Fabrication Week 3 – I Love Laser Cutter

Fabrication Week 3 – I Love Laser Cutter

Source design scanned from a “Mandala coloring book”:

Photoshop used to cut out center portion, convert to true black and white, up the brightness and contrast.

Next, converted the jpg in Illustrator using Image Trace > Expand. I had to play with the details a bit, by upping the stroke to 22 increase the width of the portion I wanted to cut out, and then reversing the image and adding a 0.01 stroke to all of the edges for a vector cut. Then I expanded each of the corners out in two dimensions to give a wider center area so I could draw a cut out and eventually interlock the pieces.

Round 1

I decided to prototype on cardboard to see how the design printed. Cardboard didn’t seem to appear on the materials list for the laser cutter, so I consulted those around me. Getting the settings right on my first try was a major fail. I went with the advice of the ER staff (15% speed and 100% power), which turned out to be bad advice, as tiny campfires lit over and over throughout the cut.

Eventually it was more than a tiny campfire and I had to open the laser cutter door to stop the cut and blow out the “birthday candle flame”. Oops.

I ran into many more issues while using the 60W laser cutter, such as the Y disabling multiple times (I think that means the Y axis belt got off track).

Finally a cut out that didn’t disable, or catch on fire and I discovered the settings with some more trial and error.

Eventually, I had to redo my design in Illustrator because I couldn’t find the hidden lines in my file that kept making cuts across the design, as shown at 2 o’clock here.

Two cardboard prototypes!

I manually cut slices in the middle with a utility knife and joined the two together. I was delighted with the result!

Round 2

After a chat with ITP resident Daveed, it was time to get my material and I chose a Basswood sheet. I forgot the photograph the sheet, however it was 8″x 24″ and 3/16″ thick. It cost $10 from Blick Art Supply.

I had booked another 90min session with the laser cutter after a two hour session the night before. However when I arrived, my heart sank:

Fortunately, a classmate finished early on the 50W and I was able to sneak in an hour between classes. I knew I needed to test the depth of the Bassword for the interlocking design width. At the same time, I got familiar with the 50W settings for the material I was using.

Apparently I had misused the perfect digital callipers, when I got a reading of 0.156″ for the material depth. I first made the interlocking piece with a width of 0.16, and noticed the wood stretching to fit, and recalled Daveed’s warning that the reasonably sturdy wood in one direction could easily snap when bent in the other direction. (Sure enough, my sample piece snapped a few moments later).

Here I am testing the width.

Fortunately, I realized there must have been an error in my measurement and reused the digital callipers on the wood. This time I got 0.185″. I must have zero’d out the callipers just off. I changed my design to have 0.19″ interlocking openings, and this time the pieces fit great. I know there is some debate over using the exact sizes because the laser is so precise, but I was running out of time and was happy with the fit allowed by a 0.005″ difference.

Round 3

After over three hours on the laser cuter, I thought I would be done, but I still hadn’t cut my pieces. The schedule was booked for the rest of the night on all machines, but I got lucky when a classmate had overbooked for padding and didn’t need the time slot Tuesday night, giving me two more hours which is fortuanate because cut time alone for the final design took about 75min.

Cross your fingers!

Here’s the laser cutter hard at work.

To be continued in the morning….

One Reply to “Fabrication Week 3 – I Love Laser Cutter”

  1. Nice work. I like how you prototyped in cardboard first, then tested the fit of your slot in wood. Always a good idea before going for it on your expensive material.

    Can’t wait to see it all together.

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