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Working with the Workshop 

Andy Edgar

If you can buy it from a catalogue, buy it, don’t build it.

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US $400

Strategies

• Don’t be lazy – design it yourself –that way you get what you want, or at least asked for.

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• But get the WS to check a sketch first for manufacturability.

• Get as much right as possible first time, but allow for mods.

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Find 10 things wrong with this job request

1. No date

2. No charge code

3. Who is Dave? Contact details (room, phone #)

4. No idea of urgency

5. Material not specified

6. Thickness not specified

7. Quantity not specified

8. Depth of 5 x 5mm recess not specified

9. They can’t easily make a 4.37mm hole

10. They can’t make a square recess with a milling machine

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The lathe - turning

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What can be done on a lathe

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Routine Tolerance

0.1mm

Making Holes/Threads

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Drills – only fixed sizes –typ. 0.5 mm incrementsTolerance - ~ 0.1mm

The Vertical Mill

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For making flat surfaces

Tolerance ~ 0.1mm

CNC – Numerically controlled

Sheet metal working

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For a 6mm screw, the 6 mm means

1. The distance between consecutive turns

2. The diameter of the head

3. The maximum diameter of the threaded part

4. The minimum diameter of the threaded part

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Screws and Bolts

• Which of the following heads are described as,– Phillips– Knurled– Countersunk– Allen/Cap– Hex– Cheese– Posidrive

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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.

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“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)

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Optical Windows – Glass & Acrylic

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Optical Windows - Silica

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Broad Spectral Range Windows

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UV windows

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IR Optical Window Materials

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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,

1.A cryostat for liquid nitrogen/helium?

2.A sample holder for cryogenics

3.A good electrical insulator for T<200˚C

4.An electrode holder for high temperatures?

• Which metal would you not use for vacuum?• Which metal is the most expensive?

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Joining Materials

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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)

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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)

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• Superglue (cyanoacrylate)• Soluble ceramics for furnaces• Low vapour pressure resin (Varian)• Silver-filled epoxy, silver conductive

paint

Two Examples of Clever Design

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“Kinematic” Bearings

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Translation Platform

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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)

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Table of Contents

1. Mechanical design and fabrication2. Working with glass3. Vacuum technology4. Optical systems5. Charged-particle optics6. Electronics7. Detectors8. Measurement and control of temperatureIndex.

3d Printing - Justin

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3D Printing

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

Solidworks

• 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.

• 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.

IR Optical Window Materials

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IR Optical Window Materials

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