Expert: Martin Meyer - 12/31/2009

Question
QUESTION: I have a 1920s crystal mantle clock from Tiffany and Co.  It has a mercury pendulum.  The clock was made in France for Tiffany and Co.  The clock has run well for many years.  Recently the hour hand falls straight down between the hours of 10 and 2.  Tiffany and Co claims that someone must have wound the clock backwards.  We are fairly certain that this has never happened.  Can we repair this ourselves?  My husband has successfully repaired 3 antique clocks in our home, but we are hesitant since this one is a Tiffany.  Please advise. Thank you!

ANSWER: Hi Debbie,

It sounds like the hour hand has become loose on its pipe (shaft), and gravity is simply causing it to fall. If this is the case, it will be quite apparent that the hand is hanging loose if you give it a gentle push. To correct this condition, remove the minute hand (noting what position the minute hand is pointing in so you can reassemble correctly), either by unscrewing the small nut at the tip of the minute hand shaft, or by pulling out the taper pin that goes through this shaft. The taper pin only comes out in one direction, so be careful to pull it in the right direction, or you may make it hopelessly tight in the hole. Also, be careful not to lose any washers that are behind the taper pin. Next, pull off the hour hand. Tighten the hour hand collet (the part in the center that goes on the shaft) by VERY GENTLY squeezing it with a small pliers. If you squeeze too hard, you will crush the collet. Simply reverse the procedure to reassemble. If the hour hand is then striking the wrong number of hours, just move it to point to the number of hours struck; it is a simple friction fit on its shaft.

There are other less likely conditions, such as broken gear teeth, which can also cause this problem. What connection there could possibly be between winding the clock backwards (which is almost impossible to do) and the problem you describe is a complete mystery to me.  http://www.clockmasteronline.com

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QUESTION: Thank you so much for your detailed answer.  To clarify: I didn't mean "wound" backwards, but rather they say the hour hand was moved backwards.  Also I have tried to pull out the taper pin as described above.  It does not come out without alot of force and I have been worried about causing damage to the piece.  I am assuming that I work from the face of the clock and not the works behind.  Is there somewhere I can see pictures of how to do this?

Thanks again.

Answer
Hi Debbie,

On many antique clocks turning the hands backwards can cause serious damage, but probably not make the hour hand become loose. I don't know of any picture descriptions of removing the center arbor taper pin, but this is one of those operations which is 'simple but not easy".

You are absolutely correct that forcing the pin can break or damage the clock. Taper pins on old clocks often become tight due to minor corrosion. First, examine the pin with a magnifying glass to be absolutely certain which is the small end, and which is the large. If the pin is long enough, you can try twisting it while pulling out on the large end of the pin. I would recommend holding the center shaft firmly while doing this avoid bending it. But if the pin is very tight, this will not work without bending the center shaft, and you will have to try to push the pin out from its small end.

You need to use a small pliers, preferably with pointed jaws (called "chain nose" in clockmaking). The key factor here is that the center shaft must always be supported when you are pushing on the taper pin, or it will bend. I squeeze the pin out by positioning one jaw on the center shaft (not covering the taper pin) and the other jaw on the small end of the taper pin. This will place the pliers at an awkward angle, but can be done. Usually the taper pin pushes out quite easily this way. One important point to note is that, if the small end of the taper pin sticks out beyond the center shaft hole very far, you can break the pin off when you perform this operation. If the pin is broken off flush with the center shaft, you will have a problem that will require the services of a professional clock repairer to correct. One thing that you can do to help prevent this is to cut the small end of the taper pin short enough that it is unlikely bend, using a fine diagonal cutter.  http://www.clockmasteronline.com