Welding Inspector’s Stopwatch User Guide

Heat Input Stopwatch

User Guide

The Welding Inspector’s Stopwatch calculates:

  • Average Amperage
  • Average Voltage
  • Travel Speed (inches per minute)
  • Heat Input (kilojoules per inch)

The user defines:

  • Observed amps and volts while the stopwatch is running (meters not provided)
  • Measured weld length while the stopwatch is running and/or while it is paused

While this stopwatch is running, the user enters amperage and voltage by just adjusting the reels to match the values on the meters (meters not supplied). Every second, the amps and volts on the reel are used to calculate average amperes and average voltage. When weld length is known, the user adjusts the reel to show the length of the weld bead. Touching the Calculate button updates the calculated travel speed and heat input based on this formula:

The Reset button will usually be used after each weld pass.
Touching this button will:

  • Clear the average amps and volts
  • Clear the heat input
  • Clear the travel speed
  • Reset the reels to match the values defined in the settings page

Use the reset button to update the stopwatch after any amps, volts, or weld length reels settings are adjusted or if the factory defaults are applied.

Demonstration Video

Suggested Procedure

Here’s a suggested procedure and a quick video in how to best measure Heat Input using this tool:

  • Start with the settings page to get the Amps, Volts and Weld Length reels to match typical operating parameters
  • Open the stopwatch page; touch the Reset button
  • Start the timer when the weld starts
  • While the timer is running, watch amps and volts on your meters and adjust the reels as the amps and volts change
  • Calculate heat input and travel speed by either:
    • When the welder has finished, measure the length traveled and input that into the Weld Length reel. Touch the Calculate button to update the Heat Input and Travel Speed values.
    • Mark the base metal ahead of time with distance mark. When the arc passes these mark, update the weld length and hit calculate to get heat input and travel speed while the weld is in progress.


Reel Settings

Settings Pane

Customization for the amps, volts, and inches reels allow for specific needs of the Stopwatch interface to be met. Users may select increments and the range of each reel of the stopwatch. Any changes made must be committed by touching the Save Reels button. Touch the Reset button on the stopwatch to update the reels to reflect new increments and ranges.

The Settings page also contains an option to reset the reel parameters to a factory default state, and links to access the built-in Documentation page and the Setup Wizard.

Setup Wizard

Stopwatch Setup Wizard

Run the very first time the app is used, and on demand from the Settings pane, the Stopwatch Setup Wizard provides an easy mechanism for configuring the stopwatch amps and volts reels. The increment values used by the wizard are fixed at 5 amps and 1 volt; fine-tuning of the values picked may be done in the Settings pane.


Manual Calculator

Manual Calculator

Welding Inspector’s Stopwatch provides an interface for building a complete Heat Input equation through manual variable entry. Travel Speed and Heat Input results are calculated from the four variables provided when the Calculate button is pressed.

Press Done to dismiss the number pad from view.