Body Grain Direction

[avengers63]

Yes, I did a search. No, I couldn't find the answer.

Traditionally, the grain on the body runs North/South. I understand why it runs that way on the neck: strength. Is that the same reason for it on the body? I was considering the possibility of either horizontal or diagonal grain for a body. If it's structurally a bad idea, can y'all tell me why?

Another thought is a back going horizontal with the top going vertical. This might have a stabalizing effect similar to plywood.

[Mattia]

Slightly angled is common on V shaped guitars, matches the body shape.

Reasons NOT to do it:

1) Wood is floppier across the grain than along the grain. Try flexing a piece of wood to test this

2) Wood expands and shrinks more across the grain (= in the direction of the strings if you do this) than along the grain

3) Wood warps more easily across than along the grain, and you'd need waaaay wider pieces of wood

4) You end up with about 4 times as much endgrain to sand as on a guitar built the regular way. Pain to route, pain to sand, pain to route. I'm all for avoiding end-grain, me.

5) You end up with cross-grain joints at the neck pocket, expanding in different directions. Maybe no catastrophic, but suboptimal in every other way.

A thin top, sure, whatever, if you really like the grain that way and feel the need to make plywood-style laminations. Remember, though, that ply is stable because you have an ODD NUMBER of EQUAL THICKNESS (or at least balanced out) laminations. That way the warp overall compensates. And you need only go to a hardware store to see how flat that stuff stays (hint: not very).

Overall: I'm sticking with my boring traditional grain orientation :-)

[fryovanni]

+1 to what Mattia said.

When your looking for dimensional stability you want to consider width, length, length and thickness. Ideally you would want the grain oriented in such a way that the largest dimension has the grain orientation with the least movement, second has the second least and such. Longtitudinal grain shrinks and expands much less than any other direction. Radial(quarter) usually changes much more, but less than the tangential(flat). With a quartersawn piece of wood, long grain running from the neck to the heal, you achieve this ideal.

As an example,

Alder average dimensional change per. percentage of increase or decrease in moisture content, per. inch of thickness. Whe the wood starts with a moisture content between 6-14%(dry wood in service).

Radial-.00151"

Tangential-.00256"

Longtitudinal- closer to .0002"

Body dimensions of 20"(longest) x 12.5"(widest) x 1.75"(thickest)

You could expect these kinds of changes per. percentage of change in moisture content.

*With long grain neck to tail, and quartersawn.

Length- +/- .0040"

Width- +/- .0188"

thickness- +/- .0045"

*With long grain neck to tail, and flatsawn.

Length- +/- .0040"

Width- +/- .0320"

thickness- +/- .0026"

*With long grain side to side, and quartersawn.

Length- +/- .0302"

Width- +/- .0025"

thickness- +/- .0045"

*With long grain side to side, and flatsawn.

Length- +/- .0512"

Width- +/- .0025"

thickness- +/- .0026"

Since your scale length is going to be effected most directly by the orientation from neck to tail(actually bridge or tailpiece). You would want that as stable as possible. Big variations would lead to tuning and intonation issues. A 3% change could really muck things up with a flatsawn body, long grain running side to side.

[sunnydaze]

Yes, I did a search. No, I couldn't find the answer.

Traditionally, the grain on the body runs North/South. I understand why it runs that way on the neck: strength. Is that the same reason for it on the body? I was considering the possibility of either horizontal or diagonal grain for a body. If it's structurally a bad idea, can y'all tell me why?

Another thought is a back going horizontal with the top going vertical. This might have a stabalizing effect similar to plywood.

Hi Avenger,

Checkout this topic - I had pretty much the same question about a year ago and got a couple of pages of useful replies. FWIW - I couldn't find this using the search function either - I tried using my handle, the title etc. nada....

Found it in my personal profile.

http://projectguitar.ibforums.com/index.ph...mp;#entry337875

Anyway, hope it helps.

Good Luck

Michael

[avengers63]

Well, that's that! I knew there was a perfectly legitimate reason, I just didn't know what it was. Thanks!