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10th June 2014, 09:56 AM #1New Member
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I need a second opinion on the orientation of wood for making surfaces.
There are two methods i'm considering to use for joining wood together for creating a surface. Firstly, the wood being used are just pine 2x4's that I cut down so that they are perfectly square and straight. They have been cut and ready for the next step for several days now. The pieces are about 35" long and just under 3" wide with a thickness just over 1.25". The surface im looking to create will have final dimensions of 29.5" x 14.5" x 1.25". The images are pretty self explanatory. I and worried about bowing and cupping. More cupping than anything. Im thinking the method in the first pic will cup overall across it's width. I would glue and cure them within 3 sets of cauls I have. This would be the easist method for joining all these pieces together as well.
s1.jpg
This is the next method. It looks cool but that's not the reason why I am considering this method. At least for this project because the boards will be kind of hidden. But by cutting down the boards real short the overall bowing of each piece, if they even bow at all, wont be as drastic as a piece of a longer length. By having them turned every 3 pieces by 90 degree's they will be supporting each other. Some say the joints would break do to the bowing and cupping that might happen. What do you think? Which would be a better way to go?
s2.jpg
Just so you know I will be using four of these in such a way to create a desk for my stuff. So there will be framing under the surfaces etc. Thanks in advance people.
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10th June 2014 09:56 AM # ADSGoogle Adsense Advertisement
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10th June 2014, 06:50 PM #2
With the 2nd method it's not cupping and bowing that you have to worry about: it's wood movement.
Timber will absorb/lose moisture from/into the air depending on ambient humidity, so it expands and shrinks constantly. Where it becomes a problem is that it shrinks at a different rate across the grain than it does along. For some timbers this difference is almost negligible but for others it can be quite dramatic.
This places quite a bit of strain on the glue joints when end-grain is butted to long-grain, until eventually they fail. (In general, the smaller the squares/glue-lines involved, the longer they'll last. It's still not a good idea though.)
Personally, given what you've said, I'd go for option A. If you look at the end-grain on each board you should be able to see if it's rift-sawn, quarter-sawn or flat-sawn (aka plain-sawn).
In the first two cases cupping shouldn't be a major problem, but if the latter...
One workaround for this is to alternate the directions of the rings when laying out the boards so that even if they do cup they sorta cancel each other out. ie. for each board determine which side the heart of the tree would be, then lay the boards side-by-side as heart side up, heart side down, heart side up... etc.
- Andy Mc
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10th June 2014, 06:54 PM #3Taking a break
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The joins between each square will break/crack - I guarantee it.
Because timber moves (due to changes in humidity and temperature) much more over the width than the length, you'll essentially end up with rectangles instead of squares and they won't line up.
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10th June 2014, 09:18 PM #4well aged but not old
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If the ratio of width to thickness is about 3 to 1 you should not have much of a problem with option one. Just be carful with the method you use to attach the final surface. Allow for changes in dimension over time. How you dominos depends on what you are making.
My age is still less than my number of posts
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