Introduction: Plastic Gear Clock

I was scrolling through Instructables and i found this contest.At this moment i thought,why not make something that could be functional,a good decoration and can learn some things through the whole process. And the idea was about a clock with a more industrial/mechanical style.As of this,the gears were the best idea and i started designing it.The first idea was to create a gear train with 3 different types of gears.The design was made with Autocad and is shown in the first two pictures. Although, in the middle of the construction i changed it a little, because it didn't work out well(at least not with the tools i have).

Gear Train

A gear train is a mechanical system formed by mounting gears on a frame so the teeth of the gears engage.


In order to design the gears,calculate the diameter of each one and the necessary dimension i used an older instructable (

After some hours of learning and calculating i figured out how to do it and the final dimension are in the pdf below.

Now lets collect the tools and the materials we need.

Step 1: Collecting Tools and Materials


-white acrylic spray

-black acrylic spray

-black acrylic marker

-white acrylic marker

-stick glue

-electric jigsaw

-jewellers saw


-P180 sandpaper

-electric drill

-2mm,3mm,4mm,5mm,6mm drills

-super glue


-round and flat shaper



-30x30cm 4mmgl plexi glass(gears)

-6x14cm 8mm plexi glass(base)

-3 screws ,the length depends on the clock mechanism you will find and less than 3mm thick)

-a clock

Step 2: Getting the Clock Mechanism

Once you buy or find a clock you have to take out the mechanism. In most cases, this will be an easy task.

First, unscrew/unplug the top round thing that covers the indexes.Then,take off slowly the indexes so as not to harm or break the mechanism.

After that, unscrew the gold bolt. If you had it all right, you will be able to take it out from the back of the clock.If not,check if there is any glue.If yes,try to take off the glue or gently push the mechanism out.

Step 3: Cutting the Gears

This will be one of the most difficult tasks of the whole project as you have to be careful and not rush at all.

First of all, print out the pdf with the gear design(you might have tou print it out twice in order to get 4 small gears)

When you have the papers then you can start cutting the gears. Cut with scissors and a razor the perimeter of each gear and then glue it ,with the stick glue, on the 4mm plexi glass.

After this, take with this order (2-3-4-5) the drills and start doing holes in the center of each side of the teeths.If its necessary,attach the plexi on a table with the clampers and be very carefull so as not damage the rest surface of the plexi. For that it's important to start with a small drill and raise diameter step by step. At the end of the process,all the parts.Then,by using the electric jigsaw or the jewellry one, you can cut the plexi on smaller pieces so that you can handle it better when cutting the teeths.Also,drill the center of each gear with the drills that are shown on the picture.If it is necessary,drill with the diameter your clock mechanism has for its indexes.

At this point you sould have 6 parts. Take the jewellry saw and gently start cutting the shape of the teeths. Be carefull: don't turn the saw blade around because it will break .I had to brake quite enough blades in order to get familiar with this tool,but every failure is a lesson ;)

Afterwards, take the round shaper and start trimming the inside of the teeths so as it is the same with the paper. Then ,with the flat shaper start trimming the tor of the teeths until they are all similarto the paper. You have to be very carefull with the teeth,not only because the can break easily but because if they are not the same ,the gears won't cooperate with each other.

Tip: The shaper cuts in only one direction.For that, you have to be careful so as not to damage the material so much.

Then,sand all the parts with the P180 sandpaper. The reason is to make a rough surface ,so that the color can have a better 'grip'.

Step 4: Making the Base

In order to keep the gears together we will need a base . For that we will use 8mm plexi glass so that it is more durable and stable. Once you cut or take the 6x14 piece you will have to mark the mechanism spot and the screw spots.

Tip: If your piece is covered with paper (most of them have plastic wrap)and you want to take it off you can do the next steps. Boil water, put the piece in a pan( a bowl might melt from the water :) ) with the water and leave it for a few minutes.Then, with a sponge or wire wool start scrubbing the paper.

After that, and once you have decide where you will attach the mechanism, measure and cut the part where the batteries go.And when this task is done, trim the edges with the flat shaper and sand the whole base with the P180 sandpaper.Then glue the mechanism with super glue.

Then,put on the gears and see where you want to put each center of the gears. Then stick the screws with the super glue. Be careful so that the gears work well and don't have problems turning around.

At the end of this process, all we have to do is to protect the mechanism with some tape so as not to destroy it while painting it.

Step 5: Cutting Some More Parts

In order to keep the gears in place we will need bolts or some plexi parts. Because i didn't have the necessary bolts i decided to cut out some parts. I cut the smaller squares that i could so as they can have a 3mm hole(the one my screws had).

We need three squares with a hole in the middle and three without. These ones will be used for the outer side.

Again, we will sand them so we can paint them.

Step 6: Painting the Parts

The next step is to find an outside spot where you can paint .If it is necessary put a paper on the floor so as not to mess the whole thing :-)

First of all we will paint all the parts black,except the one small square that we will paint it white, with the black spray.

After that, we will need a copy of the pdf of this step. In this pdf,there are the necessary shapes so as to paint an inner gear in our gears. When, you have the copy you must decide whick one of the two dimension you will use (two for the big gears and two for the smaller ones). Again you will need douple copy in order to cover all the gears.

Once you have the prints in hand,start cutting the shapes off with scissors or the razor.

I decided to paint a black inner gear on the big ones and a white small gear on the small ones. For this, in first place i cut the shape of the gear and kept the 'gear' shape and on the other i kept the rest of the paper.

Now,stick the papers on the gears so that we can paint them

Tip: To center the paper gear with the big gears is easy because you can see the center.But when you have to stick the small gears it is difficult to find the center. For that,if you put the piece and the paper against the light it will be easier to center them.

Once all the papers are in place, paint them with the white spray.

Also, you will need two more smaller squares that will be used as spacers between the big gear and the small gear so that the big gear won't hit the screw on its side.

Paint them also black :-)

Step 7: Putting All the Parts Together

Now,you have to put all the parts together .Be careful,because that's one of the most important parts of the project so that we can have a beautiful result.

Start by sticking the spacers between the gears. In order to keep the gears centered, you can use the 3mm drill to hold them in place.

Next, you must start putting glue first to the smaller gears and the big ones at the end. The gear with the 6mm hole goes to the mechanism. The next to are the ones with the 3mm holes. But be careful WE DON'T GLUE THE GEARS ON THE SCREWS. First you put the squares with the holes and when you find the right position so that the gears cooperate, you glue it. Then the gear, and at the end the

square without the hole. Also choose the square with te same color as its background so that it can blend with it.

Also,we will need some indexes. For that, i used the ones the old clock had. Of course i cut them so they can fit in my scale. For the right gear i used the circle thing the old clock had that protected the indexes. Paint it black, stick up the one small index and insert it in the hole. The same thing with the left gear but now use the white small square.

At the end all you have to do is to write the numbers. Remember the right gear must have the numbers going anti-clockwise because now the numbers turn and not the indexes.

Hope you good luck with this! :-)

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