Hey everyone. I’m new to the “Knots Forum” and I look forward to gaining insights from all of you. I also hope to be able to share what limited kowledge I have gleaned from my own woodworking experience.
I work in a three-man, custom cabinet shop in Utah. The shop has been in operation for over twenty years, and was started by a local woodshop teacher. It has since been handed over to the son of the proprietor. Both father and son have taught me a great deal. As far as kitchen cabinets go, these guys really know what’s up. I feel very fortunate that they involve me in all aspects of each project. From design to installation they have taught me all they know, and they frequently ask my opinion regarding many matters.
I have a question regarding a table leaf for a table I built. When originally constructed the leaf was perfectly flat. Now the leaf (built of solid alder and walnut measuring 18″ wide by 48″ long) has a definite crown. In the future, what precautions can be built into a similar leaf that would solve this problem?
Replies
Use quarter sawn lumber. Put battens or cleats on the bottom if the table design allows for that.
Edited 11/18/2004 12:37 am ET by Uncle Dunc
Thanks for the tips.
Hi Jeff,
You could ensure the you alternate the crown in the boards so that they don't all face the same way. That works to some extent. This can be difficult sometimes, cause it means you may loose the grain pattern of the wood. Anyway, that's my thought. Hope it works for you. I'm sure there are many experts on here that know better then I do, how to remedy this situation.......Loran
Jeff,
Using well dried lumber, acclimated to the shop (don't run out and buy stock, or bring down from the loft, in from storage shed, and dress and glue it immediately), then finishing equally on both sides of the leaf will usually keep it flat. As unc said, battens provide add'l insurance, but you must allow for seasonal movement, or you'll have cracks instead of warp.
What causes a board to cup is moisture loss, usually. If the leaf had excess moisture in it, as it dries, the growth rings will tend to "straighten", due to uneven shrinkage. Wood shrinks more parallel to the growth rings than it does perpendicular to them. That's why as unc says, quartersawn stock will stay flat.
If there is more finish on the top side of the leaf, humidity changes will cause movement of miosture to take place more on the bottom of the leaf than the top, causing it to cup.
Additionally, drying stresses in a board can be released in dressing it to thickness, especially if more wood is removed from one side than the other. Letting the stock rest for a day or two after dressing, will let this show up before it is glued up into the middle of a leaf.
Is the leaf alder and walnut glued alternately (like a butcher block) or laminated one on top of the other? Differences in shrinkage rates between the two woods could have caused your problem.
Regards,
Ray
Thanks for the tip.
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