Inspection and error detection is a common quality assurance feature in 2D printing. Several 3D printers also come with webcams and alert systems to notify the user if something has gone wrong. But most of the time, when the alarms go off, it is too late to fix the printed product. The Australian engineer Chris Barr now devised a way to detect common problems in 3D printing such as layer shifting and correct them, thus salvaging the print.

Layer shifting is one of the most common problems in 3D printing, especially on consumer machines. This is usually the case when the print head skips a step in the printing process and the nozzle becomes misaligned. There are several reasons that can cause this problem. The motor of the printer could be running too fast or the rods could be set up unevenly.

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Bumping into the printer during the printing process could also cause the printhead to move to a new position. The malfunction could also be due to other problems, as troubleshooting guides explain. “If the printer suddenly shifts the layers it is most likely that one or more pulleys are not secured properly to the axis/axes”, says the explanation at 3DVerkstan.

Aus3D Director Chris Barr found the problem frustrating and didn’t want to rely solely on after-the-fact inspection when the print was already ruined. He developed a low-cost solution using magnetic encoders. After some trial and error, he came up with a prototype.

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The module consists of a magnetic encoder IC, a microcontroller, and two RGB status LEDs to detect and relay the stepper motor’s position. When the axis is moved out of its proper position, the printer quickly moves it back to the right position. “It doesn’t fix it instantly, it takes a little while to move back into place – but this happens while the print continues, without interrupting operation”, he writes.

After he proved his concept with the first prototype, Chris Barr worked on the second iteration. His blog post provides insights into all the technical challenges he had to overcome. He estimates that he will be working on it for another few weeks before he can release them for testing and eventually plans to sell them on his website Aus3D.