Week 03

Lab Safety Training

General Lab Safety

Safety is the top priority in any lab environment. Before operating any machine or handling materials, it is crucial to understand and follow the necessary precautions. The lab contains high-powered equipment, sharp tools, chemical substances, and pressurized systems that can pose risks if not used properly.

The following are the safety steps to be followed in the lab:

To minimize hazards, always wear appropriate personal protective equipment , such as safety glasses, gloves, and closed-toe shoes.

All the students are provided with personal gloves and masks to ensure safety. Loose clothing and jewelry should be avoided, and long hair must be tied back to prevent entanglement in machinery.

It is essential to maintain a clean and organized workspace. Cluttered areas increase the risk of accidents and hinder efficient workflow.

Fire Extinguisher

Before using any equipment, ensure it is in proper working condition, and report any malfunctions immediately.

Emergency stops, fire extinguishers, first-aid kits, and eyewash stations should be easily accessible, and all users must be familiar with their locations.

The location of the fire extinguisher, emergency exit and floor plan was also introduced.

CO2 Laser Cutter Safety

The CO2 laser cutter is a powerful tool used for cutting and engraving various materials. Due to the high-intensity laser beam, there is a risk of fire, eye injury, and toxic fume exposure.

Exhaust System

The exhaust filtration system in the laser cutter is designed to extract and filter fumes generated during the cutting process. As the laser vaporizes material, the system pulls the smoke and airborne particles through a series of filters. One of the key components is activated charcoal, which helps absorb harmful gases and odors by trapping volatile organic compounds (VOCs) released from materials like wood, acrylic, and plastics. This ensures that the air expelled is cleaner and reduces exposure to toxic fumes, improving both safety and air quality in the lab.

Before using the machine, verify that the exhaust system is active to remove smoke and gases generated during the cutting process. The laser must be correctly focused for precise cutting, and the material should be securely placed to prevent movement during operation.

The temperature of the room should be maintained low for safe machine operating temperature.

Certain materials, such as PVC and ABS, should never be cut with the laser cutter as they release hazardous fumes. It is crucial to monitor the machine while it is in operation to prevent fires, which can occur if the laser remains focused on a single point for too long. In case of a fire, the machine should be paused immediately while keeping the lid closed.

A CO2 fire extinguisher should be used if necessary. Once the cutting process is complete, wait for all fumes to clear before opening the lid, remove any debris from the cutting bed, and ensure the machine is turned off properly.

What to Do If a Fire Starts in the Laser Cutter:

1. Do Not Open the Machine Lid Immediately – Opening the lid can introduce more oxygen, potentially making the fire worse.
2. Pause the Laser Cutter – If safe to do so, immediately stop the machine to cut off the laser source.
3. Suppress the Fire with an Extra Material – If a small flame starts, place a larger non-flammable material (like another sheet of the same material) over the burning piece to cut off its oxygen supply.
4. Monitor the Situation – If the fire does not go out quickly, prepare to take further action.
5. Use a CO2 Fire Extinguisher if Necessary – If the fire spreads or becomes uncontrollable, use a CO2 extinguisher to put it out. Avoid using water, as it can damage electrical components.
6. Call for Help if Needed – If the fire cannot be controlled, evacuate the lab and call for emergency assistance.

Vinyl Cutter Safety

The vinyl cutter is a precision machine that requires careful handling to avoid injury and material waste. Before using the machine, the cutting blade should be properly installed and adjusted to the correct depth. The vinyl sheet must be aligned correctly to prevent misfeeding and ensure an accurate cut.

While the machine is in operation, hands should be kept away from the moving blade and rollers. If a material jam occurs, the machine should be paused before attempting to clear the obstruction. Once the cutting process is finished, excess material should be carefully removed using a weeding tool, and the machine should be cleaned to avoid residue buildup.

Sandblasting Machine Safety

The sandblasting machine uses pressurized abrasive media to clean or texture surfaces. This process can generate a significant amount of dust and flying debris, making protective gear essential. Safety goggles, gloves, and a dust mask must be worn at all times to prevent eye and respiratory hazards. The machine’s cabinet should be fully sealed before operation to contain the blasting media.

During operation, the nozzle should never be directed at oneself or others. Only approved media, such as glass beads or aluminum oxide, should be used to avoid health hazards. After completing a sandblasting task, users should wait for the dust to settle before opening the cabinet. The work area must be cleaned thoroughly, and excess abrasive material should be properly disposed of.

Chemicals Area Safety

Handling chemicals requires strict safety measures to prevent burns, poisoning, and inhalation risks. Protective gear, including gloves, safety goggles, and a lab coat, must be worn at all times. Working in a well-ventilated area or under a fume hood is necessary when dealing with volatile substances.

All chemicals must be clearly labeled and stored correctly. Flammable substances should be kept away from heat sources, and acids, bases, and solvents must be stored separately to prevent dangerous reactions. Before using any chemical, users should read the Material Safety Data Sheet to understand its hazards and proper handling procedures.

In the event of a spill, absorbent materials should be used for cleanup, and large spills should be reported immediately. If chemicals come into contact with the skin or eyes, the affected area should be washed with running water for at least fifteen minutes. In cases of inhalation exposure, the individual should be moved to fresh air, and medical attention should be sought if necessary.

Conclusion

Adhering to lab safety guidelines is essential for preventing accidents and ensuring smooth operations. Proper use of equipment, personal protective measures, and awareness of emergency procedures help create a secure environment for all users. By following these safety protocols, individuals can maximize efficiency while minimizing risks in the lab.

Laser cutting

Laser cutting is a material removal process that involves heating and cutting a part along a predefined trajectory. This heating is achieved by directing a high-energy, finely focused light beam vertically onto a sheet or plate of material. The laser moves along the X and Y axes of the machine bed, cutting the material into a two-dimensional profile. This process follows a precise pattern dictated by computer-generated instructions, known as G-code, which control the movement and cutting path. . The most commonly used lasers in this process are CO₂ and solid-state lasers. The choice of laser type significantly affects both the machine’s configuration and the overall cutting process.

https://doi.org/10.1533/9780857094940.335

Laser cutter

CO2 Laser

A CO₂ laser cutter, also known as a carbon dioxide laser, differs from other CNC laser cutting systems in how it generates and directs the laser beam. It produces high-intensity infrared light by exciting a gas mixture containing carbon dioxide with an electric current. The continuous infrared laser beam, is then guided and focused onto the workpiece using a series of mirrors and lenses.

Fiber Laser

A fiber laser is a solid-state laser that generates a concentrated beam by guiding light through a doped optical fiber. A pump laser diode excites electrons in the fiber, causing them to release photons as they return to their original state. These photons are amplified and reflected by Fiber Bragg Gratings within the fiber core, creating a powerful and precise laser beam.

Power

In laser cutting, power refers to the amount of energy the laser beam delivers to the material, typically measured in watts . It directly affects cutting depth, speed, and quality—higher power enables cutting thicker materials at slower speeds, while lower power is used for thinner materials and finer details to minimize burning or damage.

Speed

The speed of a laser cutter refers to how fast the laser head moves across the material during the cutting process, typically measured in millimeters per second . The cutting speed affects the quality and efficiency of the cut—faster speeds are used for thinner materials or less detailed cuts, while slower speeds are needed for thicker materials or more precise, intricate cuts.

Focus

In laser cutting, focus refers to the precise point where the laser beam converges to its smallest diameter, achieving maximum energy density. This is crucial for effective cutting, engraving, or marking.

Rate

Pulse rate refers to the number of laser pulses emitted per second, measured in Hertz . A higher pulse rate results in smoother cuts but can generate excess heat, affecting material quality. Lower pulse rates deliver more energy per pulse, making them ideal for deeper cuts with less heat buildup.

Kerf

Kerf is the width of material removed by the laser during the cutting process. It results from the laser beam melting, burning, or vaporizing a small portion of the material. Adjusting for kerf is important to ensure accurate dimensions and a proper fit in laser-cut designs.

Trotec Speedy 400 Flexx

Our lab is equipped with the Trotec Speedy 400 flexx laser cutter, which includes a fume extraction system and features dual laser sources—a CO₂ laser and a fiber laser. This machine utilizes Trotec’s patented flexx technology, allowing seamless and automatic switching between the two laser types within a single job.

The CO₂ laser is ideal for engraving and cutting materials such as wood, plastics, leather, and rubber, while the fiber laser specializes in marking metals.

Trotec Speedy 400 flexx with Fume extractor and filter.

Specifications

Work Area	1016x610mm
Max Workpiece Height	305mm
Laser Power - CO2	60-120W
Laser Power - Fiber	20-50W

Control Panel

Controls

Although the machine is equipped with an autofocus feature, there are instances where manual focusing is required. This tool is specifically used to manually adjust the focus when needed.

Setting the Machine

To power on the laser cutter, turn the key switch clockwise and wait for the initialization process to complete. Initially, the lights will turn on, followed by Z-axis calibration, where the Z-axis moves slightly downward before returning upward. Next, the X and Y axes are calibrated, during which the laser head moves to the top-left position, accompanied by an audible signal tone.

After initialization, manually turn on the fume extractor and filter, then check the activated charcoal percentage. If the charcoal level is sufficient, the laser cutter is ready for operation.

To find Thickness

Using the vernier caliper, we take multiple measurements of the thickness of the material.

https://www.notion.so

To make sure you get accurate measurements, once you release the jaws they should not allow free movement easily. Make sure to tighten the vernier enough to avoid errors in measuring

Thickness of cardboard

Reading 1	T1	3.24
Reading 2	T2	3.22
Reading 3	T3	3.31
Average Thickness	Tavg	3.25

Average thickness of cardboard, Tavg = 3.25 mm

To find Kerf

Operating the laser cutter

• The ambient temperature should be set to between +15 °C to +25 °C before the machine is turned on.
• Switch on the nearest exhaust vent before operating the machine. The vent should only be switched off 15-20 minutes after the laser cutter is switched off.
• Once done with creating the vector image, switch on the machine.
• These are the controls of the machine

• When the machine is turned on, it will take some time to calibrate.

• Once calibration is done, we open the lid to place the material to be cut at the edge and/or corner of the cutting bed

  

• Move the laser head away from the corner and edges before autofocusing. In case autofocus is not possible, we use the key to set the focus manually.

• Once autofocusing is done we move the laser head to the point at which to start the cut, making sure that we waste as less material as possible when doing so. The laser cutter machine is now ready

Drawing the vector image in Inkscape

We used Inkscape to make two squares to test cutting operation and added text to test the engraving operation. We used the shortcut command Ctrl+ R To resize the canvas to only include the outer boundary.

Press Ctrl + P to send print command to the laser cutter, then select Trotec Engraver for laser cutting and click ‘Print’.

Once done, the software for the laser cutter TROTEC JobControl will automatically open.

We adjust the parameters, setting an operation for each control. Here we have set black colour for engraving process and red for cutting. Once we have set the required parameters for the material we have chosen we press the ‘Play’ icon to begin cutting.

Calculating the kerf

• Once the cut is made we use vernier calipers to measure the inner length of square and the outer length of the square and subtract them to get the kerf value.

To calculate Kerf

Total Gap Width = 20.11-19.86 = 0.25 mm

Total Gap Width is made by cuts made by two laser beams

So , Kerf = Total Gap/2 = 0.25/2 = 0.125 mm

Kerf of Cardboard material is 0.125 mm

We repeat these steps for cardboard, wood, & acrylic. Here are the results.

Material	Kerf	Thickness
Cardboard	0.23	3.25
Wood	0.245	3.72
Acrylic	0.125	2.82

Types Of Joints

REFERED A VEDIO TO UNDERSTAND ABOUT DIFFERENT JOINTS A basic guide to laser cut joints.

Laser cutting offers a variety of joint types that you can use for assembling parts.

The key to successful laser-cut joints lies in understanding proper clearance - the gap between mating parts that ensures they fit together correctly. This clearance typically ranges from 0.1mm to 0.3mm depending on material thickness and type. Getting the right clearance is crucial as too tight a fit can cause material cracking, while too loose a fit won’t provide adequate structural integrity.

Basic Joints

1. Finger Joints

• Interlocking “fingers” provide strong connections
• Ideal for wood and acrylic materials
• Require precise clearance for a snug fit

2. Edge Half Lap Joints

• Overlap material edges for robust connections
• Particularly effective in softer materials like wood
• Provide good structural integrity

3. Butt Joints

• Simplest joint type where two edges meet directly
• Requires reinforcement for strength
• Not recommended for load-bearing applications

Mechanical Joints Without Fasteners

4. Interlocking Joints

• Connect edges without adhesives or fasteners
• Ideal for flexible materials
• Can handle curved surfaces well

5. Loop Insert Joints

• Create disassemble connections
• Perfect for integrating fabric edges with rigid materials
• Offers a clean, stitch-less finish

6. Slot Hook Joints

• Involve slots and hooks that slide together
• Require careful design for proper alignment
• Beneficial for easy assembly/disassembly

Joints with Fasteners

7. Captive Nut Joints

• Use bolts and nuts held in place by the laser-cut material
• Prevent nuts from spinning during assembly
• Similar to cam lock fasteners in furniture

8. Screw Joints

• Quick and reliable
• Popular for many projects
• May lead to stripped holes with repeated use

9. Tapped Bolt Joints

• Involve threading the material to fit a bolt
• Provide durable connections
• May wear out with frequent use

10. Threaded Inserts

• More complex to install but long-lasting
• Ideal for frequent disassembly/reassembly
• Ensure secure fit every time

Compliant Joints and Mechanisms

11. Living Hinges

• Utilize material flexibility to create bendable connections
• Often used in packaging and folding designs

12. Snap-fit Joints

• Employ material elasticity for assembly
• Can be designed for specific angles or positions

Advanced Joints

13. Dovetail Joints

• Complex but adaptable for laser cutting
• Use etched lines as guides for manual adjustments
• Add distinctive appearance to wood and acrylic projects

14. Hammer Joints

• Use wedges to secure pieces without adhesives
• Effective for materials like wood
• Can be enhanced with glue for added strength

REFERENCES Methods for Joining Laser Cut Parts - MFG Shop

Parametric Modeling in Fusion360

Parametric design in Fusion 360 is a modeling approach where dimensions and features are controlled by parameters, allowing for easy modifications and adaptability. Instead of using fixed values, users define variables that drive the model, ensuring automatic updates when changes are made. By using constraints, formulas, and feature-based modeling, parametric design enables scalable and consistent designs, making it ideal for engineering, 3D printing, and product development. The Modify → Change Parameters tool allows users to manage and edit these values efficiently. This approach enhances automation, improves design consistency, and enables quick iterations without manually adjusting every feature.

Creating a Jig using Parametric Design and Laser cutting

Our idea was to create a jig for finding a offset value for a tight fit while making a parametric construction kit

1. we made a rough sketch . We also wanted to add a visual representation of how different power levels of the laser beam effect the engraving process.

   

2. From the calculated values of the kerf and the measured values of the material set the parameter values for length, slot length, slot gap, Jig width, slot width etc. It will be easier to make a parameter for all possible values since the design has to be changed depending on the kerf and thickness of the material. If parametric design is not used a new design has to be made for each material which will be time consuming

   

3. When giving dimensions select the name of the pre defined parameters and add any operations like add, subtract, multiply etc.

   

4. After giving all the constrains like parallel, collinear etc. so that when changing the parameter values the sketch get updated correctly

   

5. Then extrude a give the value as the Material_Thickess parameter

   

6. Then export the DWG from fusion360 and import it into Inkscape

7. Then add the text and other elements using Inkscape
8. After importing to Inkscape make the scale correct by taking one dimension from cad drawing
9. Also add different colors depending on different cutting parameters needed for each element

10. Save this file so that it can be used like a template Depending on the updated sketch for each material from cad only replace the the stroke part of the design so that all the other elements remains the same.

    

11. Then import this into TROTEC JobControl and set the parameter values for each color.

12. The machine cuts each elements depending on the order from this table.

    Note : Since the using 100% of the power is not recemented in case of all the machines for the color that is assigned for the 100% power we reduce the velocity to get a deeper engraving.

    

13. This is the final output for acrylic.

    

14. Then we repeated the same process for wood and cardboard, change the parameters an import as DWG file import it into Inkscape remember to change the color of the imported sketch to red, The standard color for cutting is red an for engraving is black
    Note : Remember to change the material and thickness in TROTEC JobControl Wile cutting different material.

    

15. After this we found the values of the compression value for each material by testing and made a table that can be referred for making the parametric construction kit.

Conclusion`

Our group had a great learning experience, starting with lab safety and learning to operate the laser cutter. We understood how to calculate kerf values and apply them in CAD modeling for better accuracy. Parametric design helped us create adaptable models, and we put this into practice by making a fitment testing jig. By designing three jigs with different materials, we learned how to adjust parameters for various materials. This hands-on experience improved our technical skills and problem-solving abilities.

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Last update: February 21, 2025