Parametric thinwall test parts, boxes, tubes, washers, bushings, rounded

This is a thin wall test with both rounded and sharp corners. My slicer says it takes about 0.29m of filament, so it's a cheap test for adhesion, elephant-foot, speed, retraction, cornering, dimensions, thin-wall extrusion, and quality.

You can set the wall thickness to be your nozzle's ideal extrusion width. These three stls have different wall thicknesses:

part	wall mm
thinwall_20_30_10_0p50.stl	0.50
thinwall_20_30_10_0p60.stl	0.60
thinwall_20_30_10_1p00.stl	1.00
thinwall_20_30_10_0p50_bottom.stl	0.50
thinwall_20_30_10_2p00_web.stl	2.00

I printed the pictured rough white part back in 2012 on a home-built Wallace with my own version of a Wildseyed MIG Welder Tip hot end, and wanted to redo the test on my new printer, but didn't have the pattern. So I hacked this up based on https://github.com/Irev-Dev/Round-Anything 

 

// thinwall_20_30 -- thin wall test piece, copied from memory
// Uses polyround from https://github.com/Irev-Dev/Round-Anything
// https://www.thingiverse.com/thing:6216210
// Wall thickness
thick = 0.5; // 0.01
// length
x = 30;
// width
y = 20;
// height
z = 10;
// corner factor -- try 0 to sharpen the corners
c_scale = 1; //0.1
// corner add -- try 3 to add 3 to the radiuses of the corners
c_offset = 0; //0.1
$fa = .01; // facet angle
$fs = $preview ? 5 : 1; // facet size
$fn= $preview ? 32 : 64; // facet number
thinwall_rounded();
// x,y,radius
radiiPoints=[
  [0,  0,  0 * c_scale + c_offset   ],
  [x,  0,  10 * c_scale + c_offset],
  [x,  y,  10 * c_scale + c_offset],
  [0,  y,  5 * c_scale + c_offset ]
];
use <Round-Anything-1.0.4/polyround.scad> // https://github.com/Irev-Dev/Round-Anything
module thinwall_rounded(){
    linear_extrude(z){
      shell2d(-thick)polygon(polyRound(radiiPoints,30));
    }
}

The attached .scad file includes a slightly modified copy of RoundAnything so it works standalone.

in customizing this code, I added several features. I added a couple terms to override the corner radii so you can scale the radii up or down, or add a constant. With settings X=40, Y=40, Z=50, C_scale=0, C_offset=5, it will make a 40mm calibration cube, with a 5mm radius on each corner, like the tall green box in the back corner.  I also added an optional bottom thickness.  Negative bottoms are interpreted as a web bridging halfway up Z.

This image shows the thinwall_20_30_10_0p50_bottom.stl holding water, and both sides of the webbed thinwall_20_30_10_2p00_web.stl part in a mirror:

The mixed-radius edges give the part a definite x-y-z orientation once it is taken off the plate: The X direction is from the sharp corner to a large radius, and Y is from the sharp corner to the smaller radius, which gives Z as up. So if you hold the part with the big radiuses to the right, and the sharp corner on the left and toward you, +X is right, +Y is away from you, and +Z is up.

The code will produce a part that will have the X and Y dimensions, and radii larger than would smoothly adjoin the walls will be constrained to meet X&Y.   So if you want a round tube of a certain diameter, set X=Y=diameter, and use c_offset =X/2 and c_scale=0 to set the radii larger than the radius of the circle.  These settings made the tube and washer in the pic.

The pieces are nice for quickly checking several features, and then the leftover hollow flat parts can work well for simple display stands.