Jeremy Elson, December 2020
Why bother decorating your entire tree when half of it is facing the wall? The best solution must be to create a motorized, rotating stand for it!
One of my favorite projects was my original motorized rotating stand meant for full-sized Christmas trees, complete with slip ring so the lights can be plugged in. The only problem is that the full-size version is hard to replicate. Many of the parts, such as the two 24-inch wood disks that make up the platform, need to be hand crafted in a wood shop. I realized that if I scaled it down to just 8 inches, I could make a version that could be entirely 3D printed!
My favorite part of this project was that it only took a few days. The original took months, but most of that time was trying different designed until I found one that worked. For the mini-stand, I already knew what to do when I started. For example, I started with a drive mechanism that used interlocking gears, rather than spending weeks trying to get belts to work like I did the first time. I was able to reuse the motor mount and some of the gears without any change to the design at all.
The basic design of the small platform is the same as the big one: two circular disks on top of each other. The bottom disk sits on the floor and supports the top disk, which rotates. I wanted to include a slip ring again so the top disk could have power for lights without tangled wires. But, like on the full-size stand, I could not use an axle, since the slip ring is in the center. I again used skate bearings against a flange to keep the top disk centered over the bottom one.
Putting this all together, the top disk has the same basic features as the full-sized stand, but all integrated into a single 3D print rather than constructed by hand out of separate pieces. From top to bottom, the features are:
A solid, circular disk on which the mini-tree sits
A gear ring that engages with the cog on the motor to rotate the disk
A flange that extends down a couple centimeters below the gear ring to engage with the centering bearings
Next was the bottom disk. Like its big sibling, it uses horizontally mounted 608ZZ skate bearings that mate with the top disk’s flange to keep it centered. Unlike the big one, which used bolts to support the bearings, this version simply uses 3D-printed towers to support the bearings directly as a single, solid piece. The spindles for the skate bearings are all the same diameter as the bearing’s hole, making for a good, firm press fit.
The top disk’s downward force is supported by three more skate bearings, vertically oriented. The bearings are also mounted on 3D-printed towers, though this was tricky to print with enough strength that it wouldn’t fail under significant weight. These vertical bearings are the biggest difference between the mini’s design and the full-sized platform, which uses furniture casters to support its top disk’s weight.
The top and bottom disks fit together beautifully. Once assembled, the top disk rotated freely.
Next was the motor assembly. This was very easy: I was able to reuse the designs for both the motor mount and the cog without any changes at all.
Once assembled and powered, the motor rotated the stand perfectly!
Finally, some finishing touches. First, I put a plug and socket on the two ends of the slip ring wires so that it can be plugged in. And finally, three rubber feet on the bottom.
Liesl put her mini-tree on the mini-stand. She used some tape on the bottom to keep the wires on the platform; they were pretty stiff.
Making Your Own
Buy this slip ring or one of the many clones on Amazon/eBay/AliExpress.
Buy one of these uxcell gear motors. Uxcell sells about 15 variations of that gearmotor with identical form factor, but different gear ratios and voltages; buy any one you like, depending on how fast you want the platform to rotate. Solder wires onto the motor and attach it to a power supply or PWM motor controller such as this one.
Buy 6 608ZZ skate bearings
- Print all the parts:
Attach the slip ring to the top platform with 3 #8 wood screws
Attach the cog to the motor axle using a small set screw and the motor to the motor mount using 4xM3 machine screws
Attach 1/2” rubber furniture feet to the bottom of the bottom platform
Attach the motor to the bottom platform with the bolt heads at the top and threads emerging through the bottom and secure with butterfly nuts. The slides in the motor mount allow you to attach the motor to the bottom platform in the “retracted” position, put the top platform on, push the motor forward until it engages, then tighten the butterfly nuts with your fingers from below.
- Turn on the motor controller, hopefully everything works!