Mechanical Toy Hotplate

This is my take on the classic toy. No batteries, just mechanics! The red filament shows through the transparent plate when you turn the knob.

Printing instructions

All parts should aldready be properly oriented in the STLs. No supports needed except for the Coil, which must be printed in this orientation so the slopes are more precise.

All parts can be printed at 0.6mm width and 0.28 mm thickness to save print time, except the Big cog and Coil, which should be printed at 0.2mm thickness to ensure the slopes slide smoothly. 

Infill around 15% is sufficient, 1.2 mm wide walls. 

The transparent part ("Glass") can be printed with a line width of 0.6 or 0.8, concentric layers and slower speed to acheive the best transparency. Ensure enough top and bottom layers to avoid infill in the flat part.

Assembly (See pictures)

The Glass part must be glued in the Casing. The square peg must be approximately aligned with the sides of the casing, mostly for eshtetics. It does not need to be precise, the mechanism will accmodate any orientation.

Slide the Coil in place, with the spiral facing down. Slide the Big cog over it, making sure the slopes are aligned (twist it slowly untill it falls in place). The mechanism works as-is, but adding a bit of grease to the slopes and the sides of the coil will provide a smoother operation.

Push the Axle into the hole of the Wedge Cog. Tolerances should be tight enough for a friction fit. Insert the Axle in the small hole in the casing, making sure the Wedge cog is oriented properly (see picture). The angle can change slightly without causing issues.

Close up the Casing with the Plate, using four screws. I used M3x8mm. 

The Knob should hold in place by friction. It can also be glued in place once the proper operation of the mechanism is verified. The coil should slide up with 1/4th of a turn clockwise.