# Week 03: Computer Controlled Cutting¶

The week 3 group assignment is to characterize our laser cutter’s focus, power, speed, rate, kerf, joint clearance, types, and document the work. The task of documenting the group assignment for this week was assigned to Rayan and Kalyani.

### Suresh Indu Laser (AccuCut 1325)¶

The SIL laser engraving machine is versatile and finds application in signage, indoor and outdoor advertising, art and craft, gifts, shoes, toys, garments, model cutting, papers and packaging, the wood and MDF cutting industry, interiors, decorators, and many more. SIL-built laser engraver, which is engineered and manufactured in India. SIL laser systems can be configured with two types of lasers: glass tubes and metal tubes.

### Kerf of the laser cutter¶

Laser cutting is a kind of burning process. Thus, when a material is burned, it melts and shrinks, causing a material loss effect on the cutting material. The outcome will be impacted by this phenomenon. Therefore, we need to make adjustments to the design’s loose measures, or what’s known as the kerf.

• LaserCAD is the software used to operate this laser machine (Suresh Indu Laser).
• Open laserCAD from file open the desired file in DXF.
• From Layer Properties Select the outline colour to cut and select the work mode as cut”. In our case, we chose “red”.

• Double-click the “cut” from the “layer option” and set the power and speed.

• The photo below depicts the thickness, power, speed, and kerf of cardboard, birch wood, and acrylic.

• Measure L1 and L2 for cardboard, wood, and acrylic using a digital vernier calliper.
• Kerf = (L1-L2)/2
• The photos below show the measurements of the outer square’s inner length and the inside square’s outer length of cardboard, wood, and acrylic.

• 3.16 mm Cardboard

Total kerf = 20.51 - 19.84 =0.67 mm

Kerf= 0.67/2 = 0.33 mm

• 3.69 mm Birch Wood

Total kerf = 20.64 - 19.57 =1.07 mm

Kerf= 1.07/2 = 0.53 mm

• 5.35 mm clear Acrylic

Total kerf = 20.37 - 19.64 =0.73 mm

Kerf= 0.73/2 = 0.36 mm

• The material, power, velocity, and laser machine will all affect the kerf value. Each material has a varied cutting power based on the materials listed below.

Cutting and Kerf Details

Material Cardboard Birch Wood Acrylic
Thickness 3.16 mm 3.69 mm 5.35 mm
Power 90% 90% 90%
Speed 40 mm/s 7 mm/s 5 mm/s
Kerf 0.33 mm 0.53 mm 0.36 mm

### Press Fit Test¶

• Understanding the press fit tolerances of each material is helpful for creating high-quality laser joins. We created a test comb in Fusion 360 to verify it, and used Suresh Indu laser cutter to cut it out.
• The scale has slots with slot widths ranging from 5.5mm to 6.5mm, and then we exported the dxf file to Inkscape for cutting.
• The below image was taken during the laser cutting process.

• The below image was taken just after the laser cutting process.

• Once the laser cutter completed cutting the comb, we used a red permanent marker to highlight the markings on the kerf scale.

• The below photos depict the measurements of the slot and the acrylic sheet using a digital vernier caliper.

• After laser cutting, we got a perfect fit of 5.7 mm acrylic sheet in the 5.5 mm slot.

• The thickness of the acrylic sheet was around 5.7 mm, and we got a perfect fit in the 5.5 mm slot.
• Power= 100 %
• Velocity= 10 mm/s
• Therefore,

Kerf = (5.7 mm - 5.5 mm) = 0.2 mm

Joint Clearance = (kerf/2) = 0.1 mm