Precision media tracking is critical when printing long rolls of wallcovering media in one pass. A small tracking error can be meaningless over a few yards of media, but when printing 25, 50 and 100 yard rolls end to end in one pass, one must pay special attention to assure that image alignment is equivalent from the beginning to the end of the roll.

Every brand and model of digital ink jet has a behavior profile all its own. Watch your machine analytically to learn and manage settings and methods that affect tracking. This is no easy task, so we have prepared a generic list of factors that will help you diagnose and manage tracking issues.

Webbing machine: Make sure the media is tracking perfectly squarely from the unwind to the rewind rolls. If you start out square, you are likely to remain true over the job.

1) check skew using printer firmware when available. Do not bypass this feature as it can be very helpful.

2) Mark one edge and feed media for a visual assessment of skew then correct as necessary.

3) If possible, sight along media edge from the feed to the take-up side of the machine to assure they are parallel.

4) For hybrid and belt driven printers, where it is difficult to see media edges from feed to take up, use a ruler or fixed measure jig to assure media is square with the machine frame on the feed and take-up sides of the belt.

5) Make sure feed path is square when taping media to the rewind core.

6) Adjust vacuum and tension (when available) so media remains flat and transports smoothly on each media feed cycle. If the media forms a temporary bump when feeding each pass, you may need to lower vacuum and/or increase tension.

During the run: Even with a true path at the start of a job, the media may drift. Following are some ideas to help manage this.

1) Some equipment offers an edge-tracking feature that will "step" your image back to alignment with the media edge. This feature may result in some aliasing when the equipment makes a correction. Decide if this is acceptable before you use this feature. It is always a better option to assure media is tracking true than to compensate with physical corrections in the image.

2) Unwind and rewind tension. It is important to maintain tension on both the feed and take up rollers so that media path remains square and true.  If your printer has a dancer bar on the unwind, make sure the dancer tension is optimized for the material you are printing. Set motor clutches and other tension devices so that media continues to pass through the machine in a smooth path without buckling or forming slack loops. If you have a machine with air bars, set the winder clutch or power on both sides of the machine to assure that there is no slack in the media while printing. This may take some experimentation but it is worth the investment overall.