## 3 Materials and Methods  
Considering the ongoing research and the requirements for the measuring device outlined in the previous chapters, it becomes apparent that, in the case of the apparatus intended for adhesion tests, a certain form of compatibility with FFF devices is necessary. The materials used in the construction of the adhesion testing device and the specifications of the model tested for adhesion are pivotal components in evaluating the adhesion properties of 3D-printed objects on various substrate materials [13]. This section provides a detailed description of the materials used in the construction of the testing device and emphasizes the specifications of the polyethylene terephthalate glycol (PETG) material model used for adhesion testing. It constitutes a relatively straightforward concept consisting of few fundamental parts. The first part comprises a compact frame made of aluminum profiles of 20 \(\times\) 20 and 20 \(\times\) 40 mm dimensions. This frame serves as the supporting section of the entire device, directly placed onto the print bed of the FFF device. The construction of this frame includes:* Aluminum profiles of specific lengths, 20 \(\times\) 20 and 20 \(\times\) 40 mm: an aluminum frame measuring 20 \(\times\) 40 mm served as the foundational frame for the testing device, ensuring structural stability. * 3D printed parts: specially designed components essential for ensuring the functionality and stability of the testing device, as well as the placement of other components, were manufactured using ABS material in the 3D printing process. * Fastening materials: a range of screws and nuts were employed for securely fastening and assembling various parts of the testing device, ensuring strength and stability during evaluation. Given the compactness of the entire measuring system and the endeavor to position it on the print beds of FFF devices, it is evident that there is no room in the design for dimensionally large measuring devices. For this reason, the EMS20-5 kN sensor (EMSYST spol. s r.o., Trencin, Slovak) was selected [14]. This sensor, in collaboration with the DAQ device and EMS Center v1.0 software, enables the measurement, transformation, and recording of the tensile force over time. The measurement section of the proposed device thus consists of:  
* Force sensor (Emsyst EMS20-5 kN): the experiment utilized the Emsyst EMS20-5 kN force sensor, visible in Figure 2, along with its parameters, which were pivotal for quantifying adhesive forces between the 3D printed model and various substrate materials. * Data Acquisition System (DAQ) (Emsyst EMS650, EMSYST spol. s r.o., Trencin, Slovak): the data acquisition system, Emsyst EMS650 (Figure 2), was integrated with the force sensor to ensure the collection and recording of adhesion-related data during evaluation using the corresponding EMS Center v1.0 software. The Prusa Mk3s+ was selected as the testing FFF device, and four types of materials were placed on its print beds. This device is equipped with a direct extrusion head, enabling more precise material dosing, and features a wide range of 3D print beds with recommended manufacturer settings. The only adjusted parameter was the temperature of the printing bed. It had to be corrected for better adhesion of the model to its surface. Models designed for the optimization of the printing process were not subjected to measurements due to their frequent deformations. The result of the optimization of the printing process for the chosen material-produced parameters is presented in Table 1. Subsequently, these parameters were employed in the production of all samples designated for testing purposes. Among other components, such as threaded rods and guiding nuts, an indispensable part of the device, or the diagnostic system, is the test model [15]. PETG was chosen as the material for this model, which is one of the most commonly used materials in the realm of FFF technology, whose adhesion to print beds has been a perennial subject of discussion.