Adjusting Belt Tension

I do not own a Shapeoko, but your forum is very lively and full of useful information so I visit often. One recurring theme that I see is how do I know when my belts are tensioned properly. Many responses allude to it being tight and when plucked it makes a sound. Has any one experimented with using one of the tuner apps, like Pano Tuner or one of the free guitar tuning apps to see if the correct tightness can be established by matching and measuring the frequency of the sound of a properly tightened plucked belt and thereby made reproducible by others?

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A guitar tuning application might work. However experience is the best app. It requires no extra hardware or electricity or battery. The thing about most Shapeoko tuning is what you feel. Not sure the belts would make a discernible tone that would be recognized by a listening application. Give it a try to see if it works.

Usually when belts are loose an exercise of cutting squares and measuring them help the most with getting a belt tight enough. You draw a square like 2 inches and cut it and carefully measure it. If it is two inches either your belts are not tight enough and/or you need to calibrate the stepper motors. If the squares are made multiple times and they are consistently the same size then stepper motor calibration is in order. If the squares are inconsistent in size the belts are most likely.

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Apparently @WillAdams and others already tried that method, I don’t know why it didn’t stick, there may be too much variations depending on how exactly the measurement is performed.

My own un-scientific rule of thumb, or rule of index in this case, is to have the belt tight enough that when the carriage is homed, I cannot quite slip my index finger under the middle of the belts.


Hi Julien,
Doesn’t finger size come in to it then, one size does not fit all as I’m sure you know.


Yeah I can live with that source of inaccuracy I guess :upside_down_face:


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