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MachPro Pendant Jog Tuning and Troubleshooting

MPG Pendant Jog Tuning and Troubleshooting in MachPro (Mach4-based)

Scope

This document helps you tune an MPG (manual pulse generator) handwheel pendant in MachPro.
This document also helps you separate pendant tuning problems from hardware problems.
This document assumes inch units.
This document assumes the servo drives are tuned or are in auto-tune mode.

MachPro is based on Mach4.
Standard Mach4 systems often use plugins for hardware and features.
Your MachPro system incorporates MachMotion plugin features into the core for improved reliability.
This changes packaging and support.
It does not change the basic physics of jog motion.

Tutorial: Set up a safe, usable 1x / 10x / 100x feel

1) Prepare for testing

  1. Remove the cutting tool if possible.

  2. Clear the machine work area.

  3. Keep access to the E-stop (emergency stop).

  4. Select 1x on the pendant.

  5. Set a low MPG Max Jog Velocity % for the first test (example: 25%).

2) Confirm the pendant “click” matches the control

MPG Counts per Detent must match the pendant encoder.

  1. Set the 1x jog increment to a small value (example: 0.0001 in).

  2. Turn the handwheel exactly 10 detents, slowly.

  3. The axis must move 10 × the 1x increment (example: 0.0010 in).

If the axis moves the wrong distance, change MPG Counts per Detent.
If the axis moves when the wheel does not move, check for electrical noise first.

3) Set the jog increments (distance per detent)

Use these goals:

  • 1x is for fine positioning.

  • 10x is for normal setup moves.

  • 100x is for travel moves.

Typical inch increments:

  • 1x: 0.0001 in or 0.001 in

  • 10x: 0.001 in or 0.01 in

  • 100x: 0.01 in or 0.1 in

Use values that match your machine and your work.

4) Tune MPG acceleration per scale

MachPro exposes separate acceleration values for 1x, 10x, and 100x.
Many industrial controls do not expose this as a user setting.
They often use fixed internal profiles.

Tune in this order:

  1. Tune MPG Jog Increment X1 Acceleration first.

  2. Tune MPG Jog Increment X10 Acceleration second.

  3. Tune MPG Jog Increment X100 Acceleration last.

Procedure for each scale:

  1. Turn the wheel slowly for 1 to 2 seconds.

  2. Stop the wheel.

  3. Watch the stop behavior.

  4. Increase acceleration in small steps until the stop feels crisp.

  5. Decrease acceleration if you get vibration, noise, or faults.

5) Set the final max jog speed limit

Increase MPG Max Jog Velocity % until travel moves feel fast enough.
Do not set it higher than your safe manual control speed.
Lower the limit if the axis “runs on” after a fast spin.

How-to guide: Fix common MPG symptoms

Symptom A: The axis “coasts” after you stop turning

Causes can be different.
You must identify the cause before you tune.

Do this test:

  1. Select 1x.

  2. Turn 1 detent, slowly.

  3. Stop the wheel.

Results:

  • If motion stops at the correct distance but stops slowly, increase deceleration capability by increasing the relevant MPG Jog Increment X* Acceleration.

  • If motion continues past the expected distance, suspect extra pulses or queued pulses.

Actions to reduce run-on:

  1. Reduce MPG Max Jog Velocity %.

  2. Reduce the 100x jog increment value.

  3. Increase MPG Jog Increment X100 Acceleration in small steps.

  4. Keep 100x for travel only.

Symptom B: The axis moves the wrong distance per detent

This usually means the counts do not match.

Actions:

  1. Verify MPG Counts per Detent.

  2. Verify your inch jog increments for the pendant scale (1x, 10x, 100x).

  3. Repeat the “10 detent” test from the Tutorial.

Symptom C: The axis moves when the wheel is not moving

This usually means electrical noise or a bad connection.

Actions:

  1. Do not tune acceleration first.

  2. Inspect the MPG cable and connectors.

  3. Move the cable while the wheel is still.

  4. Watch for unexpected motion.

  5. Separate MPG wiring from motor power wiring.

  6. Verify shielding and grounding.

Symptom D: The axis lags behind fast handwheel turns

This happens when commanded speed changes faster than the axis can follow.

Actions:

  1. Increase the relevant MPG Jog Increment X* Acceleration.

  2. Reduce the jog increment value for that scale.

  3. Reduce MPG Max Jog Velocity % if needed.

Symptom E: The axis shakes at start or stop

This usually means the acceleration is too high for the mechanics.

Actions:

  1. Decrease the relevant MPG Jog Increment X* Acceleration.

  2. Reduce the jog increment value for that scale.

  3. Check for loose couplings and mechanical play.

Reference: MachPro MPG and jog settings

Terms

  • MPG (manual pulse generator): A handwheel that sends pulses to command jog motion.

  • Pulse: One electrical count from the MPG encoder.

  • Detent: One mechanical click of the handwheel.

  • Jog: Manual axis movement.

  • Acceleration: The rate of increase of speed.

  • Deceleration: The rate of decrease of speed.

  • Velocity: Axis speed.

  • Following error: The position difference between commanded position and actual position in a servo system.

  • Backlash: Free motion caused by clearance in screws, gears, or couplings.

  • Stick-slip: Motion that alternates between sticking and slipping due to friction.

  • Electrical noise: Unwanted signals that look like pulses.

MPG parameter descriptions (from your MPG screen)

  • MPG Jog Increment X1 Acceleration
    Sets MPG jog acceleration when the pendant is at 1x.

  • MPG Jog Increment X10 Acceleration
    Sets MPG jog acceleration when the pendant is at 10x.

  • MPG Jog Increment X100 Acceleration
    Sets MPG jog acceleration when the pendant is at 100x.

  • MPG Max Jog Velocity %
    Sets the maximum MPG jog speed as a percent limit.

  • MPG Counts per Detent
    Sets how many pulses equal one detent.

Jog increment tables (pendant and on-screen)

MachPro can use different jog increment tables for:

  • the pendant

  • the on-screen jog buttons

Do not assume they match.
Verify both tables if behavior differs between pendant jog and on-screen jog.

Typical starting point for inch systems

Use these as a starting point only.
Machine size and axis load can require different values.

  • 1x: 0.0001 in or 0.001 in per detent

  • 10x: 0.001 in or 0.01 in per detent

  • 100x: 0.01 in or 0.1 in per detent

  • MPG Max Jog Velocity %: start at 25%, then increase

  • MPG Counts per Detent: set to the pendant specification

Explanation: What causes MPG “coasting” and how to isolate hardware issues

Why “all pulses complete” can still feel like coasting

An MPG produces pulses as you turn the wheel.
The controller must process those pulses.
The controller also limits acceleration and speed.
The controller cannot stop instantly at high speed.

Two common MPG behaviors exist in CNC systems:

  1. Increment (distance) mode
    Each pulse (or detent) commands a small distance move.
    Fast wheel spins can queue many distance moves.
    The axis can keep moving after you stop because the queue is not empty.
    This feels like “run-on.”

  2. Velocity (rate) mode
    Wheel speed commands jog speed.
    When you stop the wheel, the commanded speed goes to zero.
    The axis decelerates based on limits.
    This usually feels more direct.

Your tuning steps work for either behavior.
The tests help you identify which effect dominates.

How to separate tuning issues from hardware issues

Use this isolation sequence.
Do the steps in order.

  1. Compare pendant jog to on-screen jog
    If both have the same problem, suspect axis limits or mechanics.
    If only the pendant has the problem, suspect MPG input or MPG settings.

  2. Check for unexpected motion at standstill
    If the axis moves with a still wheel, suspect noise or wiring.
    Do not increase acceleration to “hide” this symptom.

  3. Test slow single-detent moves
    If single detents behave wrong, suspect MPG Counts per Detent or noise.
    If single detents behave right, suspect backlog at high speed.

  4. Test direction reversal
    Jog +0.0100 in, then jog −0.0100 in at 1x.
    Repeat three times.
    If results differ by direction, suspect backlash or binding.

  5. Watch for servo or drive faults
    Faults under MPG jog often mean the commanded accel or speed is too high.
    Faults can also mean a mechanical load problem.

Other machine options that can affect MPG feel

These options are not pendant settings.
They can change jog behavior.

  • Axis-level acceleration and deceleration limits
    These can limit how fast any jog can start or stop.

  • Jog speed limits separate from feed limits
    Some systems apply separate caps for jog motion.

  • Input filtering or debounce for encoder signals
    Filtering can remove false pulses.
    Too much filtering can add lag.

  • Mechanical condition
    Backlash, loose couplings, and stiction change the feel of MPG jog.

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