The Nozzle Tip Changer allows OpenPnP to automatically choose the best nozzle tip for a given part. It can optionally Z calibrate the nozzle tip.

The following shows a nozzle tip load and Z probe motion sequence.

OpenPnP supports the so-called "Four Positions" changer style. You can configure four motions that load a nozzle tip. To unload a nozzle tip, the four position motions are executed in reverse. You can set the relative speed between the way-points. Furthermore, actuators can be actuated in between. This actuators are of boolean style and actuated True on load and False on unload.

Note that the First Location is approached from Safe Z above it and the last move is returning from Last Location to Safe Z.

See the Nozzle Tip Probing Configuration documentation, if you have a ContactProbeNozzle.

Using computer vision Nozzle Tip Changer locations can be calibrated in X and Y. The process uses two template images, of the empty and occupied changer slot respectively. It can therefore also detect if the slot is empty/occupied as expected.

Vision Location determines the changer location at which the template images are taken. Chose a location where the nozzle tip is visible when it occupies the slot.

Calibration Trigger determines when the vision calibration takes places:

• Manual allows only manual calibration. The calibration will be stored in the configuration (machine.xml)
• Machine Home invalidates the calibration when the machine is homed. As soon as nozzle tip load/unload is requested, the slot will first be vision calibrated.
• NozzleTipChange recalibrates the the locations on each nozzle tip change.

Template Width and Template Height determine the dimensions of the template image. Use a crop that includes relevant horizontal and vertical edges of the changer slot surrounded by an extra millimeter or so. The nozzle tip must be visible, when it occupies the slot. You can use the Capture buttons to optimize.

Tolerance determines by how far from the nominal location the vision detected location may be.

Wanted Precision determines at what distance the obtained template image match location is close enough. Otherwise, the camera is centered to the detected location and another vision pass is made (drill down).

Max. passes limits the maximum number of vision passes.

Minimum Score determines how similar the camera image must be in comparison with the template image (0.0 ... 1.0). If the score is not reached, the calibration fails.

Last Score shows the template match score obtained from last live or test calibration.

Use the Test button to test the calibration.

Use the Capture button to capture the respective Template Empty or Template Occupied image. The camera will automatically move to the selected Vision Location. You can hover the mouse over the captured template thumbnail to see it enlarged in the camera view.

Use the Reset button to remove templates images.

The two images are both compared, and the better match tells OpenPnP if the slot in question is empty or occupied. If this does not correspond to the state internally stored by OpenPnP, it will abort the calibration and therefore the nozzle tip load/unload operation. Nasty collisions can be safely prevented.

Note: with the CP40 black nozzle tips, the difference between empty and occupied is slight. I had mis-detects on one nozzle tip that was still pristine and black i.e. it was mistaken as empty. Slightly scraping off the blackening on the top rim helped.

All the settings can be cloned to/from other nozzle tips, so you need to configure them only once. The various Locations are automatically translated according to the First Location of each tip, so you only need to enter this one location for each additional nozzle tip slots. The First Location of a nozzle tip must be set, before any cloning to that tip takes place.

• Marking a nozzle tip changer slot as the Template makes it the template that others can be cloned from. Use the Clone Tool Changer Settings to all Nozzle Tips button to distribute the settings to all the other nozzle tip changer slots.

  It will not clone to nozzle tips that are marked as Locked (see below), or that have no First Location set.

• Marking a nozzle tip changer slot as Clones from Template lets you clone it from the template. Use the Clone Tool Changer Settings from Template button to clone the settings to this nozzle tip changer slots.

  If the First Location is not yet set, you'll get an error:

  

• Marking a nozzle tip changer slot as Locked prevents any cloning to/from it. Use it if this slot is different from others. This should also be used for the "unloaded" stand-in for the bare nozzle.