This research aims to design and build a 3D printer machine using Arduino Mega 2560 and compare it to a standard 3D printer using a 3D printer module and bed temperature. The design simulation between the two machines is compared from the von Mises stress, displacement, and safety factor values. In contrast, testing machine performance by comparing the tensile strength and dimensional accuracy of the printing results. A cost comparison is also presented to complete the analysis. From a design perspective, the von Mises stress ratio is 10.94: 2.24; displacements 0.04: 0.03; and the same safety factor, which is 15 for the newly designed 3D printer and the standard one respectively. In terms of dimensional accuracy and power, the two machines are equivalent. While the new-designed machine can save costs of Rp.1.639.000 or 40% off. It is concluded that the machine with the Arduino Mega 2580 deserves to be used as an alternative to 3D printer machines at a lower cost.

Keywords: Rapid Prototype; 3D Printing; Dimensional Accuracy; Tensile Strength

In the era of industrial revolution 4.0, the industrial world's development is rapidly increasing with new innovations, one of which is the 3D printer machine. 3D printer, also known as additive layer manufacturing, creates 3D objects/objects that display designs in printed form [1]. Designs made to produce 3D printers must go through a product design process using CAD (Computer-Aided Design) software and other supporting software such as Creality or Cura to print designs [2].

In the 3D printing process with the FDM (Fused Deposition Modeling) technique, the dimensions and geometry are essential factors that affect the quality of 3D Printer printouts [2,3]. These factors are the primary considerations in designing or making 3D printer machines.

3D printer technology has experienced significant developments in print quality, manufacturing costs, and models in recent years. With the flexibility of the 3D printer function, some researchers were very fond of maximizing the machine properly [2]. However, 3D printers are equipment that is quite expensive for small enterprises [4]. Amri & Sumbodo designed a 3D printer type core XY FDM using Autodesk Inventor 2015 [5]. The simulation showed that using V slot type, the von Mises stress was 0.03 MPa, displacement of 2.4 mm, and safety factor of 15. It was adequate strength for a frame. However, it was only a design that had not reached to real product [6]. Recently, Kosasih et al. have designed and manufactured a 3D printer- Cartesian type with V slot. They found a 3D printer that is more user-friendly, but there were stringing on the printed part. It was designed using AutoCAD then fabrication without simulation [6]. Rosli et al. developed a cheap 3D metal printing by installed a MIG welding torch on an FDM type printing [4]. They used Ardunio Mega 2560 and Nema 23 stepper motor and Stepper driver 8825. It works for metal filament, but accuracy is relatively low [4]. There was also no simulation in design before manufacturing. Sevvel et al. have designed and fabricated an innovative desktop 3D printing machine. The main innovation was replacing affordable components, and the accuracy of this design was good [7].

Previous attempts to create a new 3D printer have some limitations: (i) the design followed by manufacturing without simulation, (ii) simulation only without developing the real machine. In order to find a better-designed machine, it needs to do a complete sequence from design, simulation, then try it in actual production. This shows that it is not impossible to build an affordable 3D printer. This research aims to design and test the performance of a new system 3D printer FDM technique. The main change of machine is using Ardunio Mega 2560 and no bed temperature. The research target is to obtain a new 3D printer design that has design performance and work performance equivalent to standard machines with lower machine manufacturing costs.

This research began by designing a new 3D printer machine with an Arduino Mega 2560 as a microcontroller and not using a heater on the 3D printer bed. Inventor software was used to develop frame designs, specimens, and loading simulations. The design results would be compared with a cartesian type 3D printer that uses a temperature bed and a V slot frame. For simplifying sake, the former printer will be termed a custom printer. The latter will be called printer X. Analysis of von Mises stress, displacement and safety factors was carried out to determine the design strength. After manufacturing and assembling the machine, tests were carried out to print tensile test specimens according to the ASTM D6838 (type I) standard. An infill pattern of 80% and 100% was given as the printing variables. Tensile strength and dimensional accuracy were measured and calculated from outputs. The material (fed filament) used for testing was PLA. According to Kovan, Polylactic acid (PLA) is commonly used in the FDM process. PLA is a biopolymer produced from renewable sources such as corn or sugarcane starch. Its amorphous structure makes PLA an excellent choice for FDM systems [5,8]. According to Spoerk, for PLA and ABS, the minimum temperatures good for specimen printing are 220 and 255°C [9]. Properties of PLA are presented in Table 1.

Table 1: PLA material properties.

The test product is in the form of a tensile test specimen with the ASTM D6838 standard (type I) as shown in Figure 1, which was replicated from [10]. The test of this specimen is in the form of dimensional accuracy and tensile test. The dimensional measuring instrument is a caliper or micrometer with an accuracy of 0.01 mm. The tensile testing machine used is the HT 2402 Tensile Testing Machine as depicted in Figure 2.

Figure 1: Design of ASTM D6838 (type I) specimen dimension [10].

Figure 2: HT 2402 Tensile test machine; red arrow shows tensile test specimen.

An analysis was also carried out on the cost of making this machine compared to an equivalent standard 3D printer on the online market.

The main differences between the newly designed machine from the existing machine are presented in Table 2.

Table 2: Comparison of 3D printer components.

In designing a 3D printer for the mainframe using an axle or rod, besides being strong, the price is relatively low compared to the V slot. The leading mainboard uses Arduino Mega and Ramps, because it is perfect for running programs, and the price is very affordable. The connector for the LCD frame and holder uses materials from 3D Printer prints so the price is lower. The drive axis is chosen to use a ball screw in order to produces good printing accuracy. The nozzle fan uses a laptop fan because it has high rotation per minute and low power consumption. In addition, the laptop fan is compatible with a DC power supply as listed in Table 2 above.

For the controlling system, the primary controller uses the Arduino MEGA 2560 because it can run open-source programs. Besides, the input power needed is also minimal. Therefore, the DC adapter is still able to supply power to the Arduino Mega. In addition, the price of this controller is also affordable.

The bed is a fixed type. Therefore, there is no need to adjust the height during the initial setup of the machine. Based on the authors' experience, leveling the bed is time-consuming. Therefore, to make the fix hopefully will reduce the setting time. The driving parts of the X, Y and Z axes use a ball screw to gain more accurate printing results. The design in the form of CAD drawings is presented in Figure 3.

Figure 3: Design of the custom 3D printer.

Information:

1. Extruder 3D Printer
2. Nema 17
3. Flexible Coupling
4. Frame
5. Bed (made from glass)
6. Ball Screw
7. Rod

The custom 3D printer was designed according to works of literature data collection, survey, and product development. An Autodesk Inventor software was used to observe the strength analysis of the frame. A load of 50 N was applied based on half the weight of the machine. A comparison of both printers' designs is presented in Figure 4.

Figure 4: Frame 3D printer (a) custom 3D printer model using frame axle, (b) 3D printer X model using frame V slot.

Both designs use bolts to fix the connectors. Between rods of the custom printer are connected by plastic connectors (black cubes at Figure 4a) made by 3D printer, then locked with a bolt.

The next step is to perform simulations, namely: von Mises, displacement, and safety factor. Von Mises stress comparison of both printers is depicted in Figure 5.

Figure 5: Comparison of von Mises 3D printers values: (a) custom design, (b) printer X.

Von Misses stress value is obtained from the theory of failure due to energy distortion. If the von Mises stress exceeds the yield stress of the material, the design will fail. The following formula was used for calculating von Mises stress:

σ1 : material starts to reaches the yield strength
σ3 : material reach to yield strength.

In the simulation results, the von Mises value can be seen by looking at the color changes. The red color shows the most significant stress and the blue one indicates lower stress. The maximum value of von Mises for the custom 3D printer and the printer X are 10.94 MPa and 2.24 MPa, respectively. Besides the different frame profiles, the difference in maximum stress may be because of the other materials used. The rod frame of the custom printer is made of stainless steel, while the V-slot of printer X is made of aluminum.

Furthermore, a displacement analysis is carried out. The results of the study of these two printer models are presented in Figure 6 as follows.

Figure 6: Comparison of 3D printer's displacement values.

Displacement is a change in the shape/deflection of the material after being subjected to load. The frame integrity is observed based on the results of the displacement simulation. From Figure 6, it is evident that the maximum displacement the rod frame and V-slot frame are 0.04 mm and 0.03 mm, respectively.

Subsequently, the safety factor of both designs will be observed. Safety factor of both models are presented in Figure 7. A safety factor is a factor used to evaluate the safety of a design. The safety factor value ranges from 0-15 for a better safety factor, more than 1 [11,12]. In the safety factor analysis, both machines are 15, which mean both designs are safe.

Figure 7: Comparison of the safety factors of two engine designs.

The value of the safety factor (SF) can be calculated by the following formula [13]:

SF: Safety Factor
σ Ultimate: Yield Strength
σ Max: von Mises stress

At a load of 50 N, the highest safety score = 15, while the lowest safety value=15. According to [12], the minimum safety factor depends on the load type; (i) static load (1.25-2), (ii) dynamic load (2-3), (iii) shock load (-5). Based on the construction of the 3D printer, it is among the dynamic load group. Therefore, the safety number is at least 2.

Finally, the comparison of both 3D printer machines form design perspective is presented in Table 3.

Table 3: Simulation recapitulation.

After all the design criteria state that the design is safe, then the assembly is carried out. Photos of two machines are presented in Figure 8 below. The bed of the custom machine is without bed temperature as directed by a red arrow at Figure 8a. It means there is no need to set the bed temperature prior to printing.

Figure 8: Comparison between two 3D Printer designs: (a) custom 3D printer without bed temperature (shown by a red arrow), and (b) 3D printer X using bed temperature.

Printing Product Analysis

Printed specimens of these two machines are presented in Figures 9 and 10. From the observation, there is no significant difference between the two groups of specimens. Then the dimension measurements and tensile tests were carried out.

Figure 9: Specimen print results using the Arduino 3D printer machine.

Figure 10: Specimen print results using a 3D Printer X.

Table 4: Dimensional measurements on the custom 3D printer and 3D Printer x; with p: length, l: width, t: thickness.

The results of the calculation of dimensional deviations are presented in Figure 11. There are differences in the variation of each specimen due to several things. It may relate to the nozzle speed and the given temperature. If the nozzle is at an excessive speed and temperature, the printed products tend to deviate. It can be seen the significant difference in surface size.

Figure 11: Comparison of dimensional deviation of the printed products: (a) of Custom 3D printer, and (b) 3D Printer X.

Tensile Test

The size of the nozzle, the direction of the nozzle print, and the type of material are significant factors in determining the strength of the material [14-16]. The following equation was used to calculate the tensile strength:

F: Force (N)
A₀: Area before loading (mm²)

Engineering stress, σ (Stress) (MPa), F load applied in a direction perpendicular to the specimen (N) and A0 initial cross-sectional area before the specimen is loaded (mm²) [17]. Table 5 presents the tensile strength comparison of specimens made by both machines.

Table 5: Results of 100% and 80% infill tensile tests.

The tensile test results show that the average maximum stress is 34.2 MPa and 36.2 MPa of the specimens made by printer X and custom printer, respectively. Figure 12 shows the comparison of tensile strength of specimens produced with different infill by both machines. The custom 3D printer results in stable tensile strength compared to the competitor machine, regardless of the infill used. When there is no bed temperature, the heat on the custom 3D printer is focused on regulating the nozzle's temperature. Therefore, there is no waiting time for heating. Specimens 1-5 were printed sequentially in one program. At infill 100%, the custom printer results in comparable tensile strength that of 3D printer X, except that the custom 3D printer achieved the maximum tensile strength sooner than that of the printer X.  In the case of 80% infill, both machines can result in a product with a similar tensile strength at the beginning. However, the printer X gained higher strength products after a while.

Figure 12: (a) 100% infill bar graph and (b) 80% infill bar graph.

Based on the tensile strength value and dimensional measurements, it is concluded that the quality of the printed product is influenced by the bed temperature, the alignment of the 3D printer bed height, and the nozzle heating quality. The custom 3D printer has a stable improvement compared to the 3D printer X. The former is able to start printing faster because there is no need to warm up the bed. The absence of bed temperature also makes the printed products more quickly cooling and be a solid phase.

A detail of component cost is presented in Table 6.

Table 6: Cost Estimation. (Note: Currency rate USD1 = Rp14,241 at the time of submitting the paper).

It can be seen in Table 6 that the total manufacture of a custom 3D printer reaches Rp. 1,639,000. It is cheaper than the price of 3D printer X, which comes at Rp. 2,700,000 (based on the cost of 3D printers in online stores). It is about 60% of the normal price of the competitor.

Based on the simulation results, the comparison of the 3D printer frame shows that the von Mises displacement and safety factor values of the custom printer are 10.94 MPa, 0.04 mm, and 15. At the same time, the von Mises, displacement and safety factor values of the Printer X are 2.24 MPa, 0.03 mm, and 15. Both machines are reliable, designed, and safe.

Measurement of printed product accuracy also proved that both machines have acceptable deviations. While product strength shows that the custom printer results in more stable tensile strength than the competitor.

Economic analysis proved that the custom 3D printer is cheaper and may be more acceptable for the small-scale enterprises. To conclude, the custom printer is feasible for production.

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Corresponding author: Mahros Darsin, Mechanical Engineering Department, Universitas Jember, Indonesia.

Gaguk Jatisukamto, Mechanical Engineering Department, Universitas Jember, Indonesia

Mohd Sabri Hussin, Faculty of Mechanical Technology Engineering, Universiti Malaysia Perlis, Malaysia

Copyright: © 2021 All copyrights are reserved by Mahros Darsin, published by Coalesce Research Group. This work is licensed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.