Top Down design shrinkage and displacement questions

[heyarn]

Hi Everyone,

As I'm trying to lock down some design features, I'm having questions about the top down approach:

1. as the part being printed grows, obviously, the collective shrinkage increases. This will affect the resin level, thus making the top layers slightly thinner than the lower layers.

On the other hand,

2. as the build plate submerges itself deeper and deeper into the vat, the resin level will increase from the displacement.

While both processes kind of compensate each other, the error isn't exact and repeatable. So the question is how do top down machines compensate for it? Is it all in the software? Or is the error so small that it doesn't really matter? Do I need to design a larger volume vat to reduce the errors? (ex a 5% shrinkage error from a 5sq.in. part on a 10x10 inch vat will have very small error)

Would very much appreciate your thoughts

[PomeroyB]

In my experience, the error doesn't matter all that much... but that's just anecdotal. I don't believe CWS has any sort of software compensation.

[greglab61]

Hi. I am new here, but we are using a machine that has a metal block that submerges into the resin tank as the build progresses. It acts as displacement for the tank volume. The whole thing is controlled by an Arduino circuit, with a laser measuring the tank level. That way, no matter what you build and how much each layer consumes, the tank resin should be consistent.
However, your post caught my eye because we are having issues with the final print being smaller than the original file. The machine we are using is in beta test, so it may be the leveling hardware or software control is inadequate.