Introduction

I would like to introduce you to the belt tension measuring device from BIQU called Belter.

Some people have trouble using the Prusa Belt Tuning app. Especially in noisy environments, it’s virtually impossible to work with the tuner app. Problems with the smartphone can also occur. Otherwise, in my experience, the app works very well on iOS. The results are quite precise when used correctly and, in most cases, sufficiently accurate. However, if you have one of the problems mentioned above or don’t trust the measurement results and therefore want to take a second measurement, you can now check this inexpensively with this tool. Of course you can also use this tool for any 3D printer.

It’s also possible that the frequency measured with the tuner app doesn’t reflect the actual belt tension. (More on this at the end)

What do you need

• The BIQU Belter
• Printable Measurement Position Tool
• Print the Parts for the Belter or here.
• Something straight to calibrate the zero point. This can be a ruler or an alignment square.

Calibration of the Biqu Belter

First, attach the printed parts to the belter.

Now we’ll calibrate the zero point of the gauge. To do this, we hold something very straight to the front as shown and then press the zero button. In my case, I use a stop angle.

Measuring the belt tension on the Prusa XL

First we need to align the CoreXY carriage correctly for the mesurements. Here you can see how to align the XY carriage to measure the belt tension. On the Y-axis, the front of the carriage must be flush with the rear part of the Z-axis mount. Just use the positioning tool I designed.

Now I will show you how to attach the measuring device.

You can determine the exact center using the holes in the guide rails. If you count from the front, the center is exactly between the 6th and 7th holes.

Now attach the measuring device there as shown above. Make sure that the belt is parallel to the rollers of the measuring device at the bottom. Use only one finger to stabilize the measuring device to ensure an unaffected measurement result. You can also wiggle it slightly with your finger to release unwanted tension and thus eliminate inaccurate readings. Do this until you achieve a stable reading. This should only fluctuate between +/-0.05.

Final advice

The measurement results on the left and right should differ only very slightly. This should not exceed approximately +/-0.05. Otherwise, the belt tension is not balanced. However, a difference of +/-0.1 is probably acceptable.

Measurements between 4.80mm and 5.30mm should be good. Forget the minus sign. You can also compare this with the tuner app. In my case, 5.20mm is approximately 84Hz.

Important Note

Caution! When using the Prusa Belt Tuner app, problems can arise that can be misleading. It’s possible that even though the belts are actually equally tensioned, the app displays different frequencies. This isn’t an error with the app, but rather with the belt’s vibration. If, like me, you’ve adjusted the belt tension with the BIQU Belter and then noticed a significant deviation with the tuner app, it’s because In this case, the frequency does not reflect the actual belt tension. This finding can also be easily verified: Align the Y-Carriage correctly for measuring and place the tool changer exactly in the middle instead of left or right. Now check the frequencies on both sides again. You’ll notice that the belt tension is now balanced in terms of frequency:

Now we place the tool changer at the center instead of on the right or left.

So if you go by the Tuner App and the measuring position as Prusa specifies, you may never achieve balance.

I therefore recommend using the BIQU Belter.

I have also written a guide that allows you to perfectly calibrate the belt tension and alignment: