Chapter No.3 - Calibration Procedure of Resin Printing

Chapter No.2 - Exposure Tests And How To Read Them Lettura Chapter No.3 - Calibration Procedure of Resin Printing 6 minuti Prossimo Chapter No.4 - 3D Printing Resin

Da zouzoey20 lug 2023

We discussed about the most important settings, how they influence the results and how to read different exposure tests available. Now it’s time to define a repeatable procedure to determine the parameters to have the best quality from our printer and resin. Don’t be afraid of failures: report them because they tell the limits of the resin and the printer.

Structured Procedure

Print the XP2 Validation Matrix. Use the parameters suggested by the resin manufacturer, which generally works for all printer models, to have a solid base to start. Start using a 50µm layer height because the exposure times of different layer heights can be derived from this one. Then look at the result and judge if it’s correctly exposed or not; if it’s not over- or under-exposed, let’s move to the next step. If it’s over-exposed, decrease the exposure time and re-print it; if under-exposed, make the opposite. In this step you can adjust the exposure time of 0.5s at a time, then proceed to 0.1 to 0.2 s increments to be more accurate.

2.Print the Phrozen RP Finder using the successful parameters from previous step. From here we can have a better look at how the resin behaves in different aspects and judge it following what we said in the previous chapter about the exposure test files. If there are some parts not ok, try to change the related parameters in order to make the most perfect you can. It will always be impossible to have a 100% perfect print, but we’ll always have to find a trade off between level of detail (that leads to under-exposure) and printability (which leads to over-exposure to make the supports stronger). In this step is better to adjust the exposure by 0.1s at a time to be more accurate. When the result is satisfactory, let’s move to the next step.

Print some benchmark models: these models will be the final verdict about the calibration. Compare them to the digital file to judge if the level of detail obtained is enough. As the files are pre-supported, if the model will be ripped from the supports it means we have to increase the exposure to make it printable although we have perfect details. As I said before, it’s all a matter of trade-off. If all prints perfectly, then it’s time to test different layer heights.
Repeat step 3 for different layer heights, deriving the exposure settings from the already calibrated ones. To do this, use the currently calibrated exposure time and layer height as base. Let’s suppose it’s 2.5s for a 50µm layer height, follow this method:

(1).Determine the layer height you want to test, suppose 30µ

(2).Calculate the % reduction of layer height: 30/50 = 0.6 = 60%, which means a 40% layer height reduction.

(3).Calculate the new exposure time using this empiric rule: the new layer exposure time decreases by half the percentage reduction of the layer height. So, if we reduced the layer height by the 40%, we must reduce the exposure by the 20%. From the 2.5s at 50µm, switching to 30 µm we must reduce the time by the 20%, and the new time will be: 2.5*80% = 2s. As this rule is reliable, we just need to test the benchmark models to be sure to obtain the same level of detail and a successful printer. If there are problems, modify the settings according to the problems found.

(4).Adapt the same way the bottom exposure time. Don’t modify the other parameters, it’s not necessary.

How Aceaddity Elite Resin Performed

The first thing to make to obtain crisp models with high success rate is to use a good quality resin. What are the characteristics of a good resin?

Low viscosity: reduces a lot the suction force between FEP film and the printed object.
Low exposure time: this not only reduces the print speed, but also preserves the screen because it won’t be overheated as the UV curing produces heat.
High pigmentation: this is responsible for the surface detail the resin can capture. The more the pigmentation, the more details are captured without fading them due to light scattering.
High stability: responsible of the dimensional accuracy if we have different pieces to assemble.
High strength/flexibility: this depends on the use of the printed objects. For example, a showcase statue doesn’t need the flexibility of a miniature for tabletop gaming.

Aceaddity Elite Resin has all these characteristics, which puts it at the same quality level of other resin with a lot higher cost. Moreover, it’s very affordable, a feature that makes high-quality printing affordable to most of the 3D printing community.

Now it’s time to make the results speak for themselves.

We can see that, overall, the 2.0s exposures performed well in terms of details and strength, as more pillars were successfully printed (even the 0.3 mm one was printed, but it was accidentally broken during the cleaning process). From the other hand, 1.8s is a bit under-exposed because of the less pillars being printed and, but the detail is at the same level. I decided to take the risk to print some benchmark models using 1.8s of exposure and the result is shown in the next images.

The details are awesomely captured by this resin, as you can see by the fine texture of the cyclop’s skin and the wood tables, or boots of the warrior and the crossbowman’s face. There are no visible layer lines as we can see from the cloack of the warrior or the cap of the gnome. Even if the test files told that the resin was under-exposed, the benchmark models told that the times were perfect because the detail is awesome and there weren’t failures. This resin also has a very good dimensional stability and sccuracy, because the characters fits oerfectly in the slots for the feet located in the bases and there is no warping of the bases.

Now that the exposure and main parameters are set, in the next chapters we will see how to optimize the parameters to maximize the printing speed. This is very useful for professionals who needs to have high quality combined with low production times.