Intro: Servo Controlled Toy Carousel
This is a toy carousel controlled by a hobby servo. Why would we build such a thing? Well, we have this site where you can control fun robots and devices via the Internet, and I have a daughter who wanted to get involved. So, the carousel is her project - you can make it go left or right, and she gets to decorate however she wants - usually seasonal.
You can check her current toy selection online at the TeleToyland Carousel.
In addition to it being a live web project that you can play with, it has two other interesting maker features: It uses a regular hobby servo to drive a much bigger load, and we used small magnets to attach the carousel to the base so it can be removed and replaced easily - it just magnetically snaps on and off.
Step 1: The Carousel
For the Carousel, we cut a 12" circle from some MDF, then drilled some holes for the vertical dowels. We ended up using a standard kitchen lazy susan under that, and used 6 thin magnets to hold them together. We glued the magnets by putting them together in pairs, adding a drop of crazy glue to one side, and gluing it to the lazy susan, then adding a drop of glue to the magnets and placing the carousel on top. Once the glue dried, we were able to remove the carousel easily, and replace it precisely. We marked the two circles to make placement easy.
Note that we had originally tried a metal lazy susan bearing, but in testing, it seemed to lock up. Maybe we got some junk in the ball bearings. We did use oil etc. to no avail. So, we went to the local store and found a wood lazy susan in the kitchen department. We replaced the metal bearing with that, and it works great. We should have just started with that first instead of the MDF wood circle, but since we had the other circle already cut and dowels glued on, we just put the existing one right on top.
Step 2: The Servo Drive
To move the Carousel, we use a standard hobby servo with a rubber wheel on it that rests against the Carousel wooden wheel.
First, we modified it for continuous rotation. You can find out how to do that in other Instructables and numerous web sites. You can even buy pre-modified ones at a lot of places.
Then, we attached a Lite Flite wheel to the servo horn, and made a bracket to let it swing back and forth. To attach the wheel, we drilled the hole in the center of the wheel (the hub) a bit larger to allow for the servo horn screw. Then we sanded down the hub ridge, and used a couple self-tapping #4 bolts in pre-drilled holes to hold the horn to the wheel.
We made a custom hinge to allow the wheel to move back and forth to compensate for irregularities in the platform circumference.
We used a cup hook on the base and a small spring to the servo to keep the tension on. The spring goes from the cup hook to the servo mounting holes opposite the custom hinge. We did try a rubber-band before the spring. It worked fine, but after a couple months it broke, so the spring should require less maintenance.
(Note that the pictures below were taken before we used the kitchen turntable, so that is missing from the pictures, but is in the final project.)
Step 3: The Base
For the base, it turned out that a 2x4 was the right height for the servo wheel. So, we built the base from a few 2x4s. The middle one sticks out to hold the camera mount for TeleToyland. We used two carefully placed screws (to avoid the ball bearings and tracks) through the base into the bottom of the lazy susan to hold it on.
Since the Carousel is viewed from a web cam, we added a curved board behind it to hold a curved poster board with a background scene on it. We made the curved part form some 1x10 pine, and attached it with a 1x2 cleat.