Cutting Speed (Vc) Calculator for Threading

Optimize your machining processes with our online cutting parameters calculator. Select the operation type (turning, milling, drilling or threading) and instantly get the critical calculations for your shop: cutting speed (Vc), revolutions per minute (RPM), feed per revolution or per tooth, machining time and the theoretical roughness (Ra / Rz) based on the insert nose radius. To fine-tune those values live at the machine, use the interactive machining calculator.

Cutting calculator

Step 1

Which operation are you machining?

TurningRPM per part diameter and feed per revolution.MillingRPM per cutter diameter and feed per number of teeth.DrillingRPM per drill diameter and axial feed per turn.ThreadingRPM, synchronised feed, lead and time for tap, lathe threading or thread mill.

Paso 2

What do you want to calculate?

Cutting speed VcCalculate Vc from diameter and RPM.RPMCalculate revolutions from Vc and diameter.FeedWork out the programmable feed or its linear equivalent.Theoretical roughnessGuideEstimate Ra/Rz with feed and tip or edge radius.

Paso 3

Enter diameter and RPM

Diámetro rosca / piezaRPM (n)

Formula

Vc=π × D × n1000

Result

Vc calculada

0m/min

Where D is the diameter of the part or tool in millimeters (mm) and n is the revolutions per minute (RPM).

Material, power and warnings

Pick material and tool: that gives you the Vc and feed ranges, and also whether your machine can take the cut.

ToolingCut typeCondition

Do you want to adjust these values live?

Here you get the recommendation (Vc, feed, roughness, threading). In the interactive machining calculator you can move Vc, diameter, RPM and feed with linked scales, locks and time/power estimation.

Open interactive calculator →

Cutting speed in threading: formula, example and table

Vc = π × D × n / 1000

Vc is the cutting speed in m/min, D the thread diameter in mm and n the spindle speed in rpm. In threading the diameter that counts is the thread diameter.

Worked example: Medium-carbon steel C45 / 1045 in threading, Ø20 mm, Vc 95 m/min → n = 1000 × 95 / (π × 20) = 1512 rpm.

In threading Vc is much lower than in turning because the feed is the pitch and cannot be chosen. With a tap on a machine without rigid tapping, stay at the low end of the range: if the axis cannot follow the spindle at reversal, the tap breaks in the hole.

Speeds for coated carbide at mid Vc of the range; with HSS use about a third. Diameters typical for threading.
Material	Vc (m/min)	Roughing	Finishing	HSS tool	Pitch
Low-carbon steel S235 / St37	70–158	97	125	40	P
Medium-carbon steel C45 / 1045	63–126	80	104	33	P
Alloy steel 42CrMo4 / 4140	53–108	68	89	28	P
16MnCr5 carburizing steel	56–113	72	93	30	P
Austenitic stainless 304 / 1.4301	42–90	56	73	23	P
Austenitic stainless 316 / 1.4401	35–81	49	64	20	P
Martensitic stainless 420 / 1.4021	39–81	51	66	21	P
Gray cast iron GG25 / EN-GJL-250	53–113	71	91	29	P
GGG50/EN-GJS-500 nodular cast iron	46–99	62	80	25	P
Aluminum 6082 / AlMgSi1	140–450	251	325	103	P
Aluminum 7075 / AlZnMgCu	122–405	224	290	92	P
Brass CuZn39Pb3	70–225	125	162	52	P
Titanium Ti6Al4V	14–36	21	28	9	P
Inconel 718	7–23	13	17	5	P
Hardened steel 50-55 HRC	28–68	41	53	17	P

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