myCNC Online Documentation

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===== MyCNC Constant Velocity Mode (CV) =====

In classic "Exact Stop" mode CNC control Toolpath planner adds Acceleration/Deceleration for each g-code command block. 

For Constant Velocity (CV) mode Toolpath planner tries to make a motion without stops. Figures below demonstrate Speed profile and Toolpath for **Exact Stop** and **CV Mode**.

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Fig.1  Exact Stop Mode Toolpath and Speed profile example.

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Fig.2  CV Mode Toolpath and Speed profile example.

In CV Mode Control software Toolpath planner reduces cutting speed on corners to keep Toolpath tolerance in a range given in "CV tolerance" in "Motion" configuration dialog

S-curve Speed profile is implemented in myCNC for CV-mode. It makes a smooth motion for all axes and significantly reduce machine vibration, step loss and cutting time.

Here is a fixed time interval for S-curve transition from one command to another ("command" can be linear or arc interpolation). The time interval can be set from 5ms to 41ms.


myCNC has a few settings to tune CV mode.

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  * **CV tolerance, units** - Tolerance value
  * **S-curve Smooth Filtering** -  The Time interval, transition time between two interpolation commands where S-curve smoothing performed.
  * **Look Ahead Break Angle.** - If an angle between 2 lines more than Break Angle, toolpath planner switches to **Exact Stop** mode - follows the toolpath exactly with deceleration, then acceleration.