Surface scan

Surface scan

How to get the height information of a work piece.

• Install a probe at your machine which triggers the Probe pin (A5 at arduino) when touching the work piece surface. A NO (normally open) switch, connected to ground and A5, is what we need. (Or when using a NC (normally closed) switch change $6=1).
  Note: if the probe is triggered, the Z axis needs some time and distance to decelerate which could cause mechnical stress to your probe (depending on mounting).
• Be sure the max. speed settings $110, $111, $112 are not too high - causing step loss
• A homing of the machine is recommended
• Find the needed travel range downwards for the Z axis. Manual probing can be started via the command "G38.3 Z-5 F200" (probe toward workpiece, stop on contact), where Z-5 a max. travel deepth of 5 units (mm) defines with a speed of 200. If the probe is not triggered until -5, a deepth of -5 will be assumed.
  With the manual triggered probing you can check the difference between Z position where the probe was triggered (check output in COM window) and the final stop position (check position in main window).
• Setup and run the surface scan

The Probe

Some examples of DIY probes:

1 with micro-switch, 2, 3 using a needle, 4, 5 made of brass

Setup of the surface scan

• Open the surface scan window via [Machine control - Surface scan].
  
• Define the area where to scan the height profile via lower-left and upper-right edge, or via lower-left edge and X- and Y-dimension.
• Set "Grid size X and Y" the distance from one to the next measurement point in units (mm)
• Set "Max deepth" the needed deepth for probing before abort a specific probing
• Set "Save height" above the work piece. Note: as less travel way the Z axis has, as faster the surface scan is.
• Finally set "Probing speed Z" the speed of the downwards movement. The upwards speed is defined by the $112 setup, because "G0" is used.
• Be sure the probe is above the work piece and Z coordinate is set to zero
• Start the surface scan via "Generate Height Map"

During the surface scan

• The main window shows the scan grid in yellow
• The deepth will be measured from the lower-left to the upper-right point, line by line, raster-point by raster-point.
• Because the final deepth-range is not known during the surface scan the result picture looks strange.
• If the probe-switch is still triggered when the next probing started, an error occurs and the scan will be aborted.
  Alarm 4 "Probe fail. The probe is not in the expected initial state before starting probe cycle, where G38.2 and G38.3 is not triggered and G38.4 and G38.5 is triggered."
  Error 9 "G-code locked out during alarm or jog state" - because there are still commands in the queue.

After the surface scan

• After finishing the surface scan, the picture will be updated with the correct color-range and interpolated values (steps will be smoothed)
• The offset to the max. measured Z value can be reomved from all measure points via "set max. value = 0"
• The generated height map can be applied to an already loaded GCode. All circles (G2, G3) will be converted to tiny line-segments All G1 movements will be converted to tiny line-segments The interpolated Z-value from the height map will be applied to each line-segment
  Note: