This week Prof. Neil explained us about the various control systems and the control loops which is used in the existing machines. For this week our task will be to make that machine breath and draw the first Rangoli using this machine.
Goal
The goal for this week will be making first Rangoli using our machine Rangavalli as well as finish off with the documentation.
What I did?
This week is going to be very crucial as we have to make our machine to come in life and draw Rangoli with it. Though we have the materials and all in place it's time to machine them, assemble them and test it. To make it happen I did following tasks.
- Tweaking firmware
- Choice of sensors
- Documentation
- Designing Motor clamp
- Designing Bearing Housing
Tweaking firmware
As we have chosen the RAMBO board gave us the advantage of choosing from variety of firmwares available as this is one of the popular board among the 3D printing enthusiasts. I have chosen to work with the Marlin firmware which is again quite popular and lot of documentation and the instructional videos are available to start with the Marlin and RAMBO.
The process of tweaking all started with the video attached. In video he has explained very nicely about the Marlin firmware and how do I tweak it to use with the RAMBO board. Also, he has explored all other options available with Marling.
I downloaded the original i.e. untouched Marlin from the GitHub and opened it using Arduino IDE. My main task is to tweak the firmware according to my machine and it's sensors and actuators.
When I opened the Marlin.ino file after unzipping the content from I got from the GitHub. Opening Marlin.ino is the collaborative work of plenty of files all together. The most important file that we will be tweaking is the configuration.h, this is the file which contains all the information to run the entire firmware.
I've changed following lines of code present under configuration.h file
- Motherboard ID ==> 301
- Motor maximum speed ==> 200 mm/sec
- End stop configuration ==> FALSE
- Temperature sensor ==> -1
- Max Acceleration ==> 3000
Choice of sensors
Endstops are nothing but the sensors which are used to make sure that machine arm is reached the datum position. If the datum point is not got detected then possibly motor will get burn or the machine's chassis may get heavily damaged as the acceleration-speed as well as mass of the arm will result impact intensity.
To have the simple design I've used the limit switches as the end-stops. Here the switch gets pressed whenever arm hits the leaver of the switch. And when leaver is triggered this sends the notification to the main controller of RAMBO board which is the Atmega2560 with the voltage level.
As we have the sensors to judge the position of the arm or actuator this machines is closed loop control system.
Documentation
It is never perpetual job that everyone has to do to keep himself going on and keeping track of the past errors which are happened during task. Documentation reduces the time required for troubleshooting.
I made website to present our machine design group assignment which is powered by bootstrap which makes it responsive. "Responsive" means that it can be easy get molded into the desired shape according to the size of the devices. It delivers the best possible UX-UI experience by relocating the objects.
Designing Motor clamp
To hold the motor in place it is designed. I've designed the motor clamp using the acrylic which is widely available in the lab and quite sturdy to take weight of the motor. I've used very simple strategy to design the motor clamp is to have the center hole from where shaft of the motor can come out and four extra holes to tighten the motors using the small screws.
Designing Bearing Housing
Bearing housing is the necessary for holding the bearings in place with the top arm. We have lot of cardboard which was laser cutter friendly and sturdy. So, I designed the U shaped with the hole almost equal to the outer diameter of the linear bearing.
With the cardboard I've one problem with the cardboard is that the thickness of the cardboard is not enough to hold the bearing. So, I cut the multiple pieces of cardboard and pasted them together to make the bearing holder thicker.