Here, number of difficulties which are encountered during manufacturing and assembly process are described. We also draw several well-chosen tradeoff solutions. Problems and solutions are as follow:
After manufacturing a sample of few parts such as the elbow a torque and load problem revealed since the thickness of the old design of the elbow doesn’t overcome the links and end effector load, therefor the dimension of thickness increased from 6mm to 12mm, the old elbow is shown in Figure 4.31.
2- At the beginning of components collection stage of this project, getting of servo motors was a mission impossible especially from abroad markets. Thus we began replacing servomotor with stepper motors bearing in mind motion synchronization. We built a control circuit for this purpose. The circuit controls three stepper motors simultaneously using serial/USB communication and 4 PIC microcontrollers instead of Arduino UNO, Figure 4-32.
Later we managed to get three hoppy servo motors and consequently the project continued as planned.
When assembling links with elbow some friction and heavy clutching acquired, therefore a ball bearing is added in order to reduce friction, however another problem revealed which is the size of the ball bearing, the desired one is 12mm outer diameter to 6mm inner diameter, after extensive exploring we found this type of ball bearing in crank shaft of unknown motor in scrap field, Figure 4-33.
When spherical joint assembled with the closed end screw and using the normal hexagonal nuts a problem of limited movement appeared, however a new research for a better type of nuts which found in wall bolts nuts since they have thin thickness compared with the hexagonal nuts, Figure 4-34.
After assembling the delta robot a new challenge begin, since the position of end effector is higher than the down disk plat –work area- therefor the contact application is not applicable, and this challenge faced with adding height flexible plat that can be adjusted up or down with screws and nuts.
