Saturday, July 11, 2015

The Singing Laser

My entire family quilts, winning ribbons at the fair (champion, grand champion, superintendent’s choice). Emily is piecing together her latest project. I have only supplied technical support for the computer-driven quilting machine… until now. I have a vital role for this year’s fair—I get to operate the laser. I’m not joking. Igor calls it my disintegrator beam.

My wife ordered an Emblaser laser cutter for her birthday so she could save time cutting out appliqués for her kits. The idea is that she scans in the pattern and has the laser cut it out for her. She didn’t want any wimpy off-the-shelf fabric store stuff. Tammy bought the newest, biggest, most powerful she could get without needing a Bond-villain license. She can etch or cut just about anything with the right settings. I’ve already explored using Autodesk 123D to build 3D dinosaurs from cardboard cutouts.

The laser took six weeks to arrive from Australia, and we assembled it ourselves. Software took almost as long to assemble and debug. We've finally reached the stage where we're able to try it out on a project.

Emily has a chain-link border pattern with 72 rings to piece together in less than two weeks. Since the links come in nine groups of eight, we thought the laser cutter would be a real time saver. I scanned the pattern into a black-and-white bitmap and isolated just the oval with cropping. I used MS Paint to clean up the noisy and rotate the two-inch oval on its side in order to pack eight into the sixteen-inch cutting area. Then I pulled the bitmap into CorelDraw ($100 to vectorize the image. The magic command is bitmap/centerline outline/line drawing. Vectors are scalable, smooth curves and lines. I wrote the result out to a PDF file. 
Serious hackers can get this converter for free by writing a centerline function for the open-source potrace program, but I decided that my time was worth a few bucks. To do the same thing in Adobe Illustrator would run you $20 a month.

Next, I pulled the vectors into the Cut2d tool. I set the workspace in the program to the size of our cutting area (in mm) and imported the oval. I replicated the image to the right, with barely any space in between the pair. I grouped the first two and replicated them, giving me four clones. After one final group and dup, I had all eight rings lined up.

Based on experience, I told the program that the laser needs to travel at a speed of no greater than 400 mm per minute to burn through all layers of fabric and heat-and-bond completely in one pass. Normally, someone would schedule two passes to avoid areas that hold on by a thread, but I don’t trust the precision yet. Then I clicked the button which transforms the vector set into a tool path, which means cutting instructions for the Emblazer. The commands are simple like: go to this XY position, turn the laser on at power level W, move the laser at speed Z, go to second XY position, and turn laser off. Even as a novice with a tight fit, the entire pattern to instructions process took less than forty-five minutes.

Tammy ironed heat-and-bond to a 4 by 16 inch piece of fabric (less than four minutes) and opened windows. Burning any material generates smoke that needs to vent outside. We also taped the fabric down to ensure precision. Air currents from the cutter head and window can move your fabric or paper otherwise.

As the last step, we employ the PicSend command to transmit all this to the cutter. There is a bit of ritual to this. We connect the USB cable to the laptop, turn on the laser, hit the laser enable button for 10 seconds until the light comes on, open the channel from the software to the device, wait for it to give you a go-ahead, send a Home command to the device, load the “oval 8” instruction file, and hit send. The eight-oval engraving takes about 10 minutes, and the cutter actually “sings” going around curves. Watch the video.
There were a few glitches, but Emily didn’t have to spend days tracing onto heat-and-bond with a maker, cutting out the shape with a buffer, ironing it to fabric, and cutting out the shapes a second time precisely. The laser seals the edges of the fabric neatly so the pieces won't fray, but we also saw a little scotching at the edges for this project.
We peeled off the resulting rings, lined up the next color of fabric, reset PicSender, and transmitted the same instructions again. The sticky residue on the base board actually helps later cuts achieve higher precision. 

Note: always keep an eye on your cutter with your tinted goggles on. That thing is bright. Trying to cut too much in too small an area (like fancy lettering under 3 mm high) will burn a big hole in your material. You also can’t let your computer go to black screen or skip any step, or you have to start the cutting process all over again.

Here is what the multi-color result looks like:

1 comment:

  1. That's going to be a beautiful quilt! : ) And such a neat gadget to help with the cutting. It would be fun to see the finished product.
    From Sharon O. in Isanti : )