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I have a 3D printer that is going crazy with x-axis shift, and I need a tension gauge belt to measure the tension.

I've never used one before, and looking online, I can't tell which one would be the right fit.

Any ideas? What things should I look for?

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  • $\begingroup$ What kind of printer is it? Most Cartesian printers that experience X-axis shift are having problems with fatigued electrical wiring to the X stepper or X endstop. $\endgroup$
    – Ryan Carlyle
    Apr 12, 2016 at 14:35
  • $\begingroup$ @RyanCarlyle It's Cubicon. Not popular brand in West. Korean made. Supposed to be good. But soon after getting it, this started happening. Part of their troubleshooting suggested checking the belt $\endgroup$
    – Bashar Abdullah
    Apr 12, 2016 at 20:17
  • $\begingroup$ Looks like a cartesian XY gantry printer, from a quick googling. If you can pluck the belt like Tom mentioned and get a low note, but still get X axis shifting, my next guess would be bad X motor or X endstop wiring. $\endgroup$
    – Ryan Carlyle
    Apr 13, 2016 at 2:04

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It's extremely unlikely that belt tension is actually your problem. I've never heard of anyone using a gauge to measure their belt tension. Typically you just pull your belt tight by hand so that it produces a low note when plucked. It's far more likely that you're experiencing shifts due to too high or too low stepper current.

Unless your belt is so loose that it easily skips over the pulley (which should be obvious without using a gauge) or so tight that it completely binds up (it would be impossible to get it that tight without some kind of superhuman force) it's definitely not the problem.

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    $\begingroup$ I've read of people using smartphone apps that calculate the belt tension by measuring the frequency of the plucked belt. If you (the TO) are completely lost and need any kind of confirmation this might be a way to get it easily. $\endgroup$
    – kamuro
    Apr 12, 2016 at 10:00
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    $\begingroup$ I used a spring scale (meant for fishing). But it's really not critical. Just make sure it's not skipping teeth on the pulley and you should be fine. $\endgroup$
    – TextGeek
    Apr 12, 2016 at 17:34
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    $\begingroup$ I tensioned the belts of my delta printer equally tight solely based on their note when plucked. If you have an ear for music, that should be fairly straightfoward. $\endgroup$
    – Tormod Haugene
    Apr 12, 2016 at 18:42
  • $\begingroup$ @kamuro thanks, will do if needed. Although now it seems not the issue. $\endgroup$
    – Bashar Abdullah
    Apr 12, 2016 at 20:18
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    $\begingroup$ @BasharAbdullah your issue is one of possible signs of current problem :) #1. Check resistor on your SS (right next to black central chip. #2. There should be R200 or R100 so R=0.2 or 0.1 #3. Read current (I) value from motor label #4. V = I * R * 8 #5. this is max voltage which should be set on SS #6. set it and check if your printer works ok #7. if not - reduce it 10..15% and chceck if this helps. you can repeat #7. $\endgroup$
    – darth pixel
    Apr 13, 2016 at 8:54
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You may not need to adjust the tension, but you may nevertheless want to measure the belt tension, at least to ensure it's not too tight: the shaft on stepper motor has limitations.

In that case, no need to buy a tool, you can use an audio app showing the frequency spectrum and then you pluck the belt. The lowest frequency peak can be related to the tension as explained here:

https://benchtopmachineshop.blogspot.com/2019/04/printer-belt-tension.html

For GT2 belts and 27 N tension, assuming the distance between belt and motor face is 10 mm, the relation is

$$f [\text{Hz}] = \frac{28531 \frac{ \text mm}{\text s}}{length [\text{mm}]}$$

Be aware that by plucking the belt you will excite the higher harmonics more than the base harmonic, therefore identifying the lowest frequency may take some time and multiple tries. You should display the frequency spectrum as "waterfall". The app "Spectroid" for Android has it.

If the distance between middle of the belt width and motor face is twice the value assumed (for example, 20 mm instead of 10 mm), the belt tension should be halved (based on an inverse relationship).

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    $\begingroup$ heh, tuning your belts by sound? I always was going for a nice sound, not a specific frequency, but this is gold! $\endgroup$
    – Trish
    Oct 12, 2021 at 21:27
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People are using this Clothpin springs repurposed into a makeshift belt tensioner to tighten the belt but I would totally agree with @Tom - there is no need to use such devices or gauges and your problem lies in stepsticks current.

It would be also problem with endstops so PCB doesn;t know it's time to stop :)

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    $\begingroup$ @kamuro it's just a spring that you put on the belt. It isn't really a tensioner (you still have to pull the belt tight somehow) but it helps keep the tension consistent. $\endgroup$
    – Tom van der Zanden
    Apr 12, 2016 at 10:03
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    $\begingroup$ In the meantime I found the idea by image searching 'belt tensioner', too: iheartrobotics.com/2009/11/timing-belt-tensioner.html The search also turned up lots of other interesting tensioning designs used in various other (industrial) sectors, too. Sweet inspiration ;) $\endgroup$
    – kamuro
    Apr 12, 2016 at 10:05
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    $\begingroup$ On another note, I would assume that the current of the stepsticks also is a less important effect. I would take a look at the axis motion friction first. Parallelity of rods first, if the strength of the effect is varying depending on the position. $\endgroup$
    – kamuro
    Apr 12, 2016 at 10:09
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    $\begingroup$ Well - depending on drive train design - this effect can also apear because of low wrap angle. Which means that timing belt surrounds a pulley not enough. $\endgroup$
    – darth pixel
    Apr 12, 2016 at 11:32
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    $\begingroup$ Yes, I'm sure. A spring-tensioner is better than a loose belt, which is why some Ultimakers have them (particularly since getting even belt tension on a UM gantry is hard) but a rigid tensioner (adjust and lock) is superior to a spring tensioner. We use fiberglass-core and aramid-core timing belts in 3D printers for a reason, because they're as stiff as possible in tension. Spring tensioners makes the belt more stretchy. Specifically, when you turn a corner at positive velocity (jerk>0) any springiness in the drivetrain causes increased overshoot and therefore ringing. $\endgroup$
    – Ryan Carlyle
    Apr 12, 2016 at 17:01
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Added for reference. To my understanding, especially if you run multiple identical printers, having the same belt tension on all of them is essential to getting accurate and consistent results. The effects of overly loose or overly tight belts have been demonstrated in a YouTube video by CHEP.

As mentioned in the comments above, a frequency analyser on a smartphone can be used, a web-based analyser is available at belt.connect.prusa3d.com. Additionally, the article Adjusting belt tension (MK3/MK3S/MK3S+/MK4) explains the concepts and steps that can be taken for belt tensioning.

Photo of the web-based Prusa Belt (Beta) frequency analyser on a smartphone

Also, a simple belt tension measurement tool called Tension Meter for the GT2 belts of i3 MK3S+ or Prusa MINI+ that can easily be printed has been published by Prusament.

Tension Meter for the GT2 belts of i3 MK3S+ or Prusa MINI+

There is a similar printable model called True Open source tension meter for GT2 belts by ChipCE.

True Open source tension meter for GT2 belts

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