Frequent problems with SLA prints

Nothing is Printing

Despite hours of trial and error, no print is coming out quite right. The print does not begin in the first place or, after hours of excruciating attempts, the final print does not adhere to the plate and loses all structural integrity.

Cold Resin

What’s the problem?

Like many FDM 3D printing filaments, ambient temperature can heavily impact whether photopolymer resin will set during the SLA printing process.

If your resin is too cold, it is unlikely to set and, if it does, will set inconsistently, resulting in partial prints and poor plate adhesion.

Why is it happening?

Unfortunately, this is not easily explicable for those outside the material science niche. Simply, some materials require temperature balance to achieve stability. Check some scholarly articles if you want greater detail.

Temperatures as high as 25–30 ℃ can be necessary for some resins.

Troubleshooting

Move printer to a warmer area

Obviously, the ability to do this depends on the location of your home or shop. For those who do not live in very cold climates, however, moving the printer to slightly warmer spot may be suitable for getting the material to its “green” state at which it is somewhat solid but not yet cured.

Invest in a chamber heating solution

Few products are geared toward 3D printer heating, but some industrious makers have turned to the fledgling community around home incubators for the solution. If possible, try investing in an incubator heating kit, which includes a heater, fan, thermostat, and power supply for around $50.

Printing Too Fast

What’s the problem?

In SLA 3D printing, a UV light source—typically a laser—hardens photopolymer resin. Resin must be exposed to adequate light prior to solidified to ensure proper curing.

What causes this problem?

Underexposure, whether from the laser moving too fast or being underpowered laser will result in nothing printing or prints coming out weak and brittle.

Troubleshooting

Decrease print speed

Check to ensure that the resin is being heated at the recommended temperature. Then, reduce print speed. Depending on the printer, it may be possible to slow the print speed in the slicer settings.

Underpowered Laser

What’s the problem?

Similar to printing too quickly, an underpowered laser can underexpose the resin to UV light, leading to poor print quality or inconsistent printing.

What causes this problem?

If the laser is in good condition, then the laser power settings are likely to blame.

Troubleshooting

Increase Laser Power

If your printer’s settings allow for it, increase the laser power in small increments to identify the best settings for consistent and effective prints with your specific resin type and print speed.

Do not simply increase the laser’s power to the highest setting as this can produce a messy surface finish and damage the interfacing layer inside your printer’s resin vat.

Print Failure

Prints Not Adhering to Print Plate

What’s the problem?

The print is not adhering to the print plate, and peeling or full destabilization is observed.

What causes this problem?

Specific SLA 3D custom printers may reposition to the next printing layer in a manner that generates more peel force than the model can handle. With top-down SLA 3D printers, peel force is the suction effect exerted on prints each time the print plate and bottom of the resin vat separate to reposition. Depending on the mechanism by which this occurs, there are a few tricks you can do to minimize or at least mitigate this force.

Print plate preparation may also affect this issue. Bottom-up SLA printers printing onto a flat metal plate stick well when the plate is finely textured or rough. Ghosting on the interfacing layer in the resin vat may also impact how the laser sets the resin.

Alternatively, the resin may simply not be warm enough. As the print progresses and the resin level lowers, slight temperature fluctuations may impair resin setting.

Troubleshooting

Reposition your print

If your printer utilizes a tilting resin vat, a gradient is established across the print plate.

Positioning your print in an area of the print plate under less peel force can ensure effective bonding to the print plate while reducing stress on taller parts that are free standing or rely upon thinner supports.

Level vat

Level the bed and vat according to the manufacturer’s instructions. If this is impossible to do in isolation, re-calibrate the printer from scratch.

Check temperature

If the resin is too cold, it may not be setting well enough and may exhibit poor adhesion.

Heat the resin and print chamber (perhaps by repositioning the printer in a warmer room) before attempting to print again.

Check resin vat interface layer

Check the resin vat interface layer for ghosting and overall wear. If damage is observed, replace the interfacing layer with your own (such as Solaris Silicone), buy a new interfacing layer, or install a new vat.

filter your resin

If there are small set pieces of resin floating inside your vat, it can impair consistency throughout the print, leading to problematic adhesion.

Comb through your vat after each print to catch these particles and remove them and dislodge any set resin stuck to the bottom.

Remix your resin

If you’ve followed the above step and filtered your resin for print disrupting particles, but then left the machine alone for some days, there a chance the resin has settled, with the heavier pigment from colored resins settling into their own layer that will print inconsistently as the print proceeds.

Sand your print plate

Sometimes, the factory-made plate is too smooth for proper adhesion with most prints.

Gently sand the print plate with medium-grit sandpaper. Thoroughly clean the plate afterwards to avoid introducing particles to the resin that will interfere with the printing process.

Detached or Moving Print Segments/Supports

What’s the problem?

A piece of hardened resin shifted, either separating completely or moving enough to interfere with other parts of the print.

What causes this problem?

Vat conditions and print orientation are two common factors for this problem. The print may be incorrectly oriented for withstanding peel forces, resulting in distorting movements that cause parts or supports to separate. Such movement in the part will cause subsequent layers to be formed on the vat interface, rather than the print itself.

Weak support structures may also cause this issue.

Troubleshooting

Hollow large prints

For prints with large surface areas at any position, consider hollowing them and adding drainage holes where possible. Rather than forcing a large, flat surface to pull away from the bottom of the resin vat with each layer change, a thinner outline of the model detaches each time.

This requires much less force and is less likely to lead to layer separation, although this works best when drainage holes are added using modeling or slicing software. Without drainage holes, a reservoir of unset resin will be trapped inside the print, which is costly and wasteful.

Stronger Supports

Peel force may be the reason for failed prints; consider strengthening your supports. Increase the width of the tips at which the supports meet the printed portion of the model by a fraction of a millimeter and add struts between them.

If this is not sufficient, consider adding more supports. Note that this may increase post-printing time and work required to produce a clean print.

Check/Secure Print Platform

Check that your 3d printing platform is properly secured as minor variation in position from the movement of the printer may cause layers to misalign and separate.

Reorient Your Print

Check the orientation of your print. Print orientation issues can be exacerbated as the print proceeds, leading to layer shifting and curing issues. The following considerations are critical in checking print orientation:

• Positioning: Many bottom-up SLA 3D printers feature a peel mechanism to separate the print plate from the bottom of the resin vat when repositioning on the Z-axis for the next layer. Depending on the printer does this, the strength of this peel force may change in different areas of your print plate. If this is a known problem for your printer, you can increase the likelihood of the print overcoming these issues by positioning it in an area subjected to weaker peel force.
• Support overhangs: As with FDM 3D printing, extreme overhangs require some form of support for successful printing. With some 3D models, you can mitigate the need for supports by angling your model or decreasing overhang angles.
• Minimum Points (Minima): Minimum points are isolated portions of prints that are not directly connected to the main body. Such minima require supports as they are highly likely to break away and float free in your resin vat. Alternatively, you may eliminate the need to support minima with tactical model orientation, such as flipping a body model to print head-first as the body tapers out to the arms and feet without far extrusions.
• Cupping: This occurs when a hollowed area has high suction to the print surface. If the “cup” is shallow, angling the print may be sufficient to minimize the cupping effect.

Drainage holes may be added to the model using the modeling software, which allows the resin to flow freely with each layer change.

Print quality issues

No sounds, shaking, or print-process issues have been identified, but the produced print ends up being of low quality.

Layers Have Separated (Delamination)

What’s the problem?

Print layers are not bonding consistently or are separating in some parts.

Why is it happening?

Delamination—the separation or problematic bonding of print layers—can be caused by many underlying problems.

The print orientation may be off, resulting in parts printed in isolation. Poorly mixed resin and ghosting on the vat itself can cause this as well. Additionally, delamination may occur after a successful print during the post-processing stage. If your material exhibits particularly weak layer bonding, washing the part in IPA for too long may weaken layers further, causing the part to break apart or collapse.

Troubleshooting

If portions of the print exhibit weak layer bonding, over-washing it in IPA can cause it to weaken further. Restrict the IPA wash cycle to the minimum and quickly and gently agitate the unset resin off before rinsing with water.

Supports

Minima in your prints can lead to stability problems in SLA prints when they are not adequately supported. Generate supports for all severe angles and points that are not directly connected to the main print at their highest point.

Clear the laser’s path

Check the resin is debris-free and mixed well. Then, check the interfacing layer for ghosting, which may impede the laser’s path. If severe ghosting is identified, replace the interfacing layer or the entire vat, if needed.

Small Fins and Disks Attached to Print (Ragging)

What’s the problem?

Dried resin flakes have mixed in with setting resin, yielding a low-quality surface finish with extruding portions that are not part of the model.

Why is it happening?

This issue often occurs because of an unclear optical path. The laser can become diffused, causing leaking beyond the actual casting position.

Settled resin, resin clouded with large particles from prior prints, or smudged planes can also contribute to this problem.

Troubleshooting

Filter Resin

Filter resin to remove remaining clumps or debris from previous prints. Many 3D printing stores stock paper and mesh filters intended to capture large particles that might otherwise cloud your resin during the printing process.

Mix your Resin

If the resin has not been used for several days, it might have settled, causing the pigments to separate in thick layers. Mix the resin to ensure the pigment and photopolymer are evenly distributed and no streaks remain.

Check/Clean Optical Path

Some machines allow users to access the transparent internal barrier protecting the laser/galvanometers. Check that this is clear from dust, fingerprints, oils, and detritus that may prevent the laser from passing through cleanly.