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I'm really showing my ignorance here, but when properly book-matched, does the nap of the grain in each half of the joined top run in different directions?  If not, I have to unglue a set and flip one side.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Yep.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Thanks Howard.  I thought I was careful to keep them straight, but when I was scraping them, I talked myself into the possibility that I had reversed one of them before gluing.  Gotta stop talking to myself, or listening.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Maybe I'm showing my ignorance here but most of the top sets I get my hands on (3A grade) aren't perfectly quarter sawn and when glued up for best visual match up with grain pattern the respective halves of the glued up top plane better in opposite directions either side of the centreline. Ditto goes for every IRW back set Ive used to date.

It has nothing to do with quartersawn Martin .. its the runout on the edge of the pieces that counts here .. when you open in a bookmatch the angle of the runout becomes mirrored as well, thus each piece planes in a different direction.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

tony's point is esily demonstrated by drawing "runout" lines, i.e., lines on an angle, diagonally across the side of a book. when you open the book the lines will be going in opposite directions. if the lines are drawn along the long edge, representing no runout, when you open the book they will of of course still be running along the long edge.

That's what I was trying to say......the run out is in opposite directions when you properly lay out a book matched top. If you lay out a book matched set so that runout is in the same direction both sides of the centre seam then it wont always be a visual match up along the seam.

Visual continuity is surely the priority over having the runout in the same direction is it not? This was the reason for my original post.

If Waddy's top set looks best the way it is then does he need to flip the top just so runout runs in the same direction both sides of the centre seam?

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

by trying to work both halves in the same direction along the long axis your are inviting tearout. it is better to work on the diagonal, with the plane or scraper held on an angle to the direction of movement so as to cut with a shearing action.

work on one diagonal over the whole board, then work on the opposite diagonal. i'm sure cumpiano for one shows this with diagrams. i used to do this with two planes, one fitted with a toothed iron. it made it very easy to see where you had been and where you hadn't and helped avoid over planing any given area.

also, resist the temptation to set the blade for coarse cuts. this also invites tearout. take the thinest shavings you can manage, and have patience. you will get to where you want to be, admittedly slower, but with better results.

I generally plane across a spruce top on the diagonal if I can but sometimes it doesn't work and I end up working each side along the grain. Scrapers are generally less prone to causing tear out but again sometimes even with a scraper working on the diagonal isn't always workable. Each top has its own characteristics and it takes a few strokes with the plane or scraper to get the feel of the wood and how to best work it.

"If Waddy's top set looks best the way it is then does he need to flip the top just so runout runs in the same direction both sides of the centre seam? "

No. If it is bookmatched then the runout will be in opposite directions, and that is pretty well how everyone builds to my knowledge.

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David White, Toronto

"All my favourite singers can't sing."