This article was originally published as the Practical Repair and Restoration feature in the December 2002 Bulletin, page 763.

I have worked on clocks for the last 30 years and am always looking for new ways to do a better job; I have usually found that the older, accepted ways are the best. A few years ago, one of my neighbors in Cincinnati introduced me to tumbling clock movements. I was somewhat reluctant to use this method at first. But, Dave, whose profession is metal polishing, took one of my old American clock movements to work and ran it through a tumbler. I could not believe the results.  The brass had a bright, polished look. The steel lifting levers, which are always hard to clean, were free from rust and looked almost like new. The corners of the plates were not rounded.

I started to do some testing of my own. First, I used ceramic media in a solution of water and just a little dish soap. This did a good job, but I did not obtain the same results as Dave. I then tried steel media, which gave a superior job in much less tumbling time.

After trying the steel media, I borrowed some stainless steel media. This gave about the same results as the steel media but with the added benefit of stainless steel in that it will not rust—if you don’t keep the steel media covered in solution, it will rust. Due to the added expense, I chose not to use the stainless steel media.

The tumbler that I use can be purchased from a lapidary supply house or from a metal polishing supplier. The cost should be around $160 to $180.The drum interior is made out of rubber, holds about eight and a half quarts of liquid, measures 7-3/4" in diameter, and is about 8-1/4" deep. The outside is round while the inside is ten-sided, which forces the media to tune over and not just slide inside the drum. The drum turns at 27 rpm.

The media is steel with four different shapes—balls, hats, pins, and rounds. Balls are 0.135" in diameter, hats are about 0.150" in diameter, pins are 0.080" thick and 1/4" long, and rounds are about 0.125" in diameter and .175" long. When I purchased it, the supply house called it jeweler’s mix. I have also seen a mixture that has small stars in it.

In order to get ready for tumbling, I first put 20 pounds of media into the tumble drum that I described above. After putting the media into the drum, I add clock-cleaning solution to about a half inch above the media.

My procedure for cleaning a movement is to disassemble it and clean it in an ultrasonic cleaner. I polish the pivots, do bushing work, clean the spring, (I do not put the springs into the tumbler), and perform any other repairs that are necessary.

After I have done all of the repair work and am ready to reassemble the movement, I get the parts ready for tumbling. I put the plates back together, plugging any blind holes using screws or peg wood because the media will get stuck in the holes. After putting the plates together, they are then tumbled by themselves. This is to prevent the parts from banging into one another. Next, I string the gears and other parts onto a wire and tumble them. I string them so they will not bang into one another and for ease of retrieval.

I tumble the parts for about twenty minutes, rinse them under warm running water for about one minute, and then blow them with compressed air. Next I dip them into a naphtha solution to remove any water residue. (Remember naphtha is a flammable product so take proper safety precautions.) Again, blow them off with compressed air, and then put them in a dryer for about three to five minutes. Using this method, I have not seen any rust appear on cleaned movements.

Before you go any further you have to check to see if any media is in the pivot holes or inside the lantern pinions. It will be easy to remove any media at this time.

After tumbling and drying, I will reassemble the movement while wearing disposable rubber gloves, but gloves are not necessary. The result that I achieve is a much nicer looking movement without too much extra work. Some of the questions that I am asked are:

Will the corners on the plates get rounded?

I have not noticed any rounding of the corners, but you have to remember that I only tumble for about twenty minutes.

Is there any damage to the gear teeth?

I have not had any damage, but I do know of one person who did not string his parts together, and he bent several gear teeth. I tumble escape wheels from pinwheel regulators and have not had any problems.

What type of solution do I use?

I use the regular clock-cleaning solution for tumbling and for storage. You have to remember that the media has to be covered in solution or it will rust.

Does tumbling harm the polish on a pivot?

I have not noticed any change in the quality of pivot work.

Do movements that have been tumbled tarnish faster than those that have not been tumbled?

Looking at movements that were tumbled about five years ago, I see no difference to those polished by hand.

In closing, I find this method gets my movements looking much better after cleaning (with just a little extra work), and I see no negative effects. It does not give the results that I like for a highly polished movement (carriage clocks, crystal regulators, etc.). You will have to do some additional hand polishing on them.  It’s great for removing rust from arbors and posts.

I do know that several large repair shops are using this method with good feedback from their clients.

About the author

Ray Marsolek has been a member of NAWCC since 1975. He is chairman of the Education Committee, has taught at the NAWCC School of Horology, and is presently a Field Suitcase instructor. His interests are in collecting and maintaining precision regulator movements.

Ray’s workshop is a mixture of new and old technologies. He is willing to try new methods of repair—always remembering that the ultimate goal is to restore the movement to its original condition without doing any harm to it.