rauschnad wrote:
I am sort of new to this turning and started with bowls "easiest " thing I could make..... I have made about 8 , fronm popular to ash to cherry , when i get the down to about 1/4 inch or so i develop cracks across the grain. any way of avoiding this,The wood i have turned is kiln dried and should be stable.....yet they appear after Isand also, Thanks
The kiln will take the wood into equilibrium with its environment. Most timber goes to 8% moisture in the kiln, which is equal to a relative humidity of ~40%. Problem is, that's not what the atmosphere outside the kiln registers, so the wood will normally gain up to equilibrium with it. Or lose, if you're in the mountains/desert.
So if you kept that wood out in the barn or the shed, then brought it inside to a heated or air-conditioned place to turn, you're going to be vulnerable to drying stress. Now heat it while sanding, and the relative humidity will take another dive - rapid at 1/4" thick, less at a half, and so forth. Contracts and cracks.
So keep your wood storage as close to the environment it will serve in, don't go quite as thin and then don't press while sanding. That'll keep the end grain from checking. Some people spritz with water before and periodically during sanding. I'd rather sand gently without heating.
If you think the woods you mention are bad, let some of the old timers tell you about aromatic cedar