First Shadows


The diffuser is mounted on spacers in front of the shadows.  The figure 8 path of the sun is outlined on a strip in front of the diffuser. 

The tension rollers are installed.  They pivot away from the frame to keep the sprockets engaged and the map and date tapes flat.

diffuser and shadow

The lights are installed and turned on.  The day of the week tape is at the bottom, showing Tuesday and Monday.  The date tape is also installed on the very bottom.

day of the week spools

The day of the week tape needs to be longer than the map.  One day of the week is shown as the map traverses for one 24 hour day.  The map actually consists of three full images of the earth, one being shown in front and two hidden on the sides and back.  Seven of the maps need to traverse in order to show a full week.  As a result the days of the week tape must be hidden on rollers behind the map.  The rollers above are on the right side and feed the tape to the sprocket that rotates the map.

The day of the week shows through a window in the map.

week day spool bracket wear

I was surprised to see the wear on the top plates for the week day tape. 

day of the week tape

The sprocket on the tension roller pulls the tape and feeds it to the map.  The tape is going back and forth across the back of the frame.

tension spring

The rollers pivot on the axles on the right roller.  The tension on the rollers is provided by two springs pushing the rollers away from the frame.  I did not like the amount of tension provided by the springs because it increased the friction or resistance.  I worried the clock motor might struggle.

The time tape is installed.  Notice the pin on the right.  It allows the tape to be moved ahead and back one hour, to adjust for daylight savings time.

clamp on tension rollers

The spring normally fits in the hole on the other side of the left roller.  The right axle provides a pivot for the tension rollers.  I have clamped the bracket to the frame of the tension rollers to see if the clock would run with only a moderate amount of tension.

day of the week spools

Instead of springs, the tension is provided by two adjustment bolts.  Holes were drilled and tapped in the roller bracket and bolts installed.  They push on the frame of the Geochron.  Unfortunately there is no good place to put the bolts as various tapes prevent easy access.

date tape

The date tape is installed.  I synchronized the date tape with the shadow and analemma and then engaged the sprocket.



Install the case and finish the restoration.