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Speeds and Feeds Calculator
Turn a cutting speed into spindle RPM for a drill, end mill or lathe part. Inch: RPM = 12 ร SFM รท (ฯ ร D). Metric: RPM = 1000 ร Vc รท (ฯ ร D). Table feed = RPM ร flutes ร chip load. Use the diameter of the cutter when milling or drilling, and of the work when turning. Start from your tooling maker's recommended speed and chip load.
Spindle speed:
Table feed:
Surface speed at that RPM: (SFM)
Worked examples
Inch: a 1/2โณ end mill at 100 SFM runs 12 ร 100 รท (ฯ ร 0.5) โ 764 RPM; with 4 flutes at 0.002โณ per tooth the feed is about 6.11 in/min. A 1โณ cutter at 100 SFM is about 382 RPM.
Metric: a 10 mm drill at 100 m/min runs 1000 ร 100 รท (ฯ ร 10) โ 3183 RPM; with 2 flutes at 0.1 mm per tooth the feed is about 637 mm/min.
After machining, check the size of a slot or step with a gage block stack.
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