#prusa #coreone #3dprinting Resources for tensioning the belts on CoreXY printers like my [[kb/3D Printing/Prusa/Prusa CoreOne|Prusa CoreOne]]. ## Tensioning Instructions [Adjusting belt tension (CORE One) \| Prusa Knowledge Base](https://help.prusa3d.com/article/adjusting-belt-tension-core-one_845048) # Apps - Prusa Belt Website is better than the app (or so some people online say?) - Gates Belt Tuner (iOS) - ==Sound Spectrum Analysis (iOS)== - ==Can pick out overtones / harmonics more easily!== # Tuning Tips via [How I finally managed to tune my Core One belts properly : r/prusa3d](https://www.reddit.com/r/prusa3d/comments/1lj7amh/how_i_finally_managed_to_tune_my_core_one_belts/?share_id=h9HnjHb5qBmkmq83YTCI7&utm_medium=ios_app&utm_name=ioscss&utm_source=share&utm_term=1) After assembling my Core One kit, I was getting really frustrated with the Prusa belt tuner — both the app and the web versions. After some trial and error, I realized two important things: 1. **The belt tuner apps don't seem reliable when the belts are severely under-tensioned.** I was getting "just right" readings from the Prusa belt tuner even when the belts were clearly (became clear after completing the procedure I'm describing here) too loose. This might be due to my belt-plucking technique, but that was my experience. 2. **The Prusa belt tuner is finicky.** The biggest issue for me is that when the displayed value doesn't change for a while, there's no way to tell if it's because the tension hasn't changed or if the app has stalled. It's incredibly frustrating — and seems like something that should be easy to fix. Hope someone from Prusa sees this! So, here's what I did: - I printed this physical belt tension gauge: [https://www.printables.com/model/1312851-prusa-core-one-belt-tension-gauge](https://www.printables.com/model/1312851-prusa-core-one-belt-tension-gauge) Using it, I made sure both belts had enough tension to at least reach the "MIN" mark on the gauge. - I then downloaded the **Carbon Drive Belt Tension Tool** app (available on iOS and Android), set it to **Bicycle mode**, and used that instead. This app has been recommended in some comments here and there, and honestly, it deserves more attention. From there, I made tiny adjustments to each belt until I consistently got readings of 85 Hz. The best part is the app shows your last 4 readings, so you can immediately tell whether it's working and how consistent your results are. I only stopped adjusting once I got at least three readings at 85 Hz. **Result:** Using just the Prusa tuner, my belts were _severely_ undertensioned, which was clearly affecting print quality. Switching methods made a huge difference. **Some general tips:** - When using the gauge, place it right in the center of the belt, and try to use the same orientation on both sides (e.g., with the retention pin facing the toothed side). - When using the app, make sure you're in a quiet room. I hold the phone in my hand, facing the belt directly — not resting on the printer — to avoid picking up vibration noise. - Be consistent when plucking the belts: always pluck in the same spot (middle), and don't overdo it — once every second or two is enough. - As you adjust the belt on one side, you'll notice that the reading on the other side will change as result. Be patient and keep adjusting them back and forth in small increments until they're both at around the same value (3Hz max difference as per Prusa recommendations). Hope this helps someone out there! [](https://preview.redd.it/how-i-finally-managed-to-tune-my-core-one-belts-properly-v0-44mb8imaou8f1.png?width=1179&format=png&auto=webp&s=a172f340c6feb61230ec7ac8c747abc889ec6e1d "Image from r/prusa3d - How I finally managed to tune my Core One belts properly") Sort by: [](https://www.reddit.com/user/SgtCaffran/) [SgtCaffran](https://www.reddit.com/user/SgtCaffran/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzhlq4b/) On Android a good alternative is Spectroid! It shows you the waterfall plot, for even more insight. [](https://www.reddit.com/user/Hozukr/) [](https://www.reddit.com/user/Hozukr/)[](https://www.reddit.com/user/Hozukr/)[](https://www.reddit.com/user/Hozukr/) [](https://www.reddit.com/user/Hozukr/) [Hozukr](https://www.reddit.com/user/Hozukr/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzhm200/) Tried that as well but found it too distracting. Aiming for 3/4 equal readings in the carbon drive app was what worked best for me (and is cross platform). [](https://www.reddit.com/user/SgtCaffran/) [SgtCaffran](https://www.reddit.com/user/SgtCaffran/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzhmz2f/) I fully understand, it's a bit more complex. It's great to have some options next to the Prusa app/website. However, the Spectroid app does make it easier to get the belt in the right ballpark, similarly what you used the printed belt tension meter for. So with Spectroid, you don't even need the physical tension meter. [](https://www.reddit.com/user/Hozukr/) [](https://www.reddit.com/user/Hozukr/)[](https://www.reddit.com/user/Hozukr/)[](https://www.reddit.com/user/Hozukr/) [](https://www.reddit.com/user/Hozukr/) [Hozukr](https://www.reddit.com/user/Hozukr/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzho8bw/) That makes sense! One benefit of the printed gauge is that once you have your tension dialled in you can put it back on and use a permanent pen to mark the sweet spot in the scale. Then you can use the printed gauge for maintenance checks in the future. [deleted] • 21d ago [](https://www.reddit.com/user/callmecalcifer/) [](https://www.reddit.com/user/callmecalcifer/) [](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzil4yr/) [](https://www.reddit.com/user/MBkufel/) [](https://www.reddit.com/user/MBkufel/) [](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzk6f7w/) [](https://www.reddit.com/user/MBkufel/) [](https://www.reddit.com/user/MBkufel/) [](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzor2qc/) [](https://www.reddit.com/user/cjx_p1/) [cjx_p1](https://www.reddit.com/user/cjx_p1/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzjc2wb/) Regarding the Prusa tuner, I found that the one on the website is much more reliable than the one in the app. [https://belt.connect.prusa3d.com/](https://belt.connect.prusa3d.com/) [](https://www.reddit.com/user/whitebeardwhitebelt/) [](https://www.reddit.com/user/whitebeardwhitebelt/)[](https://www.reddit.com/user/whitebeardwhitebelt/)[](https://www.reddit.com/user/whitebeardwhitebelt/) [](https://www.reddit.com/user/whitebeardwhitebelt/) [whitebeardwhitebelt](https://www.reddit.com/user/whitebeardwhitebelt/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzm6w4g/) CORE One Better? As in it gives crazy numbers all over the place whereas the app version won’t get off 0Hz [](https://www.reddit.com/user/dominic_failure/) [dominic_failure](https://www.reddit.com/user/dominic_failure/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzjt1up/) • Edited 21d ago Not to dissuade the procedure the OP used, there is a belt tension tester that you can calibrate using piano wire. You can also buy the assembled and calibrated version if you prefer. There are also several remixes on Printables. [https://github.com/Diyshift/3D-Printer/tree/main/GT2%20Belt%20Tension%20Meter](https://github.com/Diyshift/3D-Printer/tree/main/GT2%20Belt%20Tension%20Meter) Fun note: The target tension is generally based off the servos' working angular force specifications. > The belt tuner apps don't seem reliable when the belts are severely under-tensioned. I was getting "just right" readings from the Prusa belt tuner even when the belts were clearly (became clear after completing the procedure I'm describing here) too loose. It's actually picking up an "overtone". When you pluck a string, you'll get the"fundamental" frequency, and a series of higher (and lower) vibrations at intervals moving up in frequency. You can see all of these if you have a spectrum analyzer (Sound Spectrum Analysis on iOS or Spectroid on Android). [](https://www.reddit.com/user/NoRaspberry700/) [](https://www.reddit.com/user/NoRaspberry700/)[](https://www.reddit.com/user/NoRaspberry700/)[](https://www.reddit.com/user/NoRaspberry700/) [](https://www.reddit.com/user/NoRaspberry700/) [NoRaspberry700](https://www.reddit.com/user/NoRaspberry700/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzho2ie/) I will try it! Thanks [](https://www.reddit.com/user/blacklabel8829/) [blacklabel8829](https://www.reddit.com/user/blacklabel8829/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzi0wv7/) On Android I used Pano Tuner [](https://www.reddit.com/user/Mastakko/) [](https://www.reddit.com/user/Mastakko/) [Mastakko](https://www.reddit.com/user/Mastakko/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzio7e1/) Thanks for the excellent write up [](https://www.reddit.com/user/grain_farmer/) [grain_farmer](https://www.reddit.com/user/grain_farmer/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzlc24h/) CORE One My opinion is not that the homing doesn’t work correctly due to the app not working, but that once they are both at 88-90Hz instead of 85Hz. I miss the micro switches from my Ender 3. No banging. No endless nozzles cleaning. No 5 mins to level the build plate and heat soak. Just a post it note and Z axis set to 0. [](https://www.reddit.com/user/Lorunification/) [](https://www.reddit.com/user/Lorunification/) [Lorunification](https://www.reddit.com/user/Lorunification/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzhymxq/) As a guitar player, it's wild how hard of a time many people have with tuning the belts. After manually tuning guitars for about 20 years, it is easy to forget that not everyone can listen and tell the difference between the sound of two vibrating strings - or belts in this case. [](https://www.reddit.com/user/ducktown47/) [ducktown47](https://www.reddit.com/user/ducktown47/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzipurw/) I have been playing for about the same time and I also tune my belts by ear. I play the tone in one ear from my phone and just tune by ear. [](https://www.reddit.com/user/whitebeardwhitebelt/) [](https://www.reddit.com/user/whitebeardwhitebelt/)[](https://www.reddit.com/user/whitebeardwhitebelt/)[](https://www.reddit.com/user/whitebeardwhitebelt/) [](https://www.reddit.com/user/whitebeardwhitebelt/) [whitebeardwhitebelt](https://www.reddit.com/user/whitebeardwhitebelt/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzm6zr7/) CORE One And isn’t 85hz a low E? [](https://www.reddit.com/user/umchoyka/) [umchoyka](https://www.reddit.com/user/umchoyka/) • [19d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzwpdmg/) I'm not a musician so I don't have a great frame of reference for absolute frequency and the associated sound, but unless one has a hearing disability it should be obvious to within 1-2 Hz if the belts aren't _the same_ at least. Human ears are/should be incredibly sensitive to these kinds of comparisons [](https://www.reddit.com/user/net-blank/) [net-blank](https://www.reddit.com/user/net-blank/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzhnuf2/) Commenting so I can come back to this when my upgrade kit arrives, the belt tensioning was a pain on my MK4S kit [](https://www.reddit.com/user/DariusH887/) [DariusH887](https://www.reddit.com/user/DariusH887/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzi33o2/) Same [](https://www.reddit.com/user/Inner_Name/) [Inner_Name](https://www.reddit.com/user/Inner_Name/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzijgf2/) The belt tensioner should be printed in petg? Or can it be pla? [](https://www.reddit.com/user/Hozukr/) [](https://www.reddit.com/user/Hozukr/)[](https://www.reddit.com/user/Hozukr/)[](https://www.reddit.com/user/Hozukr/) [](https://www.reddit.com/user/Hozukr/) [Hozukr](https://www.reddit.com/user/Hozukr/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzing7h/) PETG. The settings are listed on the printables page. [](https://www.reddit.com/user/Efarm12/) [Efarm12](https://www.reddit.com/user/Efarm12/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mziz10a/) iirc, they specifically call out prusament PETG. Has anyone used other brands? What was your result? I used Hatchbox PETG and it seems good. The prusa tuner app was waaaaay under for my mk4. I didn’t go back and check with it after I used the gauge and the layer shifts stopped. [](https://www.reddit.com/user/Hozukr/) [](https://www.reddit.com/user/Hozukr/)[](https://www.reddit.com/user/Hozukr/)[](https://www.reddit.com/user/Hozukr/) [](https://www.reddit.com/user/Hozukr/) [Hozukr](https://www.reddit.com/user/Hozukr/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzizfc6/) Don’t think too much about it. I did use prusament, because I had it around. Print it with whatever Petg you have. Aim for the MIN mark. Nail the tension with the carbon app. Put the printed gauge again, grab a permanent marker and mark the place where it’s right now. Aim for that level from now onwards during maintenance. [](https://www.reddit.com/user/tenclowns/) [tenclowns](https://www.reddit.com/user/tenclowns/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzjwtsh/) • Edited 21d ago the belt tuning on the mk4 along with other stuff tilted me towards the bambu, i just got the P1S on sale now. havent sold the mk4 yet but... [](https://www.reddit.com/user/call_me_johnno/) [](https://www.reddit.com/user/call_me_johnno/)[](https://www.reddit.com/user/call_me_johnno/)[](https://www.reddit.com/user/call_me_johnno/) [](https://www.reddit.com/user/call_me_johnno/) [call_me_johnno](https://www.reddit.com/user/call_me_johnno/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzhzyeh/) Thanks I will use your tips when my kit arrives [](https://www.reddit.com/user/Extension_Treat4081/) [Extension_Treat4081](https://www.reddit.com/user/Extension_Treat4081/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzksod0/) I have yet to test the actual part, but the app seemed to capture less bagground noise for some reason. The belt tuner would jump between 85 and 175 while the app was steady at 85. I do wish the assembly for the kit had a bit more emphasis on stuff like gantry squaring, I need to reassemble the printer at some point with all that in mind. [](https://www.reddit.com/user/umchoyka/) [umchoyka](https://www.reddit.com/user/umchoyka/) • [19d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzwpu4w/) It's not background noise, it's resonant frequencies. 170 is the 2x resonant frequency of 85 which would be detected if you pluck slightly to hard [](https://www.reddit.com/user/VorpalWay/) [VorpalWay](https://www.reddit.com/user/VorpalWay/) • [21d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzkti24/) MK3.9S The Mk3 series had a belt tension test built in, right in the firmware. It baffles me that they removed it, as it seemed to work fairly well. [](https://www.reddit.com/user/rogeranthonyessig/) [rogeranthonyessig](https://www.reddit.com/user/rogeranthonyessig/) • [20d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzo5p6p/) I'm almost certain i can tune my core one belts by ear. [](https://www.reddit.com/user/Think-Radish-2691/) [Think-Radish-2691](https://www.reddit.com/user/Think-Radish-2691/) • [20d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzohzue/) Yeah, prusa app does not react until it gets a nice clear reading. PRetty bad with all the resonances i have in the C1, right side works well, left side less so. Low tension doesnt even show up. Carbo drive works better, i am glad i had it from tuning my motorcycle. [](https://www.reddit.com/user/MartinMajewski/) [](https://www.reddit.com/user/MartinMajewski/) [MartinMajewski](https://www.reddit.com/user/MartinMajewski/) • [20d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/mzp56y8/) Thanks, mate! Even though I'm still waiting for my Core One kits to arrive, I'm using your findings to re-tune my Prusa XL belts. The Prusa belt tensioner app is much a crap and has given me headaches in the past. Thanks for pointing out the alternative! [](https://www.reddit.com/user/4GreenHoverTension/) [](https://www.reddit.com/user/4GreenHoverTension/) [4GreenHoverTension](https://www.reddit.com/user/4GreenHoverTension/) • [1d ago](https://www.reddit.com/r/prusa3d/comments/1lj7amh/comment/n32uzi0/) Not to be a buzz kill on Prusa, but all this belt tuning stuff seems like way too much hassle. Granted, I’m not a tinkerer but downloading this app for that and trying to trick fuck the process seems like rookie stuff. I would think Prusa could do way better. I was seriously considering ordering a Core One and I still might. Maybe I don’t understand the complexities. I do understand if the belts are not at the correct tension you get crappy prints but considering Prusa’s good reputation I would expect better. **Top 2%** [Rank by size](https://www.reddit.com/best/communities/24/#t5_3gwdv/) [](https://www.reddit.com/best/communities/24/#t5_3gwdv/) Created Oct 12, 2016 Public --- ## User flair  grumpyengineer89 --- ## Moderators [](https://www.reddit.com/message/compose?to=r/prusa3d) [Message Mods](https://www.reddit.com/message/compose?to=r/prusa3d) - [u/projectstew](https://www.reddit.com/user/projectstew/) - [u/elint](https://www.reddit.com/user/elint/) - [u/josefprusa](https://www.reddit.com/user/josefprusa/) Prusa team Josef Průša - [u/Mikolas3D](https://www.reddit.com/user/Mikolas3D/) Prusa team - [u/AutoModerator](https://www.reddit.com/user/AutoModerator/) - [u/Prusa3D](https://www.reddit.com/user/Prusa3D/) Prusa team Prusa3D by Josef Prusa - [u/nomadsgalaxy](https://www.reddit.com/user/nomadsgalaxy/) Prusa team The Nomad [View all moderators](https://www.reddit.com/mod/prusa3d/moderators/) [Reddit Rules](https://www.redditinc.com/policies/content-policy) [Privacy Policy](https://www.reddit.com/policies/privacy-policy) [User Agreement](https://www.redditinc.com/policies/user-agreement) [Accessibility](https://support.reddithelp.com/hc/sections/38303584022676-Accessibility) [Reddit, Inc. © 2025. 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