| Horological hints & tips | October 2002 |
Fitting a new platformMost methods suggested for fitting a new platform apply only to those mounted vertically on rear plate, and involve the use of some form of clamp and the dismantling of the movement a second time so that drilling holes can be marked. A method I have used for over 15 years works satisfactorily for both vertical and horizontal platforms, needs no clamp, and does not require the movement to be dismantled a second time for marking drilling holes. This saves time and therefore money.Having ascertained by a wheel count that the beat of the new platform is correct for the clock (usually 18,000 but not always so), assemble the serviced movement as normal. Take a piece of thin card, about the thickness of a cereal carton, and slightly larger than the platform base. Cut a hole as near as possible to the exact size of the escape wheel back-cock, and place it over the underside of the platform base. Trim the edges of the card to the exact size of the platform base. Attach two thin strips of double-sided adhesive tape (available from carpet shops) to the underside of the card. Place the new platform, with card, on the movement and move it into the position which gives correct mesh with the contrate or third wheel, and gives a good action on the balance. Press the platform and card on to the movement plates. Lift off the platform, leaving the card in position. With a large darning needle or similar, pierce through the card where the screw holes occur. Peel the card off. Dismantle the platform except for the back-cock. Replace the card on the underside of the platform base and mark through the pierced holes. Drill holes slightly larger than the diameter of the mounting screws. Clean off any swarf and reassemble the platform. The platform can now be fitted using domed washers, and the slightly oversize holes will permit final precise adjustment. With practice, the entire process takes less than 10 minutes. When dismantling and reassembling the platform, a block of hardwood with a 10mm hole to accommodate the back-cock forms a very useful base, and can be re-used indefinitely. Ivor Hayward, UK |
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