Tuning the X-Carve belt tension by the sound of plucking it

Over the last couple of days I had to replace both of my Y axis belts - one snapped and the other had a crook in it. So I was thinking about setting the belt tension and how it would be good to match them to each other. I got the idea from the instructions “Tighten the nut until the belt is taut and you can pluck it like a loose guitar string” that maybe a great way to set the tension would be by plucking them and adjusting until the notes match. I someone with a known correct belt tension were to make a video plucking them, then others could use that as a reference for setting theirs.

Here is a video of plucking my belts I don’t know how correct my belt tension is, but I think it may be pretty good. If the idea works then it could be added to the assembly instructions and save a lot of uncertainty for builders.

That’s about where I have mine “tuned.” Haven’t had any problems yet after a year or so (1000mm machine assembled in April 2015, first set of belts).


I recently found an Android app for measuring belt tension via plucking and audio analysis…


It may not support the belts that we use, but could be used to compare across different machines once common settings are chosen.

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I tune mine by ear but just for the heck of it I clipped one of my $10 guitar tuners to the Y gantry. The tuner says my belt is between a C# and a low D note. Though that will depend greatly on how long the belt is between the clip and the first roller wheel. Edit: took a tuner app on my Android phone. I’m running about 70hz with the gantry all the way back on a 1000mm XCarve. I have no idea whether that’s too loose or tight but have yet to miss a step or break a belt.

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More just a matter of choosing settings to use for comparison. :wink:


I just tried it and could not get a repeatable reading using the default belt. :frowning: