| The Gear Project 2
It all started with the Gear Painting that I first created for testing out my 3D-printer. It was just a fun idea and a good way to learn both SketchUp and 3D-printing. If you want to know more about that you can find more information here: The Gear Painting.
I thought that if I could do gears... Then why not universal joints? Checked on Thingiverse and sure enough there were people who already designed some joints. Using them as inspiration and thinking out of the frame, I came up with the 6 frame gear project. I started to design in SketchUp and after several weeks of designing and testing (printing and testing parts).
I decided that it could be done. This time, I decided that ball bearings should be used to on all parts to make the whole project quiet. After designing all parts with press fit for all types of ball bearings it was printing time... Here you can see the idea I had created in SketchUp.
To be able to transfer the rotating motion from one frame to the next I had to use a special gear with double teeth. One set of teeth to cog the surrounding gears and another set on top to transfer the rotation out on to the axis. The small gear below have a M5 nut trap so I can use a second nut to lock the gear on the axis.
However, when transferring power from one direction to another, the big gear tends to want to move down. I noticed this when I was testing out the function. So the solution to this problem was a small counter hold bearing underneath the position of the small gear. The ball bearing in the picture has a 1mm axis hole and is over all very small, as is the holder. The layer thickness is 0.25mm on all the printed parts.
Then there where the universal joints. I printed them all on one tray (all the Y:s). Total printing time for that specific tray was 11h.
Adding all the ball bearings. Two for each Y.
Then printing the smallest gears and the middle parts for the joints. In the little joint middle part, there is four nut traps for M3 nuts. The holes you see on the sides are 3mm in diameter. Layers height is 0.25mm
After the printing was done, I assembled the universal joints. I had earlier designed and printed a small M3 key that now could be used to tighten the nuts in the joint.
Because I designed everything in SketchUp, I could easily transfer the positions of all the places to drill holes and cut out for the counter bearing holders. When all the holes were drilled and filed I painted the inner side of the back plywood part white. The frames also needed some work of course and I covered them with tape to protect the surface. I measured the positions to cut out holes for all the protruding gears.
Assembling the counter hold bearing and the special designed hanger on the plywood back of the frame. I needed a special hanger because the frame has to sit still on the wall when it's up. Usually you use a thin wire or a string to hang a frame, but I could not do that because then the frame would move around when they were connected with the universal joints and axis.
For axis I used 5mm aluminum rods. Here as well I used my SketchUp designs to measure the lengths of the axis roughly and then I threaded the ends using my lathe. You can see all the "in-frame-axis" parts in the box. There are also all the M6 screws, washers and nuts for all the gears present. In the other box you can see all the printed parts. However, the printed springs you can see (the red ones) where never actually needed. I will explain this later on.
Now on to the lighting. In the Gear Painting I also used led-strips inside the frame to light up the gears. This effect is very nice and I still wanted that. I decided to take it one step further. I bought two sets of multicolored led-strips from Bauhaus. They came with a small remote for changing the color and in a set of three 1m pieces. The problem of course is that a 1m piece could not be bent in a way so it fit in my frames. So I cut them and soldered small cables to be able to stick them to the backside of the inlay of each frame. Also, the led-strips comes with their own connections. I wanted to preserve as much of this as I could. Then in the future if something breaks, it's easy to just switch parts. This is why I make all the adapter cables to connect the actual strips. Then to be able to only use one input point of power I needed to connect the frames somehow. For this I bought RJ11 Module jacks to put in the frames then used normal telephone cable (4 wires) with RJ11 Module connector to connect them all together. Now, I have 3 white frames and 3 black frames and the jacks where all black. So I just spray painted them with white to not disturb the color scheme (You may notice that all the white frames have black gears sticking out of them and the black frames have white.
Because of the brightness of leds it's necessary to cover the rest of the inlay backside with something. The last time I used thick cardboard. But this time I cut out black duct tape to do the trick.
Time for assembling the frames. Because of the protruding gears on different sides and axis sticking out. I had to put the axis in place with the small gear and axel bearing holder in the correct place before adding the back plywood part with the rest of the gears. Then try to jiggle the frame a little to find the holder holes to be able to screw them in place. After this I added the universal joints on the outsides. The whole assembly is just enough nuts to keep the bearings in its place and the axis not to move around.
Now to the driving frame. I had to drive the whole thing from somewhere. This I decided I would put in the "middle". So with six frames middle being the third. :) Also this frame was the one best located for the cable coming to it. As before in the Gear Painting I wanted to use a cam timer motor. Basically a motor that rotates VERY slow. The one I selected rotates 3 rpm. The idea is to give the viewer a calm and "Wait, is it moving!?" feeling when watching it. It was also important that is has to be quiet. The problem however was that before on the Gear Painting, I could mount the motor on the backside of the frame. But now when I'm using my special hangers. The frames will hang tight to the wall and give no room for the motor on the back. So my solution was to design a box (two parts actually because of my 3D-printer size limits) for both the electronics to the leds and the motor. You can see the Idea on the picture. This however has developed a bit. I will print the box again after some rework in the design. :)
So, the springs. When I did my testing, I noticed that the universal joints where not perfect. With perfect I mean in the tenth of a millimeter perfect. And I also did not use ball bearings on my first version (as you can see above). This resulted in movements in different directions on the axis connecting the universal joints. So in worst case, this would result in the frames "moving around" on the wall. That I did not want. So, again I searched Thingiverse for someone who already made a similar part and found one. I redesigned it a bit and thought to use it on the middle of each axis in between the frames. Also, this was a good place to split the axis if I wanted to take one frame down. However it does not seem to be necessary. It all moves smoothly without the springs and not much wobble is happening. And for the demounting part of one frame, well, I just have to live with it being a bit harder. It looks way cooler with complete axis between the frames. This is why those spring where never used. The print time however was a pain, it took 12,5h to print them. :)
In the end, this is the result. The whole installation is setup I our stairway on a wall that was empty. The total size is about 2m wide and 2,5m high. Even my wife approve! :)
Watch it live on YouTube: Here!
All the STL files and the SketchUp file is available on Thingniverse.
Inspiration sources on Thingiverse...
Everything is printed on a eMaker Huxley (beta machine).
Total project print time: 91h
Total meters of 1.75mm filament: 316,65
Total amount of printed parts: 120
Nozzle temp: 160c
Bed temp: 70c
All printed things are printed with exelent PLA from Supply3DPLA.com.
I have been using both my cell and tablet to capture pictures, that's why the quality varies from time to time...
Let me know what you think and most of all use this to make your own cool kinetic art!! :)