Universal Quoting Formula: Total Job Price = (Raw Material COGS + Machine Depreciation & Energy + Finishing Labor) / (1 - Target Margin %).
All variables calculate locally in real time. Standard commercial margins are 50%–65% for B2B contracts and 65%–80% for custom retail orders.
The Mathematics of CNC Speeds & Feeds Optimization
Whether operating an industrial 5-axis vertical machining center or a desktop hobbyist router (Shapeoko, Genmitsu, X-Carve, Onefinity), running improper speeds and feeds leads to chatter vibration, burned wood, melted plastics, poor surface finishes, and broken carbide end mills.
1. Surface Feet per Minute (SFM) Reference Standards
| Workpiece Material | Recommended SFM (Carbide) | Optimal Chip Load (1/4" End Mill) | Recommended Flute Geometry |
|---|---|---|---|
| 6061-T6 Aluminum | 250 – 400 SFM | 0.0010" – 0.0015" IPT | 1-Flute / 2-Flute Upcut O-Flute (Uncoated or ZrN) |
| Cast Acrylic / Plexiglass | 350 – 500 SFM | 0.0030" – 0.0045" IPT | Single O-Flute Polished Flute |
| Hardwood (Oak/Walnut) | 400 – 600 SFM | 0.0035" – 0.0055" IPT | 2-Flute Downcut (for top edge clean finish) |
| Softwood & MDF | 500 – 750 SFM | 0.0050" – 0.0075" IPT | 2-Flute Compression Spiral |
2. Climb Milling vs. Conventional Milling
Climb Milling (Down Milling): The cutting edge engages the material at maximum thickness and exits at zero thickness. Recommended for CNC machines with low backlash. Produces superior surface finishes, reduces heat transfer to the tool, and increases tool life.
Conventional Milling (Up Milling): The cutting edge begins at zero thickness and ramps up to maximum thickness. Recommended only on manual, loose-lead-screw milling machines where table pull-in is a hazard.