How to hide Z seams from 3D printing (Cura)

Whenever you print an object with smooth sides (not in vase mode), you may notice uneven alignment on the sides of the print. Although this phenomenon is sometimes wrongly called“Spots” or “buttons”, but a more correct term is “Z-shaped seams”. The AZ seam usually looks like a line across the entire Z axis of the model.

mostThere are A-Z stitching on all 3D printed parts. However, the visibility and severity of seams can vary depending on several different factors, including the size and shape of the model. Bump lines may be more visible on tall, round objects. This is because taller pieces will automatically have longer seams, while the smooth walls of rounded pieces make the seams more obvious.

AlthoughZ-shaped seams don’t necessarily affect the functionality of the part, but it can still be annoying, especially when printing display pieces like vases or cosplay pieces. Fortunately, there are solutions that can help you reduce the visibility of Z-shaped seams on your prints. In this article, Mohou.com will learn with youlead toThe causes of Z-seams, how to avoid them, and some Cura settings you can use to control and hide Z-seams.

A,reason

Z-shaped seams are caused by extrusion at the start or end of each layer (Source: Heijmenberg via Reddit)

As we mentioned,Zigzag is a print quality issue found in virtually all prints, but its severity depends on many factors. Let’s take a closer look at the extrusion process.

The AZ seam is formed when the print head (specifically the nozzle) moves to the next layer. Just before this jump, the extrusion stops and the printhead stops momentarily while the Z-axis stepper motor lifts it to the next layer.

During this pause, excess filament may escape from the nozzle. This unnecessary compression is due to pressure buildup on the hot end during printing. When the extruder stops briefly, this pressure is released, causing a small flow of material from the nozzle. Excess material sticks to the print in the paused position, formingRaised Z-shaped seams.

As for aligning the bumps, that question is up to the slicer. Most slicers automatically set the start point of the next layer directly above the end point of the previous layer, so the bumps line up to create a highly visible effect.Z-shaped seams.

Although this alignment seems easy to avoid, placing the start and end points in the same location is more efficient and helps keep printing time down. Additionally, moving the starting point does not remove the built-up pressure, so moving over the print to start the next layer in a new location can cause the print to look stringy.

two,prevention

Calibrate yourElectronic steps can improve extrusion (Source: m3tolli via Reddit)

deal withThere are two methods for Z-shaped seams: prevention and masking. To avoid printing problems, you must identify and resolve the source of the problem. For Z-joints, the source of the problem is pressure inside the hot end, releasing excess material onto the print.

This stress is caused by imperfect extrusion throughout the printing process, and preventing it can be a difficult task. Ideally, you want to perfect your printer’s extrusion by adjusting all the influencing factors.

Unfortunately, many slicers, firmware, and mechanical considerations can affect the machine’s extrusion, so it can be time-consuming. Here are some extrusion calibration techniques and other features that can help prevent hot end stress:

Calibrate the extruder (Step E): Calibrating an extruder involves adjustmentsStep E to ensure precise extrusion from the extruder motor. In other words, a calibrated extruder will ensure that when 10mm of filament is extruded, exactly 10mm goes into the hot end.

Adjust flow:Flow, sometimes called extrusion multiplier, is another extrusion variable. Flow rate determines the speed at which the filament is extruded (usually as a percentage). It is best to adjust this value after calibrating the extruder.

Nozzle temperature:Nozzle (or more specifically, hot end) temperature is another critical factor in extrusion. The hotter the nozzle, the faster the material melts and flows through it. Excessively high temperatures often result in excessive compression, resulting inZ-shaped seams are more visible.

Print speed:Print Speed ​​controls how fast the nozzle moves. Lower print speeds give the filament more time to extrude and help limit hot end pressure.

Too much slippage can cause some bits to be lost in the print (source:Kurvalak via Prusa Research）

slide:This feature tells the printer to stop actively extruding material but continue moving onto the last part of the layer. Sliding assumes that hot end pressure will complete the extrusion of the nozzle layer. While a little slip can help, be careful not to set the slip value too high, otherwise you may experience tiny gaps in your print when the material runs out before a layer is finished.

Retract:Withdrawal is an option that can beA printing feature enabled on a 3D slicer that tells the printer (more specifically the extruder) to retract the filament from the hot end at the end of the nozzle movement. Pulling the filament back relieves pressure from the hot end when the nozzle is paused, but pulling back too much can clog the nozzle. This setting helps avoid Z-shaped seams and reduce strings in prints.

Retract when layer changes:This has nothing to do with the overall withdrawal,“Retract on Layer Change” is a setting that can be enabled and, as the name suggests, retracts when the hot end moves to the next layer. Although this increases print time and may produce undesirable results if the shrink distance is long, it is one of the first settings to enable if there are problems with the Z-seam.

to wipe:Wiping is another slicer feature that uses a different method than retraction to relieve pressure from the hot end. Rather than reversing pressure to reduce pressure, wiping allows the hot end to reduce pressure on the printed model. This feature tells your printer to briefly move from side to side after completing a layer to relieve pressure from the hot end before moving on to the next layer.

Linear feed:Finally, linear advance is a firmware feature that, like freewheeling, adjusts based on expected hot end pressure. This feature doesn’t actually prevent pressure, but it uses pressure and a set compression value(K) to keep the extrusion and printing speed constant.

three,Slicer Settings

randomizationZ-stitching does not prevent problems, but spreads them out (Source: b3p4u, via Reddit)

If you’re like many users, you don’t want to go through the difficult and timely process of avoiding the stress of hot ends, or you’ve adjusted your settings but still have visible information.Z-stitching, then hiding the seams might be a better solution for you. The easiest way to hide or weaken the Z-Seam effect is to use the Slicer settings; we will look at some of the most important and relevant ones available in UltiMaker Cura.

Z-shaped seam alignment

These tuning options control the inevitableZ sewing bump alignment. There are four options to choose from:

Specified userAllows you to manually controlThe location of the Z seam. Once selected, you can choose some predefined options (such as “Right Return”) or set the X and Y axis coordinates. It may also be useful to enable the “Z seam” option. relative” to manually enter coordinates relative to the center of the room.

shortest settingThe starting point closest to the nozzle when making the previous layer. As you would expect, this option produces a straight bump, so if you want to hideZ-stitching, this setting should not be selected!

randomas the name suggests, sets the starting point of each layer to a random location. AlthoughThe “Random” option prevents straight Z-shaped seams from appearing, but it still results in visible stitches, just at different points.

sharpest angleChoose the sharpest corner to placeZ-shaped seams. The corners are great for hiding the Z-shaped seams, as the seams almost blend into the top.

Sewing angle preference

Putting the seams in the corners will make them less visible (source:Prusa Search）

If you need to select a corner as the start point of the layer, these options control how the corner is selected. This setting also contains a few options:

NoneTell your slicer not to set any special preferences when selecting a layer’s starting point. (If you use“Z Seam Alignment” “Acute Angle” adjustment, don’t worry, the sharpest angle will always be selected as the starting point. )

Hide the seamsPlace the seams on the inside corners of the pattern. Since the seam is in the innermost corner of the model’s shell, it should theoretically be less visible.

visible seamsDo the exact opposite of the previous one and place the seam in the outermost corner. This would seem to make the exterior more obvious, but depending on the model it might be better.

Hidden or exposed seams tell your printer to use the innermost or outermost corner as a starting point.

Intelligent concealmentSimilar to the previous one, but it tries to select as many innermost corners as possible, while still allowing the outermost corners to be selected.

Spiral outer contour

The next parameter is to“Special Mode,” often called Vase Mode, softens the Z-axis jump by gradually jumping and never stopping nozzle movement until the print is finished. The result is faster printing of single-layer objects with significantly less visible Z-shaped seams. This parameter has a subparameter:

Only if enabledSmooth spiral contours are only available when “Outer Spiral Contour” is selected. It smoothes the movement of the print in vase mode to further limit the Z-joint effect.