Cutting Torch How To Use

Selecting the Right Cutting Torch

Gas Type

The choice of gas depends on the desired cutting speed, workpiece thickness, and edge quality. Oxygen is the most common gas used for cutting, providing high cutting speeds but a rougher edge. Other gases like acetylene, propane, and hydrogen offer slower but cleaner cuts.

Preheating Intensity

Preheating is necessary to raise the workpiece temperature before cutting. The intensity of preheating determines the ease and speed of cutting. Torches with high preheat intensities can cut thicker materials faster, but require more fuel consumption and may lead to workpiece distortion.

Oxygen Pressure

Oxygen pressure influences the cutting speed and kerf width. Higher pressure results in faster cutting but may cause excessive melt removal, leading to a wider kerf and reduced edge quality. Lower pressure provides a narrower kerf and better edge finish, but slows down the cutting process.

Cutting Nozzle Size

The nozzle size affects the preheat flame size and oxygen flow rate. Larger nozzles provide wider preheat flames and higher oxygen flow, suitable for cutting thicker materials. Smaller nozzles produce more focused preheat flames and slower oxygen flow, ideal for cutting thin materials with precision.

Tip Design

Cutting tips come in various designs, such as straight, angled, and multi-hole tips. Straight tips are suitable for basic cutting operations, while angled tips allow access to tight spaces. Multi-hole tips provide multiple cutting orifices, increasing cutting speed and reducing kerf width.

Preparing the Cutting Area

Before you start cutting, it’s important to prepare the work area properly. Here are the steps you need to follow:

1. Clear the Work Area

Remove any flammable materials, such as paper, rags, or solvents, from the work area. Make sure the area is well-ventilated to prevent the accumulation of fumes.

2. Secure the Workpiece

Clamp or otherwise secure the workpiece to a stable surface. This will prevent it from moving or vibrating during the cutting process, ensuring a clean and precise cut. It’s especially important to secure large or heavy workpieces.

3. Check the Equipment

Inspect the cutting torch and hoses for any damage or leaks. Make sure the oxygen and fuel tanks are properly connected and the valves are closed. Always wear appropriate safety gear, including gloves, safety glasses, and a respirator.

4. Identify the Cut Line

Mark the cut line on the workpiece using a straight edge or a template. This will help you follow a straight path during the cutting process.

Managing the Cutting Torch Flame

Choosing the Correct Flame

The type of cutting torch flame used depends on the thickness and type of metal being cut. A neutral flame, with equal amounts of oxygen and acetylene, is suitable for most metals and thicknesses. A slightly oxidizing flame, with a small excess of oxygen, is better for cutting thicker metals.

Adjusting the Oxygen-Acetylene Ratio

The oxygen-acetylene ratio is crucial for a clean, efficient cut. Too much oxygen will result in excessive oxidation and a rough cut, while too little oxygen will produce a flame that is too reducing, leaving a sooty deposit on the cut surface. The ideal ratio is typically between 1:1 and 1.25:1 (oxygen to acetylene).

Controlling the Torch Angle

The angle at which the torch is held relative to the metal surface affects the quality of the cut. For most metals, a 90-degree angle is ideal, as it allows the cutting jet to penetrate the metal cleanly without excessive slag formation. However, for thinner metals, a slightly higher angle may be used to minimize penetration.

Manipulating the Cutting Speed

The cutting speed should be adjusted to suit the thickness of the metal and the desired quality of the cut. For thin metals, a faster speed is appropriate, while thicker metals require a slower speed. Cutting too fast can result in excessive spatter and an uneven cut, while cutting too slowly can overheat the metal and cause warping.

Metal Thickness	Oxygen-Acetylene Ratio	Torch Angle	Cutting Speed
1/8 inch (3 mm)	1:1	90 degrees	4-6 inches per minute
1/4 inch (6 mm)	1.2:1	90 degrees	3-4 inches per minute
1/2 inch (12 mm)	1.3:1	90 degrees	2-3 inches per minute

Cutting Straight Lines

Cutting straight lines with a cutting torch requires precision and steady hands. Here’s how to achieve clean, accurate cuts:

Secure your workpiece firmly to a cutting table or a vice to prevent it from moving during the cut.
Position the torch perpendicular to the workpiece surface, ensuring a 90-degree cutting angle.
Start the torch and preheat the metal along the cut line by moving the torch back and forth.
Pierce the metal at one end of the cut line and slowly move the torch along the desired path.
Maintain a consistent speed and a slightly forward-tilted angle to prevent slag buildup.
Precision Cutting with a Straight Edge or Guide

For increased accuracy, use a straight edge or guide to follow along the cut line:

Clamp a straight edge or guide parallel to the cut line and close to the edge of the workpiece.
Align the torch tip with the straight edge and use it as a guide while cutting.
Slide the torch along the straight edge, keeping it parallel to the workpiece surface.

Remember to wear appropriate safety gear, including gloves, eye protection, and a welding mask, while operating a cutting torch.

Safety Tips	Cutting Torch Operation
Wear proper safety gear	Start by preheating the metal to start the cut
Position the torch perpendicular to the workpiece	Maintain a consistent speed and a slightly forward-tilted angle

Cutting Curves and Irregular Shapes

Cutting curves and irregular shapes with a cutting torch requires more skill and control than straight cuts. Here are some additional tips:

1. Trace the Shape Accurately:

Before cutting, use a template or draw the shape on the metal with a soapstone marker. Trace the lines carefully to ensure a precise cut.

2. Adjust the Torch Angle:

For curves, hold the torch at an oblique angle to the metal’s surface. This allows the torch to follow the curvature smoothly.

3. Control the Torch Speed:

When cutting curves, move the torch slowly and steadily, avoiding sudden movements that could cause irregularities.

4. Use Multiple Passes:

For thicker metal or sharp curves, divide the cut into multiple passes. This prevents overheating and ensures a clean, accurate cut.

5. Use a Jig or Template:

For complex shapes, consider using a jig or template to guide the torch and maintain consistency.

6. Practice on Scrap Metal:

Before cutting actual pieces, practice on scrap metal to develop your technique and gain confidence.

7. Advanced Techniques:

Technique	Description
Beveling	Angling the cut to create a sloped edge for welding or aesthetics.
Gouging	Using the torch to remove metal from a surface, creating a groove or cavity.
Piercing	Creating a hole in the metal by piercing through the surface with the torch flame.
Back Cutting	Cutting from the back of the metal, creating a clean and precise edge on the front side.
Burning in Place	Using the torch to cut out a piece of metal without removing it from the surrounding material.

Cleaning and Maintaining the Cutting Torch

Cleaning the Cutting Torch Nozzle

To start, you’ll need to remove the nozzle from the torch head. Once it’s removed, use a wire brush to clean out any debris or metal shavings that may have accumulated inside.

Next, soak the nozzle in a cleaning solution specifically designed for cutting torches. Follow the manufacturer’s instructions for the soaking time.

After soaking, rinse the nozzle thoroughly with clean water. Use a soft cloth or compressed air to gently dry the nozzle before reassembling it.

Lubricating the Cutting Torch

Regular lubrication of the cutting torch is essential to ensure its smooth operation and prevent premature wear.

To lubricate the torch, apply a few drops of high-temperature lubricant to the friction points, such as the joints, valves, and levers. Consult the manufacturer’s recommendations for the specific lubricant to use.

Inspecting the Cutting Torch Hoses

Inspect the cutting torch hoses regularly for any signs of damage, such as cracks, leaks, or bulges. Damaged hoses can pose a safety hazard and should be replaced immediately.

To inspect the hoses, visually examine them along their entire length, paying attention to the ends and connections. If any damage is found, replace the hoses with new ones of the same type and size.

Storing the Cutting Torch

When not in use, store the cutting torch in a dry, well-ventilated area away from flammable materials.

Cover the torch head with a protective cap to prevent debris and moisture from entering. Additionally, store the torch on a stable surface to prevent it from falling and causing damage.

Remember, proper care and maintenance of your cutting torch will extend its lifespan and ensure safe and efficient operation.

Troubleshooting Common Cutting Torch Issues

1. The torch is not igniting.

Ensure the torch is properly connected to the gas supply and that the gas valves are open. Check the spark plug and replace it if necessary. Clean the tip of the torch and remove any debris that may be obstructing the flame.

2. The flame is too small or weak.

Increase the gas flow rate or check the regulator for proper operation. Make sure the torch tip is the correct size for the application.

3. The flame is too large or erratic.

Reduce the gas flow rate or check the regulator for proper operation. Ensure the torch tip is clean and not clogged.

4. The torch is backfiring.

Close the fuel valve and then open it slowly. Adjust the gas mixture to achieve a stable flame.

5. The torch is leaking gas.

Check all connections and tighten any loose fittings. Inspect the hoses for cracks or damage and replace them if necessary.

6. The torch is cutting unevenly.

Ensure the torch is held perpendicular to the workpiece. Adjust the cutting speed and gas flow rate as needed.

7. The torch is producing excessive slag.

Decrease the cutting speed or increase the gas flow rate. Use a slag remover to clean the workpiece.

8. The torch is overheating.

Allow the torch to cool down and check for any blockages in the gas line. Reduce the cutting speed and use a heat-resistant glove to protect your hand.

9. The torch is not cutting through the material.

Ensure the torch is the correct size for the application and that the gas flow rate is sufficient. Check the torch tip for wear and replace it if necessary. Practice on scrap material to hone your technique.

Problem	Cause	Solution
Torch not igniting	Spark plug malfunction	Replace spark plug
Weak flame	Low gas flow	Increase gas flow rate
Backfiring	Improper gas mixture	Adjust gas mixture
Leaking gas	Loose connections	Tighten connections
Uneven cutting	Improper torch angle	Hold torch perpendicular
Excessive slag	Slow cutting speed	Increase cutting speed
Overheating	Blockages in gas line	Clear blockages
Not cutting through	Undersized torch	Use larger torch