There are a lot of different little things you have to account for when welding. Make: contributor Rusty Oliver recently wrote a great piece on an introduction to welding for the hobbyist in Make: Volume 50 (on newsstands March 22), but he surprised us with an even more detailed checklist on how to get a good weld that was just too long to print in the magazine. So we decided to share it online! Whether you’re just getting started, or you’re troubleshooting the sputtering mess that comes out of your welder, just follow the checklist below for clean and smooth welds. Happy welding!
1. Optimize Your Power Source
Power up your machine. Check the nameplate on the machine to ensure it is getting the required power. A 120 volt machine should be on a 20 amp breaker. Avoid using extension cords and use heavy gauge cords to minimize voltage drop.
2. Set the Correct Electrode Polarity
What process are you running, gas metal arc welding (GMAW) or flux-cored arc welding (FCAW)? A MIG machine will require shield gas if you are running GMAW and the electrode will be copper colored, ER70S6 is the most commonly used. Check that the polarity of the machine is set to electrode positive. A MIG machine running FCAW will use a flux core electrode like e71t wire these are typically silver colored and do not require additional gas. Check that the polarity of the machine is set DC electrode negative. Either process will fail to work well if the polarity is set incorrectly.
3. Consider the Thickness of Your Material
Check that your process and electrode size are correct for the material. GMAW, gas shielded is much better for welding material that is 16 gauge or thinner, but most 120 volt machines cannot produce adequate welds on steels thicker than ⅛” unless they are running FCAW. If you are welding ⅛” or thicker using a 120v input machine you must use flux core to produce a sound weld. However, it is always difficult to use flux core on materials that are thinner than 16 gauge (.062) as the higher input heat tends to melt large holes in the work.In general, the GMAW process runs a bit cooler, making it a better choice for thin materials. A larger machine (220v input, 175 or higher amp output), will be more capable of welding thicker materials in GMAW.
4. Small Electrodes Are Good for Thin Material
Smaller electrodes are better for thin materials -.024 is good for .062 and thinner, .030 works well for thicknesses in the .062 to .18 or so, and .035 works well up until about ⅜” material. The goal is to ensure that the electrode is able to melt at about the right rate, but also carry enough current to the weld. Thinner electrodes will melt at settings used for thin materials. Using a heavy electrode on thin material may result in difficulty, by the time the wire is melting correctly, the base material may be warped or melted away. Using light electrode on thick material may result in much of the electrode burning away in smoke.
5. Prepping Gas for GMAW
(GMAW only) Check that your gas tank valve is open, open it about two turns, or half way. The valve is designed to close if it is “opened” all the way. Check the bottle for a label indicating gas type. GMAW uses Argon and CO2 in a 75/25% mix or (rarely) straight CO2 for welding mild (regular old low carbon) steel. Use of any other gas type will create problems. Use the regulator to set your gas output pressure. The adjustment screw will turn IN for more pressure, and OUT for less. You will not notice any change in output pressure unless you also flow some gas by turning the machine on and jogging the trigger. Remember the machine is live at this point. Your output pressure should be from 15-22 cfh for mild steel.
6. Check Your Contact Tip
Check the working end of your welding lead frequently. The contact tip must be the correct size for the welding wire, and must be screwed tightly into the receiver. Tips take a lot of damage and should be replaced as needed, one per spool works well. Tips should be inspected, cleaned, reamed, and replaced on the fly as needed. Many welding issues stem from damaged or worn welding tips. Contact tips are inexpensive, but cheap import contact tips are not helpful.
7. Double Check Your Ground Clamp
The work lead, or ground clamp should generally be clamped directly to a clean bare metal part of your work. If your machine is not producing an arc, it is almost certainly a lack of electrical continuity.
8. Change Your Helmet’s Cover Plates
The cover plates on your helmet will rarely last for more than 10 hours of welding before becoming pitted smoky and charred. If you can’t see the material, you won’t be able to weld it. Change cover plates frequently — it always helps.
9. Cover Up!
Wear full leather gloves, and heavy cotton sleeves or a leather welding garment. Wear a sunblock if you burn easily.
10. Base Your Settings on Your Weld
Your machine will typically have a chart to help you determine your appropriate wire feed and voltage settings. These are only a rough guideline. Always base your settings on what you see in the weld.
11. Adjust Your Machine for Every Weld
Here is how to adjust your machine. You should do this every single time you set up to weld:
- Glance at the chart on the machine, adjust your voltage and wire speed for the thicker material if you are welding material of different thickness.
- Make several practice welds on pieces of scrap. Weld left to right or right to left, make sure the contact tip is within ⅜” of the work when welding, meaning that there should never be more than ⅜” of wire “sticking out”, tilt the handle to about 75 degrees. Keeping the handle close to the work is absolutely critical.
- The wire is always feeding out when the trigger is depressed. If the wire is feeding too quickly it will tend to spit wire everywhere and feel like it is pushing your hand away. Either turn your wire speed down bit by bit, or turn your voltage up to match the wire feed rate.
- When wire speed and voltage are adjusted correctly, the action will feel smooth and the weld will sit low and even and appear to flow into the base material. Tall uneven welds are much, much weaker.
- If your wire keeps burning back to the tip and shows a large glob or ball on the end of the wire consistently, either turn your voltage down bit by bit, or turn your wire speed up to match.
- If your wire is feeding inconsistently, check your contact tip. It should be tight, clean, and sized appropriately to the wire (.024 tip to .024 wire etc, tips are marked.) Try increasing the drive roll tension slightly. The drive rolls are often grooved for specific electrode sizes. Check that the rolls are set up correctly. Always set up your machine so that the lead is as straight as possible to help ensure smooth wire delivery. If none of these steps help, replace the contact tip. If wire delivery is still erratic, consider replacing the liner in your welding lead. This part is typically about 30 dollars.
- If you are punching holes in your material, either increase your hand speed, or decrease your settings in tandem.
- If your welds are tall with near vertical sides, you need more heat, this may mean increasing your voltage, slowing your travel speed, switching to FCAW, or pre-heating your weld area to about 500 degrees. For material ¼” or thicker you will probably need a 220 volt machine on a 50 amp breaker.