TIB719 - ValueJet & XpertJet Double Head Series - Simplified mechanical adjustment procedure

For more information concerning the double head alignments, please also check the following videotraining article:

Dual Head alignment for XpertJet and ValueJet

 

Commonly we receive reports from the field concerning quality-related print issues. We notice recurring errors being made in the field, that after a print head replacement, the print quality has deteriorated despite a new print head is installed. 

 

We must stress again the importance of the precision of mechanical head-alignments, which are of critical importance for good and consistent output-quality.  We have created a document that offers a simplified, but basic overview of the mechanical adjustments, including some FAQ’s.

 

This document is also a reminder of the most important points where should be paid close attention to:

• Adjustment test prints must be printed on a ‘tack-sharp’, ‘non-bleeding’ type of media.
• Generally classic production printing vinyls are totally not suitable for this job!
• All adjustments should preferably be observed with a microscope. Every digital microscope with a magnification from x20 until x60 will do and most of them won’t invert the image.
  So to simplify things for every technician, a digital (non-inverting) microscope is strongly recommended.
  Nowadays you can purchase USB microscopes, Smart-phone-connectable microscopes, etc. in all price classes (starting from 10€ or up) on sites like Amazon.
• Ensure that the nozzle-check of both print heads are perfectly ok, before starting the mechanical print head adjustments. The cleaner the nozzle check of both heads fires, the easier and more accurate the adjustment will be.
• The head slant (angle) and front & back mechanical adjustment precision are of critical importance.

 

If only the rough adjustments are done, but the micro-adjustments are neglected, it still will result in deteriorated output-quality!

In contrary to single-head ValueJet/XpertJet printers, where only replacing a print head commonly sufficed in the past, dual-head machines need more carefully and properly done (mechanical) adjustments. 

This is in fact exactly the same like Blizzard/Spitfire printers, except a little simpler because it’s only 2 print heads.

 

Neglecting these mechanical alignments of both print heads to each-other, will result in deteriorated output-quality.

 

Warning When mounting and adjusting a new print head, pay very close attention if the print head is inside the rotation-point! The head is seated and gliding on 4 pads on each corner. If the print head is loosened too much, it may not be inside the rotation-point. This may result in a misalignment and improper adjustment, which the cause is sometimes hard to determine because it’s difficult to see this!

 

 

Step 1: Head slant - rough adjustment

 

 

Step 2: HEAD SLANT - micro-adjustment

 

 

 

 

Step 3: FRONT AND BACK ADJUSTMENT - rough adjustment

 

 

 

Step 4: FRONT AND BACK ADJUSTMENT - micro adjustment

 

 

 

 

 

Frequently Asked Questions

1. When aligning the front & back micro-adjustment, it may occur that 1 of the 4 blocks are difficult to align: In the picture you can see that the bottom yellow lines are not properly aligned, between the black lines, especially in the bottom part. On top in the contrary, the yellow lines are perfectly centred between the black lines. Referring back to page 4 of this document, you should know that with the front & back micro-adjustment, there are 4 blocks. All the 4 blocks behave in exactly the same way when moving the print head front & back. If a nozzle-row of 1 block is not performing a straight-parallel jetting behaviour, try to compare the other 3 remaining blocks. Trust on it, that if these 3 remaining blocks are properly aligned, the block with the deviating nozzles will also be properly aligned.
   
   
2. Common slant issues
   To quickly verify if the slant of both heads are “equally adjusted”, check the colour density of the 2 black patches (HEAD 1 and HEAD 2).
   
   Important
   If both colour patches have exactly the same colour, it doesn’t always mean that they are properly adjusted! It’s just a quick test to compare that the slant of HEAD1 and HEAD 2 are similar.
   

    

   
   Don’t assume they are correctly adjusted until verified with a microscope! (see page 2)
   

3.  

Additional checks - Vertical slant

 

Prior to the start of the mechanical adjustments of print heads, some important adjustments, often forgotten:

 

Vertical Slant / alignment
This alignment is set in the factory and should normally never be modified. Nevertheless, it’s recommended to verify the parallelism, prior to adjusting both print heads, to check if they were properly mounted on the carriage / print head bracket.

 

Both calibrations should not change during a head-replacement as they are fixed in the factory. So this check only needs to be verified together with the head-height calibration, after the print heads are properly adjusted. If you experience any issues while adjusting, especially pay attention to this.

 

 

Additional checks - Head Height calibration

Once the vertical slant alignment has been performed, the head height needs to be calibrated relative to the print platform while the carriage is in the lowest position. .

 

 

Refer to the service manual of your machine for more information concerning the head height calibration procedure.

 

4) Which media should be used to mechanically adjust print heads?

 

** Use a media with low bleeding properties and tack-sharp line output. The finer and sharper the lines are, the more accurate you will be able to properly adjust the print heads
Use a very sharp media, which does allow ink bleed. Media with excessive “ink-bleeding” for mechanical adjustments is NOT RECOMMENDED!

 

 

 

Article changes

Revision 1.0 : 03 Mar 2017 - Initial release
Revision 1.1 : 23 Dec 2020 - Added XPJ 2H series