Working with OpenFL material files, the basics:
I have this thing I call the keys to the kingdom basically its the few items of knowledge that unlock the ability to understand an entire concept. For working with OpenFL material files I believe the following are the keys.
The layer exposure must match the resin being used, this affects how well defined and how structurally sound the printed model will be.
The concept:
At the most basic when manipulating the layer exposures in a material file you are dealing with two things and you must manipulate them both when adjusting your layer exposures: the perimeter exposure which on Formlabs printers is the outer edges of a model that the laser beam traces and the fill the “insides” of the model traced by the laser. If the model you want to print were a tree the perimeter would be the bark and the fill would be the core of the tree.
The exposure of the perimeter and fill have a balance, if you were to print a single layer of a model (in a puddle of resin, no build plate) cleaned and post cured the layer then looked at that layer closely you would be able to see both the perimeter and fill laser scan lines. The perimeter and fill should appear quite similar and be the same thickness*. If the perimeter is thicker than the fill the perimeter exposure is high in comparison to the fill, if the fill is thicker than the perimeter the fill exposure is high in comparison to the perimeter.
If the perimeter and fill match and you want to increase or decrease the overall layer exposure increase or decrease the perimeter and fill values IN THE SAME PROPORTION. If the perimeter is thicker than the fill and you want to increase or decrease the overall layer exposure increase or decrease the perimeter and fill values but with a lower perimeter value proportionally. If the fill is thicker than the perimeter and you want to increase or decrease the overall exposure increase or decrease the perimeter and fill values but with a lower fill value proportionally.
What does this all mean from a practical standpoint:
lets say that you are using this material file exposure as a base exposure:
The perimeter to fill exposure proportion is: 1 (perimeter exposure) to 1.3 (fill exposure)
NOTE: Only laser power is being manipulated in the following examples
[perimeter]
modelxyfeedrate = 800
modellaserpowermw = 35
supportxyfeedrate = 800
supportlaserpowermw = 35
basexyfeedrate = 800
baselaserpowermw = 35
[fill]
modelxyfeedrate = 1550
modellaserpowermw = 45.5
supportxyfeedrate = 1550
supportlaserpowermw = 45.5
basexyfeedrate = 1550
baselaserpowermw = 45.5
if your model prints “thick” with low resolution (layer exposures are too high) lower your layer exposure proportionally
Perimeter to fill exposure proportion: 1 (perimeter exposure) to 1.3 (fill exposure)
NOTE: Only laser power is being manipulated in the following examples
[perimeter]
modelxyfeedrate = 800
modellaserpowermw = 30
supportxyfeedrate = 800
supportlaserpowermw = 30
basexyfeedrate = 800
baselaserpowermw = 30
[fill]
modelxyfeedrate = 1550
modellaserpowermw = 39
supportxyfeedrate = 1550
supportlaserpowermw = 39
basexyfeedrate = 1550
baselaserpowermw = 39
If your model falls apart when printing (layer exposures are too low) increase your layer exposure proportionally
Perimeter to fill exposure proportion: 1 (perimeter exposure) to 1.3 (fill exposure)
NOTE: Only laser power is being manipulated in the following examples
[perimeter]
modelxyfeedrate = 800
modellaserpowermw = 40
supportxyfeedrate = 800
supportlaserpowermw = 40
basexyfeedrate = 800
baselaserpowermw = 40
[fill]
modelxyfeedrate = 1550
modellaserpowermw = 52
supportxyfeedrate = 1550
supportlaserpowermw = 52
basexyfeedrate = 1550
baselaserpowermw = 52
Strengthen your model without affecting model resolution much, increase the fill exposure.
NOTE: Only laser power is being manipulated in the following examples
[perimeter]
modelxyfeedrate = 800
modellaserpowermw = 35
supportxyfeedrate = 800
supportlaserpowermw = 35
basexyfeedrate = 800
baselaserpowermw = 35
[fill]
modelxyfeedrate = 1550
modellaserpowermw = 50
supportxyfeedrate = 1550
supportlaserpowermw = 50
basexyfeedrate = 1550
baselaserpowermw = 50
Model strength ok, lets try to increase model sharpness a bit by dropping the perimeter exposure
NOTE: Only laser power is being manipulated in the following examples
[perimeter]
modelxyfeedrate = 800
modellaserpowermw = 32
supportxyfeedrate = 800
supportlaserpowermw = 32
basexyfeedrate = 800
baselaserpowermw = 32
[fill]
modelxyfeedrate = 1550
modellaserpowermw = 45.5
supportxyfeedrate = 1550
supportlaserpowermw = 45.5
basexyfeedrate = 1550
baselaserpowermw = 45.5
You can make supportlaserpowermw and baselaserpowermw exposures higher to make the base and supports stronger but the modellaserpowermw settings for perimeter and fill are what affects the print.
you will probably notice that I only changed the *laserpowermw parameters, it’s best to only change the laser power if you can get away with it, if you get to the 62mw laser power limit and still need more exposure you can drop the *feedrate parameters (this increases the exposure) but this will also increase your print time. Changing both *laserpowermw and *feedrate at the same time to control layer exposure is asking for a very confused exposure setting.
there is some other trick stuff you can do and when I get some time I will post some of that here.
in the mean time you should test your resins using the files located here: