Exercise 3 - Computer-controlled cutting

Requirement

  1. Design, make, and document a parametric press-fit construction kit.
  2. Cut something on the vinyl cutter.

What is parametric in design?

Parametric originates from mathematics (parametric equation) and refers to the use of certain parameters or variables that can be edited to manipulate or alter the end result. In our case, alter the design dimension base on changes.

Understanding Kerf.

Before going into the laser machine to cut out the press-fit kit, we need to find out about Kerf. Kerf in short is how much material the laser cutter burns away when cutting specific materials. For better understanding of Kerf, can visit Ponoko for a much detail write-up.

Fablab@SP is equipped with a few different laser cutters. So this week, I decided to experiment with Universal laser (VLS 660): to find out the Kerf with preset setting. VLS 660 is a 60w laser cutter with a cutting table of est 800mm x 450mm.

The Preset setting contain information on how much "Power": strength of laser, "Speed": how fast the laser head move, "PPI" refer to pulses per inch and "Z-axis": for material thickness.

Setting for laser machine is like using a pen-knife, strength = how hard to press the knife, speed = how fast to move the knife and setting will varies from different materials and different thickness. With the above concept, after some trial and error with the setting on different materials, we came up with those few predefine setting.

By adjusting the Power, Speed, PPI and Z-axis for each colour used to get the optimal cut through setting.

Save predefine setting for paper, wood and acrylic.


Adobe Illustrator (AI), AutoCad and CorelDraw are some of the software use to communicate between the laser cutter and user design. As I am more familiar AI, I come up with a simple finger joint to test out Kerk of this laser cutter.

  1. Using the Rectangle tool to create the simple finger joint to test the Kerf of laser machine.
  2. Trial and error by varying the length slightly.
  3. By using the alignment tool to arrange all the rectangle properly.

  1. Using Pathfinder to unite and cut out the required shape.

  1. Instead of buying material to test Kerf, will be using left over plywood to cut out the test cut pieces.
  2. Test with 20mm, joint too loose, pieces fall apart easily.
  3. Test with 19mm, joint too small and finger joint can't go in.
  4. Conclusion, need to test within 19mm to 20mm. Back to drawing board.

New measurement: 19.9mm, 19.8mm, 19.7mm and 19.6mm

  1. Using back the original joint to test fit new dimension.
  2. Test with 19.9mm, joint is still loose, pieces fall apart easily.
  3. Test with 19.8mm, joint is still loose, pieces fall apart easily.
  4. Test with 19.7mm, joint is quite fit, but pieces still can move abit.
  5. Test with 19.6mm, joint is tight fit.
  6. Conclusion, Kerf for this laser cutter is about 0.4mm, with Power: 40%, Speed: 8% and PPI: 200

Adobe Illustrator Kerf test file.

Using the Laser cutter for press-fit construction kit.

After I found out the Kerf for the laser cutter. I design a press-fit box using Fusion 360 which equipped with parametric design: where user can define and make change to thickness, length, width, Kerf and finger length as and when needed.

  1. Open Fusion 360, go to Modify --> Change parameters, this is where user can define all the paramatics parameters.
  2. Since only 2D design is needed, click on Sketch to create the 2D drawing.
  3. Using Rectangles, Trim and with the help of Dimension, can define all the lines with the the paramatics measurement.
  4. When done, user can export/ save the Sketch as dxf for laser cut.
  5. Test cut using laser cutter with same setting.
  6. Conclusion, as and when there is change to the dimension, thickness or Kerf, user just need to make adjustment in the Change Parameters Setting.

Layout construction kit with Kerf.

Testing of Construction kit.

Press-Fit construction kit

Instead of just making a box or dice, I wanted something fun and interesting. So after surfing the web for some ideas, I come with the following press-fit kit.

I am using Fusion 360 to design the kit, with the help of parametric function I am able to adjust the size as and when there are change.

Some basic shape for my press fit construction kit.

Using corrugated cardboard 6.55mm, (Power: 30%, Speed: 10%, PPI: 200) basic shape cut out using laser cutter.

Using 1 simple shape, able to create different form.

With all the shapes, form is only limited by one's imagination and creatively. Some design done by my children.

Laser cut process

The laser machine (Universal laser system) is configure to work with Adobe Illustrator (AI), so user only need to make their design in AI and print (ctrl + p) to the laser machine. We have also predefine some setting for some common material, user will then load using the predefine setting for different material before cutting

  1. Make design in AI
  2. Print design over to laser machine (ctrl + p)
  3. Load predefine setting according to material or set your on setting in laser control panel
  4. Place and align material into machine
  5. Start laser cutting, remove all material from cutting table after done

Points to take note:

  1. Laser cutter like a color printer operate on consumables (toner) in this case Carbon Dioxide (CO2) tube. So Setting might varies over time depending on usage.
  2. Different materials require different setting.
  3. Materials must be laid flat, for best result.

Links for the above file.

  1. Kerf Design in AI.
  2. Test fit box in AI.
  3. Corrugated cardboard shape in AI.
  4. Test fit box in Fusion 360.
  5. Corrugated cardboard shape in Fusion 360.

Vinyl cutting

In our FabLab and MakerSpace (located in the library), they are equipped with Silhouette Cameo- a digital cutter which is able to do vinyl cutting.

Silhouette Cameo also comes with a free software - Silhouette Studio® which is able to work in both windows and Mac, and now there is even a mobile version for IOS, Android, Windows and Kindle.

Silhouette Studio is an easy and user friendly software where it provide shapes, lines, text where user can work on it, or user can import images (jpg), trace it then send for cutting.

  1. Silhouette Cameo is light and portable.
  2. Machine is equipped with tool to adjust the cutting tool.
  3. Setting cutting tool to predefine setting.
  4. Aligning material along the indicator line
  5. Touch Screen control, to load cut mat.

  1. Silhouette Studio start up interface.Design: User input design, Store: online store image (purchase and free), open: existing project and library: stored images in cloud.
  2. Click on design, and a predefine cutting mat is shown.
  3. Either by using tools to design your artwork or load your desire image from the file menu.

  1. By using the trace tool, image outline can be trace out.
  2. First, Select trace area require, then unchecked High Pass Filter, adjusting the threshold and Scale level to archive a sharp outline for your image.
  3. When desire, click on apply Trace Method-->Trace.
  4. Result outline and image separated.

  1. The package come with predefine setting for different material type, select the require material and adjust the cutting tool.

Final out come, pasting the cut-out on laptop cover.

Using transfer tape to paste complicated design to target


Points to take note:

  1. Cutting is easy. But if your design is complicated, pasting it will be a challenge, unless you have transfer tape.
  2. Cut setting will varies, depending on usage due to wear and tear.

Links for the above file.

  1. Venom picture.
  2. Silhouette Studio outline.

My thoughts

With the help of technology, machine like Laser cutter and vinyl cutter can replace lots of manual cutting using pen knife, but one still need to master the software first else the machine useless.

References:

  1. Ponoko
  2. Universal Laser
  3. Silhouette Cameo


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