Introduction: Halloween Skull Hourglass With Tilt Switch

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About: Mad scientist, graphic designer, mechanical drafter, sci-fi geek.

Build a Halloween hourglass made from 2 plastic wine glasses with skulls inside, who's eyes light up when hourglass is flipped and the sand pours down.

This build was inspired by a Halloween prop I saw for sale a few years ago. It was an hourglass with skulls in it so when it was tipped the sand would pour down onto one of the skulls. But that version had black sand pouring onto a black skull. There was no contrast between the skull and sand. So I decided to build my own version and to spice it up a bit.

To make it even spookier I added some red LED lights to the skulls that are triggered by a tilt switch that turns them on when the hourglass is flipped.

Supplies

Supplies:

  1. 2 plastic wine glasses.
  2. 2 hollow plastic skulls that fit inside the wine glasses
  3. Fine grain sand
  4. 4 red LED lights
  5. 100 Ohm resistor
  6. Wire
  7. Plastic tubes
  8. Steel ball bearing, that fits inside the plastic tubes.
  9. 2 battery holders for 2 AA batteries
  10. 4 AA batteries
  11. Clear Gorilla Glue or other glue that works on plastic
  12. Sand paper

Tools

  1. 3D printer
  2. Drill
  3. Dremel
  4. Soldering iron
  5. Saw
  6. Hot glue gun

Step 1: Prep the Wine Glasses

The 2 plastic wine glasses will make the body of the hourglass. Start by cutting the stems off. Sand the cuts to smooth and flatten the cut.

Drill holes in the bases of the wines glasses. I started with a small, 1/8", drill bit but when I did a test with the sand it clogged at that size, so I ended up going up to a 9/16" drill bit. Definitely test the sand pouring out of the holes to make sure it flows well.

A true hourglass comes to a point at the base. The wine glasses round and flatten out at the base so not all of the sand pours out. Maybe next Halloween I'll try martini glasses.

Step 2: Glue the Wine Glasses

Now its time to join the two wine glasses together to make the hour glass. Its important to make sure you don't glue the holes shut and that they line up. I put a nail in the holes and did my best to avoid gluing it. The nail lined the holes up and when the glue was done drying I was able to push it out of the hole.

Depending on how large your glasses are, holding them together while the glue dries can be tricky. I use some masking tape to align them and hold them in place and then set a heavy book on top of them to press them together.

Step 3: Prep the Skulls

Take the plastic skulls and drill or cut the eye sockets out so you can place the LEDs in the eyes. In addition, cut a hole in the base of the skulls to feed the wire through.

Add wires to the LEDs and then feed them through the eyes and out the base of the skull. I inserted the wires into the eye sockets first and then fished them out of the base. Once I had the LED in position I used hot glue to hold it in place and close up any gaps around the LED.

Finally seal up the hole in the bottom of the skull to prevent sand from getting in there. Hot glue works great for this.

TIP: test your LEDs and wiring before gluing them in place. Its hard to replace them.

Step 4: Build a Base

For the base of the hourglass I created a model using Autodesk's Fusion 360. I've attached the stl files for the base and lid/floor for the base. Depending on the size of the wine glasses and tubes you use you may need to modify the design.

The key elements are a hole in the center for the wire from the skull to come down into the base and a hole for the wires to be feed up into one of the tubes for the tilt switch. Also a lip to go around the mouth of the wine glass to help seal in the sand.

Use a 3D printer to print the base.

If you use the attached files the plastic tubes I used are .38" outside diameter and fit into the holes on the side of the area for the wine glass.

Attachments

Step 5: Wiring and Tilt Swith

While you could simply have the LEDs in the skulls on all the time, it much more dramatic to have the ones in the bottom skull turn on when the hourglass is flipped. The mechanism for this is pretty simple. Traditional hour glasses often have rods as supports on the sides of the hourglass. This build will use hollow tubes with a ball bearing rolling up and down one of the tubes, to act as a tilt switch.

The mechanism is pretty simple. A metal ball bearing is in one of the tubes. When the hourglass is flipped, it falls down the tube and make contact with 2 electrical wires. The metal ball bearing acts as a conductor and completes the circuit with turns the LEDs on.

Place the battery holder in the base of the hourglass. Connect a wire to the positive output of the battery holder (if it doesn't have a built in one). Rather than connecting it directly to the positive wires of the LEDs place it near, but not contacting the positive wire of the LEDs. This will form the broken connection that the ball bearing will complete. Add a wire and the 100 ohm resistor to the negative output of the battery holder and then connect the resistor to the negative wires of the LEDs. See the attached wiring diagram.

Test the switch by touching the wires of the broken connection to the metal ball bearing. That should complete the circuit and turn the LEDs on.

Building the tilt switch is tricky. You need the wires to be the same height. If one is higher than the other the ball bearing will rest on the top one and not make contact with the lower one. I tried a few configurations and finally settled on hot gluing the wires on either side of a slim piece of wood so the tips stuck out above it. Then placed this in the base of the tube and hot glued it in place. It works well enough. You can see in the video I have to shake the hourglass to make a good connection.

Partly to have the top and bottom have the same weight and mass I used 2 battery holders and 4 batteries, one of each end. If you want to, you can use only 1 set of batteries by running additional wires up the other tube to opposite base.

Step 6: Adding Sand

After your done building both the bases (skulls, wiring, battery holders), its time to put it all together and add the sand.

Glue the tubes to the one of the bases and insert the wires for the tilt switch in the base of one. Now glue the wine glass hourglass over the skull.

Once the glues has set pour the sand in to the mouth of the top wine glass and let it fall into the bottom wineglass.

Add the ball bearing to the tube that will be the tilt switch.

Now seal it up by adding the other base to the top.

Pay attention to the orientation of the skulls. Think about how you will be flipping this and witch direction the skull will be facing when flipped. Also make sure that the tube with the ball bearing lines up with the hole in the base for the base going on top.

Then glue the base onto the mouth of the wine glass and to the tubes. Insert the wires for the tilt switch into the tube with the ball bearing.

Finally add the covers to the bases.

Give it a flip and the skulls eyes will light up as it is slowly covered in sand.

Happy Halloween.