Private MachPro Planner Reference
1 Introduction
1.1 Purpose and scope
A motion planner calculates the commanded trajectory and controls changes in velocity and acceleration. This reference covers Trapezoidal, PureMotion, and the confirmed selection command for Tangential Knife.
This reference follows the relevant M31 setup topics: axis configuration, motor motion settings, final machine testing, advanced behavior, parameter reference, troubleshooting, and application notes. Wiring and installation procedures remain in the setup manual.
M31 Motion Control Setup Manual: Open Document
==Confirm the supported MachPro build. The source draft identifies the release planned for 15 October 2026 and later; a minimum build number is not supplied.==
2 Axis Configuration
2.1 Identity and calibration
An Auxiliary axis performs a machine function outside coordinated toolpath motion, such as an automatic tool changer. It does not limit coordinated toolpath velocity or acceleration.
Axis calibration establishes units and initial motion values. Those values are starting points, not verified operating limits for the installed machine.
Axis type and calibration setup: Open Document
2.2 Motion Limits
The axis Motion Limits tab is read-only. It lists every motor assigned to the axis, including master and slave motors, followed by Effective (minimum) values that control the axis motion. The supplied screen shows separate Feed and Rapid columns.
| Displayed value | Units |
|---|---|
| Velocity | units/min |
| Acceleration, 2nd order | units/s² |
| Acceleration, 3rd order | units/s² |
| Jerk Time | ms |
The 3rd-order acceleration readout is a rate representation of PureMotion acceleration; its actual configuration value remains Constant Acceleration Time.
In the supplied example, M7 limits Feed velocity to 250 units/min and both acceleration-rate readouts to 19 units/s². Effective Rapid velocity is 300 units/min. Effective Feed and Rapid Jerk Time readouts are 0 ms. These are example settings, not defaults.
Compare each motor with the effective values to identify which settings constrain that axis. Different motors can supply different minimum values. ==Confirm how an effective Jerk Time of 0 ms affects PureMotion when another motor on the axis has a nonzero Jerk Time.==
During coordinated motion, MachPro synchronizes the participating axes. Their applicable motor limits can constrain the complete move; Auxiliary axes are excluded. Use this tab to identify configured limits for an individual axis.
Coordinated-motion tests: Open Document
3 Motor Configuration
3.1 Units
Before you start
Calibration sets Units. Incorrect displayed units require a calibration correction. Motors, drives, transmissions, structure, load, lubrication, and mechanical condition determine practical motion limits.
MachPro provides separate limits for:
| Motion type | Function |
|---|---|
| Feed | Commanded machining motion |
| Rapid | Non-cutting positioning |
| Jog | Operator-commanded manual motion |
Velocity and acceleration
Velocity is the maximum commanded axis speed. A move needs sufficient distance to reach it; a high setting does not guarantee that a short move reaches maximum velocity.
Acceleration Entry switches between Units/s² and Time (ms). It changes the displayed and entered representation, not the selected planner.
The actual acceleration settings are defined in the planner comparison. Velocity and acceleration must operate reliably together.
Single-axis tuning and operating margins: Open Document
Coordinated Feed motion
Higher stable acceleration reduces move time for both long and short moves. Short moves can remain below target velocity and still finish sooner with higher acceleration. Feed acceleration can therefore affect cycle time more than maximum Feed Velocity.
For PureMotion, a shorter stable Constant Acceleration Time increases acceleration for the applicable velocity change. Do not lower Feed Velocity solely because short moves do not reach it.
Participating-motor constraints are described in Motion Limits. For tests, use the setup link there.
Rapid and Jog motion
Rapid and Jog have no cutting load, so their reliable limits can differ from Feed limits. Higher Rapid velocity is most useful with sufficient travel; short positioning moves can be acceleration-limited. Jog settings must retain predictable starts, stops, and manual control.
Configuration procedures: Open Document
Motor Units motion graph
The graph shows the commanded profile. It extends the displayed timeline to reach configured maximum velocity, even when an actual move is too short to reach that velocity. It does not predict the time of a specified machine move.
Trapezoidal shows the acceleration-rate profile. PureMotion includes both jerk transitions and its constant-acceleration portion; see PureMotion Jerk Time.
The setup comparison graphics use red for Rapid, green for Feed, velocity vertically, and time horizontally. Matching scales permit direct comparison. Actual speed, move time, and reliability require machine tests; see Final machine test.
Select the motion planner
Trajectory Mode is located at Configure > Control > Defaults. It selects Trapezoidal or PureMotion.
The following G-codes select planners modally: the selection applies to subsequent motion, rather than only the command block.
| Planner | Modal selection | Configuration tab |
|---|---|---|
| PureMotion | G38.1 | PureMotion G38.1 |
| Trapezoidal | G38.2 | Trapezoid G38.2/Tangential G38.3 |
| Tangential Knife | G38.3 | Trapezoid G38.2/Tangential G38.3 |
These commands select a planner. The supplied configuration tabs are described in Path blending and exact stop.
| Characteristic | Trapezoidal | PureMotion |
|---|---|---|
| Planner order | 2nd Order | 3rd Order S-curve |
| Actual acceleration setting | Acceleration rate, units/s² | Constant Acceleration Time, ms |
| Alternate display | Corresponding Time (ms) | Corresponding Units/s² |
| Acceleration transitions | Direct changes between zero and the configured rate | Gradual transitions controlled by Jerk Time |
| Jerk Time | Not used | Separate Feed, Rapid, and Jog settings |
| Acceleration/deceleration | Same setting | Same settings, reversed profile |
| Typical application | Required performance when precise CV path control is unnecessary | Precision applications, or smoother transitions that improve machine response |
For a long Trapezoidal move, the velocity profile has acceleration, constant velocity, and deceleration. A shorter move can have a triangular profile because deceleration starts before maximum velocity is reached.
PureMotion can reduce excitation caused by abrupt acceleration transitions. Use path-control requirements as well as machine response to select the planner. If both meet the application requirements, planner selection is not a primary tuning factor.
Planner selection and retesting: Open Document
PureMotion Jerk Time
Jerk is the rate of change of acceleration. Jerk Time controls the transitions into and out of constant acceleration and deceleration. Constant Acceleration Time specifies the constant-acceleration portion.
The complete acceleration profile is:
Jerk transition → Constant Acceleration Time → Jerk transition
Total acceleration time = Constant Acceleration Time + (2 × Jerk Time)
For example, 250 ms of Constant Acceleration Time and 25 ms of Jerk Time give 300 ms total. Deceleration uses the reversed profile, with no separate acceleration/deceleration settings.
A shorter Constant Acceleration Time produces a higher acceleration rate for the applicable velocity change. A longer value produces a lower rate. Increasing Jerk Time makes transitions more gradual; 0 ms removes smoothing for that motion type.
PureMotion does not directly tune a vibration frequency. Jerk Time changes acceleration transitions that can excite vibration. Constant Acceleration Time affects acceleration rate, which can also excite mechanical resonance.
Longer transitions can increase move time. If smoothing permits higher stable velocity or acceleration, overall cycle time can decrease. Evaluate the complete machine cycle.
The M31 setup manual gives 10 ms as an initial tuning value and describes 50 ms as high. These are tuning guidance, not a factory default or a permitted maximum.
Jerk-time tuning: Open Document
Copy settings to other motors
Copied values are starting points unless equivalent operating limits have been verified. The copy-control procedure is in Motor Units setup: Open Document
3.2 Final machine test
Accept settings when representative production motion meets position accuracy, drive stability, machining quality, and cycle-time requirements without position loss, faults, excessive vibration, or mechanical instability.
Air cutting establishes initial settings; representative cutting establishes final Feed limits. Machine response can change with travel position, direction, axis combination, tooling, workholding, and load. Significant changes require renewed verification.
Final testing and limiting-axis diagnosis: Open Document
4 Advanced Options and Information
4.1 Path blending and exact stop
Acceleration smoothing controls changes in acceleration. Path smoothing permits deviation from the commanded path. These settings serve different purposes; see PureMotion Jerk Time for acceleration smoothing.
The supplied configuration screens confirm the controls below. Displayed values are current settings, not verified factory defaults or limits.
PureMotion path tolerance
| Control | Function |
|---|---|
| Error Tolerance (units) | Maximum deviation between the commanded path and the smoothed path the planner executes |
| Arc Error Tolerance (units) | Tighter tolerance used for qualifying arcs |
| Min Sweep Threshold (deg) | Minimum total arc sweep that qualifies for the tighter arc tolerance; equality qualifies |
| Angle-Error Interpolation | Corner-angle/tolerance table; each knot is a specified angle and tolerance pair |
Angle-Error Interpolation permits tighter tolerances for sharp corners and looser tolerances for gentle corners. The screen describes larger angles as sharper corners. An empty table, or an angle below the smallest knot, uses the global Error Tolerance. + Add knot and Remove manage the table entries.
Choose tolerances from the permitted machining deviation, then verify the resulting path and machining quality. ==Confirm interpolation between knots, behavior above the largest knot, and interaction between corner and arc tolerances.==
Trapezoidal CV Angle Mode
Trapezoidal CV is not a precise path-control tool. Its preset Path error tolerance is an input to the feedrate calculation, not a guarantee of actual path accuracy. Use PureMotion when precision is required; its path-tolerance controls are described above.
CV means constant velocity. The Trapezoid G38.2/Tangential G38.3 tab contains CV Angle Mode, with Enable and Disable controls. Its table pairs Angle (deg) with Feedrate (u/min), where u/min means configured units per minute. The CV feedrate vs angle graph plots those entries.
Preset MachMotion CV formula fills every row from a single Path error tolerance, the included axes, and the slowest enabled motor. The screen identifies tolerance as units per profile. Its displayed formula uses the smallest motor acceleration and clamps the result to the slowest motor's maximum velocity. Include axes selects X, Y, Z, A, B, and C; Compute & Fill populates the table.
CV tolerance example
The supplied graphs use CV Angle Mode enabled, X/Y/Z included, and a maximum feedrate of 300 u/min. Reducing Path error tolerance from 0.001 to 0.0001 units produces lower table feedrates at the same angle:
| Angle (deg) | Feedrate at 0.001 tolerance (u/min) | Feedrate at 0.0001 tolerance (u/min) |
|---|---|---|
| 2 | 300.0000 | 217.4084 |
| 10 | 137.2915 | 43.4154 |
| 30 | 45.1778 | 14.2865 |
The 0.001 example reaches the 300 u/min cap at 0–4°; the 0.0001 example reaches it at 0–1°. Tighter tolerance reduces the generated corner feedrates while retaining the same maximum. These are configuration examples, not defaults or measured machine results. Verify machining accuracy and cycle time using the Final machine test.
==Confirm whether table feedrates are corner-speed limits or commanded speeds; the meaning of zero entries; angle convention and interpolation; behavior with CV Angle Mode disabled; and whether these controls apply identically to Tangential G38.3. Confirm the preset's handling of endpoint angles and mixed linear/rotary axes.==
Trapezoidal exact stop and constant velocity
The MachPro G-Code and M-Code Reference applies to the Trapezoidal planner: Open Document
| Command | Scope | Function |
|---|---|---|
| G09 | Non-modal; current movement block only | Decelerates to the endpoint and stops before the next block |
| G61 | Modal; remains active until G64 | Stops at the end of each commanded move |
| G64 | Modal; remains active until G61 | Constant velocity mode; attempts to maintain feedrate through direction changes |
Exact stop retains commanded corners but repeated stops can increase cycle time and leave witness marks. G64 permits corner rounding; deviation depends on feedrate and machine acceleration. See Trapezoidal CV Angle Mode for its configuration and precision limitations.
==Confirm G09/G61/G64 behavior with PureMotion and whether exact stops use the selected acceleration profile.==
PureMotion runtime parameter changes
Additional G-codes can change PureMotion parameter values while a G-code file runs. These commands are not yet published. G38.1 selects PureMotion; it is distinct from these parameter-change commands.
==Add the runtime command numbers, syntax, affected parameters, units, permitted ranges, and persistence when their specifications are available.==
4.2 Look-ahead and special motion
Short-move acceleration behavior is described in Coordinated Feed motion. It does not establish MachPro's look-ahead depth or queue behavior, or the selected planner's behavior during probing, threading, tapping, and synchronized spindle motion. These remain unresolved.
5 Reference Information
5.1 Parameter locations and definitions
| Setting | Location or owner | Definition |
|---|---|---|
| Trajectory Mode | Configure > Control > Defaults | Planner selection |
| Units | Axis calibration; displayed in Motor Units | Axis calibration |
| Feed, Rapid, Jog Velocity | Motor Units | Velocity and motion types |
| Acceleration Entry | Motor Units | Display/entry representation |
| Trapezoidal acceleration | Motor Units, by motion type | Planner comparison |
| PureMotion Constant Acceleration Time | Motor Units, by motion type | PureMotion profile |
| Feed, Rapid, Jog Jerk Time | Motor Units | PureMotion Jerk Time |
| Effective axis limits | Axis Motion Limits, read-only | Motion Limits |
| PureMotion path tolerances | PureMotion G38.1 tab | PureMotion path tolerance |
| Trapezoidal G09/G61/G64 | G-code program | Exact stop and constant velocity |
| PureMotion runtime parameter commands | G-code program; unpublished | Runtime parameter changes |
| Motion diagnostic displays | Diagnostic > M31 | M31 motion diagnostics |
| CV Angle Mode and angle/feedrate table | Trapezoid G38.2/Tangential G38.3 tab | Trapezoidal CV Angle Mode |
==Collect factory defaults, permitted ranges, increments, storage scope, controller restrictions, and when each parameter change takes effect. The tuning values above do not supply these specifications.==
5.2 M31 motion diagnostics
Open Diagnostic > M31 to view the M31 Status window supplied with the M31 software.
| Display or control | Information available |
|---|---|
| Encoder, Feedback, StepGen, Command Pos, Following Error | Indexed position and error displays; Command Pos is commanded position, and Following Error indicates the difference between commanded and feedback position |
| Properties | M31 plug-in version, Target Mach Build, device connection status, transmit/receive frequencies, and configuration polling rate |
| Buffer Transfer Size, Ethernet Compression, GCode Message Cntr, FIFO MilliSec Vectors, Buffer Fill Level | Communication and queued-motion indicators; FIFO means first in, first out |
| Inputs, Outputs, Analog Input (mV) | Digital signal indicators and the selected analog channel in millivolts |
| Motion Planner, EtherCAT Status | Buttons for the corresponding diagnostic views |
The window also has an axis selector and Clear Position control. Output indicators are interactive: the screen states that clicking an output LED activates it. They are not display-only indicators.
Use the position and following-error displays when investigating motion errors, and communication/buffer indicators when investigating interrupted motion. The supplied screenshot shows Device Offline; use connected-machine readings for diagnosis.
==Confirm display units, index-to-motor mapping, Following Error sign/source, communication/buffer thresholds, and Clear Position behavior. Obtain the Motion Planner view to identify any limiting-axis diagnostics.==
5.3 Unresolved questions
| Topic | Information to confirm |
|---|---|
| Software/controller responsibility | ==Which trajectory calculations run in MachPro and which run in the M31? Confirm equivalent behavior on supported non-M31 controllers.== |
| Planner scope and switching | ==G38.1, G38.2, and G38.3 are confirmed in Planner selection. Confirm profile/global scope, cancellation, reset/startup persistence, interaction with Trajectory Mode, and whether configuration changes require a restart. Confirm Tangential Knife operation and its additional settings.== |
| Coordinated geometry | ==Confirm mixed linear/rotary feed interpretation and effective-limit calculation. Add projection mathematics only if needed to explain configuration or diagnosis.== |
| PureMotion profile | ==Confirm constant jerk during transitions and how short moves truncate or scale the configured time periods.== |
| Jog and stopping | ==Confirm Jog profile behavior and the deceleration/queue behavior used for Feed Hold, Cycle Stop, and E-Stop.== |
| Path control | See Path blending and exact stop for confirmed controls and remaining questions. |
| Look-ahead | ==Confirm support with both planners, algorithm differences, depth, configurability, and commands that synchronize or empty the queue.== |
| Special motion | ==Arc-tolerance controls are described in PureMotion path tolerance. Confirm remaining arc behavior and planner behavior during probing, threading, tapping, and synchronized motion.== |
| Filtering | ==Confirm whether filtering modifies the final Trapezoidal output.== |
| Graph scope | ==Confirm Jog display and whether the graph represents individual or coordinated axes.== |
| Diagnostics | See M31 motion diagnostics for confirmed displays and remaining questions. ==Confirm how to distinguish planner limits from drive limits.== |
| Validation | ==Confirm a standard test program, acceptance criteria for vibration, and guidance for rounded corners, segment pauses, and unequal axis response.== |
| Setup consistency | ==The M31 overview states 80% operating values and 20% margin; its detailed procedures state 80–90% and 10–20%. Confirm the intended guidance and how the acceleration margin is converted to PureMotion time.== |
| Published links | ==Confirm that the published M31 page contains the working manual's HTML anchor IDs. The private page was unavailable for verification.== |
6 Troubleshooting
6.1 Vibration or oscillation
Vibration can indicate excessive motion demand, abrupt transitions, mechanical defects, resonance, drive instability, or cutting-condition problems. Definitions and physical effects are in Mechanical response.
PureMotion addresses acceleration-transition excitation; it does not correct every cause of chatter. Cutting-only vibration can originate in tooling, workholding, spindle condition, or cutting parameters.
Diagnostic steps: Open Document
6.2 Programmed feed is not reached
Possible constraints include move length, acceleration, participating-motor limits, direction changes, and path control. A short move can end before programmed feed is reached. See Short moves, Motion Limits, and M31 motion diagnostics.
Diagnosis and machine tests: Open Document
6.3 Cycle time increases with PureMotion
See PureMotion Jerk Time for the transition-time/performance tradeoff. The tuning and testing procedures are linked there.
7 Application Notes
7.1 Vibration, oscillation, and mechanical condition
Oscillation is repeated motion about an equilibrium position. Vibration is unwanted oscillatory motion, such as shaking, buzzing, chatter, or ripple.
Mechanical looseness, wear, excessive backlash, poor lubrication, damaged components, and unstable drives can produce vibration that planner tuning cannot correct. Correct known defects before optimizing motion.
Vibration does not change physical inertia or moving mass. For linear motion, force = mass × acceleration. Acceleration and oscillatory motion create reaction forces that can increase structural deflection, drive load, position error, or following error.
Mechanical response also depends on stiffness, load, position, direction, spindle operation, tooling, workholding, and cutting forces. Reduced vibration is one verification result; apply the full acceptance criteria.
7.2 Cutting load and planner choice
Use the distinctions in Rapid and Jog motion, the criteria in Final machine test, and the comparison in Select the motion planner. Use the path-precision distinction when selecting a planner for precision machining.