direction of annual rings in the neck wood - why?

[baroquecello]

I apologise in advance as I realise I don't know how to put this into words correctly, but I hope my question is clear nonetheless.

One of the problems in necks, particularly cello necks, is that over time many of them bend, either in the neck area or in the neck root area or both, causing the scoop to increase and/or the projection to fall.  Also, necks can break at the neck root and if the do, they usually break pretty cleanly along an annual ring. And thirdly, the pegs in the pegbox are friction held, and quite often peg boxes crack along an annual ring.

Wood is stiffer if the force is excerted perpendicular to the annual rings (like in a quarter cut top or bass bar) than it is when it is excerted parallel to the annual rings. Why then is it that in necks and pegboxes, the wood is invariably cut in such a way that the annual rings are parallel to the fingerboard, and the weaker side of the wood is chosen to hold the tension of the strings? Wouldn't the wood be more resistant to bending if it were cut the other way? And wouldn't the neck be more impact/crack resistant if the wood were cut the other way? And wouldn't the peg box be less prone to crack if the annual rings were positioned the other way?

I've never constructed a violin. There is probably an obvious reason for the placement of the wood in the neck, that anyone who has constructed a violin knows.

[jacobsaunders]

Violin (Cello) necks are normally “cut on the quarter” (what I think you are trying to say). One might expect a neck “cut on the slab” (the opposite) to bend more with string tension, with the associated problems. One does encounter old instruments where the neck/scroll (mostly only scroll left) is cut “On the slab”. In this case, cracks between peg holes are more frequent

[Delabo]

Makes you wonder why cellos do not have a truss rod like guitars have.

[J.dV]

17 minutes ago, Delabo said:

Makes you wonder why cellos do not have a truss rod like guitars have.

Lots of folks have been using CF rods of various designs for a while now, I believe.

[baroquecello]

Thank you for the replies.

I wasn't thinking of slab vs quartered, I was thinking of quartered wood. As I find it had to describe, I've made a picture to illustrate what I mean. The blue lines are the direction the annular lines are showing in this example, with the black lines being what I believe is generally aimed for. The lilac lines show what I'd expect to structurally be the strongest. 

The only reason I can think of for not doing it that way is possibly optical: maybe the flames won't show?

[HoGo]

The wood is generally easier to crack in radial direction (from bark to center) so the standard pegbox is cut in the more favorable direction against splitting. On cellos the long neck heel makes it necessary to have large chunk of wood and wood cut the traditional way is more economic to cut ("pie cutting") and more stable during drying - less prone to cracks and twisting/ cupping across width. Stiffness of the maple wood neck along the grain is pretty much identical whatever direction of cut you have. There may be some differences in stifness across the wood depending on angle of yearrrings but this is not in the play with necks.

[jacobsaunders]

25 minutes ago, baroquecello said:

Thank you for the replies.

I wasn't thinking of slab vs quartered, I was thinking of quartered wood. As I find it had to describe, I've made a picture to illustrate what I mean. The blue lines are the direction the annular lines are showing in this example, with the black lines being what I believe is generally aimed for. The lilac lines show what I'd expect to structurally be the strongest. 

The only reason I can think of for not doing it that way is possibly optical: maybe the flames won't show?

That is what I would call “on the quarter” (black lines) or “on on the slab” (pink lines) and I believe most of my colleagues would too

[Brad Dorsey]

2 hours ago, baroquecello said:

...Why then is it that in necks and pegboxes, the wood is invariably cut in such a way that the annual rings are parallel to the fingerboard...?...

Could it be because that is the easiest way to maximize the number of neck blanks that can be cut from a log?

Consider that a neck blank can have a trapezoidal cross section because the ears of the volute are wider than the neck foot where it glues to the back button.  This means that if you take a round log of neck material, make a bunch of radial cuts and flatten the inner and outer edges, the log is easily processed into neck blanks.  Something like this:

[Don Noon]

It's all of those things...

The grain orientation minimizes the chance of splitting at the heel and pegbox

It shows the flame the best

You can cut more necks out of the tree

The problem is that it's wood, and can split, and isn't super-stiff... but the traditional way is about as good as you can do with it, unless you want to use modern material reinforcements.

[David Burgess]

7 hours ago, baroquecello said:

Thank you for the replies.

I wasn't thinking of slab vs quartered, I was thinking of quartered wood. As I find it had to describe, I've made a picture to illustrate what I mean. The blue lines are the direction the annular lines are showing in this example, with the black lines being what I believe is generally aimed for. The lilac lines show what I'd expect to structurally be the strongest. 

The only reason I can think of for not doing it that way is possibly optical: maybe the flames won't show?

Wood has varying expansion and contraction ratios on the three different axis, as moisture content varies.

If the end-grain was running in the same direction as your purple marks, not only would there be the highest of expansion and contraction ratios throughout the length of the heel on a cello, but also the highest expansion and contraction of the peg holes, which may explain Jacob's observation that slab-cut necks have more cracks between the peg holes.

[Don Noon]

Although tangential expansion/contraction of pegholes might contribute, I'd bet that it's the lack of tangential strength that is by far most responsible for peg hole cracks in slab-cut necks.  And slab-cut backs.