Scratch Start TIG
As mentioned in the Welding Machine Guide article, we outlined that stick and TIG machines can be used interchangeably. This is because they are both DC power sources. Therefore, they provide the proper current needed for both stick and TIG welding.
The reason MIG isn’t included with this combo is because a MIG machine has a separate drive roll mechanism to feed the wire. It is also powered by a constant voltage setting instead of amperage. It is possible to stick weld off of some multiprocess MIG machines. However, this article will focus more on scratch start TIG – and the similarities between DC machines (and how you can use them for TIG/stick).
If you decide to go the inverter machine route, many are marketed as TIG welders because they have the inputs to use a shielding gas. However, with modern style DINSE connectors, a user can plug in stick leads no problem. This can be done with a lot of transformer machines as well.
In the previous article, we mentioned the introduction of “Multi Process” machines into the welding world. These machines can perform all three of the main welding processes. The downside is that they generally don’t do all of them as well as a dedicated machine for one process.
If you want to get into TIG welding but you just have a basic DC stick welder, you may want to look into a scratch start TIG setup. It can allow you to perform stick and TIG functions for a reasonable price.
Scratch Start TIG Overview
The video shown above is by welding tips and tricks. After watching Jody break down the scratch start setup, the items listed below will make more sense. It may seem like a lot of gear to get started with this process, but the setup can be assembled very quickly while on the job site.
With scratch start TIG, the stick stinger clamps on to a power block that is attached to the TIG hoses. This provides the DC (negative) current needed for TIG welding. The user adjusts the amperage on the stick machine which powers the TIG torch. Instead of the current flowing from the stinger to a stick electrode, it is actually powering the TIG torch through the stinger.
A downside to the simplicity of this process is that there isn’t as much amperage adjustability while welding. Accessories like foot pedals and TIG torch dials allow the user to control the amperage while welding. If you sense the weld is too hot, you can let off the foot pedal and get the welding puddle back in control.
These pedals and dials are found on higher end machines and torches. Unfortunately, scratch start does not allow these controls. It will require the welder to control the puddle with their travel speed while the amperage stays the exact same during the weld.
Keep in mind that for TIG welding steel and stainless steel, most welders use a negative polarity or DCEN. Let’s say your stick welder is set on a positive polarity for burning electrodes. For scratch start TIG, you simply switch the leads around – and the stinger clamp will now be negative instead of positive. This will hook up to your power block adapter and you can begin TIG welding.
The advantage of scratch start TIG is that you can get into TIG welding for a lesser cost than buying a dedicated TIG machine. It is the choice for welders out in the field who need to TIG weld in a pinch. They usually just have a DC machine with no gas ports, or an engine driven stick machine on their truck.
Equipment Needed for Scratch Start TIG
Here is a list of items you need to start scratch start TIG, assuming you already have a DC stick welding power source. The list is in order from the gas cylinder all the way to the TIG torch. With these items, you can turn your stick welder into a nice little TIG operation.
The items listed above can be put together for about $500. Keep in mind that prices change based on availability and demand.
Again, if you don’t already have a DC machine, you might want to just put your money towards one of the newer inverters with gas ports. Doing this, you will be TIG welding in no time. A lot of these new inverters will come with most items to get you started, minus the gas cylinder and a gas refill (most likely argon).
However, if you have been stick welding for awhile, your old stick machine has more capabilities than you may have realized. If you get set up with the items listed above, you can produce some beautiful TIG welds. Some high caliber TIG pipe tests are passed using a scratch start setup. Experienced welders know how handy this process can be, and a lot of these welders are used to taking tests using scratch start.
A Word on Gas
The gas flow for any TIG or MIG welding is measured in cubic feet per hour (CFH). A lot of TIG welds will require a gas of flow of 10-25 CFH. If you buy a 40 cubic foot cylinder, it may only last a few hours of weld time. A lot of welders and welding schools tend to use cylinders that are 125 cubic feet and larger. This means less refills and more money saved.
Keep in mind that it is always more economical to buy more gas at once. A larger gas cylinder will cost more up front, but the price per cubic foot is less than filling a tiny cylinder. This is a common rule for a lot of welding consumables (and purchases in general). If you buy a 50 pound box of stick electrodes, the cost per pound is much less than if you bought a 10 pound box of the same electrodes.
This being said, larger gas cylinders weigh a lot. This can make it tough to exchange cylinders at your welding supply store. If you plan on being able to move your cylinder yourself, a smaller one might be the best bet.
Types of TIG Arc Starts
The scratch start TIG welding arc is initiated by scratching the sharpened tungsten against the steel being welded. Similar to starting a stick arc, it is a quick scratch and then a lift to initiate the welding arc. The scratch start method is the most primitive of TIG processes, but it is used in many industries to perform x-ray quality welds – and shouldn’t be underestimated.
There are two other main types of arc starts for TIG welding – these are considered higher end techniques. Some machines have a lift arc start, in which the user just touches the tungsten to the steel and then lifts up to start the arc. This is similar to scratch start, but it is a little easier to get the hang of and is considered more of a luxury for the welder.
The most desirable TIG arc is the high frequency start. On newer and higher end TIG machines, a foot pedal or a switch on the actual torch is used to control the amperage while welding. With high frequency starts, the welder holds the torch with the tungsten about 1/16” from the weld metal. Once this is done, the welder pushes the foot pedal or switch to initiate the arc.
The high frequency amperage burst initiates the arc without the welder touching the tungsten to the workpiece at all. This makes it less likely to contaminate the tungsten and is just more enjoyable in general.
If you have not yet purchased a welding machine, you may decide to buy an inverter with all of the bells and whistles. However, if you have been stick welding already and would like the option to TIG weld when needed, scratch start TIG is an economic option that is worth checking out. All of your scratch start supplies can be stored in a compact area, and you’ll be happy to have the option available.