Modifying the Harbor Freight 120v welder (if you already own one)

Brian, after some thought, my suggestion didn’t sound so brilliant. It looks like what you have is working. The inductor is a good thing, and 68,000uf is quite a lot of storage. I guess modern solar panels are fairly rugged if they survive direct connection to a water heater element. Lately my welding skills have been shown to be inconsistant. I am good at melting random holes in a lawn mower deck attempting repairs. We will see how long that repair holds!

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Mike my memory failed me. It is an AC225 Lincoln Electric.

Well my inverter has arrived so now I can connect 18 of my solar panels up and also connect to the grid permanently and I will have all the power I will need.

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I worked with electric vehicles for a while. The rule of thumb is never discharge a 12V lead acid battery below 10.4V.
Rindert

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Ideally you have enough battery capacity that you never push your batteries beyond the manufactures recommendation.
Some types of battery might go a little deeper than others depending on the chemistry.
But the less deeply discharged the better for making your batteries last
For many years we got along pretty good by trying to keep the batteries always charged as possible.

Example of you know you are going to need a lot of DC.
And if you have a delco plant start it before you draw your batteries down.
If you do draw your batteries down charge them asap to reduce large crystal hard sulphate formations that are the killer of batteries.

Some people will want to avoid gasoline powered lighting plants.
I get is you want something that’s wood fueled.
By all means built that! But have a gasoline back up lighting plant too

On hold but not a still born project this will one day be an automatic battery charger.
See the automatic choke?
That’s my special doing, made from Kohler lawnmower parts ( XT-6 series engine )
Stick with a good Chinese Copy of a Honda and you never go wrong.
There will be parts and pieces of these around forever.
Cost of this build to day is about 60 bucks in scrap parts including an old Ford alternator not shown.

The alternator is an old FORD G1 with external regulator.
It can charge or it can also weld as long as you stick with small rods and light duty jobs.
You might even get creative and re power an old flux core with one

Out yard saling with the wife?
This little fellow is an APU off military vehicle from the 40s.
Its a Johnson chore horse generator rated at 300 watts.
But its electric start and frugal in gas.
if your batteries are low and you just need lights for an evening these little lighting plants are still out there to provide you with some AC late at night.

So, off on a ramble there, but you get the message don’t abuse your batteries by deep discharging.
Have a back up ready to provide supplemental power and lighting and your batteries will thank you for it.

You guys may have noticed always a paper bag from the liquor store seems to appear in my photos…
One might think I have a problem ha ha.
No I keep all paper bags and these are all filled with charcoal.

Adding great vid of a DC chorehorse ( mine is AC 120v for a radio )

Not a great welder, but you can stick things…

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Did anyone ever make a proper video on how to do these mods such that i don’t kill myeslf?

I can do the labor to build this modded welder, but I don’t have intimate knowledge about electrical parts, etc or not know where to stick them.

Any suggestions on a DC welder from factory?

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You shouldnt attempt these mods as a first project.
here are some basic tips if you insist:
your welder takes 120 or 240vac from the wall and drops it down to lets say 10v-25v at what ever the number on the side is (usually) in amps. Most list open circiut voltage but there will be a sag with actual weld. so lets first demonstrate some theory. volts = ohms * amps and power in watts=amps*volts…

allweldgeneric 90 … number is usually amps but wait what? do they make a breaker that big? lets say 15v actual weld v on average 15*90 = 1350 watts of power using algebra we can see that to get amps at 120v we can then divide the watts by wall side voltage… and 11.25a is the answer.

how much does it take to stop a heart? 0.01a to 0.02a is actually the most effective. heres the good news, your dry unbroken skin has a resistance of around 100k ohms.

volts = ohms * amps and visa vi algebra …
amps = volts / ohms

Normally 120v isnt going to kill you. but things like sweaty hands high humidity and capacitors, or some kinda fetish for sticking things up your… 120v CAN kill you do not treat it otherwise. 120v ac is also a RMS measure. Add a capacitor on the 120v side and around 170v is actually the shock you will be getting.

usually under 50v the shock risk is minimal. you can google around but I think all relevant agencies will deliver with in 15v of what i just said as advice. ALWAYS TREAT 120v wall power as deadly, once you get down to under 50v… shocking burning blinding fire etc still risks

and again the big Capacitor(s) found on the low v side of a welder, could blind or burn the hell out of you, possibly blow up if shorted out. Assume Any Capacitor on the wall plug side of things will stop your heart, as well as make you wish it had for the blind, burn, blowup reasons.

google proper way to discharge a capacitor. before you open the box.

otherwise there is a rule called one arm behind the back. this works better with another bit of kit called an isolation transformer but is decent as is. the theory is you minimize the chances of actually getting a shock across the heart.

google electronics types of passives and familiarize your self with what they look like.
understand the hazards i said above and reread. I cant hold your hand here. Its great if you have an interest. im not trying to be elitest here which is why i include the reasoning and some advice on how to acquire the knowledge you need. I do want to make sure you stay safe and tried to point you in the right dirrection down that path.

one last tip. 60/40 leaded electronics solder. Flux made for electronics soldering. wash your hands…dont go lead free especially learning and or trying to do a big first project. lead was used for so long because it was hard to beat the preformance of it for what it was used for. some argue it hasnt been done yet. its also pretty easy going on the soldering profile / doesnt need exact temps and times… just the right flux

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Just try this. I think you’ll like it. Clean your soldering iron, solder, circuit board and all surfaces you want to solder with vinegar. THEN assemble everything. Do not use flux. Flux just makes a mess. Use white vinegar, the cheap kind you can buy by the gallon at the grocery store. Just as a sanity check, put a drop of vinegar on an old brown penny, wait for an hour. You will see a color change. The vinegar will have changed the copper oxide back into copper metal.
Rindert

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Rindert,
Well, I kind of like solder flux, but I will try the vinegar. I once heard that lemon juice also works, have not tried that either!! Thanks for the tip! As for lead vs. lead free, I am old school, have seen too many failed solder connections using the new lead free stuff. My advice; don’t lick your circuit boards. :upside_down_face: Lead free works OK for copper plumbing joints, and for water supply pipes, its worth the trouble.

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This is the flux I use for most electronics repair. It is designed to be inert after use, you don’t have to clean it off if inconvenient. From Digi-Key, Mouser, Newark, etc.

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John,

Welcome to Drive on Wood. Thank you for your input. While everything you said is probably true, and not to diminish the value of your input, there are only two principles that anyone needs to know to be safe for this project. 1) Unplug the machine from the wall, and there is no way to possibly be electrocuted while touching the machine. 2) After the mods are completed (properly) with the resistor across the capacitor that automatically discharges it, it is again impossible to be electrocuted with the machine unplugged from the wall and the case closed.

Enjoy your stay.

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White vinegar doesn’t leave behind any kind of residue. Most acids will work but white vinegar is the best because it evaporates, leaving nothing behind.
Rindert

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Re: electrical safety- The guys who did it wrong aren’t here to tell you what happened.
Many years ago, during safety training, we were taught that 120 vac is about a dangerous as it can get because the AC all too often causes ventricular fibrilation (uncontrolled beating of the heart) the net result of which is that no blood goes anywhere.

Re: Solder flux- This is my 73rd year of soldering (I am 81). I do very little soldering of copper plumbing for potable water supply, but I have been doing a fair amount of copper plumbing lately for the work coils of the small induction heaters that I am playing with.
https://spaco.org/Blacksmithing/ZVSInductionHeater/1000WattZVSInductionHeaterNotes.htm
I use rosin-based flux and rosin core solder for all of that with no problems. And, of course, I still am a fan of leaded solders.
My thinking is that, if the parts are clean enough, the rosin flux will work just fine.
About a year ago, I finally ran out of the tube of rosin flux that I’ve had for many years. I bought a new several ounce container off of Ebay.
A few months later, I started having an occasional nose bleed. Nothing serious, but annoying, since I hadn’t had any for a loooonnnnggg time previously. After a few of those events, I traced them back to days when I had been soldering. I looked up the chemistry on the rosin flux and found that it apparently changes chemistry when heated and does produce an acid vapor!
Why didn’t it bug me all those years ago? Maybe old age, but----- for the last year or so I have been wearing a magnifying visor when I am doing electronic soldering, and the visor was trapping the smoke right under my nose!
So now I pay close attention. I also now see that there are several suction options; little fans that pull the fumes away from the worker. So I made one up for myself. But, if I only have a couple of joints to do, I simply hold my breath and/or blow the fumes away as i proceed.
No more nosebleeds.

Pete Stanaitis

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Pete I have to say you are one of the most articulate people I have ever incountered. Whether you are sorting chips for wood gas or building and testing this induction heater. TomC

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I learned with lead-free solder. I don’t think I have ever used leaded solder. I don’t have any. I don’t want little bits of lead in my house. Not worth it. I have heard leaded solder flows better and what not. If I do what I am supposed to do and clean surfaces, keep the iron clean, etc you don’t have many issues. I know leaded solder is easier and cheaper, but I usually don’t have any issues.

I would actually suggest taking the 20 minutes to learn and practice soldering prior to starting the first big project especially on something that costs more then 5 bucks. grab some busted electric device and take it apart then desolder and resolder the connections.

I now prefer the bulb type vacuum desoldering tool but I used to like the desoldering braid better.

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A mig is already DC. That is the whole point of this mod.

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It’s a good habit to wear goggles when doing any kind of electrical work. There is a direct shock hazard but also the risk of sparks and splatter getting in your eye where it will do real damage.

I’ve taken 120 volt shocks more than once but the near-miss that sticks out my mind is the time I bridged a live 20 amp circuit with a pair of pliers. Molten metal flew past my face. It was bright enough to leave trails in my vision for some time.

In terms of protective gear, gloves are also a good option too and helps prevent lead on the skin and adds resistance against higher voltage circuits delivering current where you don’t want it.

I’m a 60/40 guy too and started young. No question in my mind I ingested trace amounts and got some vapors at a time when it could do real damage. I’ve been thinking about switching to expensive high silver solder to get the flow of 60/40 without the lead.
I use very little in my projects so the cost is not really a factor. It’s really just piece of mind, especially if I’m teaching my own boys.

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