CNC machining, mold making or turning out components require basic knowledge of geometry. This is a simple guide to the basics of high school geometry. Of course our forefathers never went to high school but still learnt the basics via common sense.
Take a long thin and flat piece of wood or foam or any material that can be cast. Let the object be 1cm wide, 2mm thick and 15cm long. Lay the object on its side and try to break it. There will be resistance as the object flexes. Now lay the object on its 2mm thick edge. Apply the same force from the other side and try to break it. The long object will resist forces and will also not flex. Although the cross section is still the same it exhibits greater resistance to forces. This is the principal used in designing any part particularly plastic parts for improving rigidity by increasing the maximum span of the object in the same direction that is subject to bending force. The engineering trick is to add ribs – example ‘C’ sections, ‘U’ sections or ‘F” sections.
CNC Routers Machining
Robotic engineering makes use of rib engineering as it allows very thin chassis to maintain rigidity. The ribs are routed in such a manner that areas requiring additional clearance are factored in the mechanical design.
Robotic Engineering Design
Mold designs use the principle of reinforcing sharp corners and holes that are subjected to forces and stresses. Simple reinforcement ensures that stress is distributed. CNC routers can simplify the designs when using foam as the router follows the tool path to produce ribs as delicate as 100 microns (twice the width of human hair). The CNC router is an indispensable machine tool that can tackle large mold designs (such as blades for windmills) or as small as the drones that are slated to carry 1 kg packages for Amazon delivery services. Recently Elon Musk OD SpaceX identified that the ribs supporting the landing fins of the Falcon booster rocket buckled because of faulty reinforcing design of the rib. The simple act of strengthening the rib allowed the Falcon booster stages to land perfectly in the vertical position. This was tested by CNC machining.