Linear pitch compensation
The accuracy of the screw pitch varies over the length of the screw. The linear pitch compensation is a way to improve the machine's accuracy when the linear displacements are not precisely correct. For example, cheap rolled ball bearing spindles may have an inaccuracy of several 0.1 mm at a meter length. Also, the pitch may vary a bit depending on the position. This compensation feature allows us to correct this.
The compensation can be switched on and off through the setup at the 'Machine General' item.
Related CNC.INI settings are:
INI entry | Values | Example |
|---|---|---|
pitchCompensationOn | 1 to switch compensation ON, 0 to switch OFF | pitchCompensationOn = 1 |
pitchCompensationFileName | Name of the file with the correction table | pitchCompensationFileName = "Joint-X-pitchCompTable.txt" |
| | |
When you switch on the compensation and the compensation table does not exist, one is created as an example for you; it is only an example to show the syntax. You need to modify it for your machine.
Below is an example of a correction table:
The left value is the position of the machine. The right value is the calibrated position you have obtained by measuring.
The table must be sorted, small to big values. Please note that 0 is bigger than -100, so if you have negative numbers, the highest negative number comes first.
You can make the compensation value visible by checking Show in DRO on the coordinates window.
You will see this in the DRO a small number above the position showing the pitch compensation value.
Related Videos
The video below is in German. It shows how to use pitch and cross-compensation.