smiley wrote:for the sake of clarity, and not trying to pick a fight with Jimustanguitar, 26 thousandths of an inch = 0.026" = 0.66 mm. So if your first layer height is set to 0.3 mm, an error of 26 thousandths is more than twice the height of the first layer, which would be more than enough to explain the 1st layer problems that people have been describing.

No offense taken, you're exactly right. That is precisely what we're trying to pin down.

smiley wrote:I am struggling with the paper's description of virtual columns. If I take a sloppy tape measure to my Max, my tower spacing is about 320 mm, the radius of the circle the cheapskates sit on is about 190 mm, and the delta arms are about 265mm. All of these measurements are off from the base measurements used to generate the error maps at the end of the paper.

The "virtual columns" are a way to simplify the math involved. Since the arm pivot points on a carriage are always parallel to the corresponding points on the platform, you can subtract the platform and carriage offsets from the model because they don't change the angles involved. This is why the distance between the virtual columns is less than the towers in the previous diagram.

Then, if the arms are always parallel, which they are, they can be represented as a single line instead of a double because they're always the same length too.

Because we removed the platform offset, all 3 arms meet at a single center point instead of the edge of the platform.

It's just a simplified representation of what's mathematically happening. The dimensions are different than your machine because the dimensions in the technical writing are from a different machine, but the principals should remain the same.