Antique Clocks/Ships Clock Circa 1890
QUESTION: Dear Mr Williams,
I have found my movement oscillates at a frequency of 14,700 or thereabouts.
As most modern platform escapements oscillate at 18,000 what can I do to replace my old one which is in a very poor state and a1 broken spring
ANSWER: Timesavers,www.timesavers.com, offer a number of platform escapements. These appear on pages 5 and 6 of their catalog.
---------- FOLLOW-UP ----------
QUESTION: Dear Tom,
Thanks for reply.
The pages 5 & 6 platforms oscillate at 18000 p/h.
I need one to run at 15000 p/h!
I have tested an 18000 - the time gain is unmanageable.
Is it still possible to obtain a 15000? Can an 18000 be modified to 15000?
The old platform is badly worn, broken spring etc.
kind regards---- Grahame.
I have, on two occasions,increased the moment or inertia of a balance wheel to slow the beat rate. It is easily done on balance wheels which have screws ascending radially from the rim. turn the screws counter clockwise to increase the moment of inertia. If there is insufficient range longer screws can be substituted. You will probably have to re balance the balance wheel after you have done this in order to get accurate timekeeping. Do this by removing the hair spring from the wedge fork and the beat rate adjusting fork and adjust the screws so the balance wheel is not weighted to stop at a particular point when the balance staff is horizontal.
Those without the adjusting screws will require fastening weights to the inner rim of the balance wheel. Wire works well for this if it is neatly bent into a circle. The most positive way to fasten it is with solder, however, glue will probably suffice. This is an approximate 15% beat rate reduction you are trying to achieve so make the cross section of the wire equal to about 15% of the cross sectional area of the balance wheel rim. A little experimentation will probably be required here. After you get the beat rate where it has to be you will surely have to rebalance the wheel. Drops of glue, hardened for at least a day, or solder will do a good job here too. A good glue to use is Lazer bond and is available from Lazer Bond, 7850 Ruffner Avenue, Dept.4000, Van Nuys, CA 91406. It has the advantage of giving you plenty of working time and then hardens in 3 seconds when exposed to the lazer light built into the applicator.
If longer screws are not available for the process shown in the first paragraph, you might be able to add loops of wire or tiny washers under the screws. Again the wheel will have to be rebalanced after you do this. Be very careful when working with the balance wheel as the staff is easily broken. It is best to have the platform balance removed completely and the balance wheel handled with a pair of long nose pliers when subjecting the adjusting screws to more than a gentle turn.