I have some 4″ thick birch that has a small twist. Should I first resaw, then flatten the wood, or flatten the wood, then resaw it?
Carol Reed: The picture of trying to resaw and follow the twist with a powered saw gives me the heebie-jeebies (technical term, sorry). Flatten first, please.
Richard Jones: Flatten and then resaw. Be careful of deep ripping solid wood. It may have stresses built in due to improper drying. It’s always a good idea to do the fork or prong test to see if the wood you propose to deep rip or resaw is case hardened or reverse case hardened, both of which can lead to failure. To do the test, cut, at about 18″ or more from one end of the plank, a length approximately 2″ long. Put the end grain of this short piece on the table of the band saw and cut in from either face a prong about ¼” or 3/8″ thick, stopping about an inch from the far edge, and clear out the waste in the middle. If the forks open or close you have reverse case hardening in the first instance, and case hardening in the latter, indicating internal stresses and likely failure in resawing. If the forks remain about parallel you’ll most likely be able to resaw with success. I know you didn’t ask about this, but I thought I’d throw the information in anyway.