Harbor Freight Flux 125 DCEN Mod

Convert your Harbor Freight Flux 125 Welder from an AC Flux Core Welder to a DC Electrode Negative DCEN Flux Core Welder. This video will provide technical details to guide you with the conversion. I also review several components and features of the welder. I don't go step by step through the actual conversion, but show the components needed to do the modification. I describe the finished mod in detail and explain the functions of the major components.

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I also look inside an Eastwood MIG 135 welder which is a true DC welder to show comparable components. The Eastwood welder can weld with Flux Core wire in DCEN mode and I'll compare the welds using the Eastwood to those produced by the HF Flux 125 pre and post mod.

Note that I got my HF Flux125 at a substantial discount for only $37 at a clearance sale. I couldn't pass it up, and it worked perfectly after removing a birds nest of flux core wire. If you paid full price the mod may not be worth the expense. The total for the parts was about $75, and I already had several parts in my workshop parts box. A new DCEN Flux core welder such as the HF Titanium Easy-Flux 125 DC welder (does not need any conversion) is about $200. There are similar Flux125 mods here on YouTube. View them to gain ideas and decide whether this project is one you would like to do.

This mod is not a new concept nor an original approach. I bought my Flux125 Welder back in 2018, used it for several projects and decided to mod it. Although the welds served their purpose, they just didn't look very good. I videoed the project, but didn't edit it until early 2021. A few months prior to the mod project, I bought an Eastwood MIG 135 which is an entry-level DC welder and uses either shielding gas (DCEP) or Flux core wire (DCEN) after a simple cable change. I use both depending on the project. With the mod the HF Flux125 works exceptionally well and produces much nicer welds than without the mod. Welding is a skill and requires practice and good technique. A good machine does help.

If you would like a separate video review of the Eastwood Mig 135 welder please leave a comment with a request for that. I've had very good results with the Eastwood. Also, please subscribe, leave a comment, press the LIKE button and SHARE the video with friends who might be interested. This will help my new channel grow.
Ken - FTRR - Thanks!

[dylanbuchanan]

After many of these Chicago Electric DC upgrade videos, yours is the best. You are the most descriptive and you go over the entire process. Love the fact you had an actual DC welder to compare to for reference. I did this all to mine and I couldn't be more happy with the result. Thank you, sir for doing what you do! 8:01

[crazyDIYguy]

This is a really thorough video I've watched a bunch but nobody really mentioned the resistor on the Cap, thank you.😎👍

[Tony_]

You did an amazing job for your first YouTube video 👏🏻👏🏻👏🏻 thank you for your knowledge

[bklynman]

Wow professional looking job! It’s amazing how well these Harbor Freight products are

[CFBtechnologies]

It would be nice to the output on an oscilloscope. Both with and without the coil, would be interesting to see the difference. nice work.

[DIYHomesteadProjectsDIYHP]

Nice job with the video and modifications! 👍

[bcirocz]

Great video. What value capacitors did you use? Nice to see HF made a lot of improvements to the welder compared to the blue 90 that I have.

[Fabguy]

Great video I plan on doing g this to mine as well. How is the welder still holding up?

Tip Forney, or Yes welder wire works so much better than the Vulcan wire.

[KFRogers]

Just starting my upgrade to DC on the older 90A model. You are the only person on YT I've seen use that inductor? Do you think it really makes a difference? (VS just the RC add to the circuit)? My gut instinct is that the inductance will slow the initial arc, and prolong it on the release...but...could be some other circuit magic I'm not thinking of

[davidchavarria]

Where can I buy the 5in choke? Also what is the model for that axial fan? I was planning on upgrading the older 90amp model. Thanks in advance.

[BlindDude]

I would like to know the difference with and without the toroidal coil.
Kinda tough sourcing a big arse ferrite core like that.

[billarroo]

NICE job, I could tell the difference in sound, it also seems to have more power, check it with a Clampmeter, see what amps and volts your getting? GREAT VIDEO thanks

[ayebee]

I welded in high school shop. Miller industrial stick. Seven years ago I bought one of these HF boxes. Utterly disappointing. Lesson learned?
Solid wire shielded gas machine for four times more money.

[elipsonj]

Hi! How much a project like that cost approximatively?? thank you

[jimcatanzaro]

I know your already done this project and i love your project and planning on doing mine as we speak with it on my bench making a schematic first .
Say if you added 1 smaller capacitor before the choke and then added the other capacitors after the choke coil you would have a really good dc with low ripple since the choke has some resistance
I study power supply’s for high voltage tube amplifiers and this is how they would make there circuit
Am I wrong about this I feel the capacitors all before the choke will drop some voltage and current and did you measure how many ohms your choke coil was I was just interested if you took a measurement?
Thank you for your videos i hope everything is good

[PBAB]

So the gun should be neg and the clamp pos?

[steven]

Did you add that fan also? How's that doable? that's an AC connection to the stock fan. Those CPU style fans are DC right?

[billlymperis]

Can one 2 watt 100 ohm resistor be substituted for the (2x) 10 watt 50ohm resistors you used ?

[NSilver]

I have 4 capacitors @ 560 Microfarad and 400 volt. Would that work? I saw another guy working with only the bridge rectifier so I wonder if my capacitor will make any difference or they will just explode.
Thank you.

[DanWright-wx]

Today it not worth doing this with a HF90-125 welders You Can By a Nice 140amp Inverter DC Mig Welder for around $80, Try using Blue Demon E71T-11 Wire its good stuff !