Gantry Alignment. How to use it?

What is it for?

The "Gantry Alignment" function is designed for software adjustment of the home position on gantry machines. While adjusting the portal machine, may occur some difficulties related to accurate installation of the home sensors, which are used for restoration of the gantry alignment. Mechanical adjustment of the sensors position with a displacement from several hundredths of a millimeter to several dozens can be a rather difficult operation. In order to simplify this operation enhancing the quality of perpendicular installation the program uses classical procedure of measuring the rectangle diagonals with specified dimensions. A special program is launched on the machine. It passes through the 4 vertices of the rectangle and then the diagonals are measured. Considering diagonals, dimensions of the rectangle and distance between sensors of the portal, it is possible to calculate correction for the position of a home sensor. Such a program correction makes it possible to completely eliminate the distortion and jamming of the portal also minimizing the deviation of the manufactured part from the specified shapes.

How to use Gantry Alignment?

The menu item "Configuration" → "Calibration Wizard" contains two tabs, one of which is "Gantry Alignment". The tab contains hints describing the stages and illustrations to simplify understanding of the algorithm.

The more detailed description of Software Gantry Alignment is given in the text above.

Preparatory stage

Before opening the "Calibration Wizard", it is necessary to preform home search and bring the working tool (spindle, cutter, etc.) approximately to the middle of the machine working field so the center of the future rectangle coincides with the starting point of stage 1.

Stage 1

Select the axis with two motors (portal axis) and set the parameters of the calibration zone. It is recommended to choose a zone large enough comparatively to the working field to increase the accuracy of the final result. For example, for setting up a machine with a working area of 2000x6000 mm, then recommended alignment is at 90% scale (1800x5400 mm). In order to make the make the interface more comprehensible, the program highlights the location of the corresponding axes when the values are entered (the distance along X, Y, the width of the portal is the distance between the home sensors on the portal axis).

In the "Gantry Width" field, specify the distance between the base sensors. You can measure the distance both manually and automatically.

The system will move to each vertex of the rectangle with a stop to set the mark. After moving to each point, set the mark that is the actual vertex of the calibration rectangle using a pen or a marker, and then return and press the button "Go to 2nd (3rd/4th) Point" to continue the operation. After making the last mark, click "Go to Start Point" and proceed to the second stage.

Stage 2

Define the diagonals of the zone using a measuring instrument (tapeline, rule, laser rangefinder). On the diagonals measurement accuracy depends the perpendicularity. Take measurements between the marks set at the previous stage.

Measure the first diagonal from the angle with the minimum coordinates. The procedure takes about a minute.

Enter the data in the field according to the scheme. Aiming the cursor in the input field, the program will highlight the corresponding diagonal on the right side of the window.

Since the measurements are completed, click the "Calculate Correction" button, and the program will display the correction value in the corresponding field and highlight the motor on the diagram, for which the received value is to be manually entered.

In the menu "Configuration" → "Settings" → "Motors" in the "Advanced Settings" panel values are entered for the specific motor. To determine which motor of the portal axis needs to be corrected in the program settings, open the "Diagnostics" tab, in the "Motor signals grouped by axes" section expand the list of signals related to the portal axis (in this example - Y). Now trigger the home sensor on the side of the portal that was marked on the machine schematic image at the end of previous step. In the diagnostics window, it will be shown with which engine the sensor triggers "Home Pin" signal. Remember the name of the engine and make correction in the field "Software correction of the homing switch".

Conclusion

Recapitulating the chapter, an amendment was calculated and made in order to programmatically eliminate portal non-pendicularity relative to the guides. To check the results, perform the actions described in step 1 again. If the measured value of the diagonals coincided with the desired accuracy, then the procedure successfully completed. If the measured values do not meet the desired ones, then it is necessary to repeat the whole procedure again.