Feed & Speed Calculator for Brass
Free-machining brass is about as easy as metal gets — the main thing to get right is matching feed to grade so the chip breaks instead of stringing.
Brass starting ranges
| Tool | Cutting speed (SFM) | Chip load, 1/2" 3-flute (in) |
|---|---|---|
| Carbide | 500–1000 | 0.004–0.008 |
| HSS | 150–300 | 0.003–0.006 |
Leaded, free-cutting grades (C360) run toward the top of these ranges; lead-free brass (C260 and similar) is noticeably gummier and should run toward the bottom.
Not all brass cuts the same way
Leaded free-cutting brass (C360) is specifically alloyed to produce short, clean chips and is genuinely one of the easiest materials to machine well — but environmental regulations have pushed lead-free brass grades into wider use, and those cut noticeably gummier, closer to copper's behavior. If a part's chips are stringing instead of breaking, check whether the stock is actually a lead-free grade before assuming the feeds and speeds are wrong.
Zero rake and positive rake tools behave differently here
Free-cutting brass is one of the few materials where a slightly negative or zero-rake tool geometry can actually cut cleaner than an aggressive positive rake, because the leaded chips shear more predictably under those conditions — this is the opposite of what works best in steel or aluminum, and it's worth knowing before assuming a "sharper is always better" tool will give the best finish.
Watch for chip stringing on lead-free grades
If chips are coming off long and stringy instead of breaking into short pieces, that's the clearest sign you're in a gummier lead-free grade — raising chip load (not speed) usually helps the chip break more cleanly, similar to the fix for copper.