Description of Issue

A sandpaper belt roll-up can be the cause of many machine errors like board tracking issues, measuring errors, and even damage to the X drive gears.  The errors appear when the rolled-up sandpaper belts lift the workpiece off of the board tracking sensor that tracks the position of the board.  It is often not noticeable at first glance so make sure to inspect the edges of the belts for the telltale hump, especially on the keypad side of the machine (see photos below).  It is very important that the root cause of the roll-up be addressed before sending replacements belts so that the same issue does not happen immediately to the new belts.

Possible Causes

In almost every case, the cause of a sandpaper belt rolling up is that the head pressure is too low.  Very skinny boards (in the width) can also contribute to belts rolling up.

Troubleshooting Steps

  1. If the user is seeing repeated belt rollups during carving of skinny boards (<3”) then recommend the rubber belts to eliminate this problem.
  2. Check and adjust the head pressure.  Please refer to the document titled “Checking and Adjusting the Head Pressure” found on the service section of the website to resolve the low head pressure issue.  Usually a simple lubrication of the vertical guide posts and lead screws will bring the pressure into range.
  3. Check that the belt guides on the bottom of the belt trays are in place and are not significantly worn.  Check wear against the other guides as a reference.

Example of good sandpaper belt

This picture is looking at the rear belt tray up next to the squaring plate on the keypad side of the machine.  Notice that you can see the whitish edge of the belt and that there is no bump where it has rolled under itself.  Also notice that there is a little of the roller visible.




Example of a rolled up sandpaper belt

The picture above-left is looking at the front belt tray up next to the squaring plate on the keypad side of the machine.  You can see (and feel) the bump where the belt has rolled under itself.  Also notice that the rolled up side is shifted to the end of the roller.  You can see the shift if you look at the opposite end of the bet as seen in the right picture.