You Will Need
- Kitronik Robotics Board (one can power the entire fair diorama!).
- Stepper Motor.
- BBC micro:bit.
- 5mm red Perspex.
- 5mm yellow Perspex.
- 6mm acrylic rod (or bubble rod).
- Countersunk M3 8mm screws.
- Our design files for your laser cutter.
- Our example code for the microbit.
You May Also Need
- Either superglue, hot glue, or poly cement.
- A 4xAA battery pack if you are running the model by itself.
Kitronik Christmas Fair - Stepper Ferris Wheel:Cut the red pieces in 5mm Perspex. There should be two A-frames, 21 spacers and enough pieces for eight gondolas. You will also need to cut the yellow pieces in 5mm Perspex. There should be two wheels (one with a slightly larger hole), two supports and eight restraining bars for the gondolas. Take the gondola pieces and glue them together. We used super glue, but hot glue or poly cement will work well too. While the gondolas dry, take the A-frames and slot them into the yellow supports. If the fit is loose it may need a little glue. Take the M3 screws and attach the stepper motor through the holes at the top of the red piece. Measure 65mm lengths of the acrylic rod and cut them to size with a junior hacksaw. We used 6mm bubble rod for an interesting finish. You should also smooth off cut ends with a file in order to avoid sharp edges in the finished model. Insert the rods into the eight holes around the wheel. These should push into place without glue and also sit flush with the other side of the wheel. Put a spacer on each post. TIP: Check any bearing parts (such as the gondolas, A-Frames and these spacers) after cutting them for rough edges as these will make the model grind as it turns. Try lowering the laser speed slightly or using a file if you find this from popping the parts out of the Perspex sheet. Place a gondola onto each rod, making sure they all face the same way. Put another spacer on the other side of each gondola. Press the other wheel onto each post, closing the gondolas in place. Be patient and take care to line up the rods in place, otherwise the wheel will wobble as it turns. Place three spacers onto the shaft of the stepper motor, then press the wheel onto the shaft. One side of the wheel will be a tight fit, whilst the other will be loose. For the motor to drive the wheel, it will need to be in the tight-fitting side. You will need to cut a smaller section of acrylic rod as the other axle. Push this through the other A-Frame, two spacers, and finally the other yellow wheel. This will be a tight fit so take care that it is not off centre. Wire the stepper motor to the all-in-one robotics board as shown. The 6V provided by the battery pack is enough to drive the stepper motor, however, if you are running the entire Christmas fair diorama you may need a larger battery or mains power supply. Open MakeCode for microbit and select "Advanced" then "+Extensions". Type "Kitronik" in the search box to find the custom blocks for the robotics board. You can then drive the stepper motor to precise angles either in degrees or steps, ready to give an uplifting ride at the Christmas fair! Stepper motors (as the name suggests) move in short steps of 1.8°. This allows them to move to very precise angles. Since precision is their biggest advantage, they're very often found in CNC machines such as 3D printers! To do this they use two coils rather than one like a conventional motor. These coils work against each other to hold the motor shaft at a set angle, and the charged coils pulse on and off to move it forward one step at a time. A common control circuit for this is the H-Bridge featured on our robotics board.
The Christmas Fair Resources:
|Ferris Wheel.||Helter Skelter.||Bandstand & Stalls.|
|A Perspex Ferris Wheel, driven by a stepper motor connected to an All-in-one Robotics Board.||A Helter Skelter featuring a moving ZIP LED slide, driven by a ZIP Halo.||A Bandstand and stalls, animated with a servo that is connected to an All-in-one Robotics Board.|
©Kitronik Ltd – You may print this page & link to it, but must not copy the page or part thereof without Kitronik's prior written consent.