Determine settings for 3D printing resins
Channel: Sparks workshop
Date: 2020-05-10

A "working curve" describes the thickness to which a resin cures as a function of the light "dose" for a given light source. While this may sound pretty lame, understanding this concept is key to understanding SLA and DLP 3D printing. With the working curve one can quickly generating printing settings without a lot of testing. It also allows one to quantitatively compare the curing properties of one resin versus another.

The other reason the working curve a powerful tool, is that the measurement is very easy and can be done in less than 10 minutes (with practice!). The only required tools are a micrometer and 3D printer. The measurement is pretty straight-forward for pure radical systems as the layer thickness depends on the dose. Light intensity, oxygen inhibition, and the polymerization exotherm certainly can play a small role, but the technique is surprisingly robust. The only situation where I would expect significant deviations is in cationic and other living polymerizations.

That being said the measurement is not necessarily easy, as the resulting films are delicate. It takes practice to produce consistent measurements of 50 to 200 micron thick films, but the results are definitely worth it.