Week 3 - Computer Controlled Cutting Group Project - Collin Kanofsky, Kabir Nawaz, David Vaughn¶
Group Members : Collin Kanofsky, Kabir Nawaz, David Vaughn
Goal :¶
The goal is to characterize our lasercutter’s focus, power, speed, rate, kerf, joint clearance and types through testing.
Finding the Kerf of our laser cutter - Collin Kanofsky¶
To find the kerf of the laser cutter, we designed a 1 in by 1 in square box in correl draw and cut it out on the laser cutter. After cutting, we used a calliper to accurately measure the size of the square and found out that in reality, it was only 0.97 in. This means that the kerf for our laser cutter is 0.03 in.
Finding the Focus, Power, Speed, and Rate of our laser cutter¶
To characterize the power, speed, and rate, we decided to cut out a file with shapes at different colors, then map these colors to the desired power/speed/rate settings with the Epilog software. Inspired by last year’s week 4A group, we set up a CorelDRAW file with shapes in 30 different colors. Each shape was a star with one line segment missing; this allowed comparing the thickness and other effects of each cut, as the piece does not fully separate from the material, while also making it easy to see which cuts would not have worked and could not be pushed through the cardboard.
In this way, the blue component of the RGB color represented a different power setting, the red component represented a different speed setting, and the green component represented a different frequency setting. When a setting was not specified by the color, we used the existing settings of 40% speed, 100% power, and 10% frequency. After sending the file to the Epilog software, we split it by color and manually adjusted each color’s settings (with the text set to engrave):
The results:
We can see that a higher power resulted in a thicker cut, lower speed resulted in a thicker cut, and a higher frequency resulted in a thicker cut. Speed’s effects were the most evident, while frequency was harder to see (although it is more evident when looking at the back side of the cut cardboard:)
To find the focus, we created a file with a single cut star, similar to the shape we used for characterizing speed, frequency, and power. Then, we set this up to cut via Center-Center positioning, where the cut position is specified in the laser cutter menu rather than in the Epilog software. This allowed running the job to cut a single star in many different positions without needing to reposition it on the computer after every cut.
For the first cut, we manually focused the laser at 0.261 in using the Manual Focus Gauge, and we adjusted later cuts to show a variety of different focus levels.
Evidently, focuses that are more accurate produce a thinner cut. At higher focuses, the laser cutter produced more flame and smoke while cutting, and cut a larger area of the cardboard. This aligns with our understanding of how the laser cutter lens works: as the focus becomes more misaligned, the area actually getting hit by the laser becomes thicker.
A Joint Effort - David Vaughn¶
To characterize different joint types, we created a set of joints so that we could evaluate them. To do this, I took the file given on the Fab schedule for an assortment of different types of joints. I opened the file in Fusion360 so I could replicate the shapes using the dimensions.
However, Landon Broadwell showed me that I could just export it as a .dxf file from Fusion360, which I could put in Inkscape. I then reoriented the joints in Inkscape, and exported it as an .STL file. I then imported this file into a folder in the EngProj google account Collin Kanofsky created for our group. I could then download this file onto a computer next to the laser cutter, import it into CorelDRAW, at which point a bunch of the lines did some funky things and a lot of random lines appeared which I had to remove. It then looked a lot better.
It still had some minor errors that I had to remove such as the one below (the legs were not fully connected and the line of the square should not go over where the legs connect).
Below is the interface of the print screen after you select file>print in CorelDRAW on the computer next to the large epilog.
I then began the cut, but soon realized that the laser kept recutting most of the lines and had too much power, so it was beginning to burn some of the cardboard. Below is an image of a piece that started burning before I finally had to stopped the cut.
I went back to the drawing in CorelDRAW, found some duplicate lines, and spent some time deleting as many as I could, but there were not enough to justify how repititive the cut was. However, Mr. Dubick soon informed me of a problem: I had been using the laser cutter settings detailed on the sheet next to the small epilog, but there were built in settings that I had completely forgotten about for the large epilog. Because of the difference in these two laser cutters, the settings differed as well, and so I was using the wrong settings. I selected the correct settings (in the picture below it shows where to click to get to the already downloaded settings) this time, and cut. It still went over the same place multiple times, but once it went over everything it needed to at least once, I stopped the cut.
Below is an image of the pairs of cardboard joints in the laser cutter during the cut, and then one after the cut. In the second one, you can see the failed attempt on the right side of the image.
Putting Things Together¶
Each of these joints would have different applications, but generally, the complexity of the design of the joints is correlated with its efficacy. However, some of these joints would work better when scaled to a size due to the nature of their respective joints. For instance, the fourth joint pair down in the image above had a width for its little hooks much too large, so it did not function as it might if it was scaled larger. Despite this, almost all of them worked well as shown below. The following connected joints are shown in the order which they appear (top to bottom) in the previous image of them after being laser cut.
Finding Joint Clearance - Collin Kanofsky¶
To find the best joint clearance, we created 5 slots in a cardboard piece. The middle slot is exactly the material width with no kerf. Then, I created slots on both sides of the original that were 0.025 smaller and bigger. Finally I added 2 more slots like before and made them 0.05 bigger than the middle slot. I cut this piece out along with a square and tested the joint clearance as shown below.
Surprisingly, the best joint clearance was no clearance when using cardboard. Though 0.025 more space still worked, as did 0.025 less, neither had the perfect fit that the middle slot had. Therefore, the best joint clearance for cardboard is no joint clearance and just the material width should be taken into account when creating joints.
