Fuzzy Skin Test Geometry

(What's a fuzzy skin?)

Unless you're printing a single wall, it's good to have nuanced understanding how fuzzy skin works. This fast printing reference model presents very clearly how fuzzy skin behaves on different situations. The model is designed to present the following:

• Vertical walls
• Horizontal (X&Y) curvature
• Vertical (Z) curvature
• 45° overhang
• 90° horizontal angle
• Fillet transition from vertical to horizontal
• Seam behaviour
• Horizontal transition from curved to straight geometry and it's effect on flow rate

How to use?

The model is a set of 15 pieces. Each piece has two numbers. The upper number is "fuzzy skin point distance" and the lower is "fuzzy skin thickness". So, for example, numbers 6 and 2 mean point distance of 0.6 mm and thickness of 0.2 mm.

For your convenience, there's 20 mm and 40 mm set to suit your needs. The print time for the smaller set is 1.5 hours (A1 mini) using 30 grams of filament. This set is enough for my needs at least.

How to print?

There are .3mf files that have the settings in place. If you're printing from the .stl, you must set the fuzzy skin properties yourself. Few things to consider:

1. Use ~5mm mouse ear brim. The pieces have very little contact to the plate and will fly off otherwise. The small set also has additional support strip at the back of the model. Go fast, be fearless!
2. To test seam visibility, align the seam to the back. Experiment also on scarf joints.
3. The print is designed to "fail" in a safe manner. When the wall curves to horizontal in the top, it'll look ugly and will probably have holes. (The fillet has a radius of 20 mm on the large set and 10 mm on the small set.)
4. Decreasing wall loops is not advisable. Using only two walls, I had a print failing at 85 % due to filament collapsing away from the layer.

My results

• Without scarf joints, seam lines stay visible.
• Even with scarf joints, high point distance combined with low thickness produces more visible seams.
• On the opposite side from the numbers is where a curved line meets a straight one. There's an effect to flow rate which produces a "fake seam". See the picture with funky colors.
• The overhang portion prints without a glitch.
• Higher point distances seem to lead poor surface when curving towards horizontal.

Note

This project took more hours than I like, to transform it from private use to well documented public offering. I hope you find this useful!