Intro: Hatching Egg Coat Hook
An egg shaped coat hook 'cracks' open to reveal a baby bird when a coat is hung, when the coat is removed the egg closes up again. This fun coat hook is made with 1/8" [3mm] craft plywood and was made on a laser cutter.
When I first saw this design on the Grand Illusions Youtube channel, I really wanted to know more. The brief review did not go into the design and researching plans online was fruitless, so I had to puzzle it out on my own. My first attempt was with traditional tools (bandsaw, drills, hand tools) on 1/4" [6mm] plywood, but the results were clumsy and bulky. Instead I decided to design in CAD and use a laser cutter to get the precise geometry I wanted. I've included my CAD and laser cutting files so you can make your own.
Ready to make a fun coat hook? Let's get cracking!
You're welcome to download the CAD file I made below.
I started by looking for a simple clip art style bird that I could modify. I just did an image search for "baby bird cartoon" and got heaps of results.
I was looking for an image that either had wings spread, or would be easy enough to modify, either in an image editor or by making photocopies and sketching on top of a printed image.
Step 2: CAD It Up
I used AutoCAD to puzzle out the design and create the vector outlines used to laser cut the pieces.
After modifying the bird to the style I wanted (wings open), I started a new CAD file and imported the bird image.
There's no way to convert a raster image (JPG, BMP, TIFF) to a vector, but you can easily trace over your image in CAD to create a vector image. Using the SPLINE tool (other programs may have this function, or similar function using a 'pen tool'). I made an outline of the bird image I modified on one layer, and the details of the inside (the eye and the curve of part of one wing) on another layer. With two layers I can differentiate cutting or etching when I laser cut later.
To keep things tidy and prevent accidentally deleting a portion of the outline I created a BLOCK of my bird outline.
After making the bird outline I could start on the egg. I started with a basic oval shape, then scaled it up to roughly match the size of my bird outline. Placing the egg over the bird CAD block, I designed the egg crack sawtooth, then played with the location and size until I was happy with a design.
The CAD bird block was re-sized a few times to get the placement to line up with the egg design, and the travel distance required when the egg cracked open. This was the toughest part of the build, as the bird size and travel distance kept needing to be changed to meet the design intent. Doing this in CAD really allowed me to explore a few different design options.
After a few iterations I made a glide track inside the lower portion of the bird (which would be hidden behind the egg), and created a few mounting brackets the matched the interior diameter of the racetrack. Then copied out the final design into a new CAD file and saved it for laser cutting.
You're welcome to download the CAD file I made below.
Step 3: Laser Cut
After importing into Corel Draw I made 2 layers, one for cutting the outline of the pieces and one for etching in some detail. I used an Epilog 75W laser cutter and cut my pieces out on 1/8" plywood. I used the following settings for the laser cuts:
- Power: 40
- Speed: 40
- Frequency: 500
**Note: You should etch first and then cut. Cut pieces can fall off the parent material and become misaligned, which will cause the etching to be misaligned.**
Step 4: Sanding and Refining
After printing I sanded the faces of my pieces. Having a smooth face on the bird and on the backside of the egg will allow an easier transition when the surfaces slide past each other. I sanded to a 600 grit.
The guideway is an area that will be prone to sticking, as laser cut edges can be sticky after cutting. I tried to smooth the guideway edges and the guide pins by sanding to allow for a smoother action. Ultimately, I decided to use a wax to lubricate the guideway after assembly.
After sanding each piece was brushed to remove any dust or debris. The major assembly happens after painting, but I decided to attach the hook to the bottom portion of the egg now.
Step 5: Paint
Before assembling the coat hook everything was painted.
Each piece was sprayed with an acrylic primer and allowed to dry for about an hour. Then, I hand painted each element with a brush. The etching on the bird was used as a guide to colour the beak and wings slightly different shades of the same colour than the rest of the bird. The eye was painted black.
The egg was painted a light blue, then I flicked some watered down white paint with a brush to create a spotted effect.
Step 6: Glue + Sand Again
The top of the bird was aligned with the top portion of the egg and glued in place.
Even though I sanded the faces of the pieces before painting, I decided to sand down the back face of the egg where the sawtooth "crack" was to make a gentle transition for the sliding action.
Step 7: Attach Guide and Mounting Cleat + Wax Guideway
After the bird is glued to the top of the egg, the bottom of the egg can be attached to the bird guideway.
A sandwich of oval wood cutouts fitting inside the guideway was made and screwed into the back of the bottom portion of the egg through the bird portion guideway. An oval shape is important to have inside the guideway as it keeps the sliding action linear. Do not tighten the guideway wood sandwich, it needs to be secure but loose enough to allow a sliding action.
A cleat was screwed into the top of the back of the bird shape. This will be used to hang the coat hook.
The basic assembly is complete. To allow the self-closing action an elastic band was wrapped around the top cleat for hanging and the guideway sandwich installed on the bottom portion of the egg. To aid in the sliding action when the egg opens stiff grease ( or wax, or bar soap) was worked into guideway to lubricate for smooth operation.
Step 8: Wall Protection + Mouting
To protect the wall from damage and marks felt furniature pads were placed on the back of the cleat, and on the guideway sandwich.
A small cleat was mounted to the wall, and the corresponding cleat on teh back of the egg easily slides into place to hold the coat hook securely to the wall.
Step 9: Hang Your Coat!
You now have a fun coat hook that breaks open when you hang your coat up for the day!
Have you made your own hatching coat hook? I want to see it!
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