Printable View
Recently I purchased a LCD resin printer with the idea of printing parts for some of the prototypes I am working on.
The resin I am using is marketed as "low-shrink" however after the parts being fully cured they shrink with more than 1%. The shrinkage is inconsistent and unpredictable because as it largely depends on the geometry. It is practically impossible to make any usable parts.
Do you know of any well tested resin suitable for dimensionally accurate applications?
1% shrinkage is pretty low. Is there a reason you can't print a test piece and then scale it accordingly to achieve the desired dimensions you require? Any decent CAD system will allow it you to scale it differently in each direction. It might take a few iterations to get you within acceptable tolerances, but resin prints are still pretty cheap.
The problem is the shrinkage happens during the curing (after the printing).
To avoid any deformations/shrinkage over time the printed piece has to be cured completely. With a powerful 50W UV light the curing takes about 10 hours. In general, it is possible to get the right dimensions by trial and error (as you are suggesting). In my case, it took 5 attempts about 16 hours each. So for one usable part, I have to dedicate about a week of machine time and several hours of labor. For a different part, the process has to be repeated because each part shrinks differently. Needless to say, this is impractical.
An expert in another forum suggested that the only way to get dimensionally accurate parts with UV resin is to completely cure the resin during printing - using a laser.
In other words, low-cost LCD printers cannot be used for that purpose.