Introduction: Mr. Scoops
Mr. Scoops is a toy project that I've worked on for a "Production Materials and Techniques" design class. The basis of the project was to design and build a working prototype of a mechanical toy along with the expectation of craftsmanship and functionality.
The ideation of the toy spurs originally from the Fisher Price Corn Popper toy, which uses a pushing technique that causes a popping motion of the plastic balls inside the clear dome. I took the working mechanism from the original toy and switched up the dome shape design of the Corn Popper by adding a more personable and kid-friendly 'ice cream truck man' character to it.
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Step 1: Popping Mechanism
4. Plastic Shaft
The corn popper toy has a very basic “popping mechanism”. It consists of a linkage, spring, platform, plastic shaft, an axle which is attached to the wheel. The spring and linkage would be placed inside the indented housing on the platform then enclosed in place with the plastic shaft (through the key-hole shape on the linkage).
The wheel axle has a slight indentation in the center that when turned, would catch a small, spring loaded linkage at the center of the body. Therefore, when the toy is activated, or pushed on ground, it would cause the indentation of the axle to rotate and catch onto the hook of the linkage as shown in the image. Once the axle makes its way around 180 degrees opposite, the linkage would release from the indentation of the axle, causing it in reaction to make the popping motion.
Step 2: Parts & Materials
The mainbody housing along with the platform, casing, two linkages, and front and tail lights were modeled on a 3D CAD program called SolidWorks and printed with a FDM rapid prototyping printer.
The springs, axels, plastic spheres, and wheels were taken and used from the original Corn Popper toy.
Then the additional decos (lettering/ ice cream on top hat) were put on with the use of sticker decals.
3d Printed Parts
Sandpaper (grit: 220, 320, 600)
Spray Paint (choice of 2 different colors)
Primer (x2 cans)
Epoxy/ Krazy Glue
From Corn Popper:
Plastic Shaft (x2)
Plastic Balls (x8)
Ice Cream Stickers
Step 3: Vacuum Forming
The upper housing was created through a process called vacuum forming. It is a technique that is used to shape plastics using a mold (wood, steel, foam, etc). For this particular project I used a dense polyurethane foam which was cut and shaped with different tools such as a band saw, disc sander, and sand paper.
The design of the upper housing was to serve the ergonomic purpose of a handle for the toy. By adding the top hat, I was designing to serve the purpose of an advantageous "handle" for the user.
For shaping the overall form of the foam mold, start off with a 100 grit sandpaper to shave down the foam to the desired overall shape and then move up to about 600 grit for a smooth surface finish. The protruding eyes should be a separate piece from the main body and taped on for easier release from the molded plastic. Above are the basic dimensions of the upper housing foam mold. Approximate measurement should be done and shaped down using the casing as a guide.
Step 4: Sanding - 3d Printed Parts
Start by sanding the surfaces of the 3d printed parts with a 220 grit sand paper. The purpose for this is for a smooth surface finish and flush fitting of each of the parts. When sanding the surfaces, do so in a circular motion until it is smooth and flat to the touch. Make sure that the different parts fit each other by sanding down the edges and ridges.
Step 5: Painting
For a egg shell-like uniform surface finish, use a primer before color paint. I used a white primer for the purpose of the white details left on the body, casing, and top hat. Once these parts are masked off, you'll be able to skip the process of having to go over it with white paint.
Start off by masking off the the undesired parts of the upper housing (all parts except the eyes and extruded hat). I used scrap pieces of photo paper to fasten the masking process. Make sure the masked edges are nice and sharp and firmly taped on. Then begin laying down light coats on all of the surfaces with light sanding (600grit) in between each coats. Spray on about 3-4 coats. Primer should take less time to dry than spray paint.
Once the primer has completely dried, start masking off the white details that you want to keep. Then lay on 3-4 more coats of the color spray paint on desired areas.
Step 6: Assembly
After the paint has dried COMPLETELY, start assembling the parts.
1. Bond the wheels onto the axle inside the main body using epoxy/ krazy glue.
2. Place the springs inside the small housings on the platform and fasten linkages through the key shaped holes using small shafts.
3. Fit the platform into the main housing.
4. Place the ice cream cones and upper housing onto the main body and bond the casing onto the main body.
Then bond the rest of the preferred decorations such as the facial features, writing, front and tail lights.