[Concept instructions/Blueprint] Stargate - Rotate glyphs with stepper motor

thingiverse

This thing is a blueprint for modifying '5ft Lighted Stargate' (Thingiverse ID 2783393) so that the glyph ring can be driven by a stepper motor. Please note, I created this work for my version of the '5ft Lighted Stargate', which has only 66% of the original thing's size. I can only describe what I did or share my experiences and provide respective models and a SketchUp project concept file (the .skp file) so that you can adapt or improve it for your Stargate. In one of the comments from '5ft Lighted Stargate' (Thingiverse ID 2783393), someone mentioned using a rubber wheel, which was my starting point. It makes sense to use one of the bearing housings as a drive wheel housing. So I adapted the Bottom_Center.stl to fit a drive wheel with a 15mm diameter and its shaft (see Concept_Bottom_Center.stl). I also kept a cable tunnel for optional LEDs. The Stargate was only assembled halfway at this point, with the bottom elements, bearings, and glyph ring in place. The inner parts were not yet assembled. Before modifying other parts, I wanted to find a suitable wheel. I bought some Lego rubber wheels with and without tread patterns because I didn't know which had more friction based on contact pressure. I created a rim with a shaft, fit the tire onto it, and made some tests. In my case (this may differ depending on print material or used tires), the result was that I experienced wheel spin with each Lego tire. I searched for a different material with other friction characteristics with the print material. After rubbing various household items on PLA, I found a suitable candidate: a rubber band. I bought some rubber tube (often used for slingshots - I used 14mm in diameter), cut a 5mm piece from it, and assembled it onto the rim with the shaft. The test was successful. I designed a printable rim for a 5mm shaft -> see Concept_RubberRim.stl. The rim needs a 3mm setscrew and a 9x3mm bearing with a 5mm hole for the shaft. The bearing is the dark part in the pictures. I modified the inner part (my remix with Thingiverse ID 4348247) at the bottom to have a fixed point for the bearing and some space so that the rim can rotate freely. The first time, the rim with rubber was not properly pressing onto the glyph ring, and therefore the shaft's fix point was moved a bit more towards the ring. Then I created a plate on which the stepper motor is mounted as well as a second bearing to secure the shaft. The hole for the bearing needs to be tight, so that some force has to be used to press it into place. This should hopefully prevent the bearing from coming loose over time. The plate is glued onto the back of the Concept_Bottom_Center.stl. Be careful not to let any glue drip onto the backside of the glyph ring (by running down the parts when the glue is too watery), which can prevent it from spinning when hardened. I bought a set of 90-degree gearwheels (1:1 translation in my case) and mounted them onto the drive shaft as well as on the stepper shaft. Stepper motor: To drive the stepper motor, I use a DRV8825 stepper motor driver carrier from 'pololu'. The following website has a well-explained guide for this driver and how to set it up and program everything with an Arduino Uno: https://www.makerguides.com/drv8825-stepper-motor-driver-arduino-tutorial/. I hope this helps you modify your Stargate to make it more Stargate-like. Last note: I am working on an Arduino and PC program to dial Stargate addresses and have the glyph ring rotate accordingly. Because I planned this from the beginning, I inserted NFC tags and magnets into the glyphs, so that I can read and locate a glyph. When this also works, I will share the concept and program code as soon as possible.