[deadlykitten]

hello how does the ball bar test / software, know that the measured value is at 30 angle for example ?

this will require the ball bar device to map data with cnc position

and sometimes this tests are not full 360*, but partial arches ... how does it know where it is ? kindly

[servtech]

hello how does the ball bar test / software, know that the measured value is at 30 angle for example ?

this will require the ball bar device to map data with cnc position

and sometimes this tests are not full 360*, but partial arches ... how does it know where it is ? kindly

The ballbar program is written by the OEM, ie Renishaw so the axes follow a known path. The ballbar itself is a transducer so it's length is constantly changing during the program and the program plots its length relative to the axes positions.

All angles can then be extrapolated from the difference between program points to actual measured points. Angles and squareness is worked out and displayed as a graph or data from there including the top errors, backlash, reversal spikes etc. A full circle is not required in a lathe for example.

[deadlykitten]

i heared that the ballbar send data via bluetooth, but i don't understand how is that data paired with axis position ?

[servtech]

i heared that the ballbar send data via bluetooth, but i don't understand how is that data paired with axis position ?

The ballbar length is measured within a micron by the OEM at 20°C, its length becomes the circle radius in operation, That length and ambient temperature is stored as variables in the program. The data from the machine linear or rotary encoder is plotted point by point with the ballbar plots as a dual trace by the (Renishaw) software. The ballbar program start and sampling data is triggered by the program with a one millimetres axis movement to start both measuring systems at the same point, rather like the trigger point of an oscilloscope trace. The older systems used a cable, newer Bluetooth to transfer data to the laptop via the ballbar OEM dongle.

So, the program "knows" the circle radius and length of arc by the program, simple mathematics within the software to show squareness etc in xy or xz planes.