Working with the Workshop
Andy Edgar
1
If you can buy it from a
catalogue, buy it, don’t build it.
US $400
2
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.
3
4
Find 10 things wrong with this
job request
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
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
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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
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
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
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Broad Spectral Range Windows
17
UV windows
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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,
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?
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)
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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)
•
•
•
•
Superglue (cyanoacrylate)
Soluble ceramics for furnaces
Low vapour pressure resin (Varian)
Silver-filled epoxy, silver conductive
paint
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Two Examples of Clever Design
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“Kinematic” Bearings
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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)
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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.
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.
IR Optical Window Materials
34
IR Optical Window Materials
35