Hi Gary,
I was going to make a side table similar to the Greene and Greene side table you published an article on in 2004. You used mahogany and I wanted to do quartersawn white oak. As I understand it, quarter or rift sawn white oak will expand more across its thickness.
Will the center stretcher (for example) risk cracking the side stretcher mortise since it is expanding across its thickness compared to the plainsawn mahogany you used in the article?
Also, are there rules of thumb as to when a tenon is too long and will expand to much and risk cracking in the future? In your article, its a 7″ tenon and I know some people break it into two smaller tenons sometimes but I don’t understand how to know when I should do that. Is it experienced woodworker’s intuition, rules of thumb, scientific calculation…. or perhaps just flipping a coin? Seriously, I’d love to have furniture that didn’t crack down the line.
Thanks.
Shawn
Replies
Hey Shawn,
First I wouldn't worry too much about cracking your bottom rail with a quartersawn shelf. It won't expand that much over time in thickness. That's the advantage of quartersawn stock. The direction in which it would move the most is usually so thin, 3/4" or 7/8" in the case of the shelf, that movement should be very minor.
And if you match your grain on the bottom shelf with your rail, then both will move in the same direction. So make your bottom rail flat sawn so it will move over its width in line with the movement of the shelf.
As for tenon widths, I keep mine under 3" except in cases like this where the tenon shows through. What I did here was to not glue the entire tenon. My hope, and it is just that, my hope is that with only the center of each tenon glued, there should be be plenty of room for movement without splitting any rail or showing big cracks.
In conclusion, it is woodworker's knowledge, intuition, the flipping of many coins and sprinkling the blood of a newt about the shop that all contribute to this decision.
I am always amused by the 18th century reproduction folks who build a lowboy with 24" wide boards of cherry and glue them into posts with several very long tenons. I asked one very good maker, "Say, won't this split?" His reply: "Just like the antiques."
Have fun with it, do the best you can, try not to worry too much.
Gary Rogowski
http://www.northwestwoodworking.com
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