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View Full Version : What is Grain Runout?



Matt Clara
11-01-2009, 01:48 AM
I found a good article on the subject of grain runout, with some images of instruments built with some runout.

http://www.lutherie.net/frankford.runout.html

ukantor
11-01-2009, 01:10 AM
Interesting. Thanks for that.

Ukantor.

Dave Higham
11-01-2009, 08:08 AM
Frank Ford is a reference in luthery and instrument repair and you can depend on what he says. However, I don't agree with what this person, whoever he or she is has added.

Quote:
But! This effect can also be caused (occasionally) by "bookmatching" spruce pieces that are not truly mated, and whose grain opposes like this:
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\|////////////////////////////////

What's he talking about? "bookmatching pieces that are not truly mated". Rubbish!

As Frank explained, 'bookmatching' means sawing or splitting one piece of wood down the middle and opening it up like a book. Which makes it impossible to get the effect he shows.

Split this;
\\\\\\\\\\\\\\\\\\\
\\\\\\\\\\\\\\\\\\\
and open it up and you get this
\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\

Pete Howlett
11-01-2009, 09:52 AM
There sure are a lot of people out there talking tosh!

davidp
11-01-2009, 09:53 AM
Split this;
\\\\\\\\\\\\\\\\\\\
\\\\\\\\\\\\\\\\\\\
and open it up and you get this
\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\

Dave, I am totally without knowledge in this area, but that doesn't make sense to me. Surely if it opens like a book then it would be a mirror image?

I googled 'bookmatching' and found this definition in about.com -
Book-matching is the process by which a plank of wood is sawn down the middle and opened up like a book, so that the resulting two pieces are near mirror images of each other. The grain pattern of a 'book-matched' soundboard should reflect this symmetry.

davidp

Pete Howlett
11-01-2009, 10:06 AM
You get the symmetry on the face but the end grain is as david shows.

davidp
11-01-2009, 10:10 AM
You get the symmetry on the face but the end grain is as david shows.

ah, ok Pete, thanks. I am still not sure I can figure that, but I don't work with wood, so it's not surprising at all.

davidp

RonS
11-01-2009, 01:48 PM
Dave, I am totally without knowledge in this area, but that doesn't make sense to me.

Take a book and place a mark the on the pages on the top of the book. Open the book and see what you get.

davidp
11-01-2009, 02:05 PM
Take a book and place a mark the on the pages on the top of the book. Open the book and see what you get.

Thanks :) I didn't quite use that, but the 'ahhh, I see' lightbulb came on after my own simple test...

I used a piece of paper, drew my lines, tore it lengthwise and opened it like a book.

....just another d'oh moment in my life.

david

mzuch
11-01-2009, 02:27 PM
Split this;
\\\\\\\\\\\\\\\\\\\
\\\\\\\\\\\\\\\\\\\
and open it up and you get this
\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\

No. When you split the billet for a bookmatch, the top half is turned upside down. Unless the end grain is perfectly vertical, it will slant in the opposite direction on the two halves. A book acts differently because each page moves independently, anchored only by the binding.

davidp
11-01-2009, 02:40 PM
No. When you split the billet for a bookmatch, the top half is turned upside down. Unless the end grain is perfectly vertical, it will slant in the opposite direction on the two halves. A book acts differently because each page moves independently, anchored only by the binding.




:) thats what I thought. Please try my test. This image sort of shows what happens

http://www.davidp-inter.net/images/CAP105.JPG

sorry, just saw that you said "the top half is turned upside down" and yes, if you mean flip it around so top end becomes bottom end, that would happen I agree.

david

Pete Howlett
11-01-2009, 03:18 PM
I gotta say something here because this is getting ridiculous.

Bookmatching as it applies to our craft - luthery - means exactly what Dave says and demonstrates in his diagram.

As a former cabinet maker/designer I also thought it meant the same in that trade over here in the UK. I have never ever heard of bookmatching involving turning the wood upside down. It just doesn't apply to the term bookmatch which is in fact a metaphor that describes an action.

I have refrained from being forthright recently but I cannot hold back folks - misinformation has a way of becoming fact; witness good old Bill saying "I did not have...." and ya'll believing him because he said so! Now we are not politicians are we but civil ukelists :D :D :D :D

UkÚDan
11-01-2009, 03:22 PM
:) thats what I thought. Please try my test. This image sort of shows what happens

Thanks Dave. Very informative... I really thought the opposite although I didn't know why.

davidp
11-01-2009, 03:31 PM
:) forthright is ok in my books. especially if the information provided comes from experience...sometimes I just have to see stuff to believe it.

I always knew the faces would be a mirror image, and just assumed the ends would be the same. I was wrong, had it explained and then proved it to myself.

davidp

mzuch
11-01-2009, 05:21 PM
I stand corrected. And, unlike those who have decreed this discussion "ridiculous," I will refrain from making ignorant comments about decade-old U.S. politics on a ukulele board.

Pete Howlett
11-01-2009, 10:37 PM
Yeah was a cheap shot meant as a joke - sorry folks, I though the smilies would give the game away...

Matching wood has some interesting terms - running match or slip match used a lot in veneer panelling is an interesting effect that like flipping wouldn't work on a uke but looks great on huge flat surfaces. Actually I should have put a link to this from my YouTubes where I discuss resawing and matching but I don't think it's up any more. Want me to do it again?

ukantor
11-01-2009, 10:59 PM
The person who made the comment about "pieces that are not truly mated" was making a valid point. If he/she had used the word 'joining' instead of "bookmatching" it would have fine. The quotation marks plus the words "not truly mated" show that the writer knew what he/she was talking about.

We are supposed to be splitting billets - not hairs.

Ukantor.

Dave Higham
11-01-2009, 11:50 PM
Well, I know I'm labouring the point, but I still don't know what the person was talking about. Even "joining something that's not truly mated" is gobbledygook, and the difference between flipping or slip-matching and book-matching is not splitting hairs it's chalk and cheese.
Oh, and if you split a piece and slip-match it, the end grain will still look the same but you won't see the run-out on the front.

And yes, thank you, I do know how to spell pedantic.:D

ukantor
11-02-2009, 12:02 AM
The person was saying, "If you join wood in this way (the way they illustrated), you will get a visual effect (dark one side: light the other) which is similar to that shown by runout in a properly bookmatched set."

I've got no problem with that.

I've got no problem with pedantry either; life would be much less interesting without it.:shaka:

Ukantor.

azhiaziam
06-13-2010, 01:43 AM
yeah this was a frustrating thread. you guys are so formal and politically correct.

in granite, book-matching is opening a book like a butterfly with a mirrored image, not like putting marks on the edges of a closed book like the gold leaf on a bible.

granite slabs often come from the same block so the sheets are "bookmatched" or mirrored which allows you to seam them into larger shapes in a uniform fashion. the edge is also bookmatched when adding build-up to 2cm material. you would add 2 inches to the over-all of your pieces and then trim off 1.5 inches. when you roll that piece over, the grain matches and gives the edge the appearance of being 4cm thick. otherwise you get random grain colliding.

i've always known book-matching to be synonyms with butterflying. i don't think the other explanation should even apply because there isn't as much of a correlation. you're talking about turning something 180 degrees which produces the same //// slanted lines as you would get if you didn't flip it 180 degrees which removes any need to compare it to a book. all you're saying is to cut the piece in half and move it over, you could flip it or not. book matching (butterflying) takes a lot of precision and planning to get the center perfect. if you mess up book matching for 1 out of 3 sheets of granite, you have to buy 3 sheets of granite to start all over. which can be more than a thousand per sheet plus all other costs.