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I have some tops that would get a cleaner face if I jointed them opposite of the bookmatched marks. Anything wrong with jointing the inside edges of the tree?

Nope. I think the traditional way is done just because tighter grain lines in the center are considered better looking. Technically either way would be bookmatched and if the board behaved on the resaw should look symmetrical.

I guess there's an increased risk of runout along the joint...

Here's a discussion about it from a while back http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=43821

Basically, it depends on the grain. Does it go off quarter toward what would normally be the outer edge? Is there more runout at one side than the other?

I'm actually more inclined toward the usual tight grain center, wide grain outside being structurally worse with all but perfect wood. Reason being, tight grain is usually from the outside of the tree, and spiral growth causes more runout toward the outside of the tree, and runout affects long grain stiffness, and that needs to be highest in the center of the soundboard where the stress is most concentrated. And if the grain goes from narrow to wide due to drifting off quarter, then the wide grain part will have lower cross grain stiffness. But in the center of the soundboard, the bridge ties it all together and forces it to bend equally, whereas toward the outside, the cross grain stiffness of the plate has more of a role in spreading the stress.

But I do think tight grain center, wide grain outside looks better.

So are sounds boards on the $100,000+ guitars on display at the Martin factory reception center put together backwards? Some have wide grain at the center. Actually there is a video with Dick Boak and I think Dan E. from Stew Mac exalting the benefits of wide grain at the center. I'll find it and post.

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Ken Cierp

http://www.kennethmichaelguitars.com/

Thatd. E grat, thanks. At least I know if I go ahead, it won't be a sale breaker...

here's the vid link

http://acousticguitarconstructionforum. ... 045#p16045

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Ken Cierp

http://www.kennethmichaelguitars.com/

Some of them are. I believe Martin did it to reduce visible runout at the seam. However, the amount of runout that is usually deemed acceptable is not enough to appreciably reduce long grain stiffness. But besides appearance, there is another legitimate reason to minimize runout at the seam. That is, it reduces top damage if the bridge lifts, or if either the bridge or bridgeplate must be removed for repair.

If the tops are cut from long logs (parallel to the bole) and there is spiral present (as on most spruce logs), then runout is maximized on the bark edge of the tops.
But if the wood is cut into short blocks and split, it can be sawn parallel to the split at the bark. That minimizes runout at the seam, and allows for joining the edge that is usually (but not always) tighter-grained. It also allows better use of smaller logs....since defects like pin knots and heart checks (which are primarily near the heart) can be avoided by the layout of the pattern.
The other reason to join the bark edge is that on small logs, the growth ring radius is so much smaller in the heart that when cutting parallel plates, that edge is much more likely to be off-quarter.

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John

Since we are on the topic, what about backs?

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Wake up and smell the rosewood!

Actually the top on my '33 OM-18 and my '21 00-21 both have wider grain in the center.

Most backs don't have a bridge glued in the center with 180 pounds of string tension pulling on it. That is one way to say that it is much less important about the orientation than the top.

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John

Dick Boak -- guitar historian and Martin employee explains the "Martin" logic for grain orientation (wide/narrow) in this video starting at 1:32

http://acousticguitarconstructionforum. ... 045#p16045

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Ken Cierp

http://www.kennethmichaelguitars.com/

! epoN yaS I

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The Shallower the depth of the stream , The Louder the Babble !
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Alex

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"Indecision is the key to flexibility" .... Bumper sticker

Most tops that have spiral grain do start out fairly straight, and spiral more as they get older, but not all. I've seen tops, particularly in Red spruce, that show 'stripe', where the runout reverses as you go across the board. I have my suspicions about this, but so far as I know there's no real consensus about why trees develop spiral grain or stripe. I don't buy the notion that they're 'following the sun', but it's possible that sun exposure may have something to do with it.

But some people like to push against tradition.

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Mike Lindstrom

CHALLENGE ACCEPTED !!!

_________________
The Shallower the depth of the stream , The Louder the Babble !
The Taking Of Offense Is the Life Course Of The Stupid One !
Wanna Leave a Better Planet for our Kids? How about Working on BETTER KIDS for our Planet !
Forgiveness is the ability to accept an apology that you will probably NEVER GET
The truth will set you free , But FIRST, it will probably Piss you Off !
Creativity is allowing yourself to make Mistakes, Art is knowing which ones to Keep !
The Saddest thing anyone can do , is push a Loyal Person to the point that they Dont Care Anymore
Never met a STRONG person who had an EASY past !
http://wiksnwudwerks.blogspot.com/
http://www.facebook.com/groups/GatewayA ... rAssembly/

Do I see a new February Doofus Move candidate in the making?

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

I am seeing myself in the Doofus column on a regular basis in the coming months. I'm going to beat the rush, and get myself some new business cards.



Alex

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"Indecision is the key to flexibility" .... Bumper sticker