I get all my lumber from dead or unwanted urban trees. Often I get logs from tree cutting companies. Sometimes I respond to online ads that require me to fell the tree in exchange for the wood. Other times I simply hear a chainsaw and follow the noise. Regardless, these are trees that would otherwise go to the landfill and typically owners are excited at the thought that their tree will be given a second life as furniture.
The next step is milling the logs into slabs. Most slabs are milled at 2.5" thick and lumber to anywhere between 1" and 3". I use a bandsaw mill capable of milling logs up to 36" in diameter. A bandsaw mill has many advantages over other mills, but perhaps the greatest advantage is the minimal waste produced from the thin kerf (blade).
The milled lumber then needs to be dried before it can be used. I typically air dry newly milled slabs for 6 months to a year to lower the moisture content to about 20%. Boards are placed on stickers so airflow can get around the entire slab to ensure even drying. Air drying first is slower but helps to prevent surface and end checking as the wood dries.
I finish off the drying process in a solar kiln. The kiln utilizes solar energy as a heat source as well as for powering fans to circulate airflow through the stack of lumber in the chamber. Dry outside air is allow in where it is first heated by the solar collector, pushed through the stack where it picks up moisture and then vented to the outside through ceiling vents. This takes the moisture content of the wood down to about 10% where it will no longer move or shrink from moisture loss.