Join Date: Mar 2018
Location: Huntington Beach, California
For years I've used 1/8 inch per foot, cross grain.
Let me explain.
You start with KD wood. And it sits in your shop for a few weeks. It has reached equilibrium. You build your project and move the piece to the Pacific North West or to Phoenix, Arizona. Here in the north side of Huntington Beach the humidity rarely gets above 30%. (We are almost on the border of Westminster.)
I made a couple of solid cherry nightstands and moved them to the Portland, Oregon area. No problems.
You mentioned a panel 34 inches wide or 3 feet for rule of thumb. The wood is going to move 3/8 inch maximum, equilibrium to new equilibrium. Now before we jump in and leave the extra 3/8 all around, lets be smart and reduce the effect of wood movement to 3/16. All it takes is a bit of glue and a 23 gauge pin nail gun to reduce the effects of the wood movement.
Cut the channel for the panel an extra ¼ inch deep. As you install the panel put about 1 inch of glue, top and bottom of the panel and then shoot a very short pin nail through the frame and into the panel to keep the panel from moving. Do this in the center of the panel only. What you have done is to divide the effect of wood movement in half. The panel will still move 3/8 but only 3/16 on each side of center. I use 5/8 inch pin nails for this and remember only 1 each top and bottom.
Just a dumb old paper boy from Brooklyn, NY
Last edited by NoThankyou; 08-03-2020 at 06:25 PM.