Stratasys J850 Manual page 73

The condition of the print heads directly affects the quality of printed models.
To maintain optimum printing, you should routinely test the print heads, and
calibrate them to the best working configuration possible by running the
Head Optimization wizard every 300 hours of printing. You also need to
calibrate the print heads after changing the printing mode between
High Mix / High Quality and one of the high-speed modes.
During this procedure, you place a scale on the build tray and connect it to
the printer. Printing material (resin) is jetted from each head and its weight is
automatically recorded and the wizard determines how to optimize the print
heads.
If, during the optimization process, the wizard determines that a print head is
faulty—or that it is negatively affecting layer uniformity with the current head
configuration—the wizard instructs you to replace it. If this happens, you can
continue the wizard to replace the print head, or abort the wizard, to replace
the head at another time.
Note: To accurately test and calibrate print heads, they must be clean. If
necessary, run the Cleaning wizard before beginning this procedure.
1. Prepare—
❒ disposable cleaning gloves (any clean, powder-free protective gloves)
❒ pink paper
❒ the Missing Nozzles ruler
❒ the scale supplied for use in the Head Optimization wizard
Important: Ensure that the scale is calibrated before beginning this
procedure.