What began as a simple how-to article about making gears has turned into a major project article for Make Magazine and at last is published in volume 21. The project is candleholder with three gears and parallel action arms which move the candles up and down at different rates. In many ways, it is similar to my first candleholder, but this one is made from aluminum plate and uses tea lights or small floating candles. The design and the variable gearing also make it a more playful device.

On the project page here, I have posted all the images from the construction process (many more than in the published article) as well as some additional charts and diagrams which can supplement the material in the article. Hopefully these materials can help out with some of the more tricky parts of the project. If you have any questions, want a CAD file, or would like to share photos of you project, send me an email!

Here are most of the tools and materials I used in creating this project.

My sheet of 1/4" aluminum plate, purchased from Metal Supermarkets.

A layout diagram showing the dimensions and calculations for making gears.

Using a clear protractor and scribe to mark degrees around the center of a gear. Simply divide 360 bythe number of teeth to get the degree increments: 15 teeth need marks every 24 degrees (15*24=360).

Setting dividers using digital calipers. This is not a precise method, but it works in a pinch and saves the time of converting thousanths of an inch into fractions.

Marking the outer circle of a gear. You can see the center punch marks in place for the gear teeth.

Marking a circle for the connecting rod hole in a gear. Only a small segment of this circle is actually needed, as the hole can be located anywhere along it.

Drilling the gear teeth.

A drilled-out gear ready for cutting.

Cutting a gear on a vertically mounted portable bandsaw. This is a useful modification if you cut a lot of plate. For this operation, a hacksaw would also be efficient.

I find it easiest to cut in from one side first, then the other, to begin the tooth profiles.

Each tooth must then be filed to a half-round shape to match the gaps between them. They will still work if they are a bit small, but if they are too large they will bind.

Aluminum is soft and files very easily. This does not take as much time as it could. Nevertheless, if you have a belt sander, much of this operation can be done there.

Testing the gears on a piece of scrap wood. I mark trouble-spots with a sharpie to contine filing.

A 10-24 tap in a tap handle. If you are ordering parts for this or other projects from Mcmaster Carr or another supplier, consider ordering some good quality taps, as they work much better than the average hardware store products.

Tapping a gear.

A layout chart for the backplate. If you use the bottom edge as a reference and place the gears roughly where they fit together without binding, you can use dividers to triangulate the rest of these dimensions.

Using the bottom edge of the aluminum plate as a reference edge.

Fitting the gears along reference marks and center punching with a transfer punch.

Using dividers to triangulate locations on the backplate

Using an oval template to fill in the outline of the backplate

Outline of the backplate ready to drill and cut.

Cutting inside curves made easier by making sections.

The backplate, drilled and roughly cut.

Tapping holes in the backplate.

Filing the edge of the backplate.

Using a transfer punch to mark the first hole in the front plate. Bottom edges must be aligned.

Use a 1/4" pin or rivet to match the front and back plates together.

Then clamp with bottom edges aligned to drill the remaining holes.

The transferred holes in the front plate (below).

Drilling through both a clamp-on collar and pinion with a 1/16" bit. A 1/4" pin holds the two parts aligned so that when they are joined they fit together on the 1/4" axle which also holds the knob.

Fitting a 1/16" tension pin into the hole just drilled. This effectively joins the collar to the pinion, making a strong, yet removeable, mechanical joint. You will need a small hammer to push the tension pin all the way in.

This is my layout for the knob, which was made as a five-tooth gear with 1/2" diameter teeth.

The knob, cut and filed.

The knob with collar attached.

Here are the feet of the candleholder, cut and ready for shaping.

A foot with roughly cut slots for the front and back plates.

The two feet, cut and filed and ready for attachment

A chart showing the dimensions for the connecting and parallel arms. Red dimensions indicate hole diameter, blue dimensions show distance from center to center of holes

It is often just as easy to drill two holes at once.

Testing out the connecting and parallel arms.

Here is a top-view of the candleholder showing where the spacers go. The point of the spacers is to hold the arms in place and prevent them from operating in the same plane, which would cause them to crash into each other.

Cut and filed spacers.

Here you can see the construction of the candle brackets.

A candle bracket disc, with holes marked and drilled.

One part of the candle bracket, with pins cut and filed to fit into 9/64" holes.

A candle bracket ready for pins to be staked. A spare piece of aluminum is placed between the brackets to hold them securely in place.

Staking the pins using a center punch.

Aluminum is relatively soft, but will begin to crack if pushed too far. Here are the staked pins holding the bracket parts together securely.

The top of the disc and pins are sanded.

Here a candlecup is in place and ready to be glued.

I used one minute epoxy to fix the cups in place, but hot glue would work as well.

Here are some wave spring washers, which help to put tension on the movement so the the candles, which are pushing down on the mechanism, do not fall down.

Using blue (removeable) threadlocker to make sure all the screws stay tight unless you want to take the machine apart later.

Here are several images of the candleholder in movment. The surface has just been smoothed with scotchbrite pads, but no other coating is required.