Feed and Speed Calculator for Softwood: Chip Load Chart & RPM
Softwood is forgiving on heat and unforgiving on surface finish. Pine and fir clear chips easily and rarely burn, so the limiting factor is tear-out and fuzzing rather than temperature.
For softwood, the recommended chip load runs from 0.127–0.203 mm per tooth on a 1/8″ cutter to 0.483–0.635 mm on a 1/2″. Typical spindle speeds sit between 16,000 and 20,000 RPM.
Your chip load is 0.3425 mm per tooth, which is within the recommended 0.279–0.406 mm range for softwood with a 6.35 mm upcut spiral.
Softwood. Softwoods clear chips easily and tolerate an aggressive feed. Burning is rare; fuzzing on the cut edge is the usual sign the feed is too slow.
Upcut spiral. The baseline the published charts assume. Chips are lifted clear of the cut, which keeps heat out of the workpiece at the cost of tear-out on the top surface.
How to cut softwood on a CNC router → - the full how-to: which bit, workholding, chip evacuation and reading the cut.
How softwood fails when the chip load is wrong
The failure mode is a fuzzy, torn edge rather than a burnt one. That is usually a sign the feed is too slow for the cutter to shear cleanly, or that the bit is dull enough to be tearing fibres instead of cutting them. Softwood hides a dull cutter for a long time and then shows it all at once.
Setting up a cut in softwood
Softwood tolerates an aggressive chip load, so this is the material to use when you are learning where your machine's rigidity limit actually is - it will chatter and complain long before it breaks a cutter. A downcut bit gives a noticeably cleaner top edge on construction lumber.
The thing most people get wrong
Resin. Pine pitch builds up on the flutes and turns a sharp cutter into a blunt one within a single long job. If cut quality degrades over the course of one part rather than over weeks, clean the bit before you replace it.
Chip-load reference for softwood
Recommended chip load per tooth by cutter diameter, before any adjustment for depth of cut or bit geometry. Values between the 1/8″, 1/4″ and 1/2″ anchors are interpolated.
| Cutter diameter | Chip load (mm/tooth) | Chip load (in/tooth) |
|---|---|---|
| 1/16" (1.59 mm) | 0.127 – 0.203 | 0.0050 – 0.0080 |
| 1/8" (3.18 mm) | 0.127 – 0.203 | 0.0050 – 0.0080 |
| 4 mm | 0.166 – 0.256 | 0.0066 – 0.0101 |
| 6 mm | 0.262 – 0.384 | 0.0103 – 0.0151 |
| 1/4" (6.35 mm) | 0.279 – 0.406 | 0.0110 – 0.0160 |
| 8 mm | 0.332 – 0.466 | 0.0131 – 0.0183 |
| 3/8" (9.53 mm) | 0.381 – 0.521 | 0.0150 – 0.0205 |
| 1/2" (12.70 mm) | 0.483 – 0.635 | 0.0190 – 0.0250 |
These are estimates derived from published tooling-manufacturer data, not test results. Always prove a new setting on scrap first. Sources are listed on the methodology page.
Other materials
Already running a feed rate and want to know what chip load it produces? Use the chip load calculator.