Intervening with Tension: The Ender 3 (Pro) Belt Tensioner
If you own an Ender 3 or Ender 3 Pro, you know its efficient and reliable belts are what make the print head and bed move along their X & Y axes. However, it’s important to make sure the belts aren’t too tight or too loose otherwise they can cause a variety of problems. An ideal belt tension should be firm enough to prevent slipping and maintain smooth movements, but not so tight it causes warping or damages the machine.
Loose belts can make a huge difference in the quality of your prints, from skewed layers to poorly dimensioned parts. If too much tension is applied, it can lead to damage and wear and tear on the carriage mechanisms which can be more expensive to repair. The good news is that adjusting belt tension isn’t a difficult process; simply repositioning the pulley on the relevant axis will allow you to achieve the optimum level for your machine.

However, adjusting the belt tension on an Ender 3 or Pro is not as straightforward as it is on newer models, such as the Ender 3 V2. This is because Creality’s original designs don’t include adjustable belt tensioners – instead, they feature fixed belt pulleys near the end of the X- and Y-axes that can’t be easily moved. To adjust the tension, users have to loosen the pulley structure, push it back or forward (which requires some strength), and then secure it again in place.
Luckily, companies like other Creality and the maker community behind the Ender 3 have developed adjustable belt tensioners that make changes on an axis a breeze. With an adjustable belt tensioner upgrade, all you need is to rotate a knob in order to perfectly tension your printer belts. In this article, we’ll guide you through what parts you will need for your specific model of the printer as well as how easy it is to install and use the upgrade.
What Exactly Are They?
Belt tensioners can be a real saving grace for 3D printer owners, especially for beginners of the Ender 3 and Pro varieties. Instead of having to manually reposition the idler pulley in order to adjust the belt’s tension, belt tensioners make it possible to fine-tune with only one twist of a knob! When setting up your machine, it’s important to note that belt tensioners usually come equipped with a frame, knob, idler pulley, and screw – all designed to work seamlessly together.
By using a pulley and looping the belt around it, you can easily adjust its tension by rotating the knob attached to it. The further away from the axis you move the pulley, the tighter becomes the belt; conversely, moving it closer allows for some slack.
In particular, the Ender 3 printer relies on its tensioner to keep parts such as belts and lead screws tightly fitted to its frame. Installing a tensioner is generally very straightforward; typically the unit will attach to an aluminium extrusion of the printer with few screws.
Now that you have been acquainted with the belt tensioner and its purpose, it’s time to consider which option is best for your Ender 3 or Pro.
Various Options Available
The Ender 3 and Ender 3 Pro are surprisingly similar in many regards, but when it comes to belt tensioner design for the X-axis both models require a distinct set of parts. While a belt tensioner intended for the X-axis of either model is interchangeable, the Y-axis tensioners differ significantly between these two printers. This is because the original Ender 3 uses an extrusion made up of 2040 aluminium whereas the Pro version utilizes a much sturdier 4040 extrusion.
When it comes to buying belt tensioners, you don’t have to spend a fortune. These helpful tools can be purchased for as little as $10-$15 per piece and are typically made of metal to provide reliable and long-term use. However, if you’re trying to save money, 3D printing your own belt tensioner might be a great way to get the job done for cheaper
Here are some good options:

Purchasable
Printable
One thing to keep in mind while printing a belt tensioner for your Ender 3 or Pro, it is essential that you use the correct print settings. Not only will this affect the structural integrity of the part itself, but it will also have a direct impact on the tension of your belt. You don’t want to find yourself mid-print and suddenly realize that your belt tensioner has broken, throwing off all of your settings and requiring you to start over again.
Installing and Utilizing

Installing a belt tensioner on either an Ender 3 or an Ender 3 Pro isn’t complicated. It’s actually surprisingly easy – the process of installation is basically identical no matter which axis you’re putting it on; the only real difference is the end positioning. To ensure things are properly done, here are some helpful tips.
- Before installing it, though, make sure to use an appropriately-sized Allen key to remove the current belt pulley on the correct side of the axis. To guarantee positive results, this should be located at the opposite end of the axis than the stepper motor used to move and pull the belt in place.
- With the belt now loose, it’s time to finish installing your belt tensioner. Put the end of the belt into the slot in the tensioner’s pulley wheel and then loop it around, making sure that it is securely fastened.
- Now loosens the adjustable knob on the belt tensioner as much as possible without making it fall. This will reduce physical stress on the parts of the printer and make adding the upgrade simpler.
- Correctly placing the belt tensioner is a critical step for achieving optimal performance from the axis. To ensure it goes in the right place, start by looking at where it’s going: if it’s for the Y-axis, make sure its pulley wheel is level with that of the motor-side pulley. For the X-axis, ensure that the longer side of its frame is facing you as you insert it into the front of your extrusion.
- Check to see if the tensioner’s pulley, which has a belt wrapped around it, is stuck by moving the pulley on the motor side with your hand.
- When securing the new tensioner onto the axis, it’s important to use the same Allen key as well as original (or new, if provided) screws for a more secure fit. While it may seem natural to pull back on the tensioner with all your might, you don’t need to overdo it; there’s an adjustable knob that’ll provide precisely the right amount of tension when you’re done tightening everything down.
- Rotate the adjustable knob on the belt tensioner to achieve the desired tightness. It should be tight enough that the carriage moves smoothly but not so tight that you feel each bump along its axis. If the motion is too wobbly you should tighten the belts and if it’s too hard or rough you should slightly loosen them.
Congratulations, you successfully took a step towards gaining the most out of your Ender 3 or Ender 3 Pro! With this tensioner installed, managing the movement of your machine will no longer be a hassle. Tightening tensions won’t be an issue, and you can rest assured that working with this belt tensioner will give you an easier workflow.

Ganesh Divte
I am Ganesh Divte. I work as a Quality Assurance Engineer at Dhruvtara WireTech PVT LTD. I have experience in SLS, DMSL, FDM, and SLA additive manufacturing processes. I am very enthusiastic about additive manufacturing and its potential to change the way we manufacture products. I believe that Additive Manufacturing has the potential to revolutionize the manufacturing industry and make it more efficient and sustainable.