# Estimating the Uncertainty of Measurements for Various Methods and 3D Printed Parts
## 2 Materials and Methods
### Measurement Methods  
One of the manufactured samples is shown in Figure 4, displaying the macrostructure of the surface in its various sections using different magnifications of the digital microscope. The macrostructure (shape) of the surface affects the results of geometric quantities depending on the measurement method used, as illustrated in Figure 5. \begin{table}
\begin{tabular}{c c} \hline \hline
**Printing Parameters** & **Value and Unit** \\ \hline Base layer & Raft \\ Extruder temperature & 220 \({}^{\circ}\)C \\ Infill density & 20\% \\ Supported Materials & MakerBot PLA \\ Built plate temperature & 50 \({}^{\circ}\)C \\ Layer height & 0.2 mm \\ \hline \hline \end{tabular}
\end{table} 
Table 2: MakerBot Sketch printer parameters for PLA. Figure 3: Placement of sample models on the virtual 3D printer platform in MakerBot Print. Figure 4: Printed sample with characteristic spots observed under the microscope; (**a**)—view of the entire sample with marked observation spots, (**b**)—edge of the sample at observation spot 1, magnification 40\(\times\), (**c**)—seam of the sample, observation spot 2, magnification 60\(\times\), (**d**)—bottom part of the sample, contacting the printer working platform, observation spot 3, magnification 40\(\times\), (**e**)—top part of the sample, observation spot 4, magnification 240\(\times\), (**f**)—side surface of the sample, observation spot 5, magnification 125\(\times\). Figure 5: An example model of the effect of surface macrostructure on the result of measuring a geometric quantity, 1—the flat tip of a caliper or other contact sensor, 2—the blade of a caliper or other contact sensor, 3—the contact sensors of a measuring machine with a spherical blanket, 4—the light rays of a scanner, 5—the shadow effect from surface irregularities, 6—fragment of the sample. Figure 5 shows how the geometric structure (shape) of a printed sample can affect the measurement result. Different shapes of contact measurement sensors are used during measurements, and this has certain consequences, e.g., a flat tip (1) makes surface contact only with the tops of irregularities. On the other hand, blade-type (2) or ball-type (3) tips can plunge into the so-called \"valleys\" of irregularities, which affects the value of the final result of the measurement of a geometric quantity. The use of a scanner, which uses a light beam (4) is also not without disadvantages, as the so-called \"shadow effect\" (5) can be created, which affects the surface doping in the image processing on the basis of which the inspection of dimensions is carried out. When carrying out measurements using a dial caliper and a coordinate measuring machine, this phenomenon was considered and two types of measurements were made, the so-called diameter measurement with seam and the measurement without it. Each of the measuring tools had a different measurement strategy as described below, but in all cases, the values measured at three different heights were analyzed. It was decided to carry out the measurement with the diameter measurement omitted at the top surface due to a defect in the print in the form of excessive material flowing out, and the bottom surface due to the formation of a defect in the form of the so-called \"Elephant foot\". Metrology tests were conducted using three pieces of equipment:  
* Dial Caliper,
* Coordinate Measuring Machine,
* 3D scanner. The INSIZE 1311-150A Dial Caliper (INSIZE Co., Ltd., Suzhou, China) was the first device used to make measurements. The resolution of the Dial Caliper used was 0.01 mm, according to the producer. According to the manufacturer, the accuracy of this caliper for a measuring range of 15 mm is equal \(\pm\) 0.02 mm. The Dial Caliper had a valid calibration certificate at the time of measurement. The research involved measurement using a flat measuring tip (Figure 5--type 1) of a caliper in the place closest to the main body.