One step in thoroughly cleaning and repairing a mechanical clock movement is polishing the pivots of each wheel - that is, polishing the tiny scratches out of the endpoints of the gear that turn in holes in the front and back plates of the movement. Polishing the pivots increases the life of the clock and reduces clock-stopping friction.
In "An Analysis of Two Pivot Polishing Techniques" Robert Whiteman describes 'Scottie's technique of polishing pivots using 1500 grit and 2500 grit sandpaper. Scottie supports the sandpaper with a steel rule; other clock repairers use 'sanding sticks': sticks with grit glued to them.
You can easily and inexpensively make your own sanding sticks instead of buying them from specialty clock repair sites.
Step 1: Parts and Tools
- Pieces of 1/2 inch (about 13 mm) square inexpensive wood at least 10 inches (about 250 mm) long. I bought Unfinished Square Dowel Rods 1/2" x 36" for Crafting, Projects and Woodworking- Bag of 10 from Amazon.
- 1500 grit and 2500 grit sandpaper. I bought a pack of 5 sheets of 3M 32023 Imperial Wetordry 9" x 11" 1500 Grit Sheet, and pack of 50 sheets of 3M 02625 Imperial Wetordry 5-1/2" x 9" 2500C Grit Sheet from Amazon.
- Rough (say 60-150 grit) sandpaper. Really, any rough sandpaper you have lying around.
- A pencil.
- A ruler. I like using a metal carpenter's square.
- A saw for cutting the pieces of wood to length. I used a chop saw, but almost anything will work, because the ends of the sticks don't need to be cut precisely.
- General purpose glue. I like to use Elmer's Glue-All for making sanding sticks.
- (optional) A hobby knife (for example, X-Acto knife) is useful.
Step 2: Cut the Sticks to Length
Cut the sticks to the width of your sandpaper plus about 1 inch (about 25 mm). My sandpaper is 9 inches wide, so I cut the sticks to 10 inches long.
- Using the pencil and ruler, make marks every 10 inches on each of the pieces of wood.
- Using the saw, cut the wood pieces at those marks. Because I used a chop saw, I cut two pieces of wood at a time.
Step 3: Sand the Cut Ends of the Sticks
Depending on what kind of saw you use to cut the sticks, the ends of the sticks may be rough. Use any rough-grit sandpaper to sand the ends of the sticks smooth.
Step 4: Cut a Piece of the 1500 Grit Sandpaper, to Glue to One of the Sticks.
- Pull one piece of 1500 grit sandpaper from its folder.
- Measure one side of the square end of your stick. My sticks are 1/2 inch square.
- Cut a piece from that sheet of sandpaper that is the width of the sheet and 4 times the measured side of the stick. For example, 4 * 1/2 = 2 inches, so I cut a piece of 1500 grit sandpaper 9 inches wide (the width of the sheet) and 2 inches tall.
Step 5: (optional) Score the Grit Side of the Sandpaper
Scoring the grit side of the sandpaper will make it easier to fold it around the stick, but it's not necessary.
- Place the piece of sandpaper grit side UP (NOT grit side down as in the photo above - sorry).
- Lay the cut stick on the edge of the piece of sandpaper.
- While holding the stick firmly down on the sandpaper, draw the knife's edge along the inside edge of the sandpaper. Don't cut all the way through; the idea is to just weaken the sandpaper along this line so it will fold easily later.
Step 6: Glue the Edge of the Sandpaper to the First Side of the Cut Stick
- Pour a small amount of glue on the first side of the cut stick.
- Spread the glue evenly over that first side of the stick. I like to use my finger, both to spread the glue and to wipe off the excess.
- Lay the glued side of the stick flat on the non-grit side of the paper, lined up with the edge of the paper.
- Press the stick firmly down onto the paper.
- Wipe the excess glue off the outside edge of the stick. You may also need to wipe glue off the table you're working on.
Step 7: Repeat the Process for the Other 3 Sides of the Stick
- Spread glue on the second side of the stick.
- Turn the stick, while pressing it firmly down, so that the newly-glued side of the stick presses against the sandpaper. Scoring the paper earlier helps keep the first glued side from coming apart as you turn the stick.
- Wipe off excess glue as before.
- Repeat the process for the remaining 2 sides of the stick.
Step 8: Write the Grit Number on the Stick
Before going on to the next stick, write the grit number of the sandpaper on a bare side of the stick. This label will help you keep track of the 1500 vs. the 2500 grit sandpaper sticks as you polish pivots with one stick after the other.
Step 9: Make the 2500 Grit Sanding Stick
Now that you've made a 1500 grit sandpaper stick, repeat the process using 2500 grit sandpaper.
Once your 1500 grit and 2500 grit sanding sticks are dry, you're ready to use them to polish clock pivots. Make plenty of sanding sticks so they'll be ready whenever you want to clean a clock.