Comprehensive Guide to Scratch Start TIG Welding

Understanding Scratch Start TIG Welding

Scratch start Tungsten Inert Gas (TIG) welding is a traditional technique where the welder initiates the arc by physically scratching the tungsten electrode against the workpiece surface. While this method may not produce the cleanest or most professional results, it remains a practical solution for DIY enthusiasts and applications where precision is less critical. Mastering this technique requires careful control and practice, but it offers a cost-effective way to perform TIG welding when other start methods are unavailable.

Ideal Scenarios for Using Scratch Start TIG

Despite being considered the least advanced arc starting method, scratch start TIG still finds its place in various welding scenarios. Many budget-friendly or entry-level TIG welders rely solely on this technique. While lift start and high-frequency start methods provide cleaner and more consistent arcs with minimal tungsten contamination, scratch start remains useful in specific contexts.

For instance, if you own a basic DC TIG machine that only supports scratch start, you can perform welding on carbon steel and stainless steel with minimal investment. Additionally, hobbyists working on non-critical projects such as furniture, decorative metal art, gates, or hobbyist repairs can achieve satisfactory results with scratch start TIG.

However, it’s important to note that scratch start TIG should not be used on critical structural components where safety and integrity are paramount. The risk of tungsten inclusions and potential weld cracking makes it unsuitable for high-stakes applications. While skilled welders can sometimes produce X-ray quality welds with scratch start, it generally requires significant experience and precision. Therefore, use this method primarily for non-critical, aesthetic, or hobby projects.

Step-by-Step Guide to Properly Perform a Scratch Start TIG

Scratch starting is best suited for inexpensive DC TIG machines that operate with direct current electrode negative (DCEN) polarity. Using direct current positive (DCEP) can cause excessive erosion of the tungsten tip and lead to undesirable tungsten balling. Proper setup and technique are essential for successful scratch starts.

Connection Setup

Connect your TIG torch to the negative terminal (DINSE connector) on your welder, and attach the ground clamp to the workpiece’s positive terminal. Before starting, set your shielding gas flow rate—typically 100% argon—and ensure the regulator and hoses are correctly attached. Once configured, turn on your welder, and you’re ready to begin welding.

Cleaning and Preparation

Contamination is a common issue with scratch start TIG, especially if the tungsten electrode sticks to the workpiece. This contamination can introduce unwanted impurities into the weld, compromising its strength and appearance. To mitigate this, always re-grind and clean your tungsten electrode before each weld. Maintaining a sharp, pointed tungsten tip enhances control and reduces the risk of sticking.

Executing a Scratch Start

The key to a successful scratch start lies in gentle, controlled motion. Place your hand on the work surface to stabilize your torch, with your pinky finger resting lightly on the table. Use your other hand for additional support if needed. Initiate the arc by lightly dragging the tungsten tip across the metal surface, similar to striking a match—avoid excessive force or pressing too hard. The goal is to make a quick, light contact and lift the tungsten immediately to establish the arc.

Once the arc is established, lift the tungsten slightly—about 1/8 inch—above the weld pool, maintaining a steady distance to sustain the arc. Practice makes perfect, so don’t be discouraged if initial attempts are unsuccessful. To terminate the weld, simply lift the torch away from the workpiece, allowing the arc to extinguish naturally. Unlike other methods, you cannot simply push a button to stop the arc; lifting the torch is necessary to end the weld properly.

Tips and Tricks for Optimizing Scratch Start TIG

Sharpen your tungsten: A pointed tungsten tip facilitates easier scratching and reduces the likelihood of sticking.
Use scrap metal: To prevent contamination of your workpiece, initiate your scratch start on a small piece of clean scrap metal before moving to the actual joint.
Avoid aluminum: Scratch start is not suitable for aluminum welding, which requires high-frequency AC start methods for optimal results.
Ensure gas flow: Always turn on your shielding gas before starting and maintain flow during welding, including after extinguishing the arc to protect the cooled weld.

Additionally, watching tutorials and practicing with a DIY foot pedal or mechanical trigger can significantly improve your control and consistency. For visual guidance, refer to instructional videos demonstrating proper scratch start techniques.

Converting a Stick Welder for Scratch Start TIG

If your only available machine is a stick welder, you can modify it for basic TIG welding by adding the necessary equipment. This involves attaching a TIG torch equipped with a gas valve and connecting it to the stick welder’s power source via a suitable adapter. You will also need a 100% argon shielding gas cylinder, a regulator, and compatible tungsten electrodes.

Connections and Setup

Attach the TIG torch to the negative terminal (DINSE connector) on your stick welder, or use an adapter to connect it if your machine has integrated leads. Connect the shielding gas line from the argon cylinder to your torch’s gas inlet, and ensure the regulator is functioning correctly. Before welding, briefly open the argon cylinder to purge the lines of dust and contaminants.

Methods for Scratch Starting with a Stick Welder

Direct connection: Attach the TIG torch directly to the negative terminal of the welder. Ensure your welder is set to DCEN (direct current electrode negative) mode for best results.
Using an adapter: If your stick welder has a dedicated electrode holder, connect it to an adapter or a power block that can supply negative DC to the TIG torch. This setup allows you to scratch start effectively and safely.

For detailed assembly instructions, refer to instructional videos that demonstrate how to organize the connections, including the use of power blocks and adapters. Keep in mind that TIG torches with DINSE connectors may not be compatible with certain power blocks, so choose your equipment accordingly.

Recommended Equipment for Budget-Friendly TIG Welding

Model	Type	TIG Start Method	Input Voltage	Amperage Range	Weight	Warranty	Price
YesWelder ARC Welder 165A	Stick/DC TIG	Lift TIG (better than scratch start)	110/220V	20-165A	11 lbs.	1-year	See here
PrimeWeld 160A	Stick/DC TIG	Lift TIG (better than scratch start)	110/220V	10-160A	12 lbs.	3 years	See here

Final Thoughts on Scratch Start TIG

While scratch start TIG welding is not the most refined or professional method, it remains a valuable technique for those on a budget or working with basic equipment. If you already own a stick or multi-process welder, modifying it for TIG welding can be a cost-effective way to expand your capabilities. However, for serious or critical projects, investing in a dedicated lift start or high-frequency TIG machine is highly recommended. Modern TIG welders with lift start capabilities are becoming increasingly affordable, often priced below $200, making them accessible for hobbyists and small workshops alike.