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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This is a part of the registration and alignment series of tutorials.

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.

In 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 "vertical” direction, and the perpendicular axis (from the front of the machine to the rear of it) is the “horizontal” direction.

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.

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 three settings really need to be changed to get images properly centered:

• Vertical home position (paper feed)— left/right positioning is calibrated to change 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 also affects left/right positioning, by controlling 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.
• TPH horizontal write position (master making)—up/down positioning is controlled by where the TPH is burning the image in the stencil along the front/back axis of the riso. This is in the protected area of test mode, so should only be adjusted if absolutely necessary.

Procedure

Before starting this process, elongation/shrinkage should be checked, and calibrated if needed.

Determine offsets

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

1. Turn the riso on and load a working drum. Then lower the feed tray, and fill it with paper of a standard size.
2. 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).
3. 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 81 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.
4. Switch into normal mode by holding the RESET key for 1 second.
5. 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.
6. 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).
7. Mark the feed direction on this print, and number it ① (this will be the first reference print).
8. 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.

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.

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.

Calibrate the left/right print position

Begin by calibrating the vertical home position (paper feed). Depending on how much it needs to be shifted, an adjustment to the write start position (master making) may also be needed.

Vertical home position (paper feed)

1. Turn the riso on in test mode.
2. Run the test mode for "Vertical HP Adj" and jot down the current value.
   • On one-drum machines the test mode is 970 (type in 970 + START).
   • On two-drum machines the test mode for the first drum position is 971 (type in 971 + START, then select the first drum position on the screen and hit START again). The test mode for the second drum position is 969 (an additional stencil may need to be made for the second drum).
3. Adjust the value according to the offsets (with the test still running, type in the new value and hit START; the ✱ button will flip the sign between +/-).
   • Increasing the value by one (+1) will move the printed image to the right by 0.1 mm.
   • Decreasing the value by one (-1) will move the printed image to the left by 0.1 mm.

For example if the current value is +3 and the image needs to move to the left by 1.5 mm, the new value should be -12.

4. Turn the riso off and turn it back on normally.
5. Run another test print, number it ②, and measure and mark the new offsets. The existing stencil on the drum should be used for this (no new stencil needs to be made as the only thing this is adjusting is the paper feed).
6. Repeat to fine tune as needed.

If the final value is greater than +30 or -30 (more than 3.0 mm from neutral), consider splitting the adjustment with the write start position (master-making) (in the next section).

Write start position (master-making)

1. Turn the riso on in test mode.
2. Run the test mode for "Write Start Position Adjustment" 541 (type in 541 + START) and jot down the current value.
   • For two-drum machines, select the appropriate drum position).
3. Adjust the value according to the offsets (with the test still running, type in the new value and hit START; the ✱ button will flip the sign between +/-).
   • Increasing the value by one (+1) will move the printed image to the right (burned image closer to the clamp) by 0.1 mm.
   • Decreasing the value by one (-1) will move the printed image to the left (burned image further from the clamp) by 0.1 mm .
4. Turn off the riso.
5. Use the #Determine offsets section above to create a new stencil and test print. Mark the feed direction, number it, and measure and mark the new offsets.
6. Repeat to fine tune as needed.

Calibrate up/down print position

Calibration of the up/down position is handled with the TPHThermal Print Head horizontal write position—this adjustment is made in the protected area of test mode, so should only be made if absolutely necessary.

1. Turn the riso on in test mode (holding the left and right print position buttons while turning it on).
2. Unlock the protected area with test mode 9874 (type in 9874 + START).
3. Run the "TPH master-making horizontal position adjustment" test mode 1233 (type in 1233 + START) and jot down the current value.
   • For two-drum machines, select the appropriate drum position).
4. Adjust the value according to the offsets (with the test still running, type in the new value and hit START; the ✱ button will flip the sign between +/-).
   • Increasing the value by one (+1) will move the printed image up (burned image closer to the back of the drum) by 0.1 mm.
   • Decreasing the value by one (-1) will move the printed image down (burned image closer to the front of the drum) by 0.1 mm .
5. Turn off the riso.
6. Use the #Determine offsets section above to create a new stencil and test print. Mark the feed direction, number it, and measure and mark the new offsets.
7. Repeat to fine tune as needed.