This error can occur on the UltiMaker Factor 4 after performing the gantry skew calibration process. It indicates that the calibration could not be performed successfully. New offset values for compensation will not be applied, and the print jobs may not be accurate.
Note: In an early firmware version, the optical limit switch errors were numbered incorrectly. This was fixed in firmware 10.1.0.
If you see ER306 on the display of your printer with the title "Movement detection error", please visit the ER305 page instead and update the firmware to the latest version.
Affected system
The movements of the print head in the X and Y directions are controlled by the gantry. Despite using high-quality components and accurate and consistent assembly at the factory, there can be small offsets in the gantry system and the perpendicularity of the X beam.
The UltiMaker Factor 4 can run a gantry calibration procedure and perform some measurements to achieve optimal dimensional accuracy. The measured values will be applied during motion to compensate for any small offsets in the gantry system.
Issue
If this error appears after running the calibration, this can mean that either the calibration process could not be completed successfully, or that excessive skew was detected which the printer can not compensate for.
Troubleshooting
Follow the steps below to find the cause of the error and resolve the problem.
Calibration preparation checks
First, ensure that all pre-calibration checks have been performed correctly and that the issue was not caused by accidental user error. Some of the causes for a failed calibration include:
- Build plate present. The gantry skew calibration uses the grooves in the magnetic build plate to perform the measurements. The flexible build plate must be removed before starting the calibration. The process on the display will indicate this. If this step was accidentally forgotten, remove the flexible build plate from the printer and start the calibration again.
- Material in grooves. As mentioned above, the print head will follow the grooves in the magnetic build plate. If these are (partially) covered, or filled up with material, this affects the measurement. Make sure that the grooves and the surface of the magnetic build plate are clean before restarting the calibration.
- Dirty nozzle tip. Dirt or carbonized material on the nozzle tip can affect the reliability of the measurements. Before starting the gantry skew calibration, ensure that the nozzle tips are clean. Heat up the print core via the Configuration menu, wait for the material to soften, and remove it with tweezers or a brush. Learn more about keeping the printer clean here.
- External vibrations. Ensure that the UltiMaker Factor 4 will not be affected by external sources of vibration. If multiple printers are installed on the same surface and these are in operation, either pause the print(s) or wait with the gantry calibration on the UltiMaker Factor 4 until the print jobs on any adjoining printers have finished. Do not touch or move the Factor 4 during this calibration process.
Build plate leveling issues
The calibration process may fail if active leveling does not work, cannot be performed reliably, or if the vertical (Z) skew exceeds the allowed tolerance. Before restarting the gantry calibration, check the build plate leveling.
- Observe the Z stage movement. When the Z stage moves up at the start of the active leveling process, check that there is sufficient space between the cover of the build plate and the gantry cover. If these parts make contact before the nozzle probe is complete, this will cause leveling errors. Slightly loosen the gantry cover screws, push the cover upwards a little, and retighten the screws again. Contact support for further information and assistance.
- Leveling sensor test (noise level). In the Settings menu, navigate to Maintenance → Diagnostics → Leveling sensor test. This diagnostic feature will test the inductive sensor functionality and the noise level. If the value is above 8, please notify UltiMaker Support or your local reseller.
- Test bed leveling (tilt). Next, also in the Diagnostics menu, select Test bed leveling. This diagnostic feature will measure the tilt of the build plate. The maximum allowed tilt values are 0.347° for X (left to right), and 0.550° for Y (front to back). If the measured values during this leveling test exceed or come very close to these limits, please contact UltiMaker Support for more information on how to correct this.
Tip: Submit a case to contact UltiMaker Support if you need further assistance with any of these checks.
Excessive skew in gantry
If the failed calibration was not caused by user error or failure of a different printer system (such as build plate leveling), the measured skew values during the calibration may exceed the limits. The printer can only apply offsets for limited skew values without compromising the quality of the printed part and the components of the gantry.
Belt tension
Excessive skew may be caused by improperly tensioned or stretched belts. Loosen and retighten all of the belt tensioners. There are four:
- 2x Y tensioner (one on each side of the gantry, at the front)
- 1x X tensioner (on the right side of the X beam)
- 1x short belt tensioner (in the Y motor bracket, indicated on the coupling plate)
Ensure that all indicators fall within the tolerance range. If this is not the case, the belts may need replacement or there is a problem with one of the spring-loaded tensioners. Please contact support or your local reseller for further assistance.
Tip: For more information about retensioning the Factor 4 belts, please visit this support article.
Skewed X beam
The X beam, which carries the print head, must be perpendicular to the two Y belts. If this beam is skewed, it must be manually recalibrated. To check for skew, take the following steps:
- Note the metal end stops at the back of the gantry system. There is a small corner on each side, just beyond the end of the Y rails. The X beam touches these corners when moved all the way to the back.
- Manually slide the X beam to the back of the motion system, gently pushing with one hand on each side.
- Use a small mirror (held at a ± 45° angle) to check the distance between the metal end stop and the X beam on both sides. If the beam touches the corner on one side, but there is a gap on the other, the X beam is skewed and must be adjusted.
Tip: You can find detailed instructions on checking the X beam for skew as well as recalibrating the X beam to improve its alignment in this support article: Factor 4 - Skewed X beam
After performing the steps described on this page, try the gantry calibration process again. If the calibration was successful this time, the cause of the error was correctly resolved.
Need further support?
If you see ER306 again after trying the gantry skew calibration and you are unable to resolve it using the information in this article, please contact UltiMaker Support or your local reseller. Also reach out if you need additional assistance with performing the described troubleshooting steps, or for more information about services.
When submitting a support case, ensure you have your printer's serial number ready. Note the error code and the steps already taken. Additionally, save your log files and share them with support. The log files may contain more information about the measured skew values and the origin of the problem.
