Calibrating Resin Exposure

Exposure time is an important variable in 3d resin printing. Too short an exposure and layers can separate leading to print failures. Too long an exposure could affect part dimensional accuracy due to light bleed. In general it is better to overexpose than to underexpose due to cleanup and waste associated with failed prints. Many calibration test prints are available to evaluate whether a given exposure is acceptable. The user is required to print a given test print multiple times at different exposure settings before evaluating which exposure works best. Due to varying exposure times the calibration prints are often not printed concurrently even if sufficient space is available on the build plate.

The script "ScriptExposureFinderByGrid" for UVTools was written to simplify the process of creating a file which allows concurrent printing of multiple calibration parts with different effective exposures.

Preparing a Sliced File

Drop your favorite calibration file into your preferred Slicing software multiple times. Arrange the duplicate objects into a grid pattern on your build plate where each cell will be assigned a different exposure. Given a build plate size of 219mm x 123mm, a grid of 4 by 2 works well to test 8 different exposure times. Once the objects are arranged in a grid pattern, slice the file.

Bring the sliced file into UVTools and open the Scripting window under Tools. After loading the script, the grid size in the x and y directions should be updated to match the grid pattern used when the sliced file was generated. The exposures which will be tested need to be entered as a comma separated list. In the "Layer range selector" choose "Normal layers" then run the script. Pixel dimming will have been applied to each grid area to result in an effective exposure chosen by the user. The file can then be saved for printing on the desired printer.

Note that the chosen exposures are applied from left to right, top to bottom.

Benefits

Using "ScriptExposureFinderByGrid" allows any arbitrary calibration object to be used in a time and space efficient manner. Any user can slice their own file specific to their printer and run it through UVTools to generate the multiple effective exposure times.