So for those of you who are like me and totally disheartened by the fact that this machine can only print accurately within the center 20mm square, know that I am on the case.
The reason that we can not simply define a scale factor to print reliable geometry at any size is because the distortion seems to be a linear function of the geometry’s distance from the origin. As the print geometry gets further away from the origin, the scale factor increases.
I am creating a workaround which will pre-deform the object in opposition to the machine’s natural bias. The end result should be straight walls and predictable dimensions.
After scouring all day, I think I have found the correct modifier called the Warp modifier.
I am currently printing a series of concentric circles and squares to try and get an idea of what the falloff should be. In the mean time, here is a sample of the kind of distortion I am talking about without regard for the actual numbers.
Will post more as I progress.