In designing some components I was interested to figure out what the limitations were of the printer, and figure out how it behaves when the printed part deviates from the cad model.

My first concern was how thin a wall the printer could print at different slice thicknesses, so I made a test part that integrated short pieces of different thickness wall sections.

The same test part was printed at both 0.15mm z slice thickness as well as 0.4mm slice thickness. The top row consists of wall thickness of 0.2mm, 0.4mm, 0.6mm, 0.8mm and 1.0mm thickness. On the 0.15mm z slice thickness model, the first two (0.2 and 0.4mm) walls got ignored by the software. At the 0.4mm Z slicestep, the first 3 walls (0.2, 0.4, 0.6mm) got ignored.

Just because the walls got printed, it doesn’t mean that they got printed at the correct thickness. On the 0.15 z slice thickness part, the 0.6 and 0.8mm walls were measured to actually be around 0.8mm thick. The 1mm wall was measured to be about 1.1mm or so. On the bottom row, the 1.2, 1.4, 1.6, 1.8, 2.0mm walls all measured correctly within +/- 0.07mm which I’d say is pretty damn good.

On the 0.4mm s slice thickness part, the thicknesses had more variation (around +/- 0.12mm) in the wall thicknesses, and the wall thickness of the walls up to the 1.2 and 1.4mm walls, was not accurate at all. I have not measured all the parameters on this part.

The spacing between walls of the same thickness was designed to 5mm , and on the 0.15mm z slice thickness part, with the exception of 0.6 and 0.8mm walls (which were not the designed thickness), all the other walls came out pretty close to 5mm when measured; around +/- 0.05 or so.

The other thing to note was that at the 0.15 z slice thickness, the walls on the 1.2 and 1.4 mm walls was only made up of only an outer perimeter bead of plastic, with no fill between them. You can kind of see what I mean on the picture above on one of the 1.4mm wall. The 1.6 and 1.8mm walls seemed like they had a fill in between the outer perimeter skins, however the fill didn’t seem like it was connected very well to the skins. What this produces is 2 skins that are not connected together and loose I would think the 1mm wall would be stiffer (since the 2 sides are fused together) then the 1.2 or 1.4mm walls. I’d avoid designing with these thicknesses.

Once you get at the a 2.0mm wall thickness, the infill looks like it connects the sides together. These observations were made purely by looking at the final top layer of the print. I don’t know how well connected everything is inside the wall.

For those that want to print their own part, here’s the stl file : Thickness_Calibration_D01.zip

UPDATE:
Just found a post on the PP3DP forums talking about the same thing (HERE). In the same thread there is also a handy thingiverse generator to generate thickness calibration parts similar to mine, but parametric (HERE) and a chart of designed vs printed/measured wall thicknesses.