Swarf

Speeds and feeds calculator for CNC milling and drilling.
Free, open source, runs on macOS, Linux and Windows.

Pick your machine, material, tool and cut. Swarf gives you spindle speed and feed, explains every factor behind them, and warns you before the tool deflects, the spindle runs out of power or the chip gets too thin to cut.

Features

• Speeds and feeds for flat, ball, bull-nose and V-bit end mills, indexable face mills and twist drills, in 25 materials across the ISO groups (aluminium, steels, stainless, cast iron, titanium, superalloys, hardened steel, plastics, wood).
• Chip thinning compensation for narrow stepovers, shallow ball-nose cuts and lead angles.
• High-speed machining (HSM) option for trochoidal and adaptive toolpaths: cutting speed rises at low radial engagement.
• Workpiece hardness input for steels, stainless, cast irons, superalloys and hardened steel: cutting speed follows the difference from nominal.
• Cutting power, torque and force from the Kienzle model, with the spindle's real power curve (power drops below base speed).
• Tool deflection of shank and flutes, with a limit you set.
• Automatic limits: feed is lowered when power, deflection or the machine's max feed would be exceeded, and the display shows which one applied.
• Where the numbers come from: every multiplier from table value to programmed feed, step by step.
• Comparison charts: material removal rate and spindle power while radial width ae or depth ap changes, and side-by-side bars for full slot, roughing, trochoidal and finishing strategies plus your saved setups.
• Set speed and feed by hand: type or drag Vc, fz, spindle speed or feed in the display; the linked value follows (Vc ↔ S, fz ↔ F), the recommended values stay in view and one click brings them back.
• Metric or inch: mm, m/min, mm/min, kW or in, SFM, in/min, hp, with G20 in the G-code. The default follows your system's region.
• Ready G-code (S… M3, G1 F…, G81/G83 for drilling) with a copy button.
• Saved setups library, kept between sessions.
• 8 languages: English, Italiano, Deutsch, Français, Español, 简体中文, 日本語, 한국어. The language follows your system and can be changed from the menu.

Download

Get the latest build for your system from the Releases page:

System	File	How to run
macOS	Swarf-…-macos.dmg	Open the disk image and drag Swarf into Applications. The app is not signed: the first time, right-click it and choose Open. A portable …-macos.zip is also provided.
Windows 10/11 (64-bit)	Swarf-…-windows-x64-setup.exe	Run the installer. If SmartScreen warns about an unknown publisher, choose More info → Run anyway. A portable …-windows-x64.zip is also provided.
Debian / Ubuntu	Swarf-…-linux-x64.deb	sudo apt install ./Swarf-…-linux-x64.deb
Fedora / openSUSE	Swarf-…-linux-x64.rpm	sudo dnf install ./Swarf-…-linux-x64.rpm (or zypper install)
Any Linux	Swarf-…-linux-x64.AppImage	chmod +x Swarf-…-linux-x64.AppImage and run it. A portable …-linux-x64.tar.gz is also provided.

Chinese, Japanese and Korean need a CJK font such as fonts-noto-cjk.

Build from source

Install Rust 1.95 or newer from rustup.rs, then:

git clone https://github.com/TinyWorkshopDesign/swarf.git

cd swarf

cargo run --release

On Debian or Ubuntu, install the windowing and OpenGL libraries first:

sudo apt install libxkbcommon-dev libgl1-mesa-dev libwayland-dev libx11-dev libxcursor-dev libxrandr-dev libxi-dev

Run the tests:

cargo test

Packaging

• macOS app bundle: ./scripts/bundle_macos.sh writes target/release/Swarf.app. Set BUNDLE_ID to your own reverse-domain identifier when distributing.
• Windows from a Mac: with MinGW (brew install mingw-w64), cargo build --release --target x86_64-pc-windows-gnu. The icon is embedded by build.rs.
• Linux desktop entry: copy assets/swarf.desktop to ~/.local/share/applications/ and assets/icon-256.png to ~/.local/share/icons/hicolor/256x256/apps/swarf.png.
• Windows installer: scripts/installer.nsi is an NSIS script; makensis /DVERSION=<tag> /DROOT=<repo root> scripts/installer.nsi writes the setup .exe. The icon comes from assets/icon.ico.
• Screenshots: SWARF_SCREENSHOT=docs/screenshots cargo run --release starts from a clean state (your settings are not read or changed), saves results.png, charts.png and manual.png in that folder and quits.
• Releases: pushing a tag such as v0.1.0 runs .github/workflows/release.yml, which builds every platform and attaches a macOS .dmg (universal), a Windows setup.exe, and Linux .deb, .rpm and .AppImage (plus portable archives) to a GitHub release.

How the numbers are computed

Step	Model
Cutting speed	Handbook Vc per material and tool material, scaled by coating, by workpiece hardness (Sandvik Coromant factors), by 0.9 in a full slot and, with HSM on, by radial engagement (Kennametal factors: ×1.4 at 10 %)
Feed per tooth	Material factor × diameter, scaled by tool material and machine rigidity; −20 % in a full slot (Kennametal)
Drilling	Vc as a fraction of the end mill speed and feed per rev 2.5 × cf × Ø, both per material group from the Kennametal GOdrill tables
Chip thinning	Radial: 1 / (2·√(ae/D − (ae/D)²)) when ae < D/2; lead angle and ball nose: 1 / sin κ
Specific cutting force	Kienzle: kc = kc1.1 · hm^−mc · (1 − γ/100), with mean chip thickness hm from the engagement angle and a typical end mill rake angle γ per material group (Sandvik Coromant)
Power	Milling Pc = ap·ae·vf·kc / 6·10⁷ kW; drilling Pc = f·vc·D·kc / 240 000 kW; spindle efficiency 0.85
Deflection	Cantilever of shank (Ø shank) and flutes (0.8·Ø) under the tangential cutting force

Material data are typical values from machining handbooks, in src/data.rs. They are a starting point. Check them against your tool maker's catalogue, start conservatively and listen to the cut.

Code layout

File	Contents
src/calc.rs	Calculation engine: pure, no UI and no text, with tests
src/data.rs	Materials, coatings, machine presets, strategies
src/i18n.rs	Translations and number formatting per language
src/units.rs	Metric and inch conversions for display and input
src/fonts.rs	Loads CJK fonts from the system only when needed
src/app.rs	egui interface, DRO display, charts
src/main.rs	Window start-up and icon
assets/	Icon in every format and the Linux .desktop file
scripts/make_icon.py	Regenerates every icon file (needs rsvg-convert and Pillow)
scripts/bundle_macos.sh	Builds Swarf.app
scripts/installer.nsi	NSIS script for the Windows setup .exe
prototipo/truciolo.html	The first web prototype, kept for reference
ROADMAP.md	Planned updates

Contributing

Issues and pull requests are welcome, especially:

• cutting data you have verified on real machines, with material, tool and result;
• new materials, coatings or tool types;
• translations and corrections by native speakers.

To add a language: add a variant to Lang in src/i18n.rs and to Lang::ALL, raise LANG_COUNT, add one column to every entry of the strings! table and to material_name (the compiler lists every missing entry), then set its separators and locale code. Only left-to-right scripts are supported.

Please run cargo fmt and cargo test before opening a pull request.

Settings location

Settings and saved setups are stored in:

• macOS: ~/Library/Application Support/swarf
• Linux: ~/.local/share/swarf
• Windows: %APPDATA%\swarf\data

License

Swarf is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

Swarf is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. Cutting parameters are estimates: you are responsible for the safe operation of your machine.