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Paul writes in with some good tips for new welders… – “I’m on a couple of welding mailing lists, and am a certified welder myself. Recently, a discussion has arisen on one of these lists regarding an inexpensive MIG welder aquired from Lowe’s. The individual in question was having difficulty getting a decent weld using flux cored wire, and I wrote up a reply with some useful info on the settings of these machines and some other suggestions I’ve found to be helpful. I know when I first started with MIG/FCAW, I had no understanding of what to do with the voltage/wire speed controls. Welding being an invaluable maker skill, I thought I might send a copy of my post along to you incase it may be of interest…”I would not go any lower than a #10, that’s about the minimum for arc welding safely. I would highly recommend investing in an auto-darkenning filter, or auto-darkening helmet. Don’t cheap out, buy a quality one from a professional supplier. Flash is magnificently unpleasant, and over time can do very real damage to your eyesight. Remember to move slowly and allow a puddle to develop, people tend to want to move the gun as fast as the wire is feeding. Depending on the wire, you’ll want your puddle to be between 1/4″ and 3/8″ wide. Aim the wire towards the leading edge of the puddle, and tilt the gun so that you are ‘pushing’ the puddle forward. This ensures good coverage of the steel with shielding gas as you go(fluxcore without seperate shielding gas does produce it’s own shielding gas as the flux burns).

Now for a brief discussion of MIG/FCAW machine settings:

Remember this. Voltage sets the arc length, wire speed sets the heat. There are three ‘transfer modes’, basically ways in which molten metal gets from the wire to the puddle. There is short-circuit, globule and spray. Your machine is not capable of the last two, only the first – it doesn’t have enough power. Short-circuit transfer is characterized by a loud ‘crackling’ sound as it welds. If the voltage is too high, and the wire speed too low, the wire will burn back, feed, make contact, burn back, feed…. Over and over again, sputtering and having terrible trouble. Now, if the voltage is too low or the wire speed is too high, you’ll get what’s called ‘stubbing’. Stubbing is where the wire isn’t burning off quickly enough, and is actually striking the bottom of the weld pool. This feeling is very noticeable, and you will feel it happening. The settings on the chart are only recommendations, and there are many factors that can affect the optimum position for these settings. So don’t hesitate to play around a little. If the wire seems to be burning off, losing the arc, advancing, reestablishing the arc and burning off again, you are deffinitely either running too high a voltage or too low a wire speed.

I have two more recommendations:) Join the AWS. If you join with a two year membership, and I think this promotion is still going on, you can get a copy of the Welding Handbook for $25. This book is worth it’s weight in gold, and covers MIG/FCAW with more detail than you would believe. The Welding Journal, published montly by the AWS has very useful information – the most recent issue has a very good primer on TIG welding aluminum, and a thorough discussion of preparing your tungsten electrodes.

My next recommendation: Get a gas shielding kit. Even if you stick with flux core, the wire benefits greatly from having an additional shielding gas. 75/25 argon/CO2 is not at all expensive, and at 15 cubic feet and hour the tank lasts a long time.

Well, that’s about it for now – Hope it’s helpful.

Paul

Related:

  • Primer: Welding by Mister Jalopy. If you need metal stuck together, there is no quicker path than buying a portable 110-volt wire-feed welder. Mr. Jalopy’s introduction to welding will help you understand the process and show how you can be a welder by the end of the weekend–and end up with a couple of jigs for the effort. MAKE 03Page 158.
  • Welding archives – Link.