Belt Tension Measurement Tools

I watched Winston Moy’s helpful video on belt tensioning but my XXL is considerably heavier than the machine used in the video. Besides, I’d really prefer to have an instrument to give me consistent results and a quick way to spot check tension before the day’s runs.

I’ve been looking around for belt tension measurement tools, and most suitable (non-automotive v-belt/serpentine belt) tension measurement instruments seem to be pretty pricey. The cheapest I’ve found that appears likely to be appropriate to these little belts so far was about $250, and the tariff climbs rapidly from there, with the next stop I found at $750. Before I drop that much I thought I’d look for other options.

I’ve ordered a couple of inexpensive “fish scale” pull meters to experiment with. I also happen to have a precision powder scale I can use to make comparisons tests to see if the “fish” scales are accurate, at least on the low end.

Any other suggestions for making these measurements without spending $250+?

TIA.

If you pull on the center of the unsupported length of the belt perpendicular to the axis of the belt and measure the force for a set deflection (like 2 lbs for a 1 inch deflection of a 2 ft length of belt, or whatever the right numbers are), you can use that as a standard so that you always tension the belts to the same value. High end belt tension measuring devices measure the natural frequency of the belt as it oscillates back and forth to determine the tension.

Another way to do it would be to use a spring with a known spring constant to pull the belt. Then, you know what the tension is by measuring the deflection of the spring. IMO, it seems like that would have been pretty easy to implement into the design of the machine without much extra cost. As long as the preload on the belt is higher than the torque the motors can put out you don’t have to worry about inaccuracies due to belt deflection.

Remember to recalibrate the “steps/inch” of an axis anytime you adjust the belt tension since that number will change if the tension changes.

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Back when the belts has more clearance, one could pluck them and adjust by tune — that’s still workable on the Z-axis, and apparently there are apps which use a microphone to assist this. (And I had to use a small pry bar)

I tried tensioning by half the dead weight of my SO3, and that, as a starting point, plus an equal number of turns of the M3 screws seemed to work well.

I was thinking up some sort of spring set-up on the outside of the black metal frame could provide constant/consistent belt tension, but I haven’t really moved past the idea stage.

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The belts on one of my 3D printers uses basically clothespin springs at the end of each belt to keep uniform tension. The belts are just threaded through the tensioned spring and so far after about 2 years and lots of hot printing the machine is just as in adjustment as day 1. I’ve thought about adding some to my XXL, but I’ve never gotten past just musing over the idea. Maybe someone else will try it while I’m sleeping, haha!!! Total time maybe 10 minutes to install, total cost 3 clothespins?

Dan

Someone used it for the xxl upgrade since the Z plate dosent have the tension ajuster,im trying to remember and find the link

here you go,it was sarge

I use these on my 3d printer aswell…also you can 3d print them from thingverse

Ultimaker Belt Tensioner v2 by slouce - Thingiverse (printable)
Simple clothespin belt tensioner by mrice - Thingiverse (clothspin instructions)
Customizable Belt Tensioner by nischi - Thingiverse (printable)

Which reminds me…Are we ever going to be able to purchase this plate for the Z tension???

@carbide3d