# 3. Computer Controlled Cutting¶

This week was spent learning some of the intricacies in using a laser cutter.

## Group Assignment¶

Working as a group, me and the other fab academy students here (Cristopher Proute and Terrence Carew) investigated the settings for our laser cutter (Epilog Helix-40W). Through multiple trials, we determined the power and speed setting that achieved a clean cut for the cardboard with a minimum of scorching along the cut lines. We also investigated the kerf of the cut using this material and these settings. Details here.

## Individual assignment¶

This week’s activity was to design and cut an object in our laser cutter with interlocking parametric pieces, so that we can construct a 3 dimensional object out of the pieces. And to account for the kerf in our cut so that the pieces fit together tightly.

We used cardboard as our build material simply because it is cheap and easy to cut. Although cardboard is more flexible than other materials that we might use (plywood or acrylic sheets), the same principals apply.

However, using cardboard means that:

• If we make the slot side of our joints slightly too small, our joint parts can still fit together. This simply because the insert section of the joint can compress slightly when going into the joint.

• If we make the slot perfect, the joint can still end up slack. This again is because of the cardboard compressing slightly when being manipulated. This compression can affect both the width of the slot (expanding it) and insert (shrinking it), resulting in a looser fit than a harder material would give.

• Orientation maters. The corrugation of the cardboard has a directional and varying component, the exact placement of the actual laser cuts relative to the corrugation can result in a changes in how much the material compresses. This is especially true for smaller components and joint.

## Design:¶

• I made a simple design of a symmetrical Xmas tree using a few equivalences to achieve a uniform shape that I liked. I then duplicated (copy and paste) the drawing side by side with it so that I had 2 trees.

• I then created 1 gap down the centre of each tree, hallway down the length. One tree top to middle, the other bottom to middle. I set the width of the gap as a parameter for easy editing if changes needed to made (for different thickness cardboard, or if error were made in our kerf calculations).

• The dimension of the gap parameter was then set to (cardboard thickness – [kerf*2]). This should give us a tight fit in our laser cut joints. I also put a small chamfer on either entrance to each slot (hard to see in images)

• I then made a design of a smaller triangular piece and placed the same dimensioned gap at the top of it, half way down. I also created a gap on the Xmas tree pieces where this gap would fit (4 gaps total, 2 per tree piece). I made 6 copies of this small piece (an extra 2 for good measure). (all these slots were also chamfered)

• The CAD file: Xmas Tree Fusion 360

## Cut and Construction:¶

• I outputted the final drawing to an DXF format, imported the drawing into CorelDraw on the computer attached to the laser cutter (a separate computer was used for designing and cutting), and then “printed” the job to the laser cutter.

• Then remove the individual parts from final cut sheet.

## Vinyl cutting:¶

• I used a vinyl cutter (Roland Camm-1) to create a very simple piece of decoration for my laser cut tree.

• It was a very simple star design with a smaller star inside.

• The design was made in Inkscape, then imported into Cut Studio and “printed” onto the vinyl.

Simple svg file: tree ornaments SVG

• Then stuck on the tree.

The most interesting part of this week’s lesson was learning about the various types of joint possibilities that can be used. Although I used the most basic joint for this project (chamfer), I look forward to trying some of them out when I make more complex designs

Last update: August 9, 2023