Updated on March 8, 2018
Probably every 3D printing enthusiast prints calibration prints quite frequently. However, all of them usually end up in recycle bin, because such 3D printer test prints are technical and ugly. Therefore, we created 3D printer calibration part for resin 3D printers that will not only ease the stress of troubleshooting your 3D printer but will also produce wonderfully looking, high detailed 3D prints for you to keep or give as a present to a friend.
This time we will introduce 3D printer test print called “AmeraLabs Town”. It is designed explicitly to test materials for modelling, i.e. printing of complex, high-resolution models. This test print will help you figure out ultimate capabilities of your 3D printer and 3D printing resin. We share our 3D printing troubleshooting guide that will explain main characteristics and features of this calibration part. At the end of this post you’ll find a download link for AmeraLabs Town 3D printer STL file.
Test #1. Minimum width of the opening
This 3D printer test contains a set of slots with widths of 0.10 mm to 1.00 mm that are designed to uncover several 3D printer problems. The goal is to have all the slots on the printed model cut through all the way. If the result is not as desired, i.e. slots are closed or openings are too wide, there are several points that you should check.
- If you have DLP 3D printer, you might want to correct your focus of optical system.
- 3D printing resin might also have a lack of pigment, i.e. light blocker.
- You should adjust exposure duration. If openings are too wide, you should increase exposure. On the other hand, if openings are closed and not visible, you should decrease your exposure.
Test #2. Minimum height of the opening
This 3D printer test consists of a set of openings with variable heights of 1.0 mm to 0.1 mm. The goal is to have all of the openings visible and through all the way. The aim of this test is to balance depth of resin polymerization during the printing of the model with given settings.
During printing you want to have proper layer adhesion. Therefore, polymerization thickness (depth of light penetration into resin) should be 50‑100% higher than the single layer thickness. Poor layer adhesion, as a result of incorrect printing settings, can lead to layer delamination during the 3D printing process. If most of these openings are closed or not visible, it may be the result of excessive polymerization, i.e. over-cure. To prevent that you should lower your exposure settings or add more pigment into the material. Opposite applies when you have too high openings with incorrect geometry: increasing exposure time can lead to positive results.
Test #3. Cross-shaped bridges
This 3D printer test contains of two pillars with a diameter of 0.5 mm that intersect at the center of round cutout. The goal of this test is to have clear cross formed by those two pillars without visible light bleed, dimensional irregularities, gaps or cracks.
This test is able to characterize not only your printing parameters, i.e. exposure time, pigment concentration, but also some basic material properties. For determining 3D printer settings, similar explanation to previous tests applies. However, this test print enables you to test your resin properties as well. Some 3D inks tend to be harder and less flexible and are commonly used for printing with extreme 3D printer resolution. Micro-features of model being printed must be hard enough to withstand layer separation forces from FEP or PDM. Therefore, 3D printing resin has to be hard and tough. On the other hand, if you use more flexible materials that are typically characterized by higher elongation, flexibility and usually softer surface, such cross-shaped, tiny features might not come out perfectly. Experiment with print settings until you reach the best result possible. All in all, you always have to take into consideration the purpose of printing resin that you use. Hard resins are recommended for printing detailed parts with high 3D printer resolution, while softer-flexible resins can be used for various engineering purposes.
Test #4. Pillars
This 3D printer test contains a set of pillars with variable thickness and height. Thickness is 0.1‑0.5 mm and height is 1.0‑4.0 mm. Similarly to Test #3, the goal of these pillars is to evaluate hardness and toughness of the material. Material hardness is very important for 3D printing models with extreme details.
If you want to successfully get all the pillars, material must be really hard and exposures must be tuned properly. Sometimes only overexposure will produce entire set of pillars. These pillars must withstand separation forces from FEP film (or PDMS) at an angle of 45 degrees and also overcome gravity. Therefore, even when exposures are tuned properly, the quality of this feature mainly depends on the strength of resin. Pillars also help to determine exposure times. When over-curing occurs, it is very easy to observe changes of their shape and thickness. So, if your 3D print consists of detailed high resolution features that are thin and need to last during long printing sessions, you should use hard 3D printing materials.
Test #5. Chessboard pattern
Chessboard 3D printer test consists of square cut-outs in a chess-like pattern. Each square has a width, height and depth of 1.0 mm. The goal of this test is to have all notches with sharp edges together with proper depth (which is equal to outer edge of 1.0 mm) and not overlapping conceivable straight lines formed by neighboring cut-outs.
If you have visible deformations on cut-outs or contours, depths do not seem to be precise and consistent, you can adjust your printing settings, pigment concentration or even optical elements (if present) of 3D printing system to achieve the best result possible. All in all, this test shows performance of entire system including printing material.
Test #6. Alternating, deepening plates
This 3D printer test consists of a circle with 8 segments with depths from 0.025–0.20 mm. Each segment is deepened by 0.025 mm. The goal is to have all segments and transitions/steps between each segment clearly visible. Objective is similar to Test #2 but this one is vertical and applies to similar features on real-life models like inscribed text.
Test #7. Inscribed and raised AmeraLabs logo on the edge of the building
This 3D printer test contains two AmeraLabs logos inscribed and raised on the edge of a structure. Goal is to have both objects sharp and clearly visible on the edge. Objective of this test is similar to Test #2 and Test #6. However, this one is arranged in a bit more casual way.
In resin 3D printing, it is easy to notice that sections of the print facing away from the light source tend to have a bit wrinkled or sometimes wavy surface. This happens because we need to have long enough exposures to have good layer adhesion. However, because of longer exposures surfaces that face away from light source tend to have undesired artifacts. It is not possible to completely avoid it. But, you can adjust your system to minimize this effect and reach outstanding results with nice and flat surfaces. Based on results of this test, you can adjust pigment concentration in your material or exposure settings to get sharp looking inscribed and raised logos of AmeraLabs.
Test #8. Viscosity of the material
The general test of viscosity is quite interesting. It is possible due to overall structure of this calibration part. Buildings are tightly packed within this part thus providing the ability to check how 3D printing resin is able to drain out of spaces among buildings.
If you plan to print models with intricate details, especially deep ones, you really want low viscosity resin that can easily escape those cavities. If resin remains in those cavities it might be very difficult to clean it without ultrasonic cleaner. Subsequently, when post curing, due to excess polymerization it can result in lost details. That, for instance, is obvious when printing gears. Viscous resin tends to remain among gear teeth and that results in completely failed mechanical parts unless you spend some time cleaning each gear teeth with, for example, a toothbrush. In short, in high-detail printing you want to avoid resin residue at all cost.
Test #9. Capabilities of XY resolution
This 3D printer test consists of a block of ledges formed by cylindrical and square elements of variable size 0.20‑0.05 mm in 0.01 mm increments. The goal is to have all protrusions formed.
Since that never happens in real life, it is better to say that the goal is to figure out minimum feature capabilities. This test shows real resolution of the X and Y of printing system. By analyzing the results of this test either with magnifying glass or with microscope, it is possible to determine minimum feature that the system is capable of producing. However, it is worth mentioning that the result of this test also depends on material properties as well as concentration of such light blocking components like pigment. If one uses under pigmented resin, it is highly possible that due to serious light scattering and light bleeding just a few or none of the ledges will be formed.
Test #10. Ledges with variable thickness
This 3D printer test consists of protrusions with variable widths of 0.1‑1.0 mm. The goal of this test is to have all ledges visible, without visible cracks, equal height and vertically uniform. During this test you can evaluate slicer possibilities as well as basic printing settings and material properties.
If protrusions are damaged and broken, it might be because slicer is unable to handle small-sized structures and properly generate layers. In some cases, it is reasonable to test several slicers with the same calibration part and notice the differences among printed parts. Especially, pay attention to small-scale features that push the limits of the whole 3D printing system.
So, this is it. All features are described and you are good to go and start adjusting your printer. Remember, that you should not rely on a single test result. Always try to look for trends and common problems among all tests to get more reliable evidence of certain issues.
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- The Beginner’s Guide to 3D printing with AmeraLabs resins
- True story of why it was so difficult to choose my first 3D resin
- Attachment Layer in SLA 3D printing: what you need to know
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