Private MachPro Planner Reference
2026-10-01 This is entirely AI generated, but based on my understanding of the planners, and with temporary access to the unreleased M31 setup doc - which matches the unreleased MachPro.
The draft M31 manual answers several of the questions that were unresolved in the previous outline. Most importantly, it confirms that PureMotion is not just a marketing label: MachPro exposes it as a selectable trajectory mode, PureMotion uses a configurable Jerk Time, and MachPro provides separate jerk-time settings for Feed, Rapid, and Jog motion. MachMotion Support
It also confirms several application principles that should become part of the reference guide: establish stable axis velocity and acceleration before changing planners; test coordinated motion after single-axis tuning; use air cutting only for initial settings; and use representative cutting to establish final Feed Velocity and Feed Acceleration. MachMotion Support
Below is the updated structure I would recommend.
Motion Planner Reference
1. Purpose and scope
A motion planner calculates the commanded trajectory and controls changes in velocity and acceleration.
MachPro provides two primary motion planners:
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Trapezoidal
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PureMotion
The motion planner affects how MachPro changes velocity and acceleration during machine motion. Planner selection can affect vibration, mechanical response, stable acceleration, and cycle time.
This reference explains:
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The function of each planner.
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The settings that affect planner behavior.
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How planner behavior interacts with axis motion limits.
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How to select a planner for an application.
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How to identify incorrect planner settings.
Confirmed from the M31 draft manual
MachPro selects the active planner with:
Configure > Control > Defaults > Trajectory Mode
The available selections are Trapezoidal and PureMotion. MachPro must be disabled before you change the setting. Test velocity and acceleration again after you change the planner.
Questions still to answer
| Question | Why it is required |
|---|---|
| Is planner selection a MachPro-wide setting or can a machine profile override it? | Define configuration scope. |
| Does the M31 execute the complete trajectory profile, or does MachPro calculate part of the trajectory before it sends commands to the M31? | Define software and controller responsibilities. |
| Do non-M31 motion controllers implement both planners identically? | Define whether this is a MachPro reference or an M31-specific reference. |
| Which MachPro versions support PureMotion? | Define applicability. |
| Does planner selection require only Apply/OK, or are there cases where MachPro or the M31 must restart? | Define when the change becomes active. |
2. Motion-planning concepts
2.1 Commanded trajectory
The commanded trajectory is the planned path and motion profile that MachPro uses to move the machine.
For coordinated motion, MachPro keeps the commanded axes synchronized. Each participating axis must remain within its configured motion limits.
An axis with a lower acceleration capability can limit the complete coordinated move. For example, if the X-axis can reliably use 500 units/s² and the Y-axis can use only 300 units/s², the Y-axis can limit an X-Y move. Increasing only the X-axis acceleration does not improve that move.
MachPro does not include an axis configured as Auxiliary in coordinated toolpath motion. An Auxiliary axis therefore does not limit the velocity or acceleration of coordinated toolpath moves.
Questions still to answer
| Question | Required information |
|---|---|
| How does MachPro calculate the allowable trajectory velocity and acceleration from individual axis limits? | Needed for the mathematical reference. |
| Does the planner use vector projection of trajectory acceleration onto each axis? | Needed for diagonal-move explanation. |
| How are rotary axes combined with linear axes? | Needed for 4-axis and 5-axis machines. |
| How are mixed linear/rotary feed rates interpreted? | Needed for coordinated rotary machining. |
| Are slave motors considered independently, or only through their parent axis limits? | Important for gantry machines. |
3. Feed, Rapid, and Jog motion
MachPro provides separate motion limits for three motion types:
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Feed: commanded machining motion.
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Rapid: non-cutting positioning motion.
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Jog: manual axis motion commanded by the operator.
Velocity is the maximum commanded axis speed. Acceleration controls how quickly the axis changes velocity.
The motor, drive, transmission, machine structure, axis load, and lubrication can limit both values.
Rapid and Jog moves do not have cutting load. Their final velocity and acceleration limits can therefore be different from the values that are reliable during cutting. For Rapid motion, high acceleration can have more effect than high maximum velocity on short moves. For Jog motion, predictable starts and stops are more important than maximum performance.
PureMotion also provides separate Jerk Time settings for Feed, Rapid, and Jog motion.
Questions still to answer
| Question | Required information |
|---|---|
| Are Feed, Rapid, and Jog Jerk Time values stored for each axis? | Define parameter scope. |
| Does a coordinated Feed move use each axis's individual Jerk Time? | Important for multi-axis synchronization. |
| Must Jerk Time values be matched between coordinated axes? | This should not be assumed. |
| Does Jog use the same PureMotion algorithm as programmed motion? | Define behavioral consistency. |
| Does Feed Hold use Feed, Rapid, or a separate deceleration profile? | Important operational behavior. |
4. Velocity and acceleration
4.1 Velocity
Velocity is the maximum commanded axis speed.
A move requires enough distance to reach the configured maximum velocity. A high velocity setting does not guarantee that a short move will reach that value.
4.2 Acceleration
Acceleration controls how quickly velocity changes.
Higher stable acceleration can reduce move time even when a short move never reaches maximum velocity. This is especially important for CAM toolpaths that contain many short moves.
The M31 setup procedure gives special attention to Feed Acceleration because short toolpath moves often do not have enough distance to reach maximum Feed Velocity. In these cases, increasing stable acceleration can reduce cycle time more than increasing maximum velocity.
4.3 Acceleration display
MachPro can display acceleration as:
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Units/s²
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Time (ms)
Units/s² shows the rate of velocity change.
Time (ms) shows the time associated with the configured acceleration portion of the displayed motion profile.
Changing the display format does not change the selected motion planner.
This distinction is important. Acceleration Time is not Jerk Time.
Questions still to answer
| Question | Required information |
|---|---|
| What exact relationship does MachPro use to calculate the Time (ms) acceleration display? | Needed for parameter-reference precision. |
| Is the displayed time based on zero-to-configured-velocity acceleration? | Likely, but must be confirmed. |
| Does the time display account for PureMotion Jerk Time? | Important because it could otherwise confuse users. |
| Are acceleration and deceleration always symmetrical? | Do not assume this. |
5. Jerk and Jerk Time
5.1 Jerk
Jerk is the rate of change of acceleration.
PureMotion uses Jerk Time to control how quickly acceleration changes.
Jerk Time is therefore not constant-velocity time and is not the same as the acceleration-time display.
5.2 Effect of Jerk Time
The Trapezoidal planner changes commanded acceleration immediately at an acceleration transition.
PureMotion can spread this change over the configured Jerk Time.
Increasing Jerk Time increases the time required to change acceleration. This smoother transition can reduce vibration, mechanical excitation, and other unwanted machine response.
In some applications, the reduction in mechanical excitation can permit a higher stable velocity or acceleration. The resulting cycle time can therefore decrease even though each individual acceleration transition takes more time.
A Jerk Time of 0 ms removes the PureMotion smoothing effect for that motion type.
5.3 Application
Configure Jerk Time only after velocity and acceleration are stable.
Use the lowest Jerk Time that gives the required result.
The current M31 setup procedure uses this sequence:
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Start with a low Jerk Time.
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Increase it in small increments only when necessary.
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Test machine vibration and mechanical response.
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Determine whether the change permits a higher stable acceleration.
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Check the effect on cycle time.
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Use the lowest value that gives the required result.
Questions still to answer
| Question | Required information |
|---|---|
| What is the permitted Jerk Time range? | Required for a parameter reference. |
| What are the factory defaults for Feed, Rapid, and Jog? | Required for setup and troubleshooting. |
| What increment or resolution does the setting support? | Required for precise tuning instructions. |
| Does PureMotion use constant jerk during the transition? | Fundamental mathematical definition. |
| Is the acceleration transition linear with time? | Determines whether PureMotion is a conventional S-curve. |
| Does PureMotion use the same Jerk Time for acceleration and deceleration? | Do not assume symmetry. |
| Does a 0 ms Jerk Time make PureMotion mathematically identical to Trapezoidal motion? | The manual only states that it removes the smoothing effect. |
| Are there internal minimum smoothing or controller filters that remain active at 0 ms? | Important before claiming equivalence. |
6. Trapezoidal planner
6.1 Function
The Trapezoidal planner changes commanded acceleration immediately at an acceleration transition.
For a sufficiently long move, a conventional trapezoidal velocity profile contains:
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Acceleration.
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Constant velocity.
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Deceleration.
For a short move, the machine can begin deceleration before it reaches maximum velocity. The velocity profile can therefore become triangular.
The important MachPro-specific characteristic is the abrupt commanded acceleration transition.
6.2 Application
Use the Trapezoidal planner when the machine remains stable at the required velocity and acceleration and smoother acceleration transitions do not improve the application.
The M31 draft manual states that if both planners provide stable motion at the required acceleration, planner selection is not an important tuning factor.
This statement is useful because it prevents PureMotion from being presented as an automatic upgrade or universally preferred planner.
6.3 Expected behavior
Because acceleration changes immediately at transition points, the Trapezoidal planner can produce a stronger transient mechanical response than PureMotion on machines that are sensitive to rapid changes in acceleration.
This does not mean that the Trapezoidal planner causes vibration on a mechanically sound machine.
Questions still to answer
| Question | Required information |
|---|---|
| Does MachPro's Trapezoidal planner use mathematically constant acceleration between transitions? | Confirm implementation. |
| Is any acceleration filtering applied by the M31 after the planner output? | Needed to describe actual commanded behavior. |
| Does the Trapezoidal planner have any internal jerk limiting that is not user-configurable? | Important for comparison with PureMotion. |
| Does it use the same path look-ahead and cornering algorithm as PureMotion? | Needed to isolate the difference between planners. |
7. PureMotion planner
7.1 Function
PureMotion smooths acceleration transitions by spreading the commanded acceleration change over the configured Jerk Time.
Use PureMotion when abrupt acceleration changes cause vibration or another unwanted machine response.
The purpose is not simply to make motion slower or softer. The useful result occurs when smoother acceleration transitions improve machine response or allow a higher stable acceleration.
7.2 Performance interaction
Additional Jerk Time can increase or decrease total cycle time.
A longer acceleration transition adds time locally. However, if the smoother response allows the machine to operate reliably at a higher acceleration or velocity, total cycle time can decrease. The complete machine must therefore be tuned as a system.
7.3 Motion types
MachPro has separate PureMotion Jerk Time values for:
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Feed
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Rapid
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Jog
A value of 0 ms removes PureMotion smoothing for the applicable motion type.
Questions still to answer
| Question | Required information |
|---|---|
| What mathematical motion profile does PureMotion use? | Still the largest missing technical definition. |
| Is PureMotion accurately described as an S-curve planner? | Do not use this term until engineering confirms it. |
| Does PureMotion alter only acceleration transitions, or also corner blending and velocity planning? | Critical distinction. |
| Does PureMotion use a different look-ahead algorithm? | Needed for short-segment and contour behavior. |
| Does PureMotion change geometric path tolerance? | Critical for accuracy documentation. |
| Does PureMotion behave differently on arcs than on line segments? | Needed for contouring reference. |
| Does it apply to synchronized spindle motion such as threading or tapping? | Special-motion applicability. |
| Does it apply to probing? | Probing stop behavior can require different handling. |
8. Planner comparison
| Characteristic | Trapezoidal | PureMotion |
|---|---|---|
| Available in MachPro | Yes | Yes |
| Selected in Trajectory Mode | Yes | Yes |
| Commanded acceleration transition | Immediate | Spread over Jerk Time |
| User-configurable Jerk Time | Not identified | Yes |
| Feed Jerk Time | Not applicable as PureMotion smoothing | Yes |
| Rapid Jerk Time | Not applicable as PureMotion smoothing | Yes |
| Jog Jerk Time | Not applicable as PureMotion smoothing | Yes |
| 0 ms behavior | Not applicable | Removes PureMotion smoothing for that motion type |
| Primary application | Stable motion without additional acceleration smoothing | Reduce unwanted response from abrupt acceleration changes |
| Can affect cycle time | Yes | Yes |
| Can permit higher stable acceleration | Machine dependent | Potentially, when smoothing reduces unwanted response |
| Requires velocity/acceleration tuning first | Yes | Yes |
Do not present either planner as universally better.
If both planners give stable motion at the required acceleration, planner selection is not an important tuning factor.
Questions still to answer
Add rows for:
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Look-ahead.
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Cornering algorithm.
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Path tolerance.
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Arc processing.
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Exact-stop behavior.
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Feed Hold behavior.
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Probing.
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Threading.
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Tapping.
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Synchronized motion.
These rows should remain incomplete until engineering confirms the implementation.
9. Coordinated motion
Configure and test each axis individually before you test coordinated motion.
During coordinated motion, MachPro keeps the commanded axes synchronized. An axis with a lower acceleration capability can limit the complete move.
After single-axis tuning, test:
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Long moves.
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Short moves.
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All directions of travel.
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Different positions in usable axis travel.
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Coordinated Feed motion.
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Direction changes.
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Representative Rapid motion.
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Representative Jog motion.
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Normal production materials and cutting conditions.
If coordinated motion is less stable than single-axis motion, identify the limiting axis or axis combination. The M31 draft currently instructs the user to decrease the applicable velocity, acceleration, or Jerk Time and test again.
Documentation issue to verify
The instruction to decrease Jerk Time when coordinated motion is unstable deserves engineering review.
Elsewhere, the same manual states that increasing Jerk Time smooths acceleration transitions and can reduce unwanted mechanical response.
Both statements can potentially be correct in different conditions, but the diagnostic logic is not obvious. The reference manual should state when an unstable condition calls for:
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Lower acceleration.
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More Jerk Time.
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Less Jerk Time.
Without that distinction, the troubleshooting instruction can appear contradictory.
Questions still to answer
| Question | Required information |
|---|---|
| Does coordinated PureMotion require equal Jerk Time on all participating axes? | Important and currently unanswered. |
| If axes have different Jerk Time values, how does the planner synchronize them? | Core coordinated-motion behavior. |
| Can one axis's Jerk Time limit the entire trajectory? | Similar to acceleration limiting. |
| How does MachPro report which axis limits a move? | Important diagnostic feature. |
| Under what conditions should Jerk Time be decreased instead of increased? | Required to resolve current draft ambiguity. |
10. Motor Units motion graph
The Motor Units graph shows the commanded motion profile.
Do not use this graph to predict actual move time.
The graph extends its displayed timeline as necessary to let the profile reach configured maximum velocity. A high velocity setting can therefore show a complete acceleration, constant-velocity, and deceleration profile even when a real machine move does not have enough distance to reach that velocity.
Use machine testing to determine:
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Whether a move reaches maximum velocity.
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Actual cycle time.
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Repeatable stability.
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Behavior under representative cutting load.
The current graph uses:
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Red lines for Rapid motion.
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Green lines for Feed motion.
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Vertical scale for axis velocity.
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Horizontal scale for move time.
The graphs are scaled for direct comparison.
Questions still to answer
| Question | Required information |
|---|---|
| Does the graph show the selected planner accurately for both Trapezoidal and PureMotion? | Important interpretation question. |
| Does it graph Jerk Time explicitly or only its effect on velocity? | Needed for user interpretation. |
| Can the graph display acceleration? | Useful for PureMotion explanation. |
| Can the graph show Jog motion? | Current note identifies Rapid and Feed only. |
| Does the graph calculate coordinated-axis motion or only individual-axis profiles? | Important scope limitation. |
11. Planner-selection workflow
Do not use planner selection to compensate for incorrect axis settings.
Use this sequence:
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Complete axis calibration.
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Establish stable axis velocity.
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Establish stable axis acceleration.
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Test velocity and acceleration together.
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Test the full usable axis travel.
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Establish initial Feed settings with unloaded motion.
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Verify final Feed Velocity and Feed Acceleration under representative cutting load.
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Select the applicable planner.
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If you use PureMotion, adjust Jerk Time only after velocity and acceleration are stable.
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Test coordinated motion.
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Verify part quality, vibration, machine stability, and cycle time.
The M31 draft recommends initially setting operating velocity and acceleration to 80% of the highest repeatable stable values found during testing.
That 80% value belongs primarily in the setup/how-to manual. In this reference guide, it should appear only as a cross-reference or application note, not as part of the planner definition.
12. Verification criteria
Planner tuning is complete when representative production motion is reliable and gives the required machining quality and cycle time.
Verify that the machine has no:
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Position errors.
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Drive faults.
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Loss of position.
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Excessive vibration.
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Mechanical instability.
For Feed motion, use test cuts to determine the final Feed Velocity and Feed Acceleration.
Do not use air cutting alone to determine final Feed settings. A machine can operate correctly without cutting load and fail when normal cutting forces are present.
Questions still to answer
| Question | Required information |
|---|---|
| What MachPro diagnostics should be monitored during planner testing? | Make testing repeatable. |
| Can MachPro display following error during a test? | Important for servo systems. |
| Can planner-limited velocity be distinguished from drive-limited velocity? | Important troubleshooting distinction. |
| Is there a standard MachMotion validation program for planner testing? | Would improve consistency. |
| What constitutes excessive vibration? | Qualitative guidance may be enough if no numeric specification exists. |
13. Path blending and exact-stop behavior
This section is still required, but the M31 draft manual does not provide enough information to complete it.
A planner reference must distinguish:
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Acceleration-profile selection.
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Path blending.
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Exact-stop behavior.
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Path-tolerance behavior.
Questions that must be answered
| Question | Required information |
|---|---|
| Which MachPro G-codes select exact-stop and continuous-path modes? | Reference the MachPro G-code manual. |
| Does PureMotion operate in both exact-stop and blended modes? | Important planner behavior. |
| Does planner selection change blend geometry? | Must separate smoothing from contouring. |
| How does path tolerance affect corner velocity? | Important for accuracy. |
| Can planner selection change contour error at the same path-tolerance setting? | Needs verification. |
| Does exact-stop mode use the selected acceleration profile when stopping? | Important distinction. |
14. Look-ahead and short-segment motion
The M31 draft confirms that short moves can be acceleration-limited and that higher stable Feed Acceleration can reduce cycle time even when maximum Feed Velocity is never reached.
This gives a strong reason to include a look-ahead section, but the draft does not define MachPro's look-ahead implementation.
Questions that must be answered
| Question | Required information |
|---|---|
| Does MachPro use look-ahead with both planners? | Fundamental behavior. |
| Is look-ahead identical between Trapezoidal and PureMotion? | Needed for comparison. |
| How deep is look-ahead? | Blocks, time, or path distance. |
| Is it configurable? | Parameter reference. |
| Which commands cause the planner queue to synchronize or empty? | Important for M-codes, probing, macros, and outputs. |
| How does Feed Hold affect queued motion? | Operational behavior. |
15. Parameter reference
Each motion-planner parameter should have a standardized reference entry.
Use these fields:
| Field | Required content |
|---|---|
| Setting name | Exact MachPro label |
| Menu location | Exact configuration path |
| Function | What the setting controls |
| Applies to | Trapezoidal, PureMotion, or both |
| Motion type | Feed, Rapid, Jog, or all |
| Scope | Axis, motor, or global |
| Units | Exact units |
| Default | Factory value |
| Minimum | Lowest permitted value |
| Maximum | Highest permitted value |
| Resolution | Smallest supported increment |
| Higher value | Expected result |
| Lower value | Expected result |
| Interaction | Related settings |
| Takes effect | When the new value becomes active |
| Incorrect setting symptoms | Observable machine behavior |
| Diagnostic action | What to check next |
At minimum, this reference should include:
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Trajectory Mode
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Feed Velocity
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Feed Acceleration
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Feed Jerk Time
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Rapid Velocity
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Rapid Acceleration
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Rapid Jerk Time
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Jog Velocity
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Jog Acceleration
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Jog Jerk Time
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Acceleration display mode
Missing values to collect
For each setting, collect:
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Default.
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Minimum.
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Maximum.
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Increment.
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Storage scope.
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Axis or motor ownership.
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Any controller-specific restrictions.
16. Troubleshooting
Vibration at acceleration transitions
Possible causes include:
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Acceleration is too high.
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Abrupt Trapezoidal acceleration transitions excite the machine structure.
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Mechanical looseness or wear.
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Poor lubrication.
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Drive or servo instability.
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Tooling or workholding problems during cutting.
Diagnostic sequence:
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Determine whether the vibration occurs without cutting.
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Verify the mechanical condition of the machine.
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Verify stable velocity and acceleration.
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If Trapezoidal motion is stable but mechanically harsh, test PureMotion.
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Increase PureMotion Jerk Time in small increments if additional smoothing is required.
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Test whether the new setting permits a higher stable acceleration.
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Verify the result under representative cutting load.
Programmed feed is not reached
Do not assume that Feed Velocity is too low.
Check:
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Move length.
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Feed Acceleration.
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Participating-axis limits.
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Direction changes.
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Path-planning constraints.
Short moves can end before the machine has sufficient distance to reach programmed Feed Velocity.
Cycle time increases with PureMotion
Additional Jerk Time increases the duration of acceleration transitions.
Determine whether the smoother motion permits a higher stable acceleration or velocity. Evaluate the complete machine cycle rather than an individual transition.
Questions still to answer
Add confirmed diagnostic guidance for:
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Rounded corners.
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Pauses between short segments.
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Feed Hold behavior.
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Following error during PureMotion acceleration.
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Unequal behavior between axes.
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Different behavior with 0 ms Jerk Time and Trapezoidal mode.
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Coordinated-motion instability that improves when Jerk Time is decreased.
17. Application notes
Mechanical condition
Do not use planner settings to hide a known mechanical defect.
Correct problems such as:
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Excessive backlash.
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Loose mechanical components.
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Worn bearings.
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Incorrect lubrication.
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Damaged drive components.
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Poor tooling or workholding.
Then optimize planner settings.
Cutting load
Cutting load changes machine response.
Use unloaded motion to establish initial settings. Then use representative test cuts to determine final Feed Velocity and Feed Acceleration.
Rapid and Jog motion do not have cutting load. These motion types can therefore use different velocity, acceleration, and Jerk Time settings from Feed motion.
Vibration and resonance
PureMotion can reduce unwanted machine response by smoothing acceleration transitions.
Do not describe Jerk Time as a vibration-frequency setting. It controls the time over which acceleration changes.
A machine can have several mechanical resonances. Machine stiffness, moving mass, mechanical wear, axis load, tooling, workholding, spindle operation, and cutting forces can all affect vibration.
Planner selection
Do not select PureMotion only because it is the newer planner.
Use it when its smoother acceleration transition gives a measurable benefit.
If Trapezoidal and PureMotion both give stable motion at the required acceleration, planner selection is not an important tuning factor.
What changed from the earlier outline
The M31 draft lets us convert several previous questions into documented statements. We can now state that PureMotion uses Jerk Time to spread acceleration transitions, that Jerk Time is measured in milliseconds, that Feed, Rapid, and Jog have separate Jerk Time settings, and that 0 ms removes the PureMotion smoothing effect for that motion type. We can also document the exact planner-selection path and the requirement to retest velocity and acceleration after changing planners. MachMotion Support
It also resolves the earlier concern about “acceleration time.” MachPro has an acceleration display that can show either units/s² or Time (ms), but changing that display does not change the planner. That is a separate concept from PureMotion Jerk Time and should be called out clearly in the reference. MachMotion Support
The most important engineering question that remains is still the mathematical definition of PureMotion. The current draft supports saying that PureMotion spreads an acceleration change over Jerk Time, but it does not establish whether the profile uses constant jerk, a conventional seven-segment S-curve, a polynomial transition, or another function. I would avoid calling it an “S-curve planner” until that is confirmed.
I would also flag one internal documentation issue for review before release: the final coordinated-motion section says to decrease velocity, acceleration, or Jerk Time when motion is unstable, while the preceding section says that increasing Jerk Time can reduce unwanted mechanical response. MachMotion Support That may reflect two different failure modes, but the manual needs to state the distinction explicitly.
For Diátaxis, I would now separate the material more firmly. The existing M31 page is primarily a How-to setup document. This proposed planner guide should be Reference, with the short Application notes retained where the user needs conceptual context to interpret a parameter. Procedures such as “find maximum stable acceleration,” the 80% operating-margin method, and progressive Jerk Time testing should remain in or link back to the M31 setup/how-to manual rather than being duplicated extensively in the planner reference.