Monday 3 March 2014

Introduction to Slim CNC milS

Thank you for stumbling upon, searching, or bookmarking this blog. The purpose of this blog is to documents the design and build process of a personal CNC machine. Throughout all the posts, the intent is to give as much information as possible to help others who aspire to build their own but have many questions or don't know how to start. There are currently many DIY websites and blogs on CNC machines but this blog is written to give information overload so that those who have very little experience can follow. This is written from two university students' point of view with a starting knowledge that was minimal in terms of CADing, machining, electronics, and testing.

The rest of this post is a bit of an intro as to how each of us got into engineering. If you are trying to pack as much information into your brain because you are a student on work term with only four months to build the machine, a work term report, and that PD20 course (which is totally useless in my opinion) then skip the rest of this post.


Hello,

My name is Daniel Choi and I am an engineering student at the University of Waterloo. When I was young and naive, I said, "I want to be an engineer!" My dad is an engineering and I thought it was a cool job because he did it. Little did I know that was what I would end up studying one day.

When looking back, I can see that a few key things contributed to the birth of an engineering career. A lot of my childhood consisted of building lego vehicles with my brother and adding as many clear coloured circle pieces to the guns of our ships to make them "stronger". Also I enjoyed challenges to various problems like how to build some contraption around an egg to protect it when dropped from the second floor window.

Side note: If you are a parent reading this, I suggest that if you think your child has the slightest interest in engineering, start young! Get a cheap 3D printer and allow your kids to make designs on the computer. Buy them things to build or throw project ideas at them to try. Don't let them sit on the computer all day on facebook or become couch potatoes.

However, it wasn't until I enrolled in a computer engineering course in grade 10 at Sir John A. Macdonald SS (Waterloo) that I found my interests in engineering become more than words. This course taught basic electronics and circuits and allowed students to have hands on experience with manufacturing PCBs from a copper board to flashing fancy LEDs. Some of the projects included a line following robot and an LED chaser. Schematics were provided for both these projects but the board layout was left up to the individual. We used traxmaker to layout the components and etched our personal layout with chemicals that are probably not good for bare hands. Then we were given the privilege (or nightmare) to drill all the holes for through hole components with a fragile $1 drill bits (good thing I never broke one and still have them in my pencil case) and trusted with hot soldering irons to mount all the individual components. For the line following robot, we made the PCB and programmed a MCU to have the robot follow a windy oval loop made of electrical tape. Phototransistors and a super bright LED were used to detect when the robot was deviating from the main path.

After having a blast in grade 10 without any burns or cuts, I decided to continue on with the grade 11 course taught by the same awesome teacher. The main project for this term was to build a sumobot that would face 1 on 1 in a ring with another sumobot and try to push the competition out or immobilize them if that was even possible... All the parts were built and and assembled by my partner and I. In the class competition, our robot came out on top with a tough best out of five finals.

It came down to the last match where it was tied 2-2 and all the eyes in the class were glued on two unprofessionally made robots. When the ON switches were flipped and the robots started spinning in search for their target, the class erupted into cheering. After a couple dances around the ring and a few light nudges exchanged, there was a window of opportunity as our robot stopped, locked onto the opponent, charged forward (at 5cm/s more or less) and made full contact with the opponents side. Everything went in slow motion (partly because the opponents robot weighed a ton and was hard to get under) as all of our efforts for the win (an 100% on the project) could come down to this final collision. All of our upgrades to the robot were being put to the test; the enhancement to the plough with the two curved strips of metal (seen below), countless hours of filing done by my partner on the tip of the plough, and a hot glued hunk of aluminium under the plough for a tighter fit against the ground. The final moments could be described as a battle between a spatula and a stubborn fried egg with the spatula slowly peeling the egg off the frying pan, onto the surface and finally flipping the egg over. In this case, the opponent's sumobot was flipped on its side and the crowd went wild!



This is the only shot of the two sumobots battling with mine on the left (the true outcome is not reflected in this picture!)

In grade 12, we were given the opportunity to make a firefighter robot from scratch. Multiple sensors were used like infrared to detect a candle flame and wall distances and phototransistors/super bright LEDs to detect a line. The coding was the main challenge in this project in order to have the most efficient robot (and get 100%). In the end, my fastest time around the course (and fastest in the class) was about 27 seconds. This was achieved by increasing the voltage to the motors but required the response to sensors to be just on time and a few tweeks to the code to compensate for the higher speed.


This video is about 1 minute long with motor voltages at a nominal 9 volts...I think...it was too long ago (if not 9, then 5 volts)

In my grade 12 year, I was accepted into Mechatronics engineering at the University of Waterloo and currently I am in my third year. So far I have had 3 work terms and am in the middle of my fourth but realize that I have very little exposure to the practical side of engineering (programming, designing circuits, machining, etc). Last work term (summer of 2013) I made a moving target using an arduino, a servo motor, timing belt and pulls, a drawslide, a 10-turn potentiometer, and accelerometer. This was a fun little project but was not very impressive because the target moves at around 5cm/s and is easy to shoot from 15 meters away. I plan to upgrade the motor to a more powerful stepper motor one day when I get around to it. 

In search of a "bigger" project for this work term, I stumbled upon a CNC machines one day during the Fall 2014 term of school. I got very excited since I would be able to develop my practical skills in all the areas listed above and I would be making something useful. At this point I share the idea with Daniel and got him on board. We hope to have most of the mechanical design completed by the end of April 2014 and maybe some electronics hooked up as well. Stay tuned!

Hi,

I'm Daniel Mok, I'm also a mechatronics engineering student at the University of Waterloo and another person working on this project.

Why did I choose engineering? This is a difficult question to give a straight answer to, but it mainly started from an early interest in math and science. Drawing was also a big interest of mine, and among my doodles there were a fair amount of amateurish designs for fantastical machines that I hoped to one day bring to life. As Daniel Choi has mentioned, having parental support is a huge help: much of my early exposure to engineering came from books, magazines, some summer camps, and of course Lego.

It was not until high school that I started to seriously consider engineering as a career, during which I was strongly influenced by my technology and computer science courses. During this time I was able to work on several projects which continued to build up my interest in engineering, such as building a sumobot, learning woodworking, creating designs with AutoCAD, and developing a simple Android game. My manufacturing course was also where I first encountered CNC machines, where I used one to carve out a design into some wood.

I am now in my third year of engineering and I really enjoy my program. Last summer I was thinking about potential engineering projects and thought about making a CNC machine. One term later I was asked by Daniel Choi if I wanted to help him with creating one, so here I am. :)

Closing Remarks
One last note, you might be wondering why the name of this website was called slim CNC mils. We wanted a name that was unique (not boring like diy CNC tutorial). If you haven't already noticed, you can flip "slim CNC mils" around and it spells itself. Also, we are trying to make the CNC machine as cheap as possible yet with the best components we can get for our dollar. So if you are also on a tight budget, there will be some tips on how to save money and also ballpark prices for components mentioned.

Thank You
We would like to thank Chris McClellan for providing a lot of the aluminium used to machine our smaller mounting and connecting pieces.

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