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Eli Lewis
Eli Lewis · elilewis2029@u.northwestern.edu · elilewisportfolio.info/projects/carbon-fiber-journal

Design & craft · 2023

Carbon-fiber journal cover

Secure, sleek and unnecessary: a build that tested my precision, planning and presentation

The finished journal: carbon fiber covers, a stainless piano-hinge spine and an integrated combination lock, with no glue anywhere.

The finished journal: carbon fiber covers, a stainless piano-hinge spine and an integrated combination lock, with no glue anywhere.

The finished journal: carbon fiber covers, a stainless piano-hinge spine and an integrated combination lock, with no glue anywhere.

My second lockable journal: carbon fiber panels, stainless steel piano hinges and a combination lock, held together by internal screws with no glue, so it can't be opened unless with the password or by force. This project pushed the limits on my ability to transfer computerized precision into the physical world. I designed it in CAD, cut and squared the panels by hand, marked holes with 3D printed jigs, and drilled each hole on the drill press I had just restored. Everything fit together not even a degree off.

Role
Solo

I was responsible for everything: design, part sourcing, CAD, jigs, cutting, drilling and assembly.

Duration
—
Tools
drill-press, belt-sander, hacksaw, calipers, 3d-printer
Skills
cad-modeling, technical-drawing, jig-design, part-sourcing, mechanical-assembly, product-design

Goal & constraints

  • Impossible to open without the code or destructive methods, and no glue allowed.
  • Fix my first journal's problems: its aluminum panels had bulky, rattling hinges, a glued-on lock and screws installed from the outside.
  • Internal screws, smooth hinges and an integrated lock

Process

  • Extensively searched McMaster-Carr to find combination of hardware that matched my requirements
  • Created full 3D model, and built 3D-printed jigs to aid with marking holes, sizing panels, and squaring corners: one with tiny countersunk holes to scribe hole positions on the panels and hinges (photo 8), and one to size the two end pieces on the belt sander (photo 10).
  • Researched carbon fiber cutting equipment, safety concerns, and finishing methods
  • Cut each panel manually with a hacksaw, then squared each edge on the belt sander and checked width with calipers to within +- .1 mm
  • Drilled and countersunk every hole on the drill press. An especially slow, patient cycle was required to process the stainless steel: mark, align, clamp, lock, check, oil, drill, pause, oil again (photo 9).
  • Assemble, no glue needed!
I modeled every part from suppliers' downloadable models to check that it would all fit before buying the carbon fiber.

I modeled every part from suppliers' downloadable models to check that it would all fit before buying the carbon fiber.

I modeled every part from suppliers' downloadable models to check that it would all fit before buying the carbon fiber.
Section through the spine corner: the screws and inserts sit inside the cover, so nothing can be undone from the outside.

Section through the spine corner: the screws and inserts sit inside the cover, so nothing can be undone from the outside.

Section through the spine corner: the screws and inserts sit inside the cover, so nothing can be undone from the outside.
Dimensioned drawing: 180 × 230 mm cover

Dimensioned drawing: 180 × 230 mm cover

Dimensioned drawing: 180 × 230 mm cover
The sheet clamped between two planks so the edge could guide the hacksaw straight.

The sheet clamped between two planks so the edge could guide the hacksaw straight.

The sheet clamped between two planks so the edge could guide the hacksaw straight.
Cut and squared panels

Cut and squared panels

Cut and squared panels
Countersinking on the drill press. The countersink depth had to be exact for the screws to sit flush.

Countersinking on the drill press. The countersink depth had to be exact for the screws to sit flush.

Countersinking on the drill press. The countersink depth had to be exact for the screws to sit flush.
3D-printed marking jig: tiny countersunk holes guide a scribe point to mark hole positions on the panels and hinges.

3D-printed marking jig: tiny countersunk holes guide a scribe point to mark hole positions on the panels and hinges.

3D-printed marking jig: tiny countersunk holes guide a scribe point to mark hole positions on the panels and hinges.
The stainless piano hinges after polishing.

The stainless piano hinges after polishing.

The stainless piano hinges after polishing.
Sizing jig for the two end pieces: anything that needed sanding stuck out past the plastic edge, and a second to mark hole location

Sizing jig for the two end pieces: anything that needed sanding stuck out past the plastic edge, and a second to mark hole location

Sizing jig for the two end pieces: anything that needed sanding stuck out past the plastic edge, and a second to mark hole location

Result

Four hinged carbon fiber panels within +- .1mm and assembled with < 1 degree of radial drift.

What I’d change

I didn't fully appreciate the power of jigs at first and wasted time trying to hand-measure lines instead of jumping right to a jig

Print this page for a PDF copy (photos shrink to fit).

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