Even though it’s a small part of a model, with so many layers coming after it, the first layer of a print is notorious for problems, creating some of the most complex obstacles in 3D printing and frequently frustrating enthusiasts.
On the other hand, as the first layer is perhaps the most significant layer of a 3D printed model due to its responsibility to act as the model’s foundation, it’s essential to get the first layer right for a successful print.
In today’s article, our focus will be on the issue called the rough first layer, where the first layer becomes rough as opposed to the optimal and smooth layer that a successful 3D printing process requires.
So, what causes a rough first layer on a 3D printed model?
The factors that can cause a rough first layer on a 3D printed model are as follows:
- A build plate (printer bed) that is not level
- A first layer height that is too low
- A Z offset value that is too low
- A flow rate value that is too high
In the upcoming sections, we will take a closer look at the factors that can cause a rough first layer, find solutions for each potential cause, and examine the signs and symptoms that will help you identify the issue.
What Causes a Rough First Layer on a 3D Printed Model?
As a fair few factors can cause a rough first layer on a 3D printed model, let’s start by analyzing each one separately and in detail to understand how they can cause this issue and what other signs they bring to the table.
Build Plate Not Level
Printing with a build plate that isn’t level is a common pitfall that many enthusiasts fall into, as correctly leveling the bed isn’t the most straightforward process in most circumstances.
When the build plate is not level, there will be areas where the distance between the nozzle and the build plate get way too small for the plastic that comes out of the extruder to fit, causing the roughness on the first layer due to the nozzle dragging the plastic all over the layer.
As the existence of an area where the space between the nozzle and the plate is too small also means that there will be an area where the situation is the opposite, a build plate that isn’t level will cause partial roughness on the layer.
Alongside a rough first layer, you might experience issues such as:
- Bed adhesion problems
- Inconsistency in print lines
- Clogging of the hotend
- Gaps on the first layer
- Dimensional inconsistencies
First Layer Height Too Low
Printing with a first layer height that is too low is not ideal for many reasons, and its contribution to the issue of a rough first layer is a solid example of why.
With a first layer height that is too low, there most likely won’t be enough space between the nozzle and the build plate for the plastic to fit, causing the nozzle to smudge the plastic on the layer as it moves and create a rough first layer.
As the first layer height will affect the entirety of the first layer, it’s highly likely that the roughness will appear all over the first layer in a consistent fashion.
Some of the common issues you can also observe due to the first layer height being too low are:
- Elephant foot
- Clogging of the hotend
- Bad surface quality
- Dimensional inaccuracies
Z Offset Value Too Low
The Z offset value is one of the parameters that is often overlooked and misconfigured as it goes hand in hand with the issue of the bed not being level.
Since the Z offset value directly impacts the distance between the nozzle and the bed, a too low value will leave too little space for the plastic that comes out. As a result, the nozzle will drag the plastic across the first layer, causing the issue of a rough first layer.
With a Z offset value that is too low, you should expect a consistent pattern of roughness throughout the first layer, as there won’t be any area where the distance between the nozzle and the build plate is optimal.
Here are some of the other signs you can observe with a too low Z offset:
- Flat print lines
- The plastic sticking way too strongly to the bed
- First layer inconsistencies where parts of the print are missing
- Bumps and gaps on the first layer
Flow Rate (Extrusion Multiplier) Value Too High
While the flow rate is the least likely culprit, it can easily cause the first layer to become rough due to its direct impact on the amount of plastic that the printer extrudes.
With a too high flow rate value, the issue of too little space for too much plastic remains the same, as the printer ends up extruding way more plastic than the space below the nozzle can accommodate to cause the issue of a rough first layer in this scenario.
As the flow rate remains constant throughout the first layer, a consistent roughness throughout the first layer is the likely outcome here.
With a misconfigured flow rate that is higher than optimal, you can also see signs such as:
- Stringing and blobbing throughout the entire model
- Dimensional inaccuracies & deformation of the model
- Bad surface quality
How to Fix Rough First Layers on 3D Printed Models?
Fixing the issue of a rough first layer on your 3D printed model can become pretty time-consuming, especially if you cannot pinpoint the root cause behind it.
Below, we have created a step-by-step guide that contains fixes for all the potential causes behind the issue of rough first layers, which we recommend following in order.
- Ensure that you level the bed correctly. As manually leveling the bed doesn’t always yield the most consistent results, we highly recommend investing in an auto bed leveling sensor, such as the BLTouch, to stop bed leveling issues entirely.
- Increase the first layer height. As a rule of thumb, the first layer height should be slightly (10-20%) higher than the layer height you use for the rest of the model. Experimentation is essential to find the value that works best for the printer and the filament you use.
- Increase the Z offset value. The optimal Z-offset value is when there is only a distance equal to the thickness of a paper between the nozzle and the build plate. Note that it’s especially vital that the bed is level before you tune the Z offset value.
- Decrease the flow rate (extrusion multiplier) value. As the flow rate is a highly sensitive parameter, we recommend reducing it in increments of 1% and running test prints after each increment to see the effects.
To see whether you have successfully resolved the issue or not, we highly recommend running a test print after applying each fix. This process will save you from spending time on unnecessary solutions when you have solved the problem already and help you identify what has been causing it.
How to Identify a Rough First Layer on a 3D Printed Model?
As first layer problems can look alike at times, a significant portion of solving the issue of a rough first layer is identifying whether you’re facing this issue or some other problem that presents similar symptoms.
The issue of a rough first layer on a 3D printed model essentially refers to plastic uncontrollably spreading over the first layer, as if the printer were smearing the plastic on the first layer rather than placing the print lines carefully.
This smearing of the plastic causes the first layer to lose its smoothness and consistency, creating a look where parts of the layer both don’t look and don’t feel right due to the bumps that appear.
A rough first layer is one of the more complex issues you can face in the 3D printing world due to the many factors that can cause it and the severity of the unfavorable effects it brings to the printing process.
To quickly recap, we can list a build plate that isn’t level, a first layer height that is too low, a Z-offset value that is too low, and last but not least, a flow rate value that is too high as possible reasons behind a rough first layer.
The common point between all of these culprits is that they reduce the space between the nozzle and the build plate to a point where there isn’t enough space for the plastic to sit cleanly on the build plate after it comes out of the nozzle, creating the rough effect on the layer.