## 2 Materials and Methods
### Obtaining the CNC Position Setpoint Data  
Tests of the effect of the interpolator settings were performed on a MCVL 1000 milling machine produced by Kovosvit MAS with a Heidenhain iTNC 530 control system (see Figure 7). The MCVL 1000 is a standard three-axis vertical machine tool with a 15 kW spindle supplemented by a tilting rotary table (axes B and C).  
Two prepared part programs with a 2D path were processed in the YZ plane in \"air cut\" mode. For each of them, more than 1800 measurements were taken at unique interpolator settings. This number was only possible because of the automation of the measurements and the bulk processing of the acquired data. The design of the full-factorial experiment allowed the influence of all possible combinations of the considered machine parameter settings to be verified.  
The individual steps of the procedure of changing the machine parameter settings, i.e., start of the recording of the time histories in the individual machine axes, execution of the NC program, and termination and saving of the recording, were carried out completely autonomously without the need for intervention of the machine operator.  
The use of the Heidenhain TNCcmd tool, which enables remote control of the iTNC control system from an external computer using specific commands, was essential in this regard. For example, it is possible to temporarily change the value of a given machine parameter in the operating memory of the control system. Similarly, it is possible to change the value of the bit indicating the start of a program in memory and wait until the part program is executed. TNCcmd allows for processing a series of consecutive commands stored in a text file with the extension \"tnccmd\". This file was created in the MATLAB environment. An example sequence for executing one test is shown in Figure 8a. First, the parameter values were set according to the specific dataset using the MPSET command. This was followed by the execution of the NC program using the SETV command (the value of the specific marker is not disclosed, for security reasons) and waiting until the program was executed using the WAIT UNTIL command. The sequence was padded with delays (SLEEP command) so that the control system had sufficient time to execute all commands.  
Figure 8: **(a)** A segment of the TNCcmd batch file specifying the parameter combinations of one specific test by setting the values of the interpolator parameter in memory with the use of the MPSET function. **(b)** NC code used to run the part program as well as start, end, and save in the internal oscilloscope records.  
Figure 7: MCVL 1000 five-axis milling machine equipped with Heidenhain iTNC530 control system.  
For each of the interpolating axes (Y and Z), the time histories of the output trajectories of the interpolator were recorded using the internal oscilloscope (OSCI) of the iTNC control system. The recording was automatically started, terminated, and saved, with a name containing the measurement serial number, using commands directly from the part program (see Figure 8b).  
The experiment set-up in this fashion was then executed by loading the appropriate part program on the machine in automatic mode and setting the feedrate override displacement values to 100%. The connection to the machine was then activated (using its IP address) from the TNCcmd console running on an external PC. Subsequently, a batch file was run, which contained a sequence of commands to execute a series of tests. Records from the internal oscilloscope were continuously stored in a user-accessible section of the machine's storage, and, after all tests were completed, these records were downloaded from the machine for bulk evaluation.