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Tolerancing
Tolerancing
Mr. Budzichowski gave a lesson about tolerancing, using a cube as an example. If we set the tolerance to 20.0 ± 0.2 mm, the width of the cube could be between 19.8 and 20.2 and still be within tolerance. There were also two other terms brought up:
Maximum Material Condition (MMC)
when the object contains the greatest amount of material while remaining within its specified tolerance
Least Material Condition (LMC)
when the object contains the least amount of material while remaining within its specified tolerance
Non-Cube Challenge
Non-Cube Challenge
Design three other examples of non-cubes that are within tolerance
19.8 mm x 19.8 mm x 20.0 mm
19.9 mm x 19.9 mm x 20.0 mm
For this assignment, I stayed with 3D objects that are reminiscent of a cube, a rectangular prisms, and changed the dimensions of sides so that they are within the 20.0 ± 0.2 mm tolerance. I made sure that all sides are not the same, else it would no longer be a non-cube.
→ 20.0 mm x 19.8 mm x 20.1 mm
Cube Dimensions
Cube Dimensions
In Fusion360, I designed a cube with edges measuring 20 mm. I also de-embossed "20 mm" and my initials for clarity. Because each face is a square, the diagonal of a face should be the same and calculated using the equation:
Face diagonal = √2 x side length
√2 x 20 mm = 28.28 mm
The space diagonal (running through opposite corners of the cube) is calculated using:
Cube diagonal = √3 x side length
√3 x 20 mm = 34.64mm
the printed cube's width is 19.9 mm
a face diagonal is 27.2 mm (<28.28 mm)
the printed cube's length is 20.0 mm
another face diagonal is 27.4 mm (<28.28 mm)
the printed cube's height is 20.0 mm
one space diagonal is 33.8 mm (<34.64 mm)
Tolerance Gauge Dimensions
Tolerance Gauge Dimensions
The tolerance gauge has five square cutouts spaced 5mm apart. The gauge has a thickness of 15 mm to ensure that the cube does not get stuck when slid through. The widths of the square cutouts vary in 0.1 mm increments, ranging from 19.8 mm to 20.2 mm. Each hole is labeled with its corresponding width. Ideally, the diagonals should be 28, 28.14, 28.28, 28.42, and 28.57 mm.
measured widths: 20.2, 20.1, 19.9, 19.7, 19.7
diagonal of 20 mm is 27.3 mm not 28.28 mm
diagonal of 20.2 mm is 27.4 mm not 28.57 mm
diagonal of 29.9 mm is 27.3 mm not 28.14 mm
diagonal of 20.1 mm is 27.4 mm not 28.42 mm
diagonal of 19.8 mm is 27.1 mm not 28 mm
On the left side of the print, the base layer flares outward slightly because the printer extrudes extra material on the first layer to improve bed adhesion. Moving toward the right, the cube showed a slight indent along its edge.
The corners of the square cutouts were not perfectly sharp because the printer must both change direction and extrude additional filament at corners, resulting in slightly rounded edges for both the cube and the holes.
The printed cube measured 19.9 mm in width, which is 0.1 mm smaller than the intended 20.0 mm. Similarly, all measured diagonals of the cube’s square faces were less than the theoretical values from the original design.
For the tolerance gauge, the 20.2 mm and 20.1 mm cutouts were printed accurately, but the other cutouts were undersized compared to their intended dimensions. The measured diagonals of all cutouts were also smaller than the calculated values.
Table and Final Video
Table and Final Video
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