Distorted prints

[Skillster]

Hello. After various successful small trial prints to dial in the resin settings, placed in the centre of the build plate, I have completed a print that used the entire width of the print space. The print is for a model and consists of a base supporting vertical columns and a cross rail at the top.

The vertical columns appear to be distorted, effectively converging towards the centre - a pin-cushion type of distortion. The horizontal elements are not distorted, being flat and as they should be.

What might be causing this?

Elegoo Mars 3 pro
Standard Elegoo grey resin
Direct onto build plate; some designed-in supports plus those added by Chitubox and tweaked
30 secs for base layers
2 secs for main layers - all as found optimal using various test prints

[billtodd]

The print is soft , the forces pulling the print around when separating from the FTP film are high . The plastic does not always spring back into place . Result = distortion

Imagine that ,in the slicer, your model made of rubber and being pulled upwards by some malign force trying to wreck your day. Orient it so the minimum area is exposed (watch out for suction cups - closed peripheries of print that act one large area) . Support it everywhere with little tri-pods of support ,

Temperature: The resin gets hot when exposed , thick sections will retain the heat and can cause internal stress (force) that can bend the whole print out of shape, so hollow out and use infill where necessary (and don't forget punch vent holes to avoid suction cups) .

Sometimes it is helpful to add sacrificial supports at the modelling stage to ensure long overhanging edges have sufficient support without becoming a mess of slicer supports.