Why are trial weights inside the allowance?

Soft-bearing balancing needs trial weights to locate unbalance before a correction is made. That work happens around the balancing rate, so it belongs in the allowance rather than the base hours.

What counts as a recheck spin?

A spin after a weight change that confirms the correction held. If the recheck finds remaining unbalance, the machine adds another correction and spin, which the allowance covers on average.

How do I set the balancing rate?

Time a run of the same rotor design on the machine you will use, then divide the rotor count by the hours it takes. Include setup spins but not trial weights or rechecks.

Should I balance every rotor in the run?

This page assumes the whole run goes through balancing. If a sampling plan checks only some rotors, enter the sampled count rather than the build quantity.

Motors, Generators & Electrification Equipment calculator

Rotor Balancing Time Calculator

Work out how long a balancing run takes from the rotor count, the rate one machine holds and a setup and recheck allowance. Base hours and allowance hours are reported apart so a scheduler can place them.

What this calculator does

Balancing hours for a rotor run from the rotor count, machine rate and setup and recheck allowance.

Formula used

Base balancing hours = rotors to balance ÷ balancing rate per machine
Setup and recheck hours = base balancing hours × allowance ÷ 100
Required balancing hours = base balancing hours + setup and recheck hours

Inputs explained

Rotors to Balance This Run: Rotors entering the balancing run, counted as whole units.
Balancing Rate per Machine: Rotors one balancing machine corrects per hour.
Setup and Recheck Allowance: Setup, trial weights and rechecks as a share of base time.

How to use the result

Best suited to planning a rotor balancing run, quoting trial-weight spins for a new design, comparing two balancing machines.
A design change, a bent shaft or a weld repair adds time outside the allowance. A rate from one balancing machine may not hold for another machine or sensor setup.

Current U.S. benchmarks

The producer price index for primary nonferrous metals (a broad metals benchmark, not copper alone) stands at 544.731 (BLS, Aug 2026), up 49.3% from a year earlier. Quotes priced off last quarter's material cost miss this move. Global copper trades at $13,543 per tonne (IMF via FRED, Jul 2026).
Steel mill PPI stands at 381.162 (BLS, Aug 2026), up 23.4% from a year earlier. New factory orders are up 8.5% year over year (Census).
The U.S. has 5,397 electrical equipment and appliances establishments employing about 369,437 workers (Census County Business Patterns, 2023).

Common questions

Why are trial weights inside the allowance? Soft-bearing balancing needs trial weights to locate unbalance before a correction is made. That work happens around the balancing rate, so it belongs in the allowance rather than the base hours.
What counts as a recheck spin? A spin after a weight change that confirms the correction held. If the recheck finds remaining unbalance, the machine adds another correction and spin, which the allowance covers on average.
How do I set the balancing rate? Time a run of the same rotor design on the machine you will use, then divide the rotor count by the hours it takes. Include setup spins but not trial weights or rechecks.
Should I balance every rotor in the run? This page assumes the whole run goes through balancing. If a sampling plan checks only some rotors, enter the sampled count rather than the build quantity.

Last reviewed 2026-10-01.