View source for Calibrating print position (Z+)

{{Tutorial
|difficulty=Beginner
|time=5 minutes
|type=Maintenance, Printing
|series_type=Z+
|tools=Ruler or loupe
}}
{{Draft}}{{mbox|text=''This is a part of the [[registration and alignment]] series of tutorials.''}}

Calibrating the [[print position]] on {{Z+}} machines can be done through test modes, while making a series of test prints.

{{Info|<p>In {{Brand chip|Riso}} terminology the feed edge is the ''top'' of the page, regardless of paper orientation or the orientation of the printed image on it. So the axis along the direction of paper feed (from the feed elevator to the exit tray) is referred to as the "<u>vertical</u>” direction, and the perpendicular axis (from the front of the machine to the rear of it) is the “<u>horizontal</u>” direction.</p><p>For the purposes of this article, the terms ''left/right'' (along the axis of the paper feed), and ''up/down'' (perpendicular to the paper feed) will be used instead.</p>}}

== Strategies ==

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

<ol type="a">
<li>The position of the image burned onto the stencil.</li>
<li>How much stencil is fed under the clamp.</li>
<li>The angle the drum was rotated to when receiving the stencil.</li>
<li>The position of the MMU{{#info:Master Making Unit|note}} when loading a stencil (on two-drum machines).</li>
<li>Where the scanner starts recording an image (if scanning).</li>
<li>The timing of when the paper is fed to the drum.</li>
<li>Where the original is on the scanner (if scanning).</li>
<li>The user adjustments with the positioning buttons when printing.</li>
</ol>

{{Manual|<p>The official service manuals for {{Zplus}} 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).<ref>RISO Inc. Technical Services & Support. ''[https://archive.org/details/RisoRZ2-3-5SeriesTech/Riso_RZ_200-220-230-300-310-370-390/page/n278/mode/1up RZ2xx RZ3xx Series Technical Manual]''. Revision 3.0. Riso Kagaku (2005): 15-5 (279).</ref></p><p>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.</p>}}

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 [[Registration|misregistration]] and/or paper jams, if pushed too far towards the end of the range.
* '''Write 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 <u>adjustments to the home position (paper feed) first</u>, and only adjust the write start position if the paper feed adjustments are getting to the extreme ends of the allowable range.

== Procedure ==

{{Info|Before starting this process, [[Elongation-shrinkage|elongation/shrinkage]] should be checked, and calibrated if needed.}}

=== Determine the offsets ===

Firstly, the direction and distance of each required offset needs to be figured out.

# Turn the riso on and load a working drum. Then lower the feed tray, and fill it with paper of a standard size.
# If the riso has a wheel at the front of the feed tray to control up/down positioning, turn it to the center position (referencing the sticker on the tray).
# Turn the riso off, then start it up in [[test mode]] (turning it on while holding down the left and right print position buttons), with a working drum in, and a standard size of paper on the feed tray. Then run test mode <code>81</code> to create a stencil with the test grid and print a proof of it.
#* Alternately a stencil can be made (using a scan or from the driver—whichever is typical for how the machine is used) with a [[registration mark]] dead center on the page.
# Switch into normal mode by holding the RESET key for 1 second.
# Run 5–10 prints (both to ink up the drum and to evaluate the registration in the next step) using all the regular print settings, but without adjusting print position.
# Filter through the prints to find one that seems typical for the set (i.e. not one that is a clear misprint, or very misregistered—if all prints have different print positions, then the [[registration]] may need to be corrected first).
# Mark the feed direction on this print, and number it ① (this will be the first reference print).
# Measure how far off the printed image is, and in what directions, and mark these on the sheet.
#* When using the test grid, measure to the edge of the printed area (which will likely be the cut-off ends of the grid lines).
#* When using the center mark, fold the sheet in half in each direction, and measure relative to this center mark.

{{Info|<p>Often the rough amount of offset is already known to the operator—it is whatever are the standard adjustments needed to before fine-tuning print position (the ones they make reflexively before even looking at the printed image). This can provide a quick shortcut to this process.</p><p>Since the riso moves in 0.5 mm increments with each button click (unless [[fine adjust mode]] is enabled), if the print position must always be shifted five clicks to the right, and two clicks up (for example), then the offsets are 2.5 mm to the right and 1.0 mm up.</p>}}

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{{Blueprint|The former version of this tutorial is listed below, it goes through adjustment of the master making position, not the paper feed position. It will be removed as the above section is finished.}}

# 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. 
#* '''0541 Vertical position'''<br/>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'''<br/>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.