Face
Once the Locus Pocus case was finalized, I considered how to design the Locus Pocus clock face. Several primary design elements were needed:
- Selection of locations
- Aesthetic design
- Structural connection to the case
- Provide flexibility for refinement & customization
Research
My Earlier Fab Academy Projects
In the Computer Aided Design week, I had created basic 2D clock face designs using Inkscape, Cuttle, and GIMP. I had a good experience with the Cuttle design, so that was a strong candidate for the face design.
What Others Have Done Beforehand
I also reviewed the clock faces used in some of the previous related projects.
| Project | Clock Face |
|---|---|
| Modern Weasley Clock | Laser Cut Clock Face |
| Weasley Clock | Minalima Art Print overlay on Pre-existing Full Grandmother Clock Face |
| Where'sLy Clock Project | Custom 2D Print (designed with GIMP) overlay on hardboard clock face |
| Magic-Clock | Laser Cut Design, purchased from Hrothgar's Hoard |
Design Choices
I specifically designed the clock face as a separate piece from the frame for 2 primary reasons.
- Offset of the face from the frame provides a more interesting aesthetic and visual
- Separation of the face from the frame allows for the potential of changing the clock face - customizing for difference locations or other analog information visualizations
Clock Face Mounting
The threaded rod supports for the clock frame / case had enough length to extend beyond the frame (about 1cm). I had also sourced some tee nuts to help support differnt mounting options for the frame. The tee nuts attached to the ends of the threaded rods and provided a smoother, larger surface area for each of the 4 threaded rod mount points.
I considered both hook-and-loop fasteners and magnets as possibilities for attaching the clock face to the mount points.
Clock Face Aesthetic Design
I had a good earlier experince with Cuttle as a 2D design tool, so I wanted to create a design using Cuttle. I was interested in the scrollwork types of designs that were inspired by the movie series props. I explored some refinements on my earlier designs in the Computer Aided Design week, but a decent looking decorative scrollwork eluded me in the available time.
The overall Locus Pocus design has considered flexibility for customization in the locations, so there was some freedom in selecting locations. For the locations, I wanted to include a blend of practical locations (home, work, shopping, transit) with interesting locations inspired by the fictional clock (holidays, mortal peril, lost, prison).
In keeping with the whereabouts context, I decided to create a compass-themed design aesthetic. This included a central compass direction design with location text following the curvature around the perimeter of the clock face.
I started by creating the circular dimensions for the circumference and spindle hole to match the frame design. Cuttle provides a "text along path" feature, which I used to display the locations. I created 8 circular arcs at a uniform distance near the perimenter, one for each location. I had a notion in the back of my mind about the potential for a swappable face design, so I chose not to keep the arcs clear of the very top/bottm and left/right positions.
I spent a fair bit of time exploring the available fonts in Cuttle, and settled on the Henny Penny (regular) font. I used the text along path feature to add a location to each of the arcs, alternating the practical locations with the more interesting locations.
Swappable Face Design
Once the aesthetic design was complete, I considered the practical options for a swappable face design. It would be straightforward to attach a clock face directly to to the tee nut mount points, with adhesive hook and loop pads, or with magnets.
We had some magnets in the lab inventory. As it happens, one set was of round magnets exactly a quarter inch in diameter. I decided to try using these for clock face attachment.
The process was somewhat more involved than I had expected. Presuming a clock face of the same material - 1/8 inch Baltic Birch Plywood, there would not be much clearance left between the clock face and the closest clock hand. So it was important to economize on spacing. Both for positioning and for hand clearance, I decided to try etching the magnet positions into the back of the clock face, so they were sunken in to the material.
Precise double-sided laser cutting seems to be something of an art. The approach I took was to use a reference square that was a bit larger than the clock face diameter - 11 inches square. In Autodesk Fusion, I created a sketch that centerd the threaded rod hole configuration from the clockwork frame on the reference square. In Cuttle, I centered the face design on a reference square of the same size.
I tried several test etchings to calibrate the sizing of the magnet positions. It turns out laser kerf alone, without additional tolerance, was enough for a reasonable fit. I tried several prototypes first in cardboard to get the two-sided process down. I first cut the reference square out of the material. Next, I carefully positioned the reference square of material in the laser and homed the laser as close to the upper left corner as possible. I then ran the design to etch the magnet placement and cut the center hole for the spindle. Once complete, I carefully pivoted the material on the same corner, using the pointer of the laser to make sure the corner home spot remained as close as possible to the very corner of the material. I then ran the design to etch the face, but not yet cut - which took quite a bit longer than anticipated. Things seemed to be aligned. So far, so good.
I had a choice to make. It would be straightforward to simply cut out the clock face as a whole. Attaching a whole clock face, however, would require removing the clock hands each time. This would be workable, but I wanted a swappable design that would not require removal of the hands. So I conceived a split design, where the top and bottom halves of the clock face could be added separately behind the clock hands. And this would not prevent a full clock face being added using the same mount points, if the split design did not work out.
With this in mind, I added a horizontal cut line across the middle of the clock face design and started the clock face cut out process from the reference square. Bit of a tense moment, while the cutting proceeded, especially after taking so long for the etching. But the design was true. The round clock face was cut, with a horizontal split down the center. Measuring the magnet etching spots also seemed true.
I used super glue to attach the magnets to the magnet spots. I had come across the Easy Guide to Installing Magnets in Woodworking Projects to Secure Covers & Join Materials, and I adopted a similar process to help ensure they were positioned correctly. I held a piece of blue tape, sticky side up, over the metal frame attachment point. I then releassed a magnet, which positioned itself in attaching to the metal frame. This meant that I had the attachment side of the magnet on the sticky side of the blue tape, so I could make sure to attach the opposite side to the clock face.
Using this process, I super glued all of the magnets in place. I waited a bit for the glue to set. And then the moment of truth. The upper and lower sections of the clock face snapped almost perfectly into place. There was a bit of adjustment to get the fit of upper and lower sections together, but the swappable design worked!