Workshop Hints
400 day clocks

 

The British Horological Institute has archived and edited the following from e-mails sent to the Clock/Clocksmiths mailing lists on the Internet. The information here does not necessarily indicate a method approved by the BHI, we are only publishing this digest so that others can decide for themselves whether the methods listed below will suit them.

From: J. M. 'Abe' Abernathy, Jr., Donald A. Bisson, Sam Dubs, Jim Edwards, Murray R. Falk, Harry Gilmore, Tony Gray, Harry E. Hopkins,Dennis Kaye, Mel Kaye, Mike Loebbaka, Robert Marr, Jeff Major, Mike Murray, Norm Schreck, David J. Smith, Robert R. Taggart, Butch Tough, Jim Wright, Tim Yu, Lee Werling.

---

Index

Introduction General Repair Tips Replacing Suspension Spring Beat Adjusting tools Securing Plastic Pallets Test Pendulum Setting Up

Timing Troubleshooting - Keeps Stopping - Pallets Sluggish - Pendulum sluggish - Pallets not locking Returning the clock to the customer

---

Introduction

These are interesting and fun to work on. Also, very instructional, as to horological principles. As a practical matter, the cost of repairing them usually is more than they are worth...unless they are something unusual.
The anniversary clocks requires very, very little power to run. Therefore, any friction anywhere in the train will not be tolerated.
Conventional clock repair techniques do not apply here - learn to resist the temptation otherwise, it'll come back to haunt you. Keep in mind that any changes made to the train will take a long time before it manifests itself as it moves, oh, so slowly. Meaning that it may "appear" to be running in beat but you scratch your head 48 hours later that it stops but it'll run again when you start it up. Allow the clock to run for at least 14 days in the shop without touching it before giving it back to a customer.
One golden rule is, if you are going to repair 400 day clocks, buy the Horolovar 400 day clock repair guide by Charles Terwilliger. This is one the best 400 day reference books you can get.

Repair

• DON'T ADJUST THOSE PALLETS!!! A 1/16 in. adjustment there is a major change and is very hard to undo in the event you guessed wrong and that is not the problem.
• Due to the very low speed of the movement or rather rate of speed, pivot wear is not a significant factor unlike that of other movements. So, usually rebushing is not necessary unless the wear is really obvious.
• When re-assembling, remove the pallets and turn the entire train by hand (Do NOT apply mainspring power) to check for any unevenness or jerky motions of the train.
• Always tighten the lower post nuts. They will cause a stopping problem every time. If these screws are too tight then the lower part of the movement "buckles" slightly and you loose the parallel plane in which the gears should "lie". This caused extra friction at both the point of wheel contact and at the pivot hole in the plate. If it is too loose, it will allow the movement to jump slightly so stopping the clock
• Polish the pallets on ALL clocks. Use chrome polish. It simply works great!!! You get a mirror shine on those pallets and the clocks work much better!!!! Make sure you thoroughly clean the verge afterwards--very important.

Replacing suspension spring

• Make a Xerox copy of the applicable unit from the Horolovar Guide Book. Paste this to a piece of 1/4 inch thick foam board as found in art or office supply stores.
• Using a sharp knife, cut around the outlines of the top and bottom blocks as well as the outline of the fork. Lift out the paper layers of foamboard and Xerox copy page to expose the foam below. This creates a small depression that will "seat" the blocks and fork so that the suspension spring will lay flat on the paper surface. You can try it without the cuts/depression and see which way works best (fastest) for you.
• Start by cutting the spring to a close, approximate length by comparing it to the appropriate suspension unit in the book.
• Affix the top (or bottom block) to one end of the spring and secure it with a push pin by overlaying it on its appropriate place this assembly on the foamboard jig.
• Then pin the other block ( or if it has a pin installed, gently push it in place in the foam) and install the suspension spring.
• Lastly, position and secure the fork. Smooth jaw, parallel pliers make an excellent holding device while tightening block screws.
• One thing that I have never seen covered in any of the references, is the attachment of the TOP suspension spring block. Replacements sometimes do not fit in this area. The top block must be just loose enough so that it will freely rotate so that the weight of the pendulum hangs straight down, yet not so loose that it rotates horizontally within its slot. Make sure that the hole in the top block is the correct size for the pin which holds it, and do not be afraid to file the top block to thin it if necessary, or to insert a small piece of shim material to take up the slack at the side of it. Any excess looseness in this area will waste a large portion of the energy needed to maintain good pendulum motion.

What assortment of thickness' would you guys consider appropriate for handling the majority of 400 day requirements? I would keep a few of each of these on hand and just one or two of the less popular.

There are two assortments each of 12, packaged with "Horolovar" name. One is called Popular assorted strengths, and the other is called Intermediate strengths. Buy one of each, then you will have a replacement for any 400-day (mechanical) that comes in. . Thereafter, replace any one that you use, by buying a refill, which comes always in threes. You also need to get an assortment of forks and blocks, because sometimes one or more of the pieces are missing or cannot be re-used for some reason. I have never found the replacement recommendation in the Horolovar book to be wrong, but others tell me it does happen. From time to time, you can salvage a top or bottom block or a fork from a clock where you replace the unit with a factory-made unit, so you will soon have more odd bits than you need.

Probably the most popular sizes are .0023", .0032", .004". The other most common piece not to be found in the old movement is the bottom block. Timesavers sells the three types you will most need for $1.65 each in groups of 12.

Beat Adjusting Tools

There is no doubt that:

1. A tool with a long handle is needed to do this job.

2. The Horolovar Beat Adjusting tool is the correct length, and shape, but it is built much too light, and is of the quality of something found in a box of crackerjacks.

Some people have beefed up their Horolovar tool by replacing the hinge-fulcrum-rivet that kept breaking, with a steel machine screw.

An alternative beat setting tool is an old pair of long-nosed pliers that the tips were abused in the past. Cut approximately 1/2 inch off the end. Then using a cutting wheel in a flexible shaft machine, and cut a v-groove on each jaw inside facing each other so when they are closed, you see a small diamond. Kind of like this <> They work great for setting the beat in those stubborn anniversary clocks. The pliers have to be long enough to move it ever so slightly. Practice and you will be good at it in no time.

Securing Plastic Pallets

Some of the late model 400 day clocks have plastic anchors which, on some clocks, slip rather freely on their arbors, both radially and longitudinally. On one unit, an pallet was so loose it actually wiggled. Has anyone found a good method of re-snugging the anchor to the arbor and the pallets to the anchor?

• I hate to say it but when your dealing with plastic the only way to really secure anything in plastic is to use plastic. Crazy glue is just that, liquid plastic.
• Mike suggests Crazy glue, which I am not familiar with. As an alternative I would try a drop of superglue (cyanoacrylate). Then quickly work the pallet frame back and forth a couple of times (finishing up with it correctly positioned). The superglue should penetrate the space between the pallets and the arbor, and with some plastics will actually have a welding action by softening the plastic, probably in a similar fashion to Crazy glue. Even if it does not, it should provide sufficient friction in the joint to eliminate the problem.

Test Pendulum

Here is another trick I have found useful with 400-day clocks. I do not remember the source, but it was published somewhere in the last fifteen years: If you do a lot of 400-day clocks, make up a testing pendulum by casting a golf-ball sized lead ball, with an approximately one-inch hook protruding, the hook fashioned to catch the lower torsion spring block. Use the top of an old four-ball pendulum, or just a strip of metal with a slot, and the ends bent over. Using this as a temporary test pendulum will allow you to test-run the clock three to four times its normal speed. All running functions can be tested in this way, so that the regulation can be done without other faults showing up.

Setting Up

• Examine the escapement. The basic theory of operation may seem simple on the surface, but the actual angles, locks and drops are a bit tricky. One thing to keep in mind is EQUALITY. Whatever happens on one side must match on the other side.
• Study carefully exactly where the escape wheel lands on the pallet. This is very important. It MUST LAND above the pallet. The higher, the better. But don't forget about the equal rule. Whatever that distance on the pallet is, the other side MUST MATCH. And the angle (of the anchor) must match on both sides when the pallet drops off. Check this carefully.
• Use a tool, such as a tooth pick, to coax the verge side to side. Test the verge under various power situations. From 4 "clicks" of the ratchet wheel to middle range, to full wind. You must see a nice snap or throw to the other side.
• You should see Between 3/4 of a turn of the pendulum side to side, to one full turn. To increase this turn, raise the fork, conversely, to decrease it--lower it. (Only slightly)
• If you find the pendulum turns much more than 1 full turn, then lower the fork, because it takes more power to drive the pendulum and we want to reduce the effort needed.(However if you experience flutter, then you'll have to find a happy medium.)
• The amount of overswing (the amount of pendulum motion after the escapement. action) is more important than the amount of total swing. You should see at least 1/2 inch of overswing at low power.
• As with any clock you repair, you like to see if it will run good at the end of its winding cycle. So I simulate this by winding the clock only 4 or 5 clicks from no power. Then I start the pendulum in a circular pattern just enough to make it run-- barely locking and dropping. This is a good way to see if your clock is in beat. If it drops continuously off one side but not the other, then you will have to adjust it in beat.
• So once the clock is in beat, you want to make sure that the pendulum is turning at least 270 degrees or 3/4 of a turn from stop to stop. Adjust the fork (on the suspension spring) up or down to achieve this. You want it to be as close to 3/4 of a turn as you can get. Leave the screw or screws (on the fork) a little loose till you are sure you have it. Experiment here. You'll be surprised what a little up or down adjustment will do here. But don't kink the suspension spring!! (that's easy to do) Also, when you are satisfied, you don't have to "bull" those screws tight. Just snug. You can do this while its still on the clock.
• As the clock is running, you want to see if the pendulum picks up in motion, be it ever so slight. Your eye can't see if it is increasing or decreasing so you need a reference point. Lay a piece of something ( washer, screw, anything small) right on the base, just outboard of the swing of the pendulum. Wait till the pendulum comes around and push the object to "line up" with a point on the pendulum. Then, each time the pendulum comes around, You can see if the pendulum is picking up, or slowing down, or maintaining. Usually on 4 to 5 clicks of the mainspring, it simply maintains. And if it does pick up at all, you have a great running 400 day clock!!!
• Repeat this test at half power wind.
• Then at full wind. Obviously at full wind you want to see some "overswing", and NO flutter. If you see flutter, try raising the fork slightly. (assuming the escapement. is in proper adjustment). The amount of overswing you will see depends a lot on the design of the clock as well as the quality of repair. I have seen as much as 2 inches of overswing on the Haller's with a plastic pallet holder!!!!

Timing

Thinning a suspension spring to adjust the rate.

• The area to be thinned is the whole area between the fork and the bottom suspension block, and this is done with the pendulum still hanging on the suspension to give it tension. Use a couple of slip stones about 40mm long and 3mm square. A piece of emery held between the thumb and first finger works too but is a less elegant way of going about this.
• Set the regulator to the full slow position before you start thinning. That way you would have the regulator to protect you against your initial over-enthusiasm and you have the full scope of the regulator to play with to bring it to time. It also helps to prevent the unfortunate situation where over enthusiasm leads to a spring which is too weak. A situation which you can't recover from without replacing the suspension and starting all over again.
• Having done that set the pendulum to Max slow for an hour, and check that you have a small losing rate, thin a little more if necessary.
• Small trick: Rock the escapement. by hand and count the number of 'ticks' required to move the minute hand 5 minutes. Divide by five and this will give you the number of ticks or pendulum oscillations per minute. You can then watch the pendulum and time it with a stop watch, this should assist you somewhat in what is essentially a trial and error process and prevent you from thinning too far. A rule of thumb: Almost all anniversary clocks have 8 beats/min (generally the "Standard-sized" ones, and some mini's) or 10 beats/min (often the mini's). I think I recall doing one with 12. So, if you count the number of ticks in 5 minutes, you should get either 40 or 50 (for 8 and 10 beats/min., respectively). If all else fails and/or you don't trust your count, you can always count the gear train, and calculate the beats/min.

Troubleshooting

The clock keeps stopping

One thing you might want to check if the clock keeps stopping. If all else looks good, clean movement, MS, good SS, anchor pin tight in arbor, etc.

Check the escape wheel for straight teeth and also that they are the same length. It does not take much of a length difference to stop the clock. If you find that a tooth or two are at different length you must change the length of the rest of the teeth by putting the escape wheel in the lathe and ever so carefully make the adj. After doing this you will need to adjust the pallets to bring them back into there proper geometry. Teeth don't become longer but other teeth either wear which is unlikely or are damaged and are made shorter. This happens most likely when someone with little exp. tries to repair the clock. There could be other causes like kids they do the darndest things like wind up the pendulum on an Atmos clock to see what happens. But back to the teeth. If you do find a tooth that is short try to flatten the metal of the tooth like stretching it to make it longer. This will only work if you don't need much. If you need a lot then you must shorten the rest of the teeth or replace the short tooth this is a option also. You don't want to shorten the teeth to much because as you do the clock will loose motion in the pendulum which reflects in time keeping. Also if you do use the lathe method be careful not to bend the teeth they will bend over easy. I know the above stuff happens and that the repair will works and work well as long as care is taken.

I still can't get the crutch to "jump" to each side so to speak.

• Make sure that the suspension spring is hanging free and not caught on something like those pesky little screws which hold the s.s. covers in place.
• The fork should not be too tight or too loose on the anchor pin. There should be only enough clearance to ensure that the tines will never grip the pin in any position. The anchor pin should be tight, not loose.
• The hands should not be too tight - just loose enough to move by finger and not fall down when released. If it does work when you loosen the hands or remove it entirely, then much of the power is being dissipated in that area. - If that is it, then check for missing tension washer behind the cannon pinion or pinched cannon pinion.
• Check that the top block is being supported ONLY by it's pins in the saddle, not the sides of the top block.
• Check if the suspension wire has been installed exactly in the centre of both top and bottom blocks.
• If all goes well then the clock should be able to "tick or snap" even if it's out of beat or if you move the anchor pin back and forth by finger and the escape wheel moves. This means that the train up to the pallets is not restricted. If not, then you'll need to go back over the train to find that blockage. To check that, with power applied, if the pallets hang between two teeth without touching them, it means that there is no power from the escape wheel.
• Check for the tightness of the post nuts, under the base.

Pendulum not rotating enough

To increase the rotation of the pendulum, move the 'crutch' up. That should do it. The clock I just finished the other day would rotate only 85-90 degrees. I moved the crutch up less than 1/8 inch and now it is at a full 300 degrees.

When the anchor is manually operated (no suspension spring) with five or six clicks on the mainspring, the anchor will "snap" fully to the left (the entrance pallet bottoms on escape wheel after locking). I can't get it to do this for the exit pallet.

Based on the above the lack of the snap where the inside drop is exposed leads me to believe that either one or both of the pivots on either or both the escape wheel and fork arbor are slightly bent.

A great test is to hang the suspension spring and then the pendulum and place the clock in near perfect beat. Then remove the pendulum and "start" the escapement action by "nudging" the fork and the clock should "flutter" for two or more revolutions of the escape wheel. A clock in "perfect" shape will not stop at all but if you get two or more revolution of the escape wheel then the clock should function alright

The escape tooth locks OK, but the pallet is not drawn down into the escape wheel tooth at all beyond the point where lock occurs. Shouldn't it? Someone said everything must be symmetrical in the operation of the escapement.

Yes it should but I've seen some that it doesn't draw down yet they still work fine. Someone mentioned that you should raise the fork in order to increase the rotation of the pendulum. I agree and this should provide the "extra" draw that you are looking for.

 

Returning a clock to a customer

Give all of your customers a package containing a description of the repaired clock, adjustment/tips for the clock and a warranty sheet (not only for 400 day clocks, but for all clocks in general). There is a Horolovar pre-printed 400 Day Clock Repair Guarantee. It says it all. No guarantee for the suspension steel, etc.For 400day clocks, if it's local, always try to deliver it to the customers' home and set it up and explain it to the customer - never had one call-back from these.

---

Index of Hints and Tips