A lead-screw feed moves a guided carriage by a fixed distance for each screw revolution. Enter screw speed and lead to calculate carriage speed, advance per turn and time per revolution. The animation shows the rotary-to-linear motion; cutting conditions and motor sizing require separate calculations.
Feed Motion Interactive Calculator
Vary lead screw speed and screw lead to see the resulting linear feed rate and animated carriage motion.
Equation Used
The feed rate is the screw rotational speed multiplied by the screw lead. A 5 mm/rev lead screw turning at 60 rpm advances the carriage at 300 mm/min.
- Continuous feed motion.
- Motor RPM equals lead screw RPM.
- Ideal screw with no slip, backlash, or gearbox ratio.
How screw feed moves the carriage
The screw rotates while its nut is restrained from rotating. The nut and carriage therefore move along the screw. Guideways carry the carriage and keep its motion aligned; bearings locate the screw and react the axial load.
Screw lead is the axial distance travelled in one full revolution. It equals pitch for a single-start thread, while a multiple-start thread advances by several pitches per turn. Enter lead rather than the distance between adjacent thread crests.
This example uses continuous screw rotation. Intermittent feed mechanisms use a separate timing or indexing arrangement; they cannot be described from screw speed and lead alone.
Using the feed calculation
The calculation applies to a screw-driven positioning slide or carriage once the screw speed and lead are known. If a gearbox lies between the motor and screw, convert motor speed to screw speed before entering it.
In machining, cutting feed per spindle revolution is a different quantity from screw lead. The spindle and feed screw may rotate at different speeds. This calculator does not determine chip load, tool life, surface finish or a suitable cutting feed.
Feed speed and travel per revolution
For screw speed N in revolutions per minute and lead L in millimetres per revolution, carriage speed is v = NL in millimetres per minute. Divide by 60 for millimetres per second.
Advance per revolution is L. At nonzero speed, the time for one revolution is 60/N seconds. The tool assumes a directly driven screw with no backlash or elastic deflection.
Example: a 5 mm lead screw
At 60 rpm with a lead of 5 mm per revolution, feed speed is 60 × 5 = 300 mm/min, or 5 mm/s. Each turn advances the carriage by 5 mm and takes 1 second.
At 120 rpm with the same lead, feed speed doubles to 600 mm/min or 10 mm/s, and one turn takes 0.5 seconds. Advance per turn stays at 5 mm.
These are ideal travel rates. They do not check whether the motor can accelerate or sustain the load, or whether the screw is below its permitted rotational speed.
Choosing lead and checking the assembly
A larger lead gives more travel at the same screw speed. It also changes the torque required for a given axial force and the displacement represented by each motor step or encoder count. Neither drive torque nor positioning resolution is calculated here.
Real travel can differ from the command because of backlash, compliance, lead error or drive-position error. Measure carriage travel directly when checking an assembly. A speed discrepancy alone does not identify which component needs adjustment.
Frequently asked questions
Which speed should I enter?
Enter screw rpm. Motor rpm is the same only with a direct 1:1 drive. A gearbox or belt ratio must be applied first.
Is screw lead the same as cutting feed per revolution?
No. Lead is carriage travel per screw revolution. Cutting feed per revolution refers to the work spindle, which may turn at a different speed.
Why does doubling speed leave Advance / Rev unchanged?
Advance per revolution is set by screw lead. Doubling rpm doubles travel per minute and halves the time for each turn.
Does this calculate motor torque or cutting force?
No. The inputs describe ideal motion only. Axial force, friction, efficiency, acceleration and drive ratings require separate checks.
Does the animation specify the travel limits?
No. The repeating carriage motion illustrates screw feed. End stops, usable stroke and reversal control must come from the actual machine.
References
Building or designing a mechanism like this?
Explore the precision-engineered motion control hardware used by mechanical engineers, makers, and product designers.
