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AB belt tension


Well-known member
Printer Model
Formbot V2.4 R2
Use a pliers they say 🙂 so I used a pliers to try and tighten the AB belts and ripped the end of the belt off. My question is how tight should I be getting the belts by adjusting the length coming out of the carriage? Do I just get the belts even and use the front tensioners to get them tight? At what point do I use the front tensioners?


I loosen the front idlers all the way and get the belts equal length and as tight as I can get them by hand on the carriage. Then I adjust the front idlers equally until I find the tension I am looking for. There is some guidance on the docs site, but at this point, I know it when I feel it.


Well-known member
Yup, no need to use pliers, tighten them by hand and then use the tentioners that's what they're for.


Well-known member
Thanks for the replies. I used the tensioners and got them where they feel good to me. If am thinking of maybe get some of the electronics done so that I can test the movement before finishing the hotend.


Well-known member
That's most likely good enough to start with. The resonance testing is easy enough to do with a smartphone though. Also keep in mind belts will stretch with time especially at the beginning, you will likely need to add some tension.


Staff member
Voron Owner
For what it's worth, the best belt tension is almost always less than you think it should be.

Hot Toddy

It's probably not a new idea but thought I'd share as it could be a useful tip for others.

I've recently built a Trident and struggled with getting the belt tension right, as none of the phone apps suggested in the Voron docs seemed to give any consistent results.
Then I had a Eureka moment!
Being a guitar player, I have a guitar tuning gizmo to help tune each string to the right frequency. And it just so happens that the 5th string of a guitar in standard tuning is 110Hz - just the frequency we're looking to get when the A-B belts are tensioned correctly.
So, having set the 150mm spacing between the tensioner and idler centres (to leave the 150mm of belt on each side of the printer to twang) I placed the guitar tuner close to the belt and started twanging as I adjusted the belt tension. And it proved very satisfying to accurately get a tension that just holds the green light on (frequency spot on) or blinks the red lights to indicate frequency just too low (flat) or just too high (sharp). Much easier and more accurate than the other methods suggested.

The following link has a video demonstrating the process.



Well-known member
Since we are sharing, I have also used my mic from my Steelseries headset and some software to tune.


Active member
I bet a lot of new Voron owners overtighten their belts in the installation process, not sure if the mention of pliers in the manual is a good move. I just finished my build and i think mine are overtightened as well. I will leave it for the time being, to see if they stretch a bit.


New member
I spent hours trying to get the right "twang", I am no guitar player and every time I plucked the same belt with no adjustment, it sounded different. I have probably over-tightened them; I am quietly waiting for the whole gantry to collapse from the belts being over-tightened, but up until that day I will keep printing.