Longcase 8-Day Clocks pre c1910

David Bond Clock Repairs

On some clocks not all the instructions are strictly necessary, but if you follow them, you are guaranteed not to hurt your clock.

Transport:

The only practical way to transport traditional longcase clocks is to first extract the movement.
Anticipate having to place the movement down. Move the hands to the 12 O’clock or 6 O’clock position. Two approx. 25x25x250mm long wood blocks can be used to support the movement dial side down on a surface.
Both trains should be wound leaving about 200mm of line remaining below the barrels. If possible, the lines should be restrained on their barrels. The best way is to use some barrel clamps – these can be easily made from sealant gun tubes and are the correct diameter. Failing that, some low-tack masking tape may be used.
Next, remove the weights. These are not interchangeable and should be labelled. Generally, the larger weight is found on the strike train (the left barrel).
Next, remove the pendulum. Hold the pendulum rod at the highest point possible and move it upwards a few millimetres so that the suspension spring can be eased from its slot. Gently lower the pendulum rod to clear the suspension spring block and upper spring chops from the slot in the crutch.
Check to if there are screws holding the seat board to the case. Remove them if necessary, then the movement together with the seat board may be lifted clear of the case.
For transport, a large box with about 75mm depth of polystyrene “peanuts” can be used with the movement placed dial down. Do not use fabric or towels or similar as they do not distribute the weight effectively.
Make sure to protect the pendulum suspension spring – it is very easily damaged. A cardboard tube or similar should be used.

Location and installation:

Stability is vital. The clock should be on a solid, rigid surface – well supported floorboards or a tiled floor. Modern laminated floors are less good in that they tend to have a layer of foam insulation which permits flexing.
If at all possible, the case should be fixed to the wall. A single screw through the backboard into a block of wood fixed to the wall is fine. The case should be vertical front-to-back.
If the clock is being moved to a new location, before moving it, take note if the case is precisely vertical side-to side, or how much it is off. Try to replicate that in the new location. If that is not possible, the clock will have to "set in beat" - see below.
With the case in position, the movement can be installed.
Trial fit the hood to make sure the dial is centralised, and the door does not foul the dial.
First fit the pendulum, then the weights. Make absolutely sure the pendulum suspension chops (the small brass fitting at the top of the spring) is fully seated in the cutout on the back-cock (the bracket protruding from the back of the movement).
When installing the movement, it is essential that the pendulum bob does not touch the back board – even the slightest contact will cause erratic timekeeping and will quite possibly stop the clock. Most cases allow the seatboard to be moved forward a little. There is often, though, a very limited range of seatboard positions that allow the pendulum bob to be well clear of the back board and for the weights to not foul the case frame above the pedestal. Make sure the case is as vertical as possible front-to-back.
Before attempting to start the clock, set the clock in beat.

Setting the clock in beat (please don't attempt this unless you are reasonably mechanically minded):

“In beat” means symmetrical escapement operation. This can be heard as an even tick. It is important for reliable operation of the clock.
Place an approx. 200mm length of masking tape horizontally on the back board at the height of the bottom of the pendulum rod. This will be to mark the swing of the pendulum.
With the pendulum at rest, mark the tape at the position of the tip of the pendulum rod.
Very gently move the pendulum bob to one side and be ready to mark the exact position of the tip when you hear a tick. This takes some practice but the slower you move the pendulum bob, the more accurate it will be. You may not hear a tick in the first direction. If not, move the pendulum bob the other way and mark the position.
Move the pendulum bob to the other side and again mark the position of the tick.
You can do this procedure a few times to get a mean position either side.
What you have now is the “escaping arc” of the pendulum. This should be symmetrical about the previously marked at rest position.
Measure the distance from the tick marks each side to the at rest position. There should be no more than about 2mm difference between the distances. If there is a difference, it is known as “beat error”.
If there is excessive beat error, it can be corrected by (very slightly) bending the crutch. The crutch is the angled rod with the slot at the bottom, through which the pendulum suspension spring was inserted.
If the error is such that the distance on the right is the greatest (for example), the crutch should be deflected at its mid-point to the right, i.e. a bend introduced at the mid-point of the crutch with the convex side to the right. It is very important to not introduce a twist in the crutch – so hold it at the bottom of the vertical section while pushing in the middle. It is absolutely essential to hold the bottom rather than simply pushing against the restriction – that may severely damage the escapement.
Only tiny adjustments are needed and re-test by marking the tick positions after each. It can easily take ten or more iterations to get it right.
With the clock set in beat, it can be started by pulling the pendulum bob to one side by about twice the “tick distance” and releasing.

Winding:

There are two barrels which have to be wound; the left one powers the strike operation right one powers the timekeeping (called "going") part of the movement.
The barrels should be wound once per week.
When the clock is running, the weights provide the force to power the movement. When the clock is being wound, that driving force is removed. It is, therefore, good practice to stop the pendulum when winding the going barrel. Similarly, try to avoid winding the strike barrel during the period between about 10 minutes to the hour and just after the hour.
Try not to let the clock run down, but if it does, before doing anything, the strike should be fully wound. Then allow any striking to complete before advancing the minute hand to the correct time. Stop if you feel any restriction other than the normal hands setting friction.
If you will be unable to wind the clock for more than a week, rather than letting the clock run down, consider stopping the pendulum.
Do not wind the barrels such that the pulleys jam up against the seatboard. This is important as it will almost certainly stop the clock.

Setting the time:

Use only the minute hand for adjusting the time.
Never move the minute hand backwards.
Always move the minute hand slowly to allow the strike mechanism to work.
When adjusting the time, the strike weight should be installed and the barrel wound so the line is supporting the weight.
For the Autumn time change (clocks go back), stop the pendulum for more than the hour so that you can then advance the minute hand to the correct time. Remember to let the strike complete when you advance the minute hand.
If there is calendar or moon phase work, do not attempt to adjust them during the period when the changeover is active.

Regulating the time:

The clock is a self-contained mechanical system and is therefore subject to external influences. Temperature, barometric pressure, vibrations, location (latitude and height) can all affect the timekeeping.
The nut at the bottom of the pendulum rod sets the height of the bob (weight) on the threaded rod. By changing that height, you are effectively changing the length of the whole pendulum which then changes the frequency of the pendulum - the time taken for each swing. This sets the timekeeping (rate) of the clock. The nut is called the rating nut.
If you want to change the rate, you need to rotate the rating nut by a given amount and in the correct direction.
If the clock is gaining, you need to effectively lengthen the pendulum by rotating the rating nut clockwise when viewed from above. That is, the front of the nut should be turned to the left.
Most longcase clocks are calibrated such that one full turn of the rating nut will give a rate change of about 30 seconds per day.
For example, say the clock has gained 50 seconds over the week, the daily gain would be about 7 seconds per day. You need to turn the rating nut (front to the left) by about a quarter of a turn.
You need to stop the clock to do this - gently bring the pendulum to rest with light finger pressure. It's sometimes helpful to put a small dot on the rating nut with a felt tip just to keep track of how much you've moved it. Grip the pendulum bob so that it doesn't rotate when you move the rating nut and make sure that the threaded pendulum rod is snug against the back of the brass disc of the bob. Gently restart the clock by pulling the pendulum to one side by about 50mm and releasing. If the clock doesn't keep going, nudge the pendulum bob to give a greater swing.
Let the rate settle over a few days before further adjustment.