![]() ![]() The rear of each bearing surface is then chamfered, meaning the sharp edge left by the cutting tool is removed. By turning it inside the hole I am able to slowly enlarge the hole until the pivot fits perfectly. This tool is a tapered, five sided cutting instrument. This is shown in the photo below and is done with a tool called a broach. The next step is to make them the correct size and fit for the pivot that will turn inside it. The worn holes or bearing surfaces have been repaired but now they are too small. This small hole will be opened up to the proper size later. In order to install a bushing a series of reamers are used to open up the worn hole, being careful to maintain its original center, and then the bushing is tightly pressed into the hole creating a bearing surface that is normally smaller than necessary. The new surface on the right is perfectly round.īushings are small "donut" shaped pieces of metal made of brass or bronze, which are used to replace the metal in the badly worn areas. This error in depth can create additional drag on the gear train and will cause the clock to not function efficiently. This egg shaped hole changes the center distance of the gear’s arbor which in turn changes the depth. If you look closely at the one on the left you can see that the hole is not round but egg shaped. The left photo shows a worn bearing and the right shows the same bearing after a bushing was installed. The picture above shows a before and after of the same bearing surface. One of the main reasons we overhaul a clock is because of worn bearing surfaces. The next step describes this process in more detail. It is done with the help of a tool called a burnisher which is a finely finished, perfectly smooth piece of high quality steel in the shape of a file. This is accomplished without the use of emery buffs, abrasives or polishing compounds of any kind. Note how shiny the apppearance is compared to the rather frosted look of the pivot above. ![]() The bottom picture shows a properly restored pivot. If this occurs it will cause the new bearing surface to wear prematurely. Although this further smooths the surface there is a tendency for small amounts of the emery buff's abrasive particles to embed themselves into the surface of the steel pivot. Most clockmakers will further smooth the pivot with emery buffs and then stop there. The ruts have been removed and the sides are now straight. The middle picture shows the same pivot after being smoothed with a fine file. As dirt mixes in with the oil the dirt acts as an abrasive, cutting into the pivot surface like a file. The first picture shows the badly worn pivot. The single picture below shows three pictures of the very same pivot in various stages of the refinishing process. Therefore it is necessary to refinish both the bearing surface and the pivot. ![]() Not only do the bearing surfaces wear but the pivots that turn in them also wear. If you are having it done somewhere else, you might use this information to make sure that you are receiving your money's worth. If you are considering having a clock movement overhauled this will give you a good understanding of what will be done if we perform the work for you. If we have overhauled a clock for you in the past, you might find it interesting to know how much effort went into your repair. To avoid making this too long we have not included pictures of every small detail. Leaving out these details allow them to charge less but leaves you with an inferior repair.Īlthough this is by no means a complete step-by-step description, we have included the most critical points. I chose this clock movement as an example because it is the most common movement that most repair shops will encounter.Īll repairmen will clean and bush the clock mechanism, but many of them will leave out some of the finer details necessary for a proper repair. For the most part the same steps will apply to almost any type of clock. Below is a description of the many steps involved in the restoration of an antique American clock movement. ![]()
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