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A recent repair job on a Kundo oval base 400 day clock reminded me that the upper suspension block must fit properly in the saddle.

I cleaned the movement and replaced the suspension spring. It did not need any pivot polishing. After assembly, the clock ran, but the pendulum made a small rotation even when fully wound (about 3/4 of a turn with small overswing or supplementary arc).

The upper suspension block had some play in the direction of rotation of the pendulum, causing energy loss. I closed the slot in the saddle slightly, just enough to remove the play, but still allowing the block to pivot freely about the suspension holding screw. The swing of the pendulum increased to about one full turn. Now I am satisfied that this clock will run well.

Lately several people told me me that their 400 day anniversary clock was “wound too tight”, and that they tried to fix it by unwinding the spring! Trying to unwind the spring is DANGEROUS (unless you are experienced at clock repair and have the proper let-down key). If you try to unwind the spring, YOU MAY INJURE YOUR HAND OR FINGERS, and damage the clock as well. Don’t try it! Also, merely unwinding the spring will NOT fix the clock’s problems.

When a clock that is wound up all the way will not work, it needs to be repaired. The repair needed can range from a simple adjustment such as putting the clock in beat; up to an overhaul, in which the movement needs to be taken completely apart, cleaned, pivots polished, and any other repair work carried out. 400 day anniversary clocks seldom need to have bushings installed, but quite often, Schatz clocks from the 1950’s need a few pivots polished.

I offer repair service for Kundo and Schatz 400 day clocks and Schatz 1000 day clocks.

I just repaired a standard size 400 day clock by Herr (Horolovar back plate #1159). This clock seems to be a copy of the Schatz standard 400 day clock (movement model 49) but is not as well finished. This clock needed more pivot polishing than most 400 day clocks. Quite often a Schatz 49 will need 3 pivots polished (T2F, T3F and T4F) but this one needed 8 pivots polished (T2 - T5 front and back). Also the verge (pallet assembly) on this clock is not as well adjusted as on the Schatz. When the depth is set so that the drops are equal, the locking is not as deep as I would like. It has a one piece pallet assembly like the Schatz, so you can’t correct the lock by moving one pallet out. I made the best compromise adjustment and the clock runs well.

Another annoying thing with this clock was the process of installing a new suspension spring. A .004 inch thick spring was specified in the book. but it made the clock run slow. The next thinnest available spring is .0038, which is too thin. So I removed the blocks and fork from the spring two times to thin it. Finally after being thinned with 90 stokes of 600 grit abrasive paper, the clock could be regulated.

My Job 4496.

After repairing numerous Schatz and Kundo standard size 400 day clocks recently, I have noticed that sometimes the optimum suspension fork location is different than that shown in the “Horolovar 400 Day Clock Repair Guide”.

Specifically, for Kundo units such as 1 and 3C, I often find that the fork should be slightly higher. For Schatz units such as 6, 7, 8 or 9, sometimes the fork should be slightly lower.

Assuming that the escapement is properly set up (and it is best to leave the escapement adjustments alone if they have never been changed), and assuming that the clock is “in beat”, the escape arc of the pendulum (the minimum arc or amount of rotation at which the escapement will escape at both ends of the pendulum swing ) should be 1/2 turn.

To increase the escape arc, raise the fork. To decrease the escape arc, lower the fork. (Note: other adjustments will affect the escape arc. For example, bending the anchor pin back toward the suspension spring will increase the escape arc, and vice versa. But I do not recommend bending the anchor pin unless it is clearly already bent incorrectly, as it is fragile and you might break it.)

Note: take the suspension unit out of the clock to raise or lower the fork!

After I assemble a Schatz or Kundo standard 400 day clock movement I wind the mainspring up 1-1/2 turns for initial testing. Then assemble the suspension unit and install it in the clock. Put it approximately in beat. Then give the pendulum 1 turn of motion and time 8 pendulum swings with a stopwatch (it should take 1 minute). Adjust the regulator and retest until 8 swings takes 1 minute (plus or minus 1 tenth of a second). (If necessary, the spring is thinned or a different one installed.) Using the stopwatch allows you to make sure the regulator has enough range to bring the clock to time and give you a good starting point for final regulation.

Next, put the clock in beat and check the escape arc to see if it is close to 1/2 turn. If not, raise the fork to increase the escape arc, or lower it to decrease escape arc. After each adjustment, check the beat again. Finally, run the clock for several hours to make sure it has sufficient power (the mainspring is wound up 1-1/2 turns at this point).

Finally, wind the mainspring fully, let the clock run for an hour as the pendulum arc increases, then make sure the escapement action is correct. Sometimes an escape wheel tooth will fall onto the impulse surface of a pallet immediately after dropping from the opposite pallet (instead of the proper action of landing on the locking surface). This can happen if the fork is too low on the suspension spring or if the locking of the escapement is too shallow. I recommend that you study the “Adjustment of the 400 Day Clock Escapement” section of the “Horolovar 400 Day Clock Repair Guide” for excellent drawings and explanations of the escapement action.

Notes on my experience with escape arc greater or less than 1/2 turn

Several Kundo standard clocks that I repaired recently had only about a 1/3 turn escape arc with the fork in the standard position. They ran fine with the mainspring wound up only 1-1/2 turns. With the spring fully wound, however, the action of the fork was so “floppy” that it rebounded after each impulse, allowing an escape wheel tooth to land on an impulse face of the pallet instead of the locking surface. This caused the pendulum motion to not be as great as it should be. After raising the fork to make the escape arc 1/2 turn, the clock would run well with the mainspring fully wound, as well as wound up only 1-1/2 turns.

Similarly, several Schatz standard clocks had a large escape arc of about 2/3 turn with the standard fork setting. They would not stay running with the mainspring wound up 1-1/2 turns, and did not have much overswing when fully wound. After lowering the fork to give a 1/2 turn escape arc, they ran well both fully wound and wound only 1-1/2 turns.

Installing a new suspension spring is a delicate operation, especially with the miniature clocks, which use a very thin spring. Another problem is making the spring the correct length and getting the fork and lower block in the proper location. It is easier to install a complete suspension unit, which is a pre-assembled unit containing the spring, top block, fork and bottom block. For many clocks, you will need the Horolovar 400 Day Clock Repair Guide to determine the correct suspension unit.

The following list gives the suspension unit id number for the Schatz clocks:

• Schatz Standard model 49: Unit6789,
• Schatz Miniature model 53: Unit 10A,
• Schatz 1000 Day model 54: Unit 10B,
• Schatz midget, model JUM/7: Unit 10C.

If you run a clock repair shop, I recommend that you buy suspension units from your regular clock part supplier.

I am not a clock parts supplier and don’t intend to compete with those in the clock parts business. As a service to the individual who wants to buy a suspension unit, you may buy them from me, under the following terms:

1. Shipping to the USA and Canada only,
2. The unit MAY NOT be returned after its package has been opened,
3. Be aware that the clock may need more work beyond installing a suspension unit, so I do not guarantee that a new unit will make your clock work. If you need your 400 day clock repaired, see my Bill’s Clockworks web site,
4. Each suspension unit is $30, plus a fee of $8.00 for shipping and handling for the entire order in the USA ($10 for shipping outside the USA),
5. Please send a note with your name, address, e-mail address, the id number of the suspension unit you want, and your payment by check or money order in US Dollars to:

Bill’s Clockworks
8 W. Columbia Street
Flora, IN 46929

I will send the unit as soon as possible after receiving your check.

A company called Horolovar makes suspension springs for 400 day clocks. Various thicknesses are available. If the spring is too thick the clock will gain time, and if too thin it will lose time

Suspension Spring Thickness for Schatz 400 Day and 1000 Day Clocks

Schatz clocks have a model number inside a circle on the back plate (49, 53, 54 or JUM/7). The other numbers on the back of a Schatz clock are the date code (month and year). Here are the suspension spring thicknesses for Schatz 400 day and 1000 day clocks:

• Schatz standard size clock (49 on back plate): .004 inch
• Schatz miniature (53 on back plate): .0023 inch
• Schatz 1000 day clock (54 on back plate): .0024 inch
• Schatz midget 400 day clock (JUM/7 on back plate): .0022 inch

Suspension Spring Thickness for Kundo 400 Day Clocks

• Kundo full sized clock (about 12″ tall): .0032 inch
• Kundo miniature clock (about 9″ tall, including the oval base model): .0023 inch
• Kundo midget (similar to the miniature but the anchor pin has an offset bend and makes contact with the fork slightly behind the back plate): .0022 inch

For other clocks, you will need the Horolovar 400 Day Clock Repair Guide to determine the proper spring thickness. Note: measuring the old spring’s thickness is not a reliable method, as the spring may not be a Horolovar brand spring. The Repair Guide and suspension springs are available from Norkro.com and other clock parts suppliers.

The thicknesses given above are for genuine Horolovar suspension springs, which most clock suppliers sell. You may want to ask to be sure you are getting Horolovar suspension springs.