BRIEFLY

We made a dry, verbose report about this project, so I only want to discuss a few things here. I
found:

• Silicone negative molds making polyurethane models create incredible detail pretty quickly.
• Airbrushing is superior to hand brushing for this kind of work.
  • faster
  • more consistent
  • more efficient in paint use
  • easier to create specific colors and other effects through layering
  • cheap to use these days
• Brushes should be used at the end for fine details.
• If we weren’t thinking globally, 3D printing and painting would be a more straightforward production process with less chance for error and less skill required.

SLICER SETTINGS!

So, what do we want to achieve here? We want maximum fidelity; these are the master
positive molds. We also don’t care how long it takes, but we can use the same
settings for both our positive molds and models and print them concurrently. We
aren’t allowed to change the nozzles in the ODEK and don’t have the time to
define our own set of parameters

We’ll start with the lowest available layer height and slowest speeds. Layer height gives our Z resolution, and while XY resolution depends more on the nozzle, a slower speed generally gives the best fidelity for a fixed nozzle size.

• Start with the lowest and slowest preset.
• Change the slicer wall generator to Arachne for better small details…is what I should say. In this instance the classic generator worked better, but we missed that detail. Notice the hitch in the two below.
• Increase the infill a little more for a part with more heft. I wasn’t sure at the time what the polyurethane models would weigh, but I hoped to match it.
• Print outer walls first. A model without sloping sides prints more uniform outer
  walls when printed first.
• These models overhang at the letters, so light supports are needed. We don’t want to
  risk scaring a main wall so choose standoff tree supports.
• The models need a flat bottom, especially since we’ll sand
  the polyurethane copies, so add a brim and lower the first layer speed to improve
  bed adhesion.
• Finally, a small but very important change. Layer lines are inevitable, and on a
  sloping, curved surface, concentric top infill works best compared to
  rectilinear.

HUE WHO

I love an excuse to use color terms, but I’ll try not to mansplain. When we think of a specific color—the abstract, the platonic ideal of color—we are truly thinking of a hue. Imagine a non-segmented color wheel smoothly moving along all the colors with tints and shades filling the inner and outer spaces. Any angle you pick along the wheel is a hue. Moving from red to blue, we see carmine red, magenta, purple, and so on, an infinite variety.

 

Hue as a concept works in both additive and subtractive color theory, but we care about paints—subtractive—today, and paints mean pigments. In paints, the color wheel depends on the pigments you have, which denote “true” hues. Carmine red, titanium white, or indigo blue are colors of paint you can buy but they also are the hues created by those specific pigments…As I write this, I realize it’s not important for us since we didn’t necessarily use single-pigment paints, so scratch that.

 

What does matter for us is color layering and color matching. If we want to go from one color to another, we need to identify hues, tints, and shades. Hues we know about; tints are hues mixed with white, and shades are hues mixed with black. So if I start at one color, bubblegum pink, and I want to go wo another color, desaturated magenta pink, I need to add other hues, white, black, or some combination.

 

And this is how we approached painting in this project. We were airbrushing so each thin layer could be altered by adding a different thin layer on top, with everything summing together for the full effect. Looking at the sample models, we see 4 colors in 2 hue groups.

• 2D and 1D are a peach-pink hue, and we need to get here from our base coat of bubblegum pink.
  • Add orangish layers by mixing magenta and yellow.
  • Orange moves us from true pink to peach.
  • Re-saturate by adding color without mixing white in.
  • 2D is more saturated and darker than 1D, so add more layers.
  • Now that we have hues closer to what we want, we see 1D is more tinted than 2D Mix white into the colors we already made to create a tint. Apply this to 1D only.
• 2C and 1C are magenta-pink, so we repeated the above procedure with magenta.

 

COSTS

Cost Type	Cost	Price	Source	Quantity	Total
Materials	PLA Filament (all iterations)	$16.99 / kg	Amazon	224.37 mL	$4.7
	LET’S RESIN Silicone Rubber	$26.99 / 510g	LET’S RESIN	240 g	$12.7
	Smooth-Cast 300	$137.82 / 2 lbs	Smooth-Cast	160 mL	$29.17
	Gray Filler Primer Spray Paint	$8.99/can	RUST-OLEUM	¼ of a can	$2.25
	Cover Spray Paint	$5.98/can	Rust-Oleum	⅛ of a can	$0.75
	Acrylic Paint	$21.74/400 mL	Amazon	10 mL	$0.54
Labor	Prototyping Engineer (X2)	$25.91 / hour	indeed	5 hr	$129.55
Overhead	Utility Cost (considering both the cost of facility and electricity)	~$5.13/ hour	TexAgs	10 hr	$51.3
	Depreciation of Assets (3D printers and tools versus their typical life spans)	~$0.76/hour	ATO	4 hr	$3.04
Design	Engineering and Development	$44.34 / hour	ZipRecruiter	6 hr	$266.04
	Iterations (a continuation of the previous category)	$44.34 / hour	ZipRecruiter	2 hr	$88.68
Misc	Waste and Scrap	~$49.5/L	UltiMaker FILAMENTIVE	0.3L	$14.85
				TOTAL	$603.57

CLEAN
I forgot to post a clean table picture before noon. I understand if this mean a deduction. Sorry!