Week 3

Our assignment:

Group Assignment: 1. do your lab's safety training 2. characterize your lasercutter's focus, power, speed, rate, kerf, joint clearance and types

Individual Assignment: 1. cut something on the vinylcutter 2. design, lasercut, and document a parametric construction kit, accounting for the laser cutter kerf

Lab Safety and Tips

During my lab's safety training, I learned:

• while using the laser cutter someone should be monitoring it. be careful not to turn your back to it for too long or step away
• have the fire blanket (and extinguisher in extreme situations) ready in case of fire. Calmly suppress the fire by putting the fire blanket/material at hand to smother it
• the importance of maintaining air flow to prevent fires and to handle fumes. we must ensure proper ventilation for the laser cutter, making sure the airflow is not blocked
• the laser cutter has a built in safety feature that stops the laser if the door is opened. We should stop the cut job if we need to open the door for some reason before the cut finishes
• make sure instructor is present when using machinery

Laser Cutter Settings
In Fab Lab NODA, we have a 30 watt C02 Laser (It's an EPILOG Helix brand). This laser cutter is 24'' x 18.'' Below is a chart that notes the initial settings (to cut unless otherwise specified) I used based on various materials I've used so far:

Material	Power	Speed	Rate
Cardboard	90-100	8-15	500-1000 f
Cardboard (to engrave)	50	80	500
1/8'' Acryllic	100	9	5000 f
1/8'' Mirrored Acryllic	100	9	5000 f
that cool spacey material (to engrave)	1000	9	5000 f

These initial cut settings were before we completed our group assignments due to unexpected scheduling for this week (I had to leave town for family matters). Check out our completed group assignment here which includes an up-to-date table for our laser settings after we ran tests to more accurately characterize them.

To start to get a feel for the laser cutter, I began with a few designs using Inkscape and a tutorial to get acquainted with parametric design on Fusion. I'll include documentation for those at the end.

Vinyl Cutting

Since one of my sister's favorite video games is Kirby, I decided to make her a sticker. I found an image I liked online here. Next, I decided to try out GIMP so I imported the file there to practice converting it into a black and white PNG file. Using the threshold tool, I reduced the image to two colors then exported the PNG file. Next I opened this in Inkscape, vectorized the image, and applied the appropriate fill and stroke settings using the Fab Academy Tutorial page as a guide.

practice using GIMP; exporting final version to silhouette studio for printing

Will let me know that in order to cut effectively on the vinyl cutter, I would need to simplify/clean up the path. I started using the simplify path and smooth node features but this ended up being very time consuming and I was running out of time to complete the assignment. So I found another simpler png file of Kirby online to import directly into Inkscape. I still needed to simplify the path but it went much easier and now I was ready to send to vinyl cutter.

Parametric Design and Construction

Now on to the laser cutter! After many twists and turns, I ended up with a press-fit lamp design made from acryllic and mirrored acryllic pieces:

After looking through Fab Academy resources to familiarize myself with the process, I first attempted a tutorial of a structure with a living henge feature--I learned some cool features of Fusion which I'll share more below but wanted to do something a little more fun for the the assignment. I ended up finding a cool design by former student Abdelrahman and decided to try my hand at recreating my own version of it on Fusion -- at first thinking it would be a cool object to hold a small vase to hold flowers. As you will see, each step along the way my instructor Will challenged me to develop a better and better press-fit design.

To get started in Fusion, I used the student's documentation as a guide but started off creating something something bigger. The basic design is a circle with an array of rectangular slots that would fit into place with separate geometric shape (which I just call a "leg" throughout the documentation). I set parameters for kerf, slot width, slot length, circle diameter, and several heights and widths of the leg. I made sure that the length of the top part of the leg equalled the length of the slot created on the circle. I also learned how to make a curve using the conic curve feature. After extruding the shapes (which I also parameterized at "thickness,"), I cleaned up the circle design by trimming the gaps so that when I import the design into Inkscape it'll be ready to go.

I soon find out that due to the trimming, I need to add more constraint to the design so that I could utilize the parametric capabilities. I'm sure there was a much more efficient way to do this but I used the equal constraint to ensure each slot width was equal and each each slot length was equal. I thought all of this would do the trick and it did not! I learned later on when I started to make improvements to the design that all of this messed with my ability to actually utilize the parametric-ness of the design and after much trial and error, I learned through failure how to properly set up the design. I decided to start over, but because I'd learned practically how to use the constraints and features needed it was fairly quick to do.

sketch and extrusion of first go at the design

While prototyping in the lab, I found:

• on the Epilog dashboard you have to make sure the laser dimensions are correct otherwise it will cut off the print job at the given parameters
• cardboard material was much thicker than I had accounted for and the leg pieces were too big. I experimented by changing the thickness parameter which would change the width of each spoke. My second try the fit was too loose.
• I also added another joint into the design to make the fit better
• when testing the fit, I could cut just one fraction of the design until it fits well. then i can cut the full design
• In Inkscape, you can adjust the design to maximize space on the grid to save material as much as possible. Helpful tip: draw a box around the small section to print and use the intersection of paths feature to just get that section in Inkscape.

Will challenged me to incorporate different joint types to strengthen the press-fit. Whereas I began with a simple press-fit joint type, I then added two small bumps along the inside of each slot to create a snap-fit. I then took it one step further (especially given the rigidness of the cardboard) by cutting out some rectangles along each side of the slot to create a flexure joint type.

very helpful graphic provided by Fab Academy

In the image on top, I am mirroring the bump to create the snap-fit. I then used a circular pattern to apply to each slot. In the middle, I am simularly creating a circular pattern, this time with the flexure design so that each slot has a nearby thin rectangular cut to let it have a little give. On the bottom are some different iterations of slots in cardboard and acryllic.

On the top, a close up of the leg snapped in place with the base. On the bottom, three phases of the leg design including a gap to slide into place

Once I switched from cardboard to acryllic, the thickness went from roughly 6.7 mm to 3mm. But I could now change the thickness parameter and the design updated accordingly based on constraints I had set using these parameters.

Using the laser cutter to cut the final design for the base of the lamp

And finally, we hooked up a lightbulb to see how it'd look as a lamp! The mirrored surfaces and mix of materials for the dangling panels has a really interesting effect on the light. What's also cool is that I could make any design I like for the floating panels using materials with the same thickness and they can snap into place.

Some improvements to the design would include:

• making the flexure length a little longer and slightly closer in. Rather than constraining it in relation to the thickness of material, I would try constraining it in relation to the length of the slot
• extend the top part of the floating leg panel since it's a hanging lamp design to strengthen the overall structure
• cleaning up the file on Fusion to get rid of old sketches so that you don't have to hide unnecessary bodies when you change certain parameters

Group Assignment

Once I got to the group assignment to test joint clearance, all of the practice above allowed me to simply design a paramaterized joint clearance tool on Fusion for future reference. Looking forward to having this design for future use.

joint clearance tool design and parameters on Fusion

the smallest joint on this design was a perfect press-fit

Other Stuff

Going a bit backwards, I wanted to document a few more designs I learned from this week...

For my initial practice with the laser cutter, I cut 1. the grid for my final project using cardboard and 2. a Octavia Butler inspired 2D design on this really cool material 3. a failed living hinge box-like structure

Making the grid helped me hone in on more exact dimensions for my board. I edited my sketch in Onshape and added a dimension constraint to make the gap 360 x 240 mm. Then I headed to Inkscape, made use of align and distribute tools to make an evenly spaced grid of 9 squares by 6 squares with sides of 40 mm. For the cut and engraving we used color mapping and epilog, set the engraving path the blue and the cutting path to red. In Inkscape I changed the stroke colors accordingly and also made sure to set the stroke type to hairline to signify to the print driver the lines to vector cut.

grid in Inkscape and the board prototype. It's not much but this was the first thing I actually designed and cut using the laser cutter! I'm interested in how this would look using acryllic.

Next, I was eager to use one of the spacey materials that Will had in the lab. I created an Octavia Butler inspired design where I had to convert a raster image of a portrait of her into a vector image. With Will's help, I learned how to add nodes, break nodes, the break the path to remove pieces from the stars in the design.

here I am using nodes and operations to edit the image how I need

Once done, we set the job type to raster, 90% speed, 44% power, bottom-up engrave direction (though we re-did it top-down to better define the top part of the engraving), and set image dithering at Floyd Stein Berg. We also offset the print 1/8 inch from the x and y axes.

here's the end result. We ran the print a few times to get better quality. I'm happy with the words and the background star shape. I'll have to experiment with design to better represent faces cause this came out a little creepy! Still really cool though.

I also dabbled somewhat in Inkscape. To design somewhat parametrically in Inkscape, I learned to use the clone feature. I began by following the instructions for creating a press fit feature in Inkscape on the tutorial page. On my first attempt I couldn't successfully break apart the press fit feature. So I tried again this time by constructing the boxes using the pencil tool rather than the rectangle tool. When that didn't work, I remembered I hadn't clicked the "break path at selected nodes" feature before the "break apart" path tool.

In Fusion, I also worked on a parametric design of a box with a living hinge. I followed this YouTube tutorial on how to do this (though I didn't follow it as much near the end) and learned to create parameters that I can then use as functions for creating dimensions throughout the design process. Some fun new things I learned in Fusion 360:

• set user parameters -> that way I could account for things like material thickness, gap between slats on the laser cutter, height, etc.
• creating a sheet metal flange
• how to unfold the sheet metal
• how to project components onto a sketch
• creating sheet metal rule
• use of rectangular pattern tool to create exact number of slats needed for the hinge
• how to sketch a palette and arrange faces of the design onto the palette which could then be exported as a 2D design and used for laser cutting

On the top, design and parameters for the box hinge. In the middle, the cardboard cut of the design. On the bottom, the hinge stretched waaayy out which I found kinda cool.

After cutting, it was clear the hinge had way too many cut lines. Since it was designed parametrically, I could reduce the number of cut lines (which were rectangularly patterned with a parameter to determine number of slats). I changed the formula to reduce it to four times as few to start. I also could adjust the finger joint by changing the ply (the material thickness). However, by this point I wanted to try something else for my actual assignment so I didn't carry this any further.

Design Files

Find a zip folder of my design files for Week 3 here.