Plan your milling operations with these steps:

1. Measure Starting Thickness: Use calipers or a precise ruler to measure the thickest point of your rough board. This is your starting thickness.
2. Determine Final Thickness: Decide on the final, desired thickness for your finished board.
3. Set Max Depth of Cut: Enter the maximum amount of material you want to remove in a single pass. For most benchtop planers, 1/16" (0.0625) is a good maximum, while larger machines can handle more. Lighter passes (1/32") are better for highly figured or difficult woods.
4. Calculate: The calculator will tell you the total number of passes needed and the precise depth of your final pass.

• Thickness Planer: A woodworking machine that trims boards to a consistent thickness throughout their length.
• Jointer: A machine used before the planer to create one flat face and one square edge on a board. A board must be jointed before it is planed.
• Depth of Cut: The amount of material removed by the planer in a single pass.
• Snipe: A common planer issue where the machine cuts slightly deeper at the beginning and end of a board.
• Tear-Out: The chipping and tearing of wood fibers that occurs when the planer's blades cut against the grain.

"Don't confuse a planer with a jointer. A planer makes a board uniformly thick, but it will not make a warped board flat. If you feed a bowed board into a planer, you'll just get a thinner, bowed board. You must use a jointer first to flatten one face. That flat face then rides on the planer bed, allowing the planer to make the opposite face parallel and flat." - Professional Cabinetmaker

"For the final pass on your planer, take the lightest cut you can, maybe 1/64 of an inch. This will give you the smoothest possible finish and minimize any potential for snipe. It's worth the extra pass to get a surface that needs less sanding."

Example: Milling Rough Lumber
You buy a rough-sawn walnut board that is 1.875" thick. Your project requires a final thickness of 1.5". Your planer can safely remove 1/16" (0.0625") per pass.
Total to Remove: `1.875" - 1.5" = 0.375"`
Number of Passes: `ceil(0.375 / 0.0625) = 6` passes.
The calculator shows you'll need 6 passes. The first 5 will be at the full 1/16" depth, and the final pass will be a clean-up at 1/16".

• Taking Too Deep a Cut: Being too aggressive and trying to remove too much material at once can cause tear-out, strain the planer's motor, and increase snipe.
• Not Jointing First: Feeding a warped or twisted board into a planer without first flattening one face on a jointer.
• Forgetting to Flip the Board: To keep a board flat, you should take a pass from one side, then flip the board over and take a pass from the other, repeating until you approach your final thickness. This equalizes moisture changes.
• Ignoring Grain Direction: If you experience severe tear-out, try feeding the board in the opposite direction. Sometimes this aligns the cutters to be moving 'downhill' with the grain.

• Milling Rough Lumber: Taking raw, saw-mill lumber and turning it into smooth, usable stock of a specific thickness.
• Dimensioning Project Parts: Ensuring all parts of a project (e.g., cabinet face frames, door rails and stiles) are perfectly consistent in thickness.
• Creating Custom Thicknesses: Planing standard dimensional lumber down to a non-standard thickness for a specific design.
• Book-Matching Panels: Resawing a thick board into two thinner ones and then planing them to the same thickness to create a mirrored panel.