Nuremburg Clock Rebuilt

This is a view of the clock with Pat's original going train removed. The scape wheel arbor dangles unsupported on the centre 7.5" strip. The verge is supported in a footstep bearing consisting of a 5/32" ball from a bicycle headset resting in a rod socket. This still gives low friction but is more resistant to lateral forces when transporting the clock to exhibitions.

Bolt an 11 hole angle girder in the fourth holes from the front of the top side girders. The slotted flange is to the rear and pointing down.

Journals for the revised gearing. The bolts securing part 133 to the motor carry thin washers (between the bracket and motor side[lates) to pack it out by the thickness of motor output shaft bush. Make sure these fastenings are good and tight, they will be very difficult to reach later. It is also worth removing the output shaft and inserting a drift while tightening up. Resist the temptation to double up these strips: single strips are all that is necessary and reduce friction at the arbor journals.

The 95 teeth gear that drives the scape arbor reinstalled.

First stage (2:1) of the going train installed. See next photo for how this is set up.

The 19 teeth pinion drives a 95 teeth gear in the second stage. Note packing washers and remember to allow a little lateral play when setting up.

The sub-assembly installed in the clock. The perforated strips are bolted to the 11 hole angle girder installed in the first step, above.

A close up of the mechanism so far. This view is at 90 degrees to the one above.

Fix a fifteen hole strip where shown. Use drifts to ensure good alignment with the 11 hole strip bolted to the end of the motor side plates. The slotted flanges of the 11 hole Angle Girders, above and below, assist in obtaining a good alignment.

Set up the second stage of the going train next. The 95 teeth gear and collar locate the arbor in its bearings. The 19 teeth pinion is left loose at this stage.

A rear three quarter view showing the second stage in place.

The motion work.
The fifteen hole strip will be fixed on the centre line similarly to that already fixed three holes to the left. I used two of Jack Parsisson's spacers and washers to stand off the 9 hole strip from the 15 hole strip. Choice of parts is not critical as long as there is sufficient clearance for the gearing plus a little end play.
The 57 teeth gear at the rear top of the 9 hole strip is loose on its arbor. A spring clip (metal) retains it in place. The centre 19 teeth pinion on the minute hand arbor is an idler that reverses the drive to the hands so that they move in the traditional direction. The 57 teeth gear between the strips is the first stage of the motion work. A 15 teeth pinion is fixed to this arbor in front of the 15 hole strip.
Note. Use a shorter rod for the upper arbor to reduce the forward projection seen here. I replaced it after I had taken the photos.

The hands.
Bolt a six hole narrow strip to a crank as shown for the minute hand. The hour hand is carried on the 60 teeth gear that completes the second stage of the motion work. Fix a 5 hole narrow strip as shown, spacing it from its carrier with washers to clear the 15 teeth pinion.

The clutch.
Fix an angle bracket by its slotted hole to 57 teeth gear. Put a washer under the bolt head. Slide the angle bracket towards the arms of the spring clip until it makes firm contact with them but does not start to spread them. Tighten the securing bolt firmly. This arrangement will provide an effective slip clutch that decouples the motion work from the going train so the hands may be set.

A front right three quarter view of the motion work installed in the clock.

The motion work in place from the left showing clutch gear in mesh with its driving pinion. The latter should now be fixed to its arbor.

A front left three quarter view of the motion work installed in the clock.

Hands fitted. A suitable Chapter Ring as shown in Pat Briggs' original instructions completes the clock.