|Forum topic by Pete Tevonian||posted 08-25-2010 05:31 PM||2874 views||0 times favorited||4 replies|
08-25-2010 05:31 PM
I have some large trunk cross-sections “cookies” that I’m trying to dry to make a coffee table and end table. I’m about halfway through the drying process, and a fairly significant crack has started to form starting from one edge and reaching about 1/3 of the way to the center of the cookie.
I expect I will need to add a butterlfy key to stop the progress of that crack. But I have questions, of course:
1. Will adding a key to stop this crack simply mean another crack will start elsewhere?
2. Is there a right or wrong time to add the key? I assume the sooner the better.
3. The cookie in question is 2.5” to 3” thick, and has a diameter ranging from 39” to 49” (thus a circumference of about 140”), so even 2% shrinkage could result in over 2” of gaps in cracks —how thick should the key be to provide the necessary support for that much wood/force? I’ve seen decorative butterflies discussed that are 1/8” to 3/16” thick. I can’t image that would be enough to hold this piece of wood. I’ve some posts talk about 1” deep mortises. And do I need butterlfies on top and bottom?
4. The whole cookie is end grain—I assume the key should have the grain running the length of the key, so that the forces pulling it appart will be pulling on the strong, long grain.
Thanks in advance for any guidance. I can post pics if that’s useful.
-- Pete in Wilmette, IL