Convert AC Welder To DC!

[@thegodofpleasure]

Without a bleed-down capacitor, there's a high risk of electrocution on a mig welder if the user goes to trim off the wire immediately after using it and forgetting that there's residual current in the system.

[@unigrampa]

It is only 27 volts or so, it shouldn't be particularly painful. Humans are not great conductors. I did, however, eventually add one I think because I got annoyed with the wire arcing to my metal so aggressively when the trigger wasn't held

[@xyzebruh1083]

Holy shit that is the oldest cell phone I have seen, I had to check the published date of this video to confirm how recent and time this was

[@unigrampa]

Savage

[@roo2dee2]

"You have a HF welder, I'm sure you're not made of money." Bahaha! Great video, though. I did the DC conversion too and it's working great. I was able to get the rectifier+sink mounted outside of the housing and I also used a cool whip container to cut a shroud for the fan.

[@unigrampa]

Fantastic! Play God with your welder

[@jimcatanzaro7808]

I added a inductor today and wow what a big difference Deff look into making one it’s pretty easy

[@kenbreetz]

I just subbed. I have a feeling i am going to really like your channel.

[@unigrampa]

Thanks!

[@kevinwalker3499]

I second that!!

[@martinez1701a]

Did this to the older model HF 90a welder and my welds were like night and day, I loved that thing til someone stole it. I also replaced the ground cable with a 4awg wire better clamp and replaced the power cord with a 10awg 15ft HD extension cord makes a big difference and cheaper than the Lincoln 140c if your on a budget. Never got around to installing a choke and a new high rpm cooling fan.

[@unigrampa]

New wires should make a huge difference. Every bit of voltage drop is a colder weld. Not sure off the top of my head what you'd want a choke for? 60 hertz is the only frequency present in any real amount

[@martinez1701a]

@@unigrampa someone smarter than me told me that a choke helps with the voltage drop but then again he could have just been full of shit lol

[@unigrampa]

Off the top of my head choke is good for blocking certain frequencies, and current limiting. Can't think of any way that would advance your welder. Not enough current to limit lmao. You should be golden without I think

[@stefanopassiglia]

​@@unigrampa MIG are designed to use constant voltage. Stick welding need constant current so a capacitor is a bad idea as you'll get huge current changes on small changes in arc resistance. So: caps are good for MIG, chokes are needed for stick welding.

[@raibeartcahill4295]

@@unigrampain a DC circuit, caps resist current change - inductors (what you are calling a choke) resist voltage change. Use both and the result is better current AND voltage stability. For best results I believe your caps should be between 40000 and 50000 μF. No harm going higher but no gain either at these output levels. A bleeder resistor across those caps is a really good safety measure also.

[@larrynarvaez455]

I have an old Harbor Freight mig 200 AC electrode I bought in the 90's. I want to convert it to DC electrode negative. What voltage rectifier and capacitor do you recomend?

[@nekbiodieselworks]

Hey man funny story. I have the same little welder. I hardly use it though I prefer stick welding. Anyway I want to do this with my welder but you didn't actually show how to wire it. You jumped around so much I wasn't able to figure it out. Its a shame you really did something amazing

[@DarkLinkAD]

My rectifier has a bit more mass, can the body of the welder itself be successfully used as a heat sink?

[@unigrampa]

Would be tight but you could probably do it. The case is thin iron so it won't cool nearly as well. My guess would be you may cook the rectifier one day if you weld a lot.

[@deanfranklin9239]

but nobody seems to know you need silicone grease on the heat sink

[@robertblackshear8963]

@@deanfranklin9239 Late but thanks.

[@TLCsamshopbot]

I've just got to say that I've owned a HF Flux125 for about a year now, and that I have taken some professional welding courses at a local trade school, and I have no problem with the machine, my weld performance , overall strength and "eye" appeal. I can certainly attest that when I 've used superior shop machines in the DCEN mode, that the weld quality is better, no doubt. The videos I am seeing on YT who are doing DC conversions, can't seem to run a decent weld to begin with. So before all you Flux125 owners think you need to convert to get a decent weld, consider practicing a constant 1/2" "stick out", 5 - 10 degree drag angle, correct wire feed speed and voltage setting (hi -lo). I had to tweak settings for different steel thicknesses. I had to play with wire feeder tension. I make sure my base metals are well prepped and fitted up. All these factors can make a big difference in weld quality. The main modification that I think would be quite helpful, would be to swap out the ground clamp to a bronze unit that HF sells. I just haven't yet on my machine, because it welds quite nicely for me. Oh and I use Lincoln NR-211-MP .035"wire.

[@unigrampa]

Agree, on the machine end, 90% of your weld performance is going to be based on whether or not you have the correct settings, not whether or not welder is DC. Converting to DC gives you only very minor changes. Wire feeder tension on this machine is a disaster. Either the feeder slips and doesnt push wire, or it binds and doesnt push wire. Really hard to get it to work correctly. I am told by a friend that swapping the ground wire to something thicker also gives a noticeable improvement to weld quality. I use Lincoln .030" wire from home depot. Machine and tip are designed for .035", but I didnt notice any issues feeding .030" and I figure it gives me an advantage with the stupid wire feed. Thinner wire can be run at a higher speed. Gives you the same amount of steel at the weld, and the higher speed may help prevent the wire feed from jamming up. Been using .030" for a few years now, so I cant remember what .035" is even like anymore.

[@jimcatanzaro7808]

You say this on every video a dc welder is far superior to ac

[@mattfinleylive]

dude... SUBSCRIBED!!! That's the content we're after! *laugh*

[@Bodragon]

(5:38) - You mean we don't want a too *_low_* resistance? (You said too high)? Wot, no inductor? I ask this because others have mentioned that you also need some kind of choke. I don't get it myself.

[@unigrampa]

Actually, I did mean "high resistance." I was referring to a discharge resistor. If the resistor had a low resistance, all your welding power would get shorted through that resistor and not make it to the weld. You want just barely enough current to flow to discharge the capacitor for safety. You don't need an inductor to limit the current here because the transformer will do that. This welder should be designed so that in a short circuit condition on the output, it will only draw within the vicinity of 1800 watts, give or take, probably less. It will likely never blow a 15 amp breaker by itself in normal use.

[@otcbar4122]

You said at (5:38). and I quote you directly: "...you don't want a *_too_* high resistance, 'cause you don't want, you know, it sucking up any of your power and producing heat and burning up, so..." Surely, the resistor would "suck up" power, only if its value was too low. Not too high. And yes, I know you are referring to the discharge resistor here. Personally I would have used a resistor with a much higher value, say 10K. So long as the capacitor discharges in less than an hour, that would be fine for me. It's not as if a 50V jolt will kill you. A 160 ohm resistor is going to draw around 3 amps at 50 v by the way. And that is way too much for me. That much will definitely affect the welding profile of the machine.

[@Bodragon]

Yeah, that was me. Was logged in under my alter-ego.

[@unigrampa]

My mistake, must've misspoke. Didn't end up putting on a discharge resistor anyway. Did I say 160 ohm? I was probably just yelling numbers, didn't do any math as I hadn't planned on adding one. Although I think you may be mistaken on the 3 amp number. V/I*R. Ought to be 50v/160 ohm = 310 ish milliamps. I usually delete discharge resistors where they are installed because I'm a madman

[@nakedshorts6784]

I'm trying to do a conversion of a lincoln mig pac 100 to run off my dc gas powered arc welder, and turn it into a suitcase welder. It just wont make a good weld from generator power. I will still have 110v to run the spool. What do you think this will take to accomplish ?

[@unigrampa]

If I'm understanding you correctly, your DC stick welder is powering the MIG gun directly. The harbor freight welder is 90 amps at something like 40 volts. You would want to check the output of your stick welder and see what voltage and current it delivers. Very possible the current limit is too high or the voltage is too low or something. I don't think it would be very difficult to get this setup to work though. Power is power; if you can match what the MIG welder was designed for, it'll work as it did from the sales floor.

[@nakedshorts6784]

@@unigrampaThanks for the reply,,, No, the mig unit is 110v ac, I had a look inside and found that the power selector switch is on the ac side.Then it goes to the bridge rectifier and capacitor, transformers etc.What I was thinking is to take that stuff out. Bring the welding leads in from the dc welder. So I would have to put in a control system of some kind for voltage, I think. A bit of a science project to say the least

[@unigrampa]

Yes that's what I mean. The output on the harbor freight welder is not the 110 vac that goes in. The output is 40 volts. Only control you'd really need is current limiting, which your stick welder should already have. Just keep it low.

[@sitwithabook]

I needed to lengthen the main wires for the placement of my bridge. What is the best way to join wires? I would normally use crimp connectors, but the wire is too thick. Solder?

[@unigrampa]

Good question. The amperage is high so we have to be careful how we join these. Even if we had a crimp connector big enough, it might get screaming hot if it's less conductive than the wire. On my welder, I fed some wire into the machine so it was long enough inside. If possible, I recommend you do this. I have soldered thick wires before, this is likely the lowest resistance option, but it's a pain. Normally I use an iron to apply solder to the outside most of the way around. Then I add extra flux and use a torch. If you go for the torch first, it will oxidize the wires and solder will never stick to anything. The final and maybe easiest option is to get some sort of ground clamp from the hardware store. Insert both wires and tighten the clamp to crush them together.

[@nicksiciliano6088]

Did this extend the duty cycle?

[@unigrampa]

It wont. If anything, it would shorten the duty cycle depending on how well your rectifier is cooled, as that may overheat before the transformer does. The current draw from the transformer is basically the same, it heats and cools at the same rate as before.

[@liamcleghorn5221]

hey mate. Thinking about doing this to my cheap'o Ozito welder (with is very similar to HF). Just wondering if there is a parts list to links for the stuff needed and what wire do you use for the conversion. (new to electronics). Cheers and great video

[@unigrampa]

I haven't made a parts list but I should. I have an amazon affiliate link. I'll look into that and get back to you if I accomplish anything

[@0ddba1l]

Need a video on converting DC mig output to AC for Aluminum TIG and Spool Gun work.

[@unigrampa]

If I ever do anything with TIG, I'll post it

[@0ddba1l]

@@unigrampa OK this is my Mig to spool gun conversion but think I should have also bypassed the rectifier. kzbin.info/www/bejne/bKexmI2liLmBnLM

[@radiusnorth1675]

I realize this is an old post, but I'll try my question anyways, and that is.... will this work if my little 125 amp flux core welder uses an inverter?

[@unigrampa]

Yes. I am surprised it doesnt have a DC function? I wonder if it is possible to bypass the inverter and just shut it off when you want DC.

[@jimcatanzaro7808]

300ohm resistor 20watt should be fine

[@scottmcbride2237]

Most videos that show this. They use multiple compasitors. Most of them use up to 4. And they all say that the more compasitors that you use, the better.

[@unigrampa]

Appreciate the info, I might add more and see what happens

[@tylerhogg2241]

It needs a choke coil. Makes a big difference

[@unigrampa]

Interesting. Resists changes in current. I may have to try that.

[@tylerhogg2241]

@@unigrampa I added a rectifier, capacitor, and a choke coil I made from a microwave transformer to mine and it welds almost as good as my Hobart... the choke coil will definitely help.

[@ColinWatters]

Are we sure the capacitors have any effect? ... Google says the voltage output from a welder is 15-25V when the arc is running. Call it 20V. Lets suppose we want the capacitors to limit ripple to 10% or about 2V at 100A. I=CdV/dt so C=Idt/dV. When 60 Hz is rectified the time between peaks (dt) is about 1/120th of a second. So C = 100*1/(120*2) = 0.4 Farads. Most people seem to be using 10,000uF at most which is 0.01 Farads or 40 times too small. Someone check my maths but I would expect them to have little or no effect. Has anyone looked at the waveform?

[@unigrampa]

You may be right, the capacitor might only have a minuscule effect. Though the capacitor will absorb the peak and lower it a bit, so the peak is wider. If we say 20, then imagine like 18v for 1/40 of a second instead of 20 for 1/120. And even when the capacitor empties, the lowest the voltage will go is the current point on the wave, which is often greater than 0. Even if the capacitor was too small to do anything, you'd still have 16v and then 14v as the power ramps down. I think real DC welders tend to have a larger capacitor bank than this. Honestly, if you find a DC welder with the same amperage, see if you can figure out how many mFds of capacitance it uses. Then, you wont have to do any math. Copy the engineer's homework.

[@cri8tor]

Would it help to use a transformer with the motor that drives the wire to prevent a drop in voltage? In your explanation of the capacitor and how to determine which one is required, why did you choose 0.707? Please consider an update video. Cheers

[@unigrampa]

The voltage drop is necessary to regulate the speed of the motor. Raising the voltage would just make the wire feed too fast. The correct way to regulate speed is with the motors rated voltage with PWM, or pulse width modulation. For our purposes, that's too complicated and expensive, so we'll leave the motor the way it is. Don't remember the .707 calculation offhand. I'll check the video sometime and get back to you with more detail.

[@cri8tor]

That makes a lot of sense. Saw another video by Zero Labs where he added a transformer to his welder. After reading your explanation, I don't think I'll be adding one to my welder. Thank you so much for making this video. Please continue to make more great tutorials and consider getting a cheap tripod to steady the camera. Cheers brother

[@cilismoniker7322]

Would the same rectifier and capacitor be acceptable for the 125 amp version? Or should I be looking for a rectifier with 150 or 175 rating?

[@unigrampa]

You'll definitely want your rectifier rating to exceed the expected current rating if you want any sort of reliability. Any capacitor should suffice, really

[@kaulincurtis9665]

They are the same welder, they just changed the way it was rated.

[@charlesflaco5037]

Dude your video is pretty good but you talk too fast

[@unigrampa]

Gotta hurry so no one gets bored lmao

[@charlesflaco5037]

@@unigrampa im thinking of doing that change to mine, the capacitor you put on is it only one or can you put multiples

[@unigrampa]

I just put one but you can add as many as you want in parallel. After a certain point more capacitance won't add anything. There's a formula for that based on current. But there's no disadvantage to having too many besides massive initial arc. Go wild.

[@charlesflaco5037]

@@unigrampa what about a bleed down resister how do you add it on

[@unigrampa]

Across the capacitor. Just like a load. Make sure it's a high resistance or the resistor will get hot and/or explode when you turn the machine on.

[@chadmoyer1453]

Can you convert DC Tig to AC tig

[@unigrampa]

That's possible but I would probably have to get my hands on a machine

[@chadmoyer1453]

@@unigrampa ok. I was thinking something. I have a a/c 220 stick from harbor freight. Couldn't I retrofit a solinoid for argon and get a air-cooled Tig torch and hook it up and use it as scratch start AC tig? Just asking

[@unigrampa]

That sounds highly plausible. Just verify the output voltage and current on the stick welder is similar to what tig uses. Otherwise, sounds like an easy swap!

[@chadmoyer1453]

@@unigrampa I will check. Thank you.

[@mrz2528]

Thank you for you help

[@SirGuidemere91]

Parts list location please!

[@unigrampa]

Everything I had, I believe, except the rectifier. Just search for 100 amp rectifier, or whatever current you decide is appropriate

[@SirGuidemere91]

I have the 125 amp harbor freight. Idk what would be best tbh

[@unigrampa]

Anything that exceeds that current, 150 amp would probably be good

[@SirGuidemere91]

unigrampa's Laboratory thank you!

[@SirGuidemere91]

unigrampa's Laboratory do I need another capacitor too? Or just the rectifier. I’m lost here but need better welds. Lol

[@Bodragon]

(0:05) - I didn't know that! Really? Very few MIG welders are AC? Then why are they making and pushing these machines out? I don't quite get it. Anyway, I've just received my own "JUBA MIG130" welder machine. It's quite a common one but it's still in the box. I intend to do an unboxing video along with subsequent DC conversion. What can I say? Oh, yes: WATCH THIS SPACE!!!

[@unigrampa]

Yes, AC mig welders really only exist for cost purposes

[@ihatekate08]

unigrampa's Laboratory and welding aluminum lol

[@unigrampa]

@@ihatekate08 I'll take your word for it, I only work with real metals ;)

[@ThePiasvids]

@@unigrampa it

[@dontblameme6328]

Because they are cheap to buy and very attractive to the uninformed.

[@MegaTroyhamilton]

You need 200,000 microferads for a capacitor

[@unigrampa]

How do you arrive at this number

[@CHSElectronics]

"Better than Lucas'?"

[@unigrampa]

His didnt have integrated cooling. The other welder video on this channel shows modifying his.

[@mountainviews5025]

The name doesn't make any sense st all

[@unigrampa]

Angry react