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Mechanical Design and Fabrication Strategies for Workshop Efficiency

Learn practical tips for efficient workshop operations, from design principles to materials selection. Explore common mistakes to avoid and techniques for precise fabrication. Enhance your knowledge on joining materials and clever design examples.

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Mechanical Design and Fabrication Strategies for Workshop Efficiency

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  1. Working with the WorkshopAndy Edgar

  2. If you can buy it from a catalogue, buy it, don’t build it. US $400

  3. Strategies • Don’t be lazy – design it yourself –that way you get what you want, or at least asked for. • But get the WS to check a sketch first for manufacturability. • Get as much right as possible first time, but allow for mods.

  4. Find 10 things wrong with this job request • No date • No charge code • Who is Dave? Contact details (room, phone #) • No idea of urgency • Material not specified • Thickness not specified • Quantity not specified • Depth of 5 x 5mm recess not specified • They can’t easily make a 4.37mm hole • They can’t make a square recess with a milling machine

  5. The lathe - turning

  6. What can be done on a lathe Routine Tolerance 0.1mm

  7. Making Holes/Threads Drills – only fixed sizes –typ. 0.5 mm increments Tolerance - ~ 0.1mm

  8. The Vertical Mill For making flat surfaces Tolerance ~ 0.1mm CNC – Numerically controlled

  9. Sheet metal working

  10. For a 6mm screw, the 6 mm means • The distance between consecutive turns • The diameter of the head • The maximum diameter of the threaded part • The minimum diameter of the threaded part

  11. Screws and Bolts • Which of the following heads are described as, • Phillips • Knurled • Countersunk • Allen/Cap • Hex • Cheese • Posidrive

  12. Materials • Common W/S materials are • Aluminium • Brass • Copper • Stainless steel (magnetic?) • Machineable plastic (acetyl) • (Polyethylene). Soft • Nylon ( bearings, gears) • PTFE (Teflon) • Perspex, Lucite, Plexiglas (PMMA). Hard, clear.

  13. “Exotic” Materials • Beryllium copper, phosphor bronze (springs) • Monel 500 (Cu-Ni, low therm cond. , non–magnetic) • Macor (machineable ceramic) • Viton (elastomer, high temp O-rings) • Kapton (polyimide, vacuum, insulation)

  14. Optical Windows – Glass & Acrylic

  15. Optical Windows - Silica

  16. Broad Spectral Range Windows

  17. UV windows

  18. IR Optical Window Materials

  19. Which Material? • Which of these W/S metals are not “pure ( >99%) metals? • Brass, copper, aluminium • Which of the W/S materials would you use for, • A cryostat for liquid nitrogen/helium? • A sample holder for cryogenics • A good electrical insulator for T<200˚C • An electrode holder for high temperatures? • Which metal would you not use for vacuum? • Which metal is the most expensive?

  20. Joining Materials

  21. Soldering and Brazing • Soldering (200-300˚C) • Brass, copper • Sn-Pb (banned) • Tin-Antimony • Have to remove surface oxide first with flux • Brazing (600-800˚C) • Brass, copper, steel, SS • Brass brazing rod, or • Ag-Cu-Sn “silver solder” • Hydrogen acts to clean surfaces

  22. Welding • Mainly steel, any other metal incl. Al • Filler of same metal used to reinforce joint • Localised electric arc melting of metal and filler. • TIG – tungsten/inert gas (argon)

  23. Glues • Aim for thin joints, clean surfaces first • Standard 2-part resin (araldite). Soften in acetone, flame. • Silicone RTV • Thermosetting polymers and resins ( hot glue) • Superglue (cyanoacrylate) • Soluble ceramics for furnaces • Low vapour pressure resin (Varian) • Silver-filled epoxy, silver conductive paint

  24. Two Examples of Clever Design

  25. “Kinematic” Bearings

  26. Translation Platform

  27. Drawings • Hand drawings are fine • Ruler is good for straight lines! • Use grid/graph paper • To scale is best • Sketch, front, top, side views for clarity (conventions) • Specify ID, OD, threads, material • If frequent user, consider CAD ( eg SolidWorks)

  28. Acknowledgements • Many diagrams and info from, “Building Scientific Apparatus” JH Moore, CC Davis, MA Coplan, SC Greer (new copy ( 4th edition) ordered for library)

  29. Table of Contents 1. Mechanical design and fabrication 2. Working with glass 3. Vacuum technology 4. Optical systems 5. Charged-particle optics 6. Electronics 7. Detectors 8. Measurement and control of temperature Index.

  30. 3d Printing - Justin

  31. 3D Printing • For personalised, custom-made lab equipment. • Requires a 3D design- solidworks • 3D printer- School of Architecture and Design.

  32. Solidworks • A 3D Computer Aided Design (CAD) software used to create a model. • The design starts with a 2D sketch and is extruded to give a 3D object. • The final design is sent as a .stl file to the printer. • The design is printed by slicing the design into 2D digital cross sections and depositing the materials layer-by-layer. • Materials used include thermoplastics eg. acrylonitrile butadiene styrene, polycarbonate, polylactic acid.

  33. IR Optical Window Materials

  34. IR Optical Window Materials

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