Construction Methods, Materials, and Fabrication Methods in FRC By Akash Rastogi, Eric Drost, Alex Mills & Connor McLaughlin FRC 11 - Mt. Olive Robotics

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Construction Methods, Materials, and Fabrication Methods in FRC By Akash Rastogi, Eric Drost, Alex Mills & Connor McLaughlin FRC 11 - Mt. Olive Robotics Team Slide 2 Objectives 1.Learn about forces that structures have to withstand 2.Discuss different construction methods used by many FRC teams and the benefits of each kind 3.Discuss materials commonly found on FRC robots and their different uses and applications 4.Learn about different fabrication methods commonly used in FRC with emphasis on resources currently available to MORT Slide 3 Forces Acting on Structures There are different types of forces that act in different ways on structures such as bridges, chairs, desks, buildings, robot frames, etc... Static Loads: Student on desk or chair Dynamic Loading: force in motion Slide 4 Forces Continued... Tension & Compression - when the ends of an object are pulled apart from both ends versus pushed towards the center from both ends respectively. Slide 5 Forces Continued... Shear: applied parallel or tangential to a face of a material Torsion: occurs when an object, such as a bar with a cylindrical or square cross section is twisted Why do triangles work the best in structures? Why do we use trusses and triangles in FRC? See the following link: http://legacy.mos.org/etf/force.html See 'Types of Forces' and 'Design Strength' tabs. Skip 'Build a Skyscraper' Slide 6 Construction Methods Tubing Round Square Welded Tube Gusseted Tube Tube + Sheetmetal C-channel, Right Angle, and other extrusions Hex, round, and square bars C channel, U channel, Right angle Sheetmetal Bent Flat Plate Thicknesses Pocketing plate Slide 7 Tubing Construction Tubing is an extremely versatile and strong construction method which can create light parts without sacrificing too much strength. We use 6061-T6 aluminum tubing with varying wall thicknesses from 1/16" to 1/4" We have also used other materials in extruded tube form such as polycarbonate, fiberglass, and carbon fiber. Even very thin wall steel works in small quantities. Tubing provides: much stronger frame than just flat or right angle extrusion more mounting surfaces than flat plate Slide 8 Round and Square Tubing Round Tubing Difficult to mount to Easy to create custom bent shapes Thinner wall round may be stronger than square in many cases (arms) Square Tubing Very easy to mount to Easy to machine Easier to weld/gusset Slide 9 Gussets/Sheetmetal Using gussets is incredibly easy, especially with CNC equipment. Thin or thick plate can be used in different shapes along with rivets or bolts to connect a frame together. Sheetmetal parts are bent in a way which allows tubing to be fastened at the corners. Most sheetmetal parts have gussets designed into them. Welding Welding tubing has a high risk of warping the frame due to the heat introduced to the part. Welding must be done by a skilled professional or a well practiced mentor/student TIG welding is needed - Tungsten Inert Gas Connecting Tubing Slide 10 Connecting Tubing Continued... Slide 11 Hex, round, and square bars C channel, U channel, Right angle All of these extrusions are used in various parts of an FRC robot. Hex and round are used for shafts and standoffs which can be aluminum, delrin, polycarbonate, or several other plastics. C-channel, U-channel, and right angle extrusion are commonly used for structures. C-Channel, Right Angle, and Other Extrusions Slide 12Flat sheet Sheetmetal Construction"> Sheetmetal construction relies on strategic bends in the plate which creates stiffer parts. Thicker sheetmetal parts are made of a softer aluminum alloy 5052-H32 to avoid cracking of the material Thinner sheet Polycarbonate Not Plexiglass - acrylic shatters on impact Polycarb is strong, fairly light, and easy to use. Used for windows and is bullet resistant beginning at 3/8" Can be heated and bent for many applications Tensile Strength: Good Impact Strength: Excellent Slide 21 Fabrication Methods CNC and Manual MIlling (both available in house for MORT) CNC and Manual Turning (manual available in house for MORT) CNC Plasma Cutting (available in house for MORT) Waterjetting (available via sponsor) Laser cutting (available via sponsor) 3D Printing (available via sponsor) Slide 22 CNC/Manual Milling Use high speed spinning milling bits to cut away material. CAD files are used directly for CNC milling and manual machining requires detailed CAD drawings as instructions. Most CNC milling is high precision but can be slightly slower than other methods depending on part thickness, material being cut, and the sharpness of the cutting tool. Slide 23 CNC/Manual Turning Uses high speed lathe which spins a part to shape it against a sharp cutting tool. Lathes are also used to size, drill, and tap parts such as standoffs, shafts, and wheels, pulleys, gears, and sprocket hubs. Slide 24 CNC Plasma Cutting Not as high precision as other CNC tools. Puts a lot of heat into the plate being cut (localized hardening or annealing). Bearing bores must be finished up in a mill and small holes must be drilled out. Slide 25