.

Now a bit of perspective. How much will this wood move? That depends a great deal on the type of wood, and how thick or wide the wood is. With one inch of wood, you can expect between .0010 to .0039 in the radial(quartersawn) direction, and .0018 to .0053 in the tangential(flat sawn) per. percentage of moisture change(in wood that currently has a moisture content of 6-14%). Pretty small numbers, but neck tolerances are close. What would this mean on an acoustic(say 15" lower bout) using Sitka Spruce.. If it was extreamly well quartered you would see about .072" (a little over 1/16") of change with a 3% change in moisture across the soundboard, and if it was flatsawn the same 3% change would amount to a dimensional change of .118" (about 1/8"). Sitka has a fairly mild volumetric shrinkage rate. If you used Beech for example for that same soundboard and used a flatsawn piece of wood you would see closer to .194" of change given the same 3% change in moisture.

Will riftsawn be problematic, maybe not depending on the wood. It will not be ideal though (so you have to do your research and figure out what is acceptable to you).

Rich