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pov_globe [2017/04/29 21:13]
99.187.159.166
pov_globe [2018/01/10 12:40]
66.190.155.97
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 The first major change was the decision that 8 inches in diameter and 40 LEDs just wasn't going to cut it.  I resisted the pressure to make it large enough for a person to ride inside of it and settled on a roughly 16" diameter and 74 LEDs. The first major change was the decision that 8 inches in diameter and 40 LEDs just wasn't going to cut it.  I resisted the pressure to make it large enough for a person to ride inside of it and settled on a roughly 16" diameter and 74 LEDs.
  
-I cut a circular template on the CNC router and tried bending a piece of aluminum around this to create the circular frame, but I was unable to get anything satisfactorily close to a circle (and I wasn;t just being picky - it was pretty bad).  At that point (and why it took so long I can't say) it occurred to me that I could 3D print a near-perfect circle, and the lighter material would also be safer and easier on the motor. ​ The print bed isn't large enough for a 16" diameter circle, but it was easy to design it in Fusion 360 to be in 4 sections with connectors holding the sections together.+I cut a circular template on the CNC router and tried bending a piece of aluminum around this to create the circular frame, but I was unable to get anything satisfactorily close to a circle (and I wasn't just being picky - it was pretty bad).  At that point (and why it took so long I can't say) it occurred to me that I could 3D print a near-perfect circle, and the lighter material would also be safer and easier on the motor. ​ The print bed isn't large enough for a 16" diameter circle, but it was easy to design it in Fusion 360 to be in 4 sections with connectors holding the sections together.
  
 I used an LED strip (neopixels are apparently not fast enough for a good POV display, so I used DotStar) instead of individual RGB leds and just glued it to the frame with contact cement. I used an LED strip (neopixels are apparently not fast enough for a good POV display, so I used DotStar) instead of individual RGB leds and just glued it to the frame with contact cement.
  
-I initially used a nano as the controller and and ESP8266-01 to give it WiFi capability, but Robert suggested I just use an ESP8266 Huzzah breakout board as the controller with built in WiFi.  The built-in WiFi simplified the code considerably,​ and the faster speed (80 MHz vs 16 MHz) helped a lot as well.  Robert even gave me one to use!  Thanks, Robert! ​ (and while I'm at it, thanks also to Avi for helping me understand how to write data to the LED strip without using a library - this really sped things up.)+I initially used a nano as the controller and an ESP8266-01 to give it WiFi capability, but Robert suggested I just use an ESP8266 Huzzah breakout board as the controller with built in WiFi.  The built-in WiFi simplified the code considerably,​ and the faster speed (80 MHz vs 16 MHz) helped a lot as well.  Robert even gave me one to use!  Thanks, Robert! ​ (and while I'm at it, thanks also to Avi for helping me understand how to write data to the LED strip without using a library - this really sped things up.)
  
 The power supply is one we had at the space, salvaged from an old PC, and the motor controller was a cheap one ordered off of eBay.  And, after many attempts at balancing the rotor with no armature holding the top stationary, I finally had to admit that a stabilizing arm was a necessity. ​ The total cost of the globe was probably under $100 (but not by very much) with most of the expense coming from the LED strip and the motor. ​ You could cut the cost considerably,​ I think, by using individual LEDs rather than a strip, but boy would you add a lot of work. The power supply is one we had at the space, salvaged from an old PC, and the motor controller was a cheap one ordered off of eBay.  And, after many attempts at balancing the rotor with no armature holding the top stationary, I finally had to admit that a stabilizing arm was a necessity. ​ The total cost of the globe was probably under $100 (but not by very much) with most of the expense coming from the LED strip and the motor. ​ You could cut the cost considerably,​ I think, by using individual LEDs rather than a strip, but boy would you add a lot of work.
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 If anyone is interested in building one of these, I would be happy to share my files and advice from what I learned along way. If anyone is interested in building one of these, I would be happy to share my files and advice from what I learned along way.
 +
 +I have also set up the ThinkPad laptop that runs the RAMPS printer to control the globe. ​ Please don't do this without checking with me first, but the steps to do this are:
 +  - click the Start button and run the Anaconda Prompt
 +  - within the prompt window, type '​activate POVGlobe'​ to open the correct Python environment
 +  - if this worked, you should see <​POVGlobe>​ prepended to the prompt
 +  - type '​idle'​ to open a Python editor
 +  - select File/Open and open \Documents\POV Globe\Python_Code_POV_Globe\POV_Globe\globe_control.py
 +  - select Run/Run Module to start the program
pov_globe.txt ยท Last modified: 2018/01/10 12:40 by 66.190.155.97