Layer shifting shows up as a sudden horizontal step in the walls of a print \u2014 everything above a certain height is offset from everything below it, usually along the X or Y axis. The mechanism is always the same: the stepper motor’s rotation stopped translating 1:1 into head (or bed) movement. Either the motor lost steps, or the mechanical link between motor and toolhead slipped. Everything else \u2014 belts, pulleys, acceleration, drivers, collisions \u2014 is just a route to one of those two outcomes.<\/p>\n
This guide covers the full set of layer shifting causes and fix<\/strong> procedures, in the order you should actually check them, with real numbers where the physics gives us real numbers. Layer shifting is not<\/em> the same as ghosting or ringing \u2014 those are resonance artefacts (faint echoes near corners), not a hard positional offset. Plenty of guides conflate the two; keep them separate or you’ll chase the wrong fix.<\/p>\n Before touching a single setting, work out which of the two failure modes you have. It saves hours.<\/p>\n If you’re not sure what you’re looking at, our Diagnose tool<\/a> reads a photo of the failure and tells you which of these it is, with the exact setting to change. The step-by-step logic is also in how to diagnose a failed print from a photo<\/a>.<\/p>\n This is the most common mechanical cause. A belt that has stretched or slackened introduces play, so the pulley turns a fraction before the head actually moves. It’s especially common on the Y axis of bed-slinger machines, because a heavy bed flinging back and forth is exactly the load that works a belt loose. Prusa explicitly warns that over long print times a belt can slightly loosen and produce layer shifting or degraded quality \u2014 so re-check tension periodically, not just once.<\/p>\n Over-tightening is real but far rarer. A belt that’s too tight causes binding and accelerates bearing wear, and can itself contribute to ringing<\/a>. Loose is the problem you’ll meet ten times more often.<\/p>\n The popular “pluck it and listen for a low bass note” test is subjective and unreliable. Do it properly with a free phone spectrum analyser (Spectroid on Android, SpectrumView on iOS): pluck the longest free span between motor pulley and idler, and read the frequency peak.<\/p>\n The trap is that the target frequency depends on the free-span length<\/strong>, so a single “correct Hz” number copied from a forum is worthless unless it’s for your exact machine at your exact carriage position. The governing physics is:<\/p>\n f = (1 \/ (2 \u00d7 L)) \u00d7 \u221a(T \/ \u03bc) \u2014 where L is the free span in metres, T is tension in newtons, and \u03bc is the belt’s linear mass density (0.0083 kg\/m for standard 6 mm GT2).<\/p><\/blockquote>\n Because span changes as the carriage or bed moves, so does the reading. Here are the verified figures \u2014 treat them as span-specific, not universal:<\/p>\nStart here: is it mechanical slip or missed steps?<\/h2>\n
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Cause 1 \u2014 Loose or wrongly tensioned belts<\/h2>\n
Belt tension: use numbers, not the “guitar twang”<\/h3>\n