Hi Dr.Ullah,

Even I have faced the same problem while 3d printing (Fused Deposition Modeling or FDM) large scaffolds/objects.

(Just to avoid confusion for others - I assume what Dr.Ullah is referring to is the bending of the scaffold/object, for example if you are trying to 3d print a flat circular disc, over the course of printing process, the structure bends to eventually form a hemisphere with a very small curvature).

REASON: I think this might be caused because the printing bed (platform) is usually kept/maintained hot (>mp of the thermoplastic polymer) through out the printing process. Hence, as the scaffold progresses in z-direction, the topmost layer cools rapidly (or crystallizes) while the bottommost layer is still hot and soft (as it is in contact with the hot platform). This causes contraction of the topmost layer and pulls the structure inward. As a result the edges of the structure detach from the platform and create a curvature. This phenomenon keeps on accumulating as the aspect ratio of the structure goes on increasing and we end up with a bent structure.

SUGGESTION: Although this might not be the best solution, it's worth giving a try. You can use a glue stick (like Elmer glue or any) to coat the hot bed with a thin layer of glue before starting print. Then for your object, give a wide brim to the structure to facilitate adherence to the bed at all times. It has helped me somewhat, however I would really love to learn how other researchers on this forum address this issue.

Best,

Srujan