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Comprehensive 3d Printing Troubleshooting Guide- Part 4

Comprehensive 3d Printing Troubleshooting Guide- Part 4

More Print Quality Problems 

Infill is Visible from the Outside

What’s the problem?

The final print shows the infill structure or pattern through the outer layers.

Why is it happening?

As the infill is printed into the boundaries of the outer layers, it is more likely to be visible through these layers. This effect is most prominent with thin-walled prints.

This is commonly caused by having an incorrect wall thickness in relation to the size of the printer’s nozzle. In normal print conditions, wall thickness should be directly related to the nozzle size—if you have a 0.4 mm nozzle, the wall thickness should be a multiple of .4, such as 0.4, 0.8, 0.12, etc.`

Troubleshooting

Check the Shell Thickness

Check the shell thickness and ensure that is a multiple of the nozzle size.

Increase the Shell Thickness

If the problem persists, increase the shell thickness by the next multiple of the nozzle size. For example, if your nozzle and shell thickness are both .4 mm, increase the thickness to .8 mm.

Use Infill After Perimeters

Most slicing software will enable you to activate infill printing after perimeters.

  • In Cura, enter Expert Settings and select ‘Infill prints after perimeters’ in the Infill section.
  • In Simply3D, enter Edit Process Settings, select ‘Layer,’ and select ‘Outside-in’ next to the ‘Outline Direction’ under ‘Layer Settings.’
 Check Print Platform

If one portion of the print is showing the infill more than others, improper calibration may be to blame. Check around the model to see whether the infill visibility is the same throughout. If not, perform calibration from scratch.

 Print Shells according to print type

Depending on the type of print, you can use the infill and shell printing order to your advantage.

For intricately detailed, high-quality prints with a nice surface finish that does not require a lot of structural stability, print the model from the outside-in. If the print strength is critical, print the model from the inside-out and double the wall thickness.

Cracks in Tall or Long Prints

What’s the problem?

Larger prints are cracking or showing signs of brittleness.

Why is it happening?

As the layer height increases, the filament cools more rapidly. The heat from the heated print bed does not keep it at a higher temperature, which impairs adhesion higher in the print.

Troubleshooting

 Extruder Temperature

Increase the extruder temperature by 10 ℃. Working hot end temperatures are typically printed on the side of filament packaging; try to keep the temperature adjustment within the printed range.

Fan Direction and Speed

Check your fans and ensure they are effectively angled, on, and evenly cooling the working layers of the print. Try reducing their speed to minimize the cooling effect on higher layers.

Layers Don't Line Up Well

What’s the problem?

As the print develops, there are a few quality issues, like layers misalignment. The layers are slanting mostly in one direction, producing an uneven print.

Why is it happening?

Over time, 3D printer components, such as nuts, bolts, and belts, will become loose and require maintenance. If not addressed, layer misalignment can eventually result in shifting layers, but this issue is primarily visual without having noticeable effects on stability. The cause is usually linked directly to a loose belt.

Troubleshooting

 Check the Belts

Begin by checking each belt and ensure it is tight but not overstretched. There should be some resistance from the two belts when they are pinched together. If you find that the top section of the belt is tighter than the bottom, it requires tightening. Some printers include built-in belt tensioners. Others can be retrofitted with 3D-printed tensioners for ease of use. If neither of these works for your printer, the manufacturer likely provides instructions on manual belt tightening.

Printer belts typically comprise a continuous loop of material hooked around two pulleys. A common issue is that the belt can slip off one pulley and gradually tighten along the top, leading to misaligned layers.

 Clean and oil Rods

Over time, debris can build up on the rods, leading to portions with higher friction, which affect the free movement of the head and cause layer shifting. Wiping down and re-oiling the rods usually solves this problem.

Check for Bent or Misaligned Rods

If the print head consistently falters at specific points, it is likely that one of the rods has become slightly bent.

Turn off the machine and move the print head through the X- and Y-axis. If you feel resistance, there is something wrong.

Check the rods. If all rods are aligned, remove them and roll them on a flat surface to identify any bending.

Many printers use threaded rods rather than lead screws, and these are more likely to bend. In this case, simply use control software such as Printrun to move the print head up or down. If one of the Z-axis rods is bent, it will be immediately observable.

Unfortunately, it is nearly impossible to straighten a rod once it’s bent, but it’s a good excuse to replace old threaded rods for lead screws.

Check Drive Pulleys

Drive pulleys are typically connected directly to a stepper motor or one of the main rods that drive the print head. If you carefully rotate the pulley, you will see a small grub screw. Holding both the rod and the attached belt, tug the belt to force the pulley to turn. There should be no slip between the pulley and stepper or rod. If there is, tighten the grub screw and try again.

Some Layers are Missing

What’s the problem?

Some layers were skipped or inconsistently printed, leading to gaps in the print.

Why is it happening?

The printer did not extrude sufficient plastic for printing each layer. Infrequently skipped layers are characterized by “temporary under-extrusion.” There may have been a problem with the filament (e.g., diameter variation), the filament spool, the feeder wheel, or the nozzle.

Alternatively, friction can lead to the bed becoming temporarily get stuck. The cause may be that the vertical rods are not perfectly aligned with the linear bearings.

It is also possible that there is a problem with one of the Z-axis rods or bearings. The rod could be distorted, dirty, or overly oiled.

Troubleshooting

Mechanical Check

Begin by checking the rods and ensure they are properly seated into their bearings or clips and have not popped out or shifted.

Rod Alignment Check

Check that all rods are still in alignment and have not shifted. You can often tell by switching off the power (or disabling steppers) and gently moving the print head through the X- and Y-axes. If there is any resistance, it is easy to then diagnose misalignment, bent rods, or bearing problems.

Worn Bearing

When bearings become worn, the issue is often able to be heard as a dull metallic din when printing. You may also notice the print head moving unevenly or the machine vibrating slightly while printing. If this occurs, unplug the power and move the print head through the X and Y to locate the broken bearing.

Check for Oil

Lubricating joints is essential to keeping the machine functioning. Sewing machine oil is ideal and is relatively inexpensive.

Before application, check that the rods are clean and free of dirt and printing debris; a quick wipe of the rods before applying a fresh coat of oil is always a good idea. When all rods are clean, use a small amount of oil to lubricate them. Then, use printer control software such as Printrun to move the head through the X- and Y-axes to ensure the rods are evenly covered and moving smoothly.

If you added too much oil, wipe some off with a lint-free cloth.

Under-Extrusion

Review the under-extrusion troubleshooting tip.

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