9. Machine Week¶
As a group we created a list of ideas and settled on making a 3 axis camera slider. It was the right combination of straight forward, with enough discrete components that we can divide and conquer the design and fabrication. Griffin drew up a quick plan on what parts we could buy from OpenBuilds to take care of the large linear rail and we would fabricate the pan/tilt axes from scratch. Greg and Spencer had ordered us an Arduino CNC shield with 4 stepper motor drivers and 3 stepper motors to make the electronics much quicker to prototype.
The main inspiration for the idea was that it could be very helpful with adding some production quality to our final project documentation videos. We did a fair amount of initial research to see what existing designs had been published, and found some great examples of different potential design frameworks.
We also found that Fab Lab Cairo had designed a camera slider, which turned out to be a good resource as well.
There were several decisions to make, including the motor placement, the pan-tilt head design, and the control system. We decided to have the slider-axis stepper motor mounted to one end of the extrusion, with an idler wheel at the other end of the extrusion, and a timing belt connecting the pan-tilt head to the motor by a toothed pulley. We decided to have the pan-tilt head support the phone / camera mount on one side, rather than making a cradle to support the mount on either side. Finally, for the sake of simplicity we decided to send code to the Arduino controlling the motors directly from a computer, rather than trying to create a user interface with a LCD screen or Bluetooth connection. With these decisions made, we could divide the project amongst our team members and begin designing.
What to build vs What to buy¶
While we had a number of tools at our disposal, and we could have theoretically made the vast majority of the parts for the machine, we decided to purchase a number of parts that were readily available off the shelf to simplify development and allow us to focus our effort on the parts that could not easily be obtained. The parts that we bought included the aluminum extrusion, the mounting plate and v-wheels, the pulleys, the idler wheels, the belt, and the drag chain. One advantage of order all of these components from OpenBuilds is that they have all of their CAD models available on GrabCAD, so we could start building an accurate 3D model of our design before (*if) the parts even arrived.
The details on the design and construction of the sub-systems can be found on the individual student pages:
Slide axis: Griffin
Pan/Tilt Stage: Nick
Phone/Camera Mount: Xiaolin
Software: Jonathan Software
- Openbuilds 20x40 V-slot Extrusion (1000 mm, Black) 1x - $15.29
- Openbuilds V-slot Universal Gantry Plate x1 - $11.99
- Openbuilds Solid Wheels Kit X4 - $20.76
- Eccentric spacers (6mm) X2 $3.98
- Belts (8 feet) $19.92
- Belt Crimps X2 or just use zip ties
- Pulleys 1x $5.99
- Idler Pulley 1x $5.99
- Drag chain 1000m $15.99
- Lazy Suzan Bearing 1x $2.59
- NEMA17 Stepper Motors & drive boards 3x
We had a number of problems to overcome on this project. The largest of which was most of our parts getting lost in the mail. We ended up only finishing the pan/tilt stages and we will continue to work on the slide stage.
We had a few smaller issues to work through once we had the parts we needed. Most of them were caused by commercial parts not working or fitting quite the way we expected. As descirbed in Nick’s documentation the configuration of the CNC sheild to get microstepping wasn’t clear, but once he found the right instructions that was able to smooth out the motion. Another issue was the guide wheel assemblies for the slider plate didn’t have the right length bolts to fit on the extrusion that they were meant for. This is a simple solution just finding different bolts and adding spacers but it’s frustrating that the “kit” that should just work doesn’t fit with itself.
The biggest piece of future work for this project is to develop an interface and improve the software so that it can perform different moves instead of having the movement hard coded into the firmware. A user interface control panel could be added or just a computer interface.