Making my .png file in Inkscape 

First, I used  Inkscape  open-source software to create a design that I wanted to cut out on a vinyl adhesive sheet. In this case, I wanted to make a design that included my partner's initials and my initials. Then, I exported the file to .png to prepare it for the vinyl cutter.  

1) Use text tool to add text, and modify font & sizing (I  used Snell Roundhand font, and see  here  for instructions on how to use the text tool) 

2) Make a heart shape in InkScape (see  here  for step by step instructions, and  here  for how to rotate objects). Use  rectangle tool  to make an outline around it for convenience. 

3) Change colors, if desired (for vinyl cutting, I'd recommend black & white). See  here  for how-to. 

4) In inkscape, modify your image in the right hand menu to be 300-600 DPI

5) Export to .PNG file type (File > Export) 

Loading my file to the Vinyl Cutter & Cutting It

Next, I went to the MIT Architecture shop to use the vinyl cutter there. The detailed instructions on how to use the Vinyl Cutter were located on the architecture shop website. 

I had some difficulties (the design was cutting too small despite changing the DPI in the mods software), and I found that the solution was to change the DPI manually in InkScape software on the right hand menu, to 300-600 DPI. Don't make the same mistake as me! 

Sand Blasting My Vinyl Cut Design Onto Metal

To sand blast my vinyl cut desin onto metal, I taped my vinyl cutout onto a sheet of metal aluminum. Then, I used the sand blasting equipment (trained by Shah, one of the MIT archsop staff) to sand blast onto my design. 

1. Put on a mask (KN95 or cloth) to protect your mouth & nose 
2. Unlatch the enclosure (latch is on the right of the equipment) 
3. Put your part into the enclosure near the large gloves (note: your material is likely metal or glass; if it is metal you can use the normal vinyl but don't blast for too long or it will get through the vinyl; for glass or when blasting for a longer time, use a thicker silicone vinyl material.
4. Secure the enclosure and turn on the button/swith on the top left of the equipment; you should see the light turn on inside 
5. Stick your hands into the gloves of the glove box, and pick up the handheld sand blaster inside 
6. Press the pedal in the lower right of the equipment to blast the sand
7. Call over the shop mentors / shop staff for help if you run out of sand 
8. When done, wait for ~10 min with the light still on to let the sand in the air filter out 
9. Remove your part from the enclosure and close it after you're done. 
10. Peel off the viny and your sand blasting is now done!

Construction Kit #1: Cornhole Game 

For the construction kit assignment, I decided to design sketches of pieces in OnShape that would enable more than just 90 degree angle construction. To test this out, I first used stiff cardstock paper and made some cutouts, and tried to fit them together. I got the inspirationfor these shapes from Pinterest boards for laser cut construction kits.

1. I made the construction pieces from scratch in OnShape
2. Exported .STEP file and imported into Rhino
3. Used Array in Rhino command line to copy many iterations of the design
4. Used Scale in the command line to properly size the file (based on 0.245" slot cutout size)
5. Drew a 36x24" square in Rhino, clicking on the midpoint symbols to resize it 
6. Select everything and go to File > Print. Change to Custom Size, click on Options to manually enter 36 " horizontal x 24" vertical. In this same menu there should also be settings for power, speed, & frequency (use the charts on the wall in the archshop to guestimate what settings to start with).
7. Back in the Print menu, scroll down to where it says Window. Set the window by clicking on Set and then drag the rectangle around your existing template rectangle which encompasses outside of your design. Press Enter. 
8. Now it should take you once again back to the Print menu. But first, you need to hide the rectangle otherwise it will cut the rectangle too - oops! So, click on Close  
9. Click on the rectangle (36x24" reference rectangle that you made in Rhino) 
10. Type "Hide" into the command line 
11. Click File > Print 
12. On the laser cutter equipment, it should show a job on the screen.
13. Before you press Go, ensure the laser is focused. For the 120W in the archsop, you cannot auto-focus so you need to use the triangular tool and set the laser to 2" above the surface of the cardboard (see at the end of this page for a visual example). 
14. Press the Go button. 
15. Done! You've now successfully cut something on the 120W Epilog laser cutter! 
16. To assemble the design, I fit the smaller connectors between the triangles and I fit the larger curvy-shaped pieces into each other. Since I hadn't yet done the kerf assignment and the equipment was manually focused, the second batch of pieces had larger slots so I had to use a hot glue gun on a couple of the connections. Next time I would use the 60 Watt Epilog equipment since the auto focus works on that equipment and thus will yield morec onssiten tresults. I would also use 20 speed / 30 power / 500 frequency / 2" focus to get more optimal results, per our group project characterization of the best parameter settings. 

Construction Kit #2: Mechanical Iris 

As a bonus, I laser cut a .dxf template file similar to what I would like my final project to look like. I glued the joints using silver wire and a hot glue gun. I found that the mechanism was a bit slow/stiff, so I will choose larger gear teeth for the next iteration, and will also work on starting to learn how to use the water jet for metal cutouts.

Group Project

For the group project,Idid the following:

• Characterized speed, power, rate (frequency), and focus, with Raghav/Emily/Hannah/Sophie/Elijah (helped create part of the tables of info on results, and was there with the team for it) 
• Characterized kerf, joint types, and jont clearance with Raghav and Hannah. I made the 2 Rhino files for this part of the characterization 
• Suggested to my group to measure kerf by manually adjusting focus withthe triangle tool to slightly above/below and re-cutting to see difference 
• Understood/learned the definitions & cause-effect of varying the kerf, focus, speed, power, rate (frequency)

Kerf is essentially the "thickness" of the line that cuts into the material, since lasers have a width for the beam, and sometimes when not completely focused the kerf is larger (e.g. because the beam is like a double cone shape). We characterized it by making a series of cutouts and measuring the resulting offset with a caliper.

Kerf = 0.40 in / (11 cutouts) = 0.036in 

The first time we made the kerfcutout, we had a fire happen - oops! Since the setting we used (30 speed, 40 power, 500 frequency, 2" focus) was same as before (had not burnt it before), we concluded that this was caused by the laser going twice over each of the lines due to the overlapping design. To fix this, we simply halved the power to reduce chance of burning/fire. 

Raghav Kedia, Hannah Gazdus, and I characterized the kerf, joint clearance, and joint types above/below.

For the joint clearance, I made varying slot distancesin Rhino and we tried fitting them together to see which press fit the best (0.0245" worked nicely).

For joint types, we made one joint with diagonal angles near the entry of the slot. This made it much easier to slide the slots together when press fitting! 

For speed, power, focus, rate (frequency), we varied each of these parameters and observed the qualitative results, which are documentedin a table for our group in our google drive. Please see Emily's page here https://fab.cba.mit.edu/classes/863.21/Architecture/people/YanjunEmilyLiu/week1.html for a copy of the google drive table of qualitative characterization for our group for the different settings. The group members present for this part below were Raghav Kedia, Hannah Gazduz, Sophie Longawa, & Elijah Bell, Emily (Yanjun Liu). Emily made the Rhino files for the squares below,and Hannah inputtedthe majority of the qualitative info into the table. 

20/40, 10/40, and20/30  speed/power settings allowed the cutoutsto come out most easily. 20 speed / 30 power yielded the best result.

Learnings & More Advanced Applications

Two things I didn't try but could try in the future for more advanced applications is 1) engraving (using lower power/higher speed and using the color options in the settings) to make designs,and 2) trying more interesting joint types such as a flexure joint!

With regards to learnings, I made many, many mistakes. I burnt the cardboard when cutting out a repeated rectangle becasue the laser went over the lines twice, leading to more heat/energy leading to fire (me & Raghav had to use the fire spray since the cardboard was glowing). I also should have made my joints larger on either side of the slots (they ended up ripping a bit at the endes since they were too small). Also, for my first attempted run my power was too low (didn't cut fully through, but joint was tight and good) but the 2nd attempt I ran it too high (and/or perhaps the cardboard was slightly misaligned since I used the 120W Epilog in our shop that had the auto focus broken, so manual focus = slight human error), leading to overly burnt edges due to power being too high and slots being slightly too big due to larger kerf because of the likely out-of-focus laser (the laser focus is supposed to be ~2" from the material surface)