I'm cutting a couple of 8/4 slabs up into rocking chair pieces. The wood is Claro Walnut, cut decades ago and air dried. There are some stress cracks and a lot of crazy grain in this wood, and as I cut it, it cracks and snaps like nothing I've ever heard. I've decided to just rough out the pieces and let them be for a couple of days, but I'm really not familiar with working wood that's this tied up. When I was band sawing some parts, I could actually see and hear the wood cracking in front of my cut. Aside from letting the wood rest before cutting to the final outline, are there other things I should do or think about? These slabs have been in my shop and kept above freezing for about a month now.
(03-10-2018, 12:40 PM)ed kerns Wrote: [ -> ]I'm cutting a couple of 8/4 slabs up into rocking chair pieces. The wood is Claro Walnut, cut decades ago and air dried. There are some stress cracks and a lot of crazy grain in this wood, and as I cut it, it cracks and snaps like nothing I've ever heard. I've decided to just rough out the pieces and let them be for a couple of days, but I'm really not familiar with working wood that's this tied up. When I was band sawing some parts, I could actually see and hear the wood cracking in front of my cut. Aside from letting the wood rest before cutting to the final outline, are there other things I should do or think about? These slabs have been in my shop and kept above freezing for about a month now.
Sounds like your wood has a lot of stress in it and letting it sit isn't likely to improve things. Of course, that's all you can do, but I wouldn't be surprised if it continues to crack even afterwards, leaving you with a nice pile of pen blanks or kindling. Air dried doesn't mean properly dried. I've sure ruined my fair share of wood during air drying.
John
Lots of stress. May have some limb wood in there.
Cut it oversize and let it sit for a few days. May help, may not.
Maybe it needs to dry another decade.
Did you let it acclimatize inside before cutting?
(03-10-2018, 12:40 PM)ed kerns Wrote: [ -> ]I'm cutting a couple of 8/4 slabs up into rocking chair pieces. The wood is Claro Walnut, cut decades ago and air dried. There are some stress cracks and a lot of crazy grain in this wood, and as I cut it, it cracks and snaps like nothing I've ever heard. I've decided to just rough out the pieces and let them be for a couple of days, but I'm really not familiar with working wood that's this tied up. When I was band sawing some parts, I could actually see and hear the wood cracking in front of my cut. Aside from letting the wood rest before cutting to the final outline, are there other things I should do or think about? These slabs have been in my shop and kept above freezing for about a month now.
When you prune and train a fruit or nut tree you can introduce a lot of internal stress as the load is redistributed. Open-grown trees with naturally spreading branches can be nearly as bad. Only thing I can think of that might help is boiling the wood. Getting the temp above ~150 F will allow some lignin creep. Turners say it works even for thicker pieces. Same principle as steam bending/straightening.
That said, steaming even claro walnut (or boiling it) is going to louse up the natural color.
Stress is stress, not much can be done to get rid of it.
Sometimes it can be minimized during milling by rotating the cant. To late for that now, never know if it would've done any good.
Just do the best you can.....
Ed
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Thanks guys. I've cut out all the pieces and if the cracking is any indication, have relieved a lot of the stress - just not my own. I'll let the parts acclimate for a few days and see if anything moves. I'd like to think that, released from the 'mother' slab and milled into relatively small component parts, they will do what ever they want to do now and not in the finished chair.
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