Bouncing Snowflake

A decorative toy based on stick slip motion.  The wooden snowflake is attached by a spring to a wooden sleeve, which rides on a metal rod.  Slide the snowflake to the top of the rod, and with a flick of the finger, the snowflake takes a surprisingly long time to bounce its way down the metal rod.

I made this at TechShop www.techshop.ws

Vector drawing software (I used CorelDRAW)
Laser cutter (my TechShop has a Trotec Speedy 300)
Drill with appropriately sized bit (matches spring diameter)
5 Minute epoxy
Coarse sandpaper
3" x 8" x 1/4" poplar board
14" long 1/8" diameter stainless steel rod
Spring from a retractable pen

This instructable assumes some basic familiarity with CorelDRAW and a laser cutter.

The base consists of five wooden discs of varying diameter stacked on top of each other.  Start by drawing two concentric circles, the first 2.5" in diameter and the second 1/8" in diameter.  This will form the bottom-most disc of the base. 

Make sure that you set the line width to hairline so that the laser cutter knows that you want to cut these lines and not just engrave them.  I also use the convention here of red lines mean cut, and black images mean engrave (this information is used when setting up the laser cutter).

Now draw four more circles with diameters of 2", 1.4", 0.4", and finally 0.6".  Add a 1/8" diameter hole centered on each of these to form the remaining discs for the base.  Note that I packed the little discs in around the gaps between the larger discs to use my wood more efficiently.

Here I added text to the two largest discs: "Merry Christmas" and "2012".  Obviously you can add whatever text or images here that you would like.  Be careful to make sure that any text or images that you add remain visible and are not covered by the next disc.  For example, because the bottom disc is 2.5" in diameter and the next disc is 2" in diameter, the bottom disc will have a 1/4" wide uncovered ring around its perimeter.

To curve the text you must first select the desired circle, then choose the "Fit Text To Path" option in the text menu.  This will bind the text to the circle.  You can also use the "Mirror Text" buttons to get the correct orientation of the text, and the "Distance from path" setting to center it in the 1/4" ring.

To reduce the risk of eye injury (remember we will be using a thin stainless steel rod) we'll make a wooden cap for the top of the rod.  Draw a 0.375" diameter circle with a 1/8" diameter circle centered on it.  I saved this overall design (base and top) as its own CorelDRAW file.

The sleeve provides a connection point for the spring (to connect to the snowflake) and an appropriately sized hole to fit over the rod.  Start by drawing a 0.4" diameter circle.  Next draw a 0.15" x 0.3" rectangle attached to the bottom of the circle.  Then use the "Virtual Segment Delete tool" to remove the inner arc segment.  This completes the outline of the sleeve. 

The size of the inner hole depends somewhat upon the weight of the snowflake and the spring characteristics, so you may have to try out a few different hole sizes.  I ended up cutting out three versions, with 0.15", 0.14", and 0.13" diameter holes.  You will be able to test these in a later step before committing to any particular one.  In this case I ended up using the 0.13" diameter hole.  I saved this as its own CorelDRAW file so that I could make quick changes and not waste wood recutting all of the other pieces.

Here we make the focus piece of the toy.  Start by drawing a 1" diameter circle.  Now find a suitable piece of clipart.  I happened to have a snowflake that I drew for another project, so I imported that bitmap and centered it on the circle.  Obviously you can put whatever text or imagery you would like here.  I also saved this as its own CorelDRAW file.  We are now done with the design phase.

Now cut the three different patterns (base and top, sleeve, and snowflake) out on the laser cutter.  You will need to experiment with your laser cutter settings for the best results.  I found that a high power (100%) and very low speed (0.75%) worked well for the cutting, and a high power (100%) and medium speed (45%) worked well for engraving.  Your laser cutter should provide recommended settings for various materials.

Since we will be using 5 minute epoxy in other steps, I also used it here to glue all of the base rings together.  Use the metal rod to keep all of the discs centered, and make sure they are rotated appropriately (such as aligning the "Merry Christmas" and "2012").

At this point you don't want the metal rod itself epoxied into place.  We want to be able to remove it for testing the different sleeves in a later step.  So as the epoxy starts to set up, remove the rod being careful not to shift the discs relative to each other.

Use the sandpaper to scuff up the last 1/4" of the metal rod where the wooden cap will go.  Scuffing the rod will improve the adhesion of the epoxy.  Then epoxy the cap onto the end of the rod.

Select a drill bit as close to the same diameter of the spring as possible.  It is better to use a slightly larger drill bit rather than a slightly smaller drill bit (otherwise you won't be able to insert the spring).  Drill a hole into the flat side face of the sleeve, about 0.15" deep.  Then drill a similar hole into the center of the back of the snowflake, also about 0.15" deep.  In my case I had a drill bit exactly the same size as my spring.

Insert the spring into the hole in the sleeve. If the hole is a little large, wrap the very end of the spring with a little bit of masking tape to temporarily hold it in place.  Do the same for the snowflake side.  Now it is time to test the sleeve.  Slide it up to the top of the rod, then give it a little bounce with your finger.  If the hole is an appropriate size, the snowflake will begin bouncing and slowly move down the rod (see the video for the desired behavior).  If it doesn't bounce well, try one of the other size sleeves until you find the correct one.

Now epoxy the spring ends into the sleeve and snowflake so that they won't come loose over time.

To finish up, slide the sleeve onto the rod then insert the rod into the base.  Mine was a snug fit so I didn't add any epoxy.  This has the benefit of letting me design a new bouncy part (perhaps for other holidays) and not have to build a whole new base.  Just pull out the rod, swap out assemblies, and reinstall it.  However, if you would like a more permanent assembly (perhaps to reduce the risk of a child pulling it apart and being exposed to the bare end of a metal rod) scuff the last 1" of the rod with sandpaper and epoxy in place.

Happy Bouncing!