What resin has the highest geometrical accuracy and also strength?

For my parts a very high accuracy regarding geometry and dimension is important. I noticed that using though resin plus curing does lead to warping/little deformation of my parts. So I switched to standard white resin without curing afterwards, despite the fact that I need stronger parts. This seems to improve the geometric accuracy and is okay for testing of prototypes, but now the parts are obviously more brittle.

I want to ask here if you have experience with what resin I should use for the lowest deformation / highest accuracy and some load-bearing capacity.

that depends on what you consider strong.

The Rigid Resin is the most dimensionally stable- but like all the resins, you have to build the parts on rafts so that flat surfaces are not in plane nor perpendicular with the build platform- and then post cure the parts with their support structure attached.
Because Rigid is glass filled- it has a lower shrinkage under the laser than other resins. It is extremely tough, but with less flexural strength than Tough and Durable. It does, however, resist abrasion well because of the glass filler.
( it also looks way better than white resin.)

With the other resins… there are often tricks- such as, Most of them will give the best dimensional accuracy printed at 100 micron thickness. ( the resin has a specific amount of shrinkage when cured… more layers means a greater cumulative shrinkage- which adds greater internal stresses to the part- which are revealed as warpage in post curing )

If surface quality is not that important, I have found that DRAFT resin is dramatically tougher than even tough- though probably much worse in terms of dimensional accuracy.

the support structure on draft resin is a real bear to remove because it just doesn’t break off like the other resins.

1 Like

Thank you for your answer. Typically I print very tiny parts (approx 40ml per part) and I am trying to align them flat, so that the z-axis (which is less accurate than x and y axis I did read) does not distort the geometry to much. The rafts are indeed a problem. But grind them down under water does work well with white resin (no clue how good this works with other resins).

Aligning them flat will always get you less accurate parts.
The first several mm get squashed if they are built on the platform.

In addition- if you are printing flat areas in plane with the platform, you are laying down resin on the entire flat are at once- this Maximizes the shrinkage stresses in the resin and pretty much gurantees the flat surface will bow in post curing.

By angling flat surfaces significantly, you are orienting the shrinkage stress out of plane with the flat surface, and you are minimizing the cross sectional area of the part per layer- which minimizes the amount of cumulative shrinkage per layer.

1 Like