Pocket Duplex Slide Rule Cursors Evolution Evolution in the Cursors of the Pocket Duplex Slide Rules...
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Transcript of Pocket Duplex Slide Rule Cursors Evolution Evolution in the Cursors of the Pocket Duplex Slide Rules...
Pocket Duplex Slide Rule Cursors Evolution
Evolution in the Cursors of the Pocket Duplex Slide Rules
Shapes, materials and Manufacture
By J.G. Fernández
2012-06-09
Pocket Duplex Slide Rule Cursors Evolution
The Slide RulesThe considered pocket duplex models from Faber Castell (1958 – 1975):
62/82 62/83
62/83N62/82N
63/82 63/83
Pocket Duplex Slide Rule Cursors Evolution
The Cursors
62/82-1
62/83-1 62/83N
62/82N63/82
63/83
62/82-2
62/83-2
1 432
Evolution reasons Market competition
Technology improvements
Product optimization
Evolution tracking Patents?
Time on sale? [1]
Pocket Duplex Slide Rule Cursors Evolution
Cursor Elements
3
1
5
7
8
62
4
1. Faces (front and rear) or windows
2. Runners
3. Spring strap
4. Closure screw (and nut)
5. Cursor Lines (peripheral and central or main one)
6. Cursor Marks
7. Letters to identify the use of the marks (usage letters)
8. Sliding Rods
Pocket Duplex Slide Rule Cursors Evolution
First Cursor: 1956 (62/82, 62/83)
Runners• Two halves
• White (green text)
• Rounded corners (& square)
• Plastic?
Faces• Transparent plastic
• Red peripheral lines at same distances from face edges
• Main line not centred with face
Widths• Runners: stability without protruding from rule body
• Faces: marks and lines layout, readability, end of scales reach, aesthetic ratio?
(62/82)
Pocket Duplex Slide Rule Cursors Evolution
Main Elements
Faces• Planar surfaces from acrylic resin “plexigum” (or plexiglass) [4] from
injection
• Holes on top of runners
• Thicker at top and bottom ends
Runners• Halves of white resin, poured “through” the cursor face holes.
• Ambient temperature process, not to affect the faces.
Pouring sense Face
Runner
Assembly
Pocket Duplex Slide Rule Cursors Evolution
Other Constructive Elements
1. Riveted spring strap
2. Closure-screw nut
3. Hand assembly elements
4. Metal rods to complete cursor halves fixation
1
3
2
4
Pocket Duplex Slide Rule Cursors Evolution
Lines, Marks & Text
Engraving process [4]:
• Soft impression of lines with a “warm” dividing tool (clean and sharp results)
• Red colour rubbed into peripheral lines
• Black colour rubbed into central line and marks
• Final wet polishing of cursor inner face
Printing process:
• Thermal printing
• Green colour rubbed into characters
• Final wet polishing of runner surface
Pocket Duplex Slide Rule Cursors Evolution
Engraving OptionsW
AR
M HOT
Pocket Duplex Slide Rule Cursors Evolution
Second Cursor: 1967? (62/82, 62/83)
Runners• Two halves
• Integrated in face (white text)
• Same width as face
Faces• Transparent plastic
• Mould-injected piece combines one face and two runner halves
• Peripheral lines at same distances from face edges
• Main line not centred with face
• Only black colour
Manufacturing• Single injection process completes halves (maybe both at same time)
• Designed for much simpler assembly and adjusting process
(62/82)
Pocket Duplex Slide Rule Cursors Evolution
Constructive Elements
1. Openings to hold spring strap
2. Small assembly elements
3. Longer holes for assembly elements
4. Grooves for handling
5. Cuts for assembly positioning
1 67
5
8
2
34
9
6. Internal spacing surface
7. Star-shaped closure nut
8. Sliding rods
9. Hand-disassembling opening
Pocket Duplex Slide Rule Cursors Evolution
Mould Injection Process Summary
Injection Step 1:
• Mould parts (at least 2) are open
• Injector is filled with melted plastic
Pocket Duplex Slide Rule Cursors Evolution
Injection Step 2:
• Mould is hold closed at high pressure
• Injector fills mould cavity and plastic solidifies
Mould Injection Process Summary
Pocket Duplex Slide Rule Cursors Evolution
Injection Step 3:
• Mould opens
• Piece is attached to one part
Mould Injection Process Summary
Pocket Duplex Slide Rule Cursors Evolution
Injection Step 4:
• Mould ejects the piece
• Piece falls to container
Mould Injection Process Summary
Pocket Duplex Slide Rule Cursors Evolution
Injection Step 4:
• Mould ejects the piece
• Piece falls to container
Mould Injection Process Summary
Injection with Insert Step 1:
• Insert piece is placed in mould with mould open
• Injector fills with melted plastic
Pocket Duplex Slide Rule Cursors Evolution
Injection with Insert Step 2:
• With mould closed melted plastic is injected in cavity
• Plastic solidifies with insert
Injection Step 4:
• Mould ejects the piece
• Piece falls to container
Mould Injection Process Summary
Pocket Duplex Slide Rule Cursors Evolution
Injection with Insert Step 3 & 4:
• Mould opens and ejects the piece
• Plastic piece falls to container
Injection Step 4:
• Mould ejects the piece
• Piece falls to container
Mould Injection Process Summary
Pocket Duplex Slide Rule Cursors Evolution
Details of inserted metallic pieces
Inserted Nut1. In a cylindrical hole
2. Knurled body to interfere with the plastic wall
3. Air spaces between nut and plastic
Nut has been inserted after injection
Inserted Rod1. Cylindrical hole in the plastic
2. Rod has chamfers in the ends
3. Air spaces between chamfers and walls
Rod has been inserted after injection
1
2 3
2
2
1
3
Pocket Duplex Slide Rule Cursors Evolution
Lines, Marks and Texts
Engraving process:
• Lines, marks and usage letters from injection mould
• Black colour rubbed into all of them
• Final wet polishing of cursor inner face
• One mould per cursor (62/82 and 62/83)
Printing process:
• Thermal printing
• White colour rubbed into characters
• Final wet polishing of runner surface
Pocket Duplex Slide Rule Cursors Evolution
Third Cursor: 1970 (63/82, 63/83)
Runners• Two halves
• Integrated in face
• Wider than face (like 1st type)
Faces• Transparent plastic
• Mould-injected piece combines one face and two runner halves
• Main line centred with face
• Peripheral lines asymmetrical from face centre
• Only black colour
Manufacturing• Single injection process completes halves (maybe both at same time)
• Cost optimization by material savings, process communalization and robustness reduction
(63/83)
Pocket Duplex Slide Rule Cursors Evolution
Constructive Elements
1. Openings to hold spring strap
2. Small assembly elements
3. Openings for right cursor assembly
4. Star-shaped nut (inserted after injection)
5. Plastic sliding rods
6. Internal spacing elements
7. Hand-disassembling opening
75
2
36
14
Pocket Duplex Slide Rule Cursors Evolution
Lines, Marks and Texts
Engraving process:
• Lines, marks and usage letters by thermal printing
• Black colour rubbed into all of them
• Final wet polishing of cursor inner face
• Same mould for both cursors (63/82 and 63/83)
InjectionNut
PlacementCommonEngraving
Specific Engraving63/82 or 63/83
Paintingin Black
Cursor face manufacture process (assumption)
Pocket Duplex Slide Rule Cursors Evolution
Fourth Cursor: 1972 (62/82N, 62/83N)
Runners• Two halves
• Integrated in face
• Same width as face
Faces• Transparent plastic
• Mould-injected piece combines one face and two runner halves
• Main line centred with face
• Peripheral lines asymmetrical from face centre
• Only black colour
Manufacturing• Single injection process completes halves (maybe both at same time)
• Robustness from second type with cost optimization from third type
(62/82N)
Pocket Duplex Slide Rule Cursors Evolution
Constructive Elements
1. Small assembly elements
2. Star-shaped nut
3. Sliding rods
4. Hand-disassembling opening
53
5. Internal spacing elements
6. Closed holes for spring strap
7. Wrong assembly disabler
12
6
4
7
Pocket Duplex Slide Rule Cursors Evolution
Details of inserted metallic pieces
Inserted Nut1. In a cylindrical hole
2. Knurled body to interfere with the plastic wall
3. Air spaces between nut and plastic
4. Rests of ripped-off plastic
Nut has been inserted after injection
Inserted Rod1. Cylindrical hole in the plastic
2. Rod has chamfers in the ends
3. Air spaces between chamfers and walls
4. Heat excess when drilling or when inserted?
Rod has been inserted after injection
1
2 3
4
2
2
1
3
4
Pocket Duplex Slide Rule Cursors Evolution
Lines, Marks and Texts
Engraving process:
• Lines, marks and usage letters by ultrasounds printing
• Black colour rubbed into all of them
• Final wet polishing of cursor inner face
• Same mould for both cursors (62/82N and 62/83N)
Printing process:
• Thermal printing
• White colour rubbed into characters
• Final wet polishing of runner surface
Pocket Duplex Slide Rule Cursors Evolution
Ultrasound Thermal PrintingFirst Step:
a) US head descends, already vibrating
b) The moment it touches the plastic surface, the friction generates heat
c) US head ends descent already vibrating
Second Step:
• US stops
• US head stays in place, cooling the plastic
Third Step:
• US head returns up leaving the printed plastic
• Extra plastic rims are flattened
Pocket Duplex Slide Rule Cursors Evolution
Acknowledgements:Thank you for such good advice and support:
- Jorge Fábregas
- Antonio Medina
- Dieter von Jezierski
- Peter Holland
…although any mistake is only my fault!
Bibliography:
[1] “Rechenschieber – Slide Rules A.W.Faber, A.W.Faber-Castell”, by Peter Holland. Fourth edition of 2011
[2] “Exterior hairlines in Faber Castell cursors”, by J.G.Fernández, 2009
[3] British Plastics Federation - http://www.bpf.co.uk/Plastipedia/Processes/Default.aspx
[4] Manufacturing process indications recollected by Dieter von Jezierski
Pocket Duplex Slide Rule Cursors Evolution
Annex: Open Issues for next…1. Complete this study (more specimens per type, screw standard…)
2. Why there was no magnifying effect in these cursors?
3. Cursor assembly process in the manufacturing plant? (screws automatically inserted…)
4. Cursor dimensions ratios? Why?
5. Desktop duplex slide rule cursors?
Taking Pictures…
Impossible coloursImpossible thickness
Pocket Duplex Slide Rule Cursors Evolution
Thank You!
By J.G. Fernández
2012-06-09