User:Fishpaw/ENES-100/Polar Printer Project

Week 0 Choosing a Project
Chose to work on the polar printer project.

My two other group members are Ram Hei and David Hesley. No one in the group had worked on this project before. I choose to work on this because I am interested in how the polar printers work and their potential seems to be endless and affordable.

Week 1 Research
Searched and watched YouTube videos and read the project pages of the previous group who was working on the project.

The group decided to split up and work on separate parts of this project. Ram looked into the step motors that would control the movement of the printer head, David looked into the Arduino code that would run the step motors and I looked into the math that would allow the Arduino to move the step motors at the correct ratio to keep the printer head on a level plane.

Week 2 Figuring it out
We had to come up with a way to allow for the printer head to move out from the motor assemble and back in without changing the plane that the printer head was moving on. In order to do this we had to maintain a right angle between the motor and the printer head. We used Pythagorean Theorem to solve for the speed the step motors would run at. We know that the height of A is always 12 inches because that was the distance that the two U-bolts were mounted at. That just meant that we had to find the ratio of ∆C: ∆B. This ratio would allow us to keep the printer head level while the printer head was moved from the initial point to the next point that was required.

We are looking to find the change in B and the change in the C. First we chose two B and then using the Pythagorean Theorem we found the C.


 * A^2+B^2=C^2
 * 1) 12^2+6^2=C^2
 * 2) 12^2+9^2=C^2

For finding ∆C
 * C2-C1 =∆C
 * 15-13.42 =∆C
 * 1.58=∆C

For finding ∆B
 * B2-B1 =∆B
 * 9-6=∆B
 * 3=∆B

We now know the ratio to be 1.58:3. This means that for every 3 units the base moves (either towards the motor or away from it) hypotenuse has to move 1.58 units. The step motors can now be programmed with this ratio and the printer head should stay on a level plane.

We were also experiencing some trouble with the #2 step motor specifically. It would start out running fine and keeping pace with the #1 step motor then would start to skip and fall behind. We presented to the class about what we had done so far and that motor #2 was skipping.

We did several things to try to trouble shoot the problem. More power and slower speed stopped the step motor from skipping.
 * 1) Thought it might be a code error.  We all double checked the code to make sure that there was nothing different between the two motors codes.  None of us found anything.
 * 2) Thought it might be an issue with that step motor specifically.  Motor #1 was switched to motor #2 plug and motor #2. The new motor still skipped.
 * 3) Next we switched out the wires that connected it from the shield to the motor.  Our thought was maybe a wire was loose or there was a bad connection on the plug end.  The motor still skipped.
 * 4) Next we plugged in an external power source and slowed down how fast the step motors turned.

Week 3 Designing
I worked on designing a bracket that would allow the motor mount to attach to the all thread which will allow for vertical movement. The 3D modeling was done in Sketchup. I first had to familiarize myself with the program because I had never used it before. There were a few key things I found while making the bracket. We took some measurements and found that the size of the bracket should be 2 inches high X 1 inch wide X 3.5 inches long and are 1/4 inch thick. I measured the all-thread and the nut to find the size that the hole for the all-thread to pass threw and the indent that would be needed for the nut to sit in. It was decided that 1/4 inch holes for the bracket to attach to the motor assemble would be a good size.Once the two pieces were built I rotated one side 90 degrees and attached it to the other piece.
 * add any holes or cut outs before you extrude the design.
 * in order to get the indent for the nut to sit I extruded the piece half way then added the polygon. Once the polygon was added I extruded the piece to its full thickness leaving the indent for the nut.
 * I found it easiest to build the horizontal and vertical parts of the bracket separately then rotate the vertical piece 90 degrees and attach it to the horizontal piece.

At first we thought we would print 3 brackets to allow for optimal stabilization of the motor assembly. However, when we had presented to the class about our trouble shooting of the step motors skipping we also talked about how we planned to attach the motor assembly to the all-thread. It was brought to our attention that the more nuts that are attached to the all-thread the more likely it was going to bind from the nuts not being lined up precisely. It was decided that only one bracket would hold a nut and the others would be there to stablize the assembley.

In order to print this bracket on the 3D printer it needed to be in a .x3g file format. First we downloaded and installed an extension that would allow us to export the file as a .stl file. Once the file was exported as a .stl which allowed me to import it into Makerware. When I imported the bracket file into Makerware it wanted to convert the inches in millimeters, I am unsure if this will create an issue but there did not seem to be another way. From Makerware we were going to export it to a memory card as a .x3g file but Makerware was having some problems. We are planning on trying again to get this printed next week.



Week 4 Presenting
We were able to print two of the brackets that would allow the motor assembly to move up and down the motor mount and had an indent for the nut that fits into. We glued the nut into the bracket so that the nut will not back itself out.

Then we drilled holes into the plexi glass to attach the all thread bracket to the motor mount. We mounted two brackets to help hold the plexi glass as straight as possible. The concern was that this would cause the motor mount to bind as it traveled up and down the all thread. Once we mounted the brackets we turned the all thread to see if it would travel up and down the all thread. The nuts traveled very smoothly up and down the all thread. We were even able to attach a cordless drill to the all thread and have it travel without any problems.

While we turned the all thread we noticed that the motor mount would turn with the all thread until it hit resistance then it would travel. We decided to print two sets of guiding brackets that could attach to the all thread that we had used to support the all thread.

Once the guide brackets were completed we began to work on the presentation for the ENES 100 class. We broke the project up into five sections
 * Concept
 * Design
 * Construction
 * Future
 * Problems

The concept section addressed where this idea came from. Professor Dolge

The Final Project page