Wood Feeds And Speeds Guide
Why Settings Matter
Wood cuts best when the bit makes chips, not dust. Feed too slowly and heat rises. Feed too fast and the edge chatters. A balanced setting protects the cutter, the spindle, and the workpiece. It also gives a cleaner edge with less sanding later.
Chip Load Basics
Chip load is the thickness removed by each cutting edge. It links feed rate, revolutions, and flute count. A two flute bit at high speed needs enough table movement. Otherwise the flutes rub the wood. Rubbing dulls carbide and can burn maple, cherry, or plywood veneers.
Wood Differences
Softwoods usually accept higher feed rates. Dense hardwoods often need lower feeds or shallower passes. Plywood and MDF need extra care because glue lines add abrasion. Grain direction also matters. Climb cuts can improve finish, yet they may pull the tool into the stock. Use firm work holding and test cuts first.
Depth And Stepover
Depth of cut and stepover decide cutter load. A deep slot engages the full diameter. That is harder than a light profile pass. Lower feed for slotting. Raise feed for open edge cutting when chips can escape. For finishing, use a small stepover and steady speed. This leaves fewer tool marks.
Using The Calculator
Enter cutter diameter, flutes, chip load, and either spindle speed or surface speed. Add the pass depth, stepover, cut length, and number of passes. The calculator estimates feed rate, plunge feed, material removal, and cutting time. Adjust the wood factor when a species feels hard, gummy, or brittle.
Shop Practice
Start with conservative numbers on a new bit. Listen for a smooth cutting sound. Check chips after the first pass. Warm chips are normal. Smoke, dark dust, or a screaming tool means the setting needs correction. Increase feed, reduce speed, or lower engagement. Record the final result. Repeatable records make future jobs faster.
Safety Margin
No calculator replaces judgment. Bit brand, collet grip, machine stiffness, and dust extraction all change the safe window. Use the result as a starting point. Make one change at a time. Keep notes beside each wood type. Small records help when production jobs return. They also reduce scrap, noise, heat, and tool wear.