Setup of $89 Harbor Freight Flux Core Welder

About: I am an Aerospace Engineering freshman at the University of Colorado Boulder

As part of my quest to become an aerospace engineer, I believe that it will be valuable to have skills in the machine shop. I know some CAD already and I have a lot of experience in 3D printing, so the next skill that I want to learn is welding.

Unfortunately, welding is expensive. So, I spent months researching this either famous or infamous welder at Harbor Freight that hobbyists love and experts hate. I finally decided to give it a shot. The welder costs $99 or $89 when you find it on sale. Unfortunately, the 20% off coupons that HF advertises specifically say that they cannot be used on welders. I tried anyhow and was denied. If there isn't a Harbor Freight near you, they have very similar offers on Amazon. Here is one, maybe even a little better than that HF welder (more voltage settings) for a few dollars more.

In addition, you are going to need more equipment to weld well and weld safely. Some of those items are in the photo. You will ABSOLUTELY need a welding mask or helmet. The welder comes with a simple mask, but it is handheld and you really should weld with two hands. Harbor Freight has them for about $45.00 or about $30.00 on Amazon. They have welding goggles for like $5.00, but welding gives off ultraviolet light and your face will get sunburned (I learned that one the hard way!). Technically, it's called a flash burn, but same thing.

You must use fireproof welding gloves to protect from the intense UV and the splatter. Gardening gloves just won't do it; the splatters will burn right through. Get gloves that go way up your arm like these at Harbor Freight for $10 or these on Amazon for $16.

These other things, you might have around your house, but I'll give Harbor Freight and Amazon links in case you don't. It comes with a slag hammer and a brush, but the brush was ruined after my first time and the slag hammer is tiny. Amazon prices do not include shipping. It would probably be worth getting a Prime membership just to save shipping on these items. A jacket is better than an apron because it protects your arms from flash burn and hot spatter. The apron is a must if you weld while sitting down, which beginners should (I found this out the hard way, too).

Angle grinder for preparing metal: Harbor Freight, $15.00 or Amazon, $23.
Variety of cutters, grinders, and wire brushes for angle grinder (varies by grinder)
Wire brushes: Harbor Freight, $6.00 or Amazon, $9.00.
Slag Hammer: Harbor Freight, $6.00 or Amazon, $9.00
Welding Apron: Harbor Freight, $10.00 or Amazon, $25.00

Then, you're also going to need something to practice welding on. You can only weld "mild steel" with a flux core welder. If it says stainless, galvanized, zinc-plated, or high carbon alloy, then it won't work. I had an old steel basketball pole that I tried, but it's hard for a beginner to weld on something round. So, I used the extension to a weight bench for doing lat pulldowns (I'm a nerd, I'll never use it). I ground off of the powder coating, cut it to pieces, and welded it back together (at least I tried to).

Many people, after practicing for a while, make their first project to weld together a table for their welder. They often use square steel tube for this but angle bar should work too. Shipping is expensive and HF doesn't stock this, so you might have to go to your local hardware store to pick it up.

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Step 1: What's in the Box?

In the image, you can see what is included in the box. This is most of what you will need to get started besides those additional items listed in the Introduction.

There is a 2-pound spool of wire in there and that will last you for a while. I have read numerous reviews online that the wire that comes with this welder is garbage, so I bought a new reel myself just in case they're right. First, I bought one from Harbor Freight because it was a different brand. But, I took it back when I realized that is specifically said that it was for an "Electrode Negative DC" welder. The HF welder is AC, not DC. There are plans online to convert it to DC, but we paid for the 1-year warranty, so my parents would kill me if I modified it and voided the warranty before a year. I have read good things about Hobart, so I got this wire on Amazon for the same price as a spool at HF. After replacing the spool, my welds got better, but it could have been because I got more experience and got some tips from an expert welder. I will share some of those tips in a future Instructable on how to use a flux core welder.

There is a handle that must be installed on top of the welder (explained in another step of this Instructable).

There is a handle and the tinted glass to build the welding mask. That process will be explained in another step of this Instructable.

There is a small plastic bag with an extra tip for the welder as well as the screws to attach the handle.

They also include a small slag hammer for breaking off slag (crust after welding) and a brush for cleaning up the work area and detailing after the weld. The brush is useless. It falls apart after only one or two uses. The hammer is small, like a little larger than a pencil eraser, but it can be used for removing splatter. I bought some higher quality wire brushes for cleaning things up and I'm looking for a good wire brush wheel for my grinder.

Additionally, there is a manual and a quick-start guide. Neither is incredibly useful. YouTube videos are better for learning to weld and this Instructable will teach you how to put the welder together. The troubleshooting photos on the quick-start guide are a good start, but I had a lot of issues that weren't included (burning holes, splatter everywhere, etc.).

Also inside the lid of the welder is a guide to help you with the settings. It's a good place to begin, but you'll still have to make adjustments. For example, I'm welding on 1.5 mm steel and a speed of 2 is recommended, but 1 seems to work better.

Step 2: Building the Mask and Handle

The first step in preparing to weld is to put the handle on the welder and build the mask.

The mask is simple. You literally just slide the handle on and put the tinted plastic in.

The handle was a little more complicated, but because there was a small issue. The handle should slide into place and then one screw holds it together. On mine, however, when they punched the hole for the screw, it build up a small mound. This made it impossible for the handle to slide in properly. So, I had to get a hammer and flatten the mound. Then the handle has two grooves that must slide in simultaneously. Then just put the screw in.

Step 3: Putting the Wire In

Next thing that you have to do is put the wire in, set the tension, and feed it through the welder.

The first step is to set the feed wheels for the thickness of wire that you're using. I'm using 0.03. Take the thumb screw off of the wheel to the left in the picture and one side of the wheel says 0.03 and the other says 0.035. Flip it to whichever size you're using and then put the thumb screw back on.

Now put the spool on the holder shown in the picture and then feed it through the tube to the left. Watch the video showing how you can pull the trigger to get the wheels spinning. Be sure to loosen the thumb screw on the right so that the wire can go between the wheels. When it touches in between the wheels, press the trigger for a very short amount of time to move it a tiny bit.

Then, feed it through the second little tube that goes into the cable to the welder.

Now, the wire is going through the cable to the welder. Make sure that there are no kinks in the cable, straighten it out as much as possible and hold the trigger down until the wire comes out the other end.

Depending on who you talk to, some people say that flux core welding doesn't need the brass nozzle at the end. I started with the nozzle on, then my welding mentor told me to take it off. He said that it doesn't really do anything and I'll be able to see better without it.

Step 4: Start Welding!

Don't forget to prep your material. They say that you can flux core weld dirty material, but you shouldn't. Grind any paint/finish off and then run a wire brush over it.

Make sure that the area where you will attach the ground clamp is also clean and attach the clamp, as close to the weld as possible.

Let about 1/4" to 1/2" of wire stick out the end. Adjust the thumb screw on the right to get the right tension in the wire. The instructions say to get it to the point that if you eject the wire into an obstacle, the wire will bend. You can see a video of what this looks like.

Set the voltage level and the wire feed speed and let it rip!

I will post an instructable on how to make better welds with the Harbor Freight welder, so stay tuned but keep practicing!

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    9 Discussions

    Phil B

    8 months ago

    I used a Hobart Handler 125EZ flux core welder for about seven years. It was an affordable wire feed welder for smaller things. Flux core wire really works better with DC welding current, but the Harbor Freight welder is AC output. Some buy an inexpensive Chinese bridge rectifier to convert the output current to DC, and it improves the performance. Still, the welder will not have all of the refinements a more expensive welder has to make a good stable arc.
    Try different flux core wire. I like Hobart wire. It just performs better than others I tried.
    A common fan like you use in your home to stay cool is an asset when welding with flux core so you can blow away all of the smoke it makes. That smoke makes it really difficult to see where you are welding. Place the fan as near to the weld seam as is practical.
    Flux core is to be drug, not pushed, when welding. I now have a real MIG welder and I can pull or push the bead. Pushing puts more light on the open seam so I can see more easily and stay on the seam.
    Prepare the joint well for good root penetration. Weld 1/8" stock from both sides. Anything larger than 1/8" should be ground to make a "V" where the joint will be.
    Remove slag before welding over a previous weld.
    I like to tack the weld different places. Then weld toward a tack, dragging the gun rather than pushing it because it is flux core. "If there is slag, you drag." Light from the arc will reflect off of the nearby tack and make it much easier to see where you are welding.
    Always pick up metal while wearing gloves or use a pliers or tong. You always forget metal may be hot, and you get burned. It is no fun.


    2 years ago

    If your trying to build a jet engine, definitely go for tig. Yes. Welding is expensive. 2 choices you have. Buy a stick welder for around 200 that you can add a tig torch onto (tig is precise) because this HF welder is terrible in my opinion.

    1 reply

    2 years ago

    I would pick up tig as soon as possible. a lot of quality welding uses this process. mig is used often in assembly line environments. also, don't discount stick welding, it's very effective for welding thick pieces of steel.

    1 reply

    Tig is expensive, my parents probably wouldn't go for that. I'd happily take a donation of one if anybody in Southern California isn't using theirs.


    2 years ago

    Nice writeup, welding is not only fun it is also a money saver too.

    Keep an eye open when driving around town, very often you'll see discarded bed frames put out for trash, beat the scrappers to it and you have some fine stock to make that first real project- the welding stand. ☺

    1 reply

    This was a great suggestion and I did exactly that. I made a framework from the wheeled part of the bed frame and legs from the rest. A neighbor gave me some 1/2" sheet metal. It was difficult to weld something that thick with this welder, so I more like "hot glued" it together with melted metal.


    2 years ago

    I used the same little welder for about a year producing frames for wire mesh to fill in safety railing around a parking deck at a Hilton resort ; this welder is worth the money spent on it

    1 reply