Calibrating print position (Z+)

Calibrating print position (Z+)
Difficulty	Beginner
Duration	5 minutes
For series	Z+Any machine released with or after the RZ line, i.e. RZ/RV/EZ/EV/SF/SE and MZ/ME/MF/MH machines.
Tools	Ruler or loupe

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Calibrating the print position on Z+Any machine released with or after the RZ line, i.e. RZ/RV/EZ/EV/SF/SE and MZ/ME/MF/MH machines. machines can be done through test modes, while making a series of test prints.

Strategies

Many different factors affect the final print position on the page. In the order of low-level to top-level they are roughly:

1. The position of the image burned onto the stencil.
2. How much stencil is fed under the clamp.
3. The angle the drum was rotated to when receiving the stencil.
4. The position of the MMUMaster Making Unit when loading a stencil (on two-drum machines).
5. Where the scanner starts recording an image (if scanning).
6. The timing of when the paper is fed to the drum.
7. Where the original is on the scanner (if scanning).
8. The user adjustments with the positioning buttons when printing.

The official service manuals for Z+Any machine released with or after the RZ line, i.e. RZ/RV/EZ/EV/SF/SE and MZ/ME/MF/MH machines. machines provide instructions for calibrating all of the above (and in what order) within the "Print position adjustment procedures" section of the OTHER PRECAUTIONS chapter (towards the end of the manual).

The following instructions present a simplified version of calibration, focusing on centering the printed image at the end, rather than calibrating each individual step along the way.

In practice, only two settings really need to be changed to get images properly centered:

• Home position (paper feed)—the default timing of when each sheet of paper is fed into the drum. This method works just the same way the print position buttons do—it just changes the neutral/starting position. Any adjustments to timing, however, carry a risk of increasing misregistration and/or paper jams, if pushed too far towards the end of the range.
• Write start position (master making)—this affects where the image is actually burned onto the stencil. This adjustment is quite dependent on all of the other master making settings—the clamp range adjustment, write speed, etc. and it has a limited range at which it is effective. If the burned area is moved outside of the printable area, the printed image will be cut off.

Best practice is generally to make adjustments to the home position (paper feed) first, and only adjust the write start position if the paper feed adjustments are getting to the extreme ends of the allowable range.

Procedure

Before starting this process, elongation/shrinkage should be calibrated.

1. Enter test mode: hold left/right arrows on position adjustment control panel (for the first drum position, on a two-drum machine) while turning the machine on.
2. If the print position needs to be constantly adjusted a certain amount (for example 1.2 mm towards the front/operator and 2.5 mm towards the right/lead edge), the default vertical and horizontal offsets can be changed with the following test modes:
   • 0541 Vertical position
     This setting adjusts the default center position of the master on the long dimension of the paper. It is in tenths of a millimeter.
   • 0586 Horizontal position
     This setting adjusts the default center position of the master on the short dimension of the paper. It is in tenths of a millimeter. Positive is toward the front of the machine.
3. If stencils are coming out elongated or shrunk in the direction parallel to the feed, they scale be can adjusted in test mode so they are the correct length. Instructions for this are available here: elongation/shrinkage.