Feeds and Speeds Calculator

This turns a cutting speed and a chip load into a spindle speed and a feed rate, for milling, turning or drilling. Enter the cutter diameter, the number of flutes and the figures off your tooling data sheet, and it returns the RPM, the feed rate, the chip thinning correction for a light stepover and the metal removal rate. The drilling form adds the length of the drill point to the hole depth and gives the chip load per lip, the peck count and the time in the cut. Another form works backwards from a speed and feed already in the program. The formulas are settled but the cutting speed and chip load are not, so take both from the maker of that exact cutter in that exact material.

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Cutting speed and chip load come from your tooling data sheet. Everything else follows from them.

Surface feet per minute, or metres per minute when metric is selected. From the tooling maker for that cutter in that material. Rough published starting points for an uncoated carbide end mill: aluminium 500 to 1000, mild steel 250 to 400, stainless 150 to 250, cast iron 200 to 350, titanium 80 to 150, hard steel 100 to 200. HSS runs at roughly a third of those. In metres per minute those are aluminium 150 to 300, mild steel 75 to 120, stainless 45 to 75, cast iron 60 to 105, titanium 25 to 45, hard steel 30 to 60.
Inches per tooth, or millimetres per tooth when metric is selected. Per tooth, from the tooling maker. Rough published starting points for carbide at full diameter: 1/8 in cutter 0.0005 to 0.001 in, 1/4 in 0.001 to 0.002 in, 1/2 in 0.002 to 0.004 in, 3/4 in 0.003 to 0.006 in. In millimetres: 3 mm cutter 0.013 to 0.025 mm, 6 mm 0.025 to 0.05 mm, 12 mm 0.05 to 0.1 mm, 20 mm 0.075 to 0.15 mm. Softer material takes the top of the range, harder the bottom.
The stepover, in inches or in millimetres when metric is selected. Fill it in and the chip thinning correction is applied when it is under half the cutter diameter.
How deep the cutter is buried, in inches. Only used for the metal removal rate.
Leave it blank unless the speed you need is above what your spindle will do. Revolutions per minute is the same number in either system.
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Units

Same speed formula on the workpiece diameter, with the feed in inches per revolution the way a lathe takes it.

Surface feet per minute, or metres per minute when metric is selected. From the tooling maker for that cutter in that material. Rough published starting points for an uncoated carbide end mill: aluminium 500 to 1000, mild steel 250 to 400, stainless 150 to 250, cast iron 200 to 350, titanium 80 to 150, hard steel 100 to 200. HSS runs at roughly a third of those. In metres per minute those are aluminium 150 to 300, mild steel 75 to 120, stainless 45 to 75, cast iron 60 to 105, titanium 25 to 45, hard steel 30 to 60.
The diameter being cut, in inches or in millimetres when metric is selected. It drops as you face or turn down, so the speed should rise to match unless the lathe has constant surface speed.
Inches per revolution, or millimetres per revolution when metric is selected. From the insert maker. Roughing often 0.008 to 0.020 in (0.2 to 0.5 mm), finishing 0.002 to 0.006 in (0.05 to 0.15 mm), and never more than about half the insert nose radius if you want the finish.
How far the tool travels along the work, in inches. Fill it in to get the cutting time.
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Units

Same speed formula on the drill diameter, with the feed in inches per revolution the way a drill is specified, plus the point length that decides how far the spindle actually has to travel.

Surface feet per minute, or metres per minute when metric is selected. From the drill maker for that drill in that material. Rough published starting points for an uncoated HSS twist drill: aluminium 200 to 300, mild steel 80 to 100, stainless 40 to 60, cast iron 60 to 80. In metres per minute those are aluminium 60 to 90, mild steel 25 to 30, stainless 12 to 18, cast iron 18 to 25. Carbide runs at roughly three times those.
Inches per revolution, or millimetres per revolution when metric is selected. A drill is fed per revolution, not per tooth. Rough published starting points in steel: 1/8 in drill 0.002 to 0.003 in, 1/4 in 0.004 to 0.005 in, 1/2 in 0.006 to 0.008 in, 1 in 0.010 to 0.015 in. In millimetres: 3 mm drill 0.05 to 0.08 mm, 6 mm 0.10 to 0.13 mm, 12 mm 0.15 to 0.20 mm, 25 mm 0.25 to 0.38 mm.
An angle is the same number in either unit system.
Inches. The next box says what that figure is measured to.
For a through hole and for a blind hole dimensioned at the full diameter, the point has to travel past the figure you typed. Measured to the tip, it does not.
Inches. Leave it blank to drill in one go. A common starting rule is one diameter per peck once the hole is past about three diameters deep.
Revolutions per minute is the same number in either system.
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Units

The other direction. Put in the speed and feed already in the program and this says what cutting speed and chip load they work out to.

Revolutions per minute is the same number in either system.
Inches per minute, or millimetres per minute when metric is selected.
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