HP Latex 1500 User guide - Page 376

4. If you are using the roll-to-roll configuration with dual-roll spindles and you see smears, or the substrate is not adhering to the platen, mainly at the outer sides of both rolls, you are recommended to use the center support with both spindles. Once installed, you can try to move it up slightly from its calibrated position if you are suffering from wrinkles or the substrate is not adhering to the platen at the outer edges. This could mean that the support has been calibrated below the correct position. Otherwise, you can try to move the support down a bit if you are suffering from wrinkles or the substrate is not adhering to the platen at the inner edges near the center of the printer. This could mean that the support has been calibrated above the correct position. NOTE: Although the center support can be installed while printing, you are recommended to stop the job, unload the substrate, and reload completely, even unwinding the substrate from the output spindle. See Load a roll (dual roll-to-roll configuration) on page 55. 5. Reload the substrate and try to minimize skew while loading. Check that you using the correct loading procedure. 6. Increase the input tension in steps of +5 N/m from the recommended setting for each category until you eliminate the issue. There is skew or telescoping on the output spindle Extreme skew (approximately 10 mm peak to peak) and telescoping in the output spindle while it winds can be caused in three main ways. ● The substrate has not been correctly loaded and aligned during the loading procedure. ● The roll loaded on the input spindle is skewed, and this skew is transferred to the output spindle. ● The roll loaded on the input spindle has been wound with different tensions at its two ends. Printing on rolls that are not wound accurately during manufacturing may lead to wrinkles and skew problems and, generally, this problem can be identified easily because you can see a loss of tension at one side of the substrate between the input roll and the main roller. In that case, see the relevant information provided in the section There are wrinkles and ink smears on the substrate on page 369. NOTE: When printing with dual rolls, you are more likely to notice skew on the output spindle. However, it is not necessarily a problem. If it becomes a problem, proceed in the same way as for a single-roll configuration and consider the use of the recommended center support for dual-roll spindle in both input and output. TIP: If you notice that one of the substrate edges is not as well tensioned as the other between the platen and the main roller, showing a wave-like shape as it enters the platen, then you are likely to have skew, and you should consider the use of the center support for dual-roll spindle in both input and output. TIP: When suffering from extreme skew that tends to increase (normally with highly temperature-sensitive substrates), try to use a thicker core that is not deformed by the rubber traction grooves on the spindle when inflated. Then follow the guidelines below for reducing skew. Generally, the main contributor to skew is an imprecise substrate load, and the effects of that are worse with wide rolls. However, if you have some skew or telescoping but this does not affect your print quality, and does not generate wrinkles in the substrate (see There are wrinkles and ink smears on the substrate on page 369), there is no need to take any action. However, you are recommended to reload the substrate in order to eliminate any potential problem. Some substrate rolls already come with skew; in that case the recommendations are as follows: 1. Try to load the substrate following the correct procedure, taking as a reference of the roll's width the average between peaks of skew. 368 Chapter 12 Troubleshoot substrate issues ENWW