What Can Cause the Ender 3 (Pro/V2) to Print Circles That Aren’t Round?

Everyone who has been 3D printing for some time knows that problems can come in many shapes and forms, with some, such as layer adhesion problems or over-extrusion, being a lot more common than the others due to how a 3D printer performs its regular operations.

Because of this, while observing issues that you have experienced before is usually more straightforward to solve, noticing a problem that you have never experienced before can leave you quite puzzled, especially if you have been 3D printing frequently for a long time.

Today, we will be diving into one of the rather odd issues that you can face while printing with your Ender 3, where the 3D models that should be circular don’t really come out perfectly circular and end up having edges instead, which can be slightly or highly defined based on the severity of the problem.

So, what can cause your Ender 3 to print circles that aren’t perfectly rounded?

Below, we have listed the common factors that can cause your Ender 3 to print circles that aren’t rounded correctly:

  • Loose X-axis and Y-axis timing belts
  • X-axis and Y-axis Carriages are unable to move smoothly
  • Incorrectly configured X-axis and Y-axis steps
  • Misconfigured X-axis and Y-axis stepper driver currents

In the following sections, we will be analyzing the potential factors that can prevent your Ender 3 from printing perfect circles, discuss what we can do to fix this problem as quickly as possible, and look at the signs that can help you identify whether your Ender 3 may be having issues with printing circles or not.

What Can Cause the Ender 3 (Pro/V2) to Print Circles That Aren’t Round?

Observing that the circular models on the screen come out with edges after the 3D printing process can definitely be very confusing, especially if you haven’t experienced such an issue before.

You can find the most common factors that will prevent your Ender 3 from printing the circles correctly below, alongside their detailed explanations:

  • The X-axis and Y-axis timing belts are loose. As the timing belts are directly responsible for transferring the motion from the stepper motors to the X and Y axes of the 3D printer, loose belts will end up with an incorrect movement transfer, causing the filament to end up at the wrong positions.
  • The X-axis and Y-axis carriages cannot move smoothly. The X and Y-axis carriages connect to the rails with rollers that allow them to move smoothly, and in the case where these rollers scrape against the rail or wobble, the movement of the 3D printer will be inconsistent.
  • The X-axis and Y-axis steps are set incorrectly. Incorrect step values cause the actual movement of your Ender 3 to differ from the calculated motion, with either axis moving more or less than intended with each move, which can produce circles that aren’t round as a result.
  • The X-axis and Y-axis stepper currents are misconfigured. If the stepper motors aren’t receiving the optimal amount of current, they won’t be able to provide the precise movements required to print perfect circles, which will cause your circles to have imperfections on them.

How to Fix the Problem of the Ender 3 (Pro/V2) Printing Circles That Aren’t Round?

Due to the possibility of a few distinct issues causing the problem, both electrical and mechanical, coming up with a solution, especially if you don’t precisely know what’s causing the problem in your case, is not a very straightforward task.

Below, we have listed the detailed solutions that correspond to all the common culprits that can prevent the Ender 3 from printing perfect circles:

  • Tighten the X-axis and Y-axis timing belts. To tighten the timing belts, you will need to loosen the belt tensioner bolts, manually pull the belt tensioners with your hands until the belt is tight, and tighten the bolts back at this position. In an optimal scenario, the belts should always be able to move smoothly and not wobble.
  • Adjust the X-axis and Y-axis carriage eccentric nuts. As fully turning the eccentric nuts in any direction will put them back into the position they have started on, we recommend turning them very slowly until the wheels rotate smoothly on the rail without any wobble. You can find the eccentric nuts behind the rollers that attach the carriage to the rails.
  • Re-configure the X-axis and Y-axis step values.To find the correct values, start by clipping a paper to the print bed, and marking the starting point of the nozzle on the paper. Then, move the X-axis by 100 millimeters, and mark the ending point. Measure the distance between the two points, divide 100 by the value you have found, and multiply with your current step value. Finally, repeat for the Y-axis. You can find the area for configuring the X-axis and Y-axis step values in the Motion sub-section of the Control section, with the names Xsteps/mm and Ysteps/mm. 
  • Re-configure the X-axis and Y-axis stepper currents. As configuring the stepper currents (also known as VREF tuning) is an advanced process that will require you to unscrew the bottom cover, expose the mainboard, and interact directly with the potentiometers found on the mainboard, we can only recommend this solution if you’re already familiar with electronics, especially considering that there is a risk of permanent damage.

As always, after applying any particular solution on the list, we highly recommend running a test print to find out whether the issue has been resolved or not, which will allow you to see the exact solution that was successful.

How to Identify the Issue of the Ender 3 (Pro/V2) Printing Circles That Aren’t Round?

While identifying that an object printed with a 3D model that should have been circular isn’t circular is usually pretty straightforward when the edges are very defined, in some cases, the error could be a lot smaller and not visible to the naked eye at first look.

To confirm whether your Ender 3 is printing circles that aren’t correctly rounded, we highly recommend downloading a circle testing model and printing it, which should ideally consist of concentric circles that will allow you to determine the severity of the problem across distinct circle sizes.

If you are still unsure, you can bring the process a step forward by using the circle you have printed to draw a circle on a piece of paper and measure it with a protractor tool, which will make it very apparent if the circle is not circular.

Wrapping Up

The issue of the Ender 3 (or any other 3D printer) not being able to print round circles is definitely one of the more bizarre ones compared to other problems in the 3D printing world, especially when everything else is working just as it should be, and this particular issue is the only wrong thing that stands out.

To quickly recap, the primary culprits behind your Ender 3 not being able to print circles correctly all share the common point of the existence of an issue with the movement of the printhead on the X and Y axes, such as the motor not working, or the motion not being transferred correctly.

As mechanical, electrical, and software components can cause this problem, we believe that pinpointing the root cause in your case and applying the corresponding solution will be a slightly challenging journey and a significant learning experience if you have no prior familiarity with such scenarios.

Happy printing!