Firebox Dimensions and Tunnel Template
The firebox dimensions for the stove are set at 300x300mm with walls that are 30mm thick. This ensures a compact yet efficient space for burning fuel. The tunnel template, which is crucial for directing airflow and heat distribution, is designed with a diameter of 120mm and also features walls that are 30mm thick. These dimensions are critical for maintaining the structural integrity and efficiency of the stove.
Step-by-Step Construction of Firebox and Tunnel
- Prepare the Clay Mixture: Mix 3 parts potter’s clay with 1 part sand to enhance durability and reduce cracking. This ratio is essential for achieving the right balance between strength and flexibility.
- Form the Firebox: Lay out the base of the firebox using the prepared clay mixture. Ensure the dimensions are precisely 300x300mm. Apply the clay in layers, pressing each layer firmly to eliminate air pockets.
- Construct the Tunnel: Once the firebox base is set, begin forming the tunnel. The tunnel should be centered within the firebox and extend upwards, maintaining a diameter of 120mm. The walls of the tunnel should be 30mm thick to match the firebox walls.
- Finalize the Structure: After both the firebox and tunnel are formed, allow the clay to dry partially. This semi-dry state helps in shaping the final structure without compromising its integrity.
Air Hole Specifications
The air holes in the stove are specified to be 25mm in diameter and positioned 150mm from the base. These holes are vital for regulating the airflow into the firebox, which in turn affects the efficiency and heat output of the stove.
Importance of Proper Air Holes
- Efficiency: Properly sized and positioned air holes ensure optimal combustion, reducing fuel consumption and increasing heat output.
- Control: The ability to adjust airflow through these holes allows for better control over the stove’s performance.
Quality Control Observations and Solutions
During the firing process, several issues were observed:
– Cracking at 850°C: This indicates that the clay mixture may not be sufficiently resistant to thermal stress.
– Deformation at 1100°C: This suggests that the clay may be too flexible and needs reinforcement.
Adjustments to Clay Mix and Firing Technique
- Clay Mix Adjustment: To address the issues of cracking and deformation, the clay mix was adjusted to include 12% sand. This addition enhances the clay’s strength and reduces its flexibility, making it more resistant to thermal stress.
- Firing Technique: The Sri Lanka firing technique is recommended for optimal results. This technique involves a gradual increase in temperature, allowing the clay to slowly adjust to the heat without sudden thermal shock.
Pricing Structure and Payment Terms
The base cost for each stove unit is set at $150. An additional $20 is charged for quality inspection to ensure that each stove meets the required standards before delivery. Payment terms are structured as 50% upfront and the remaining 50% upon delivery.
Practical Tips and Getting Started
- Clay Mixing: Ensure that the clay and sand are thoroughly mixed to achieve a consistent texture. This prevents uneven drying and potential cracking.
- Firing Technique: Follow the gradual heating process recommended by the Sri Lanka firing technique. This method helps in achieving a more durable and less prone-to-cracking stove.
- Quality Inspection: Conduct a ‘zinging’ sound test on the liner to check for any cracks or deformations. A solid, resonant sound indicates a well-formed liner.
Common Mistakes to Avoid
- Incorrect Clay Ratio: Using the wrong ratio of clay to sand can lead to either too brittle or too flexible a stove, both of which can fail under thermal stress.
- Rapid Firing: Firing the stove too quickly can cause sudden thermal shock, leading to cracking or deformation.
- Ignoring Quality Inspection: Skipping the quality inspection can result in delivering a stove that does not meet the required standards, potentially leading to customer dissatisfaction or returns.