Thunderbolt 225V DC conversion...

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Now that I have my Miller 225V AC only unit all cleaned up and working flawlessly I intend to convert it to DC just like the project on my Lincoln Tombstone 225.I poured all over the AC/DC (older) welders and found that the AC component might be up to 225 Amps but the DC is always off the lower leg and maxes out at 150 Amps.Even the Miller equivalent AC/DC unit clearly shows this on page 21 of this manual :http://www.millerwelds.com/om/o316_mil.pdfhttp://www.millerwelds.com/om/o316_mil.pdfWhy do they take the DC of the LOW Amp range 30-150 range, why now use the HIGH Amp range 40-230, are there no applications in DC welding that would require higher welding Amp than 150 ?
Reply:The low range tap has a higher OCV - could be why they do it?Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:i just got a thunderbolt 225 for free but the leads i believe they are called were home made ( the parts that plug into the machine "low,high,work) id like to get proper parts not homemade stuff so a direction of where to get them would help out a lot.CAR OBD2 SHOP
Reply:Yellow pages. Welding supply.Bubble gumTooth pixDuct tapeBlack glueGBMF hammerScrew gun --bad battery (see above)
Reply:Or Craigslist, that is where I got mine, good quality used is always cheaper.
Reply:Originally Posted by freckuNow that I have my Miller 225V AC only unit all cleaned up and working flawlessly I intend to convert it to DC just like the project on my Lincoln Tombstone 225.I poured all over the AC/DC (older) welders and found that the AC component might be up to 225 Amps but the DC is always off the lower leg and maxes out at 150 Amps.Why do they take the DC of the LOW Amp range 30-150 range, why now use the HIGH Amp range 40-230, are there no applications in DC welding that would require higher welding Amp than 150 ?
Reply:I went and measured the OCV on my Thunderbolt 225V :The OCV on low range 30 - 175 is 78.3V - 85.6V, high range 40 - 225 is 55.1V - 60.3VIf I take the DC conversion off the HIGH range, is the OCV high enough for DC operation without the rod sticking ?
Reply:You will loose 2 to 3 volts ocv, with the voltage drop caused by the diodes.Limiting welder output in DC may have something to do with the duty cycle limit of the transformer.
Reply:Why would you want to use the high range?With 60 volts versus 85volts the 85volt side should weld much better after pushing all that current through the diodes and inductor.I usually weld with the low side of my craftsman buzz box when possible, higher OCVs make striking the arc easier in the presence of rust, paint, mill scale or restarting a partially burnt rod.Last edited by mad welder 4; 01-21-2014 at 01:20 PM.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:Since we're on this topic, any idea why Lincoln's AC/DC-225 only puts out 125 DC amps, while the Thunderbolt's is 150 on the older model and 160 now on the new models?  Is it that much more difficult or expensive for Lincoln to bump up their DC output to 150?  I don't understand that. Are they not basically the same machines, minus tapped vs continuous settings?Lincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member
Reply:Frecku,Keep us posted on your conversion progress. I have the same machine and the parts to do the conversion, just got to get family and medicaid issues out of the way to get back in the shop. I also scored a Miller inductor for an AC/DC machine to add to the mix, and just recently I also scored an old Craftsman high-frequency box to add on as well. Main issue I will have in finding room to squeeze in a fan, as I will have to remove the original fan to make room for the bridge and inductor. Might even have to mount some external fans. Mount all this on my vertical cart to get around the property...A few more hundred$ in cables and a TIG torch and I'll have a great all around setup. Also thinking of converting the connectors to Twecos unless I can find room to mount Miller style in the HiFreq box.Mike "Dodis"Century 135 MIGMiller Thunderbolt XL AC (working on DC converter) (SCORE! got a H/F box off eBay for this one too) now gotta get busy!!! Harbor Freight 130 TIGOxy/Propane Victor Torch
Reply:Awesome set up dodis!!!  Love that hand truck! Not to hijack but, I did a similar set up with my hand truck and a red machine, but I like your truck better with the casters and the fact the machine just "sits" there snugly.  My box is bolted to the bottom of the welded base.Frecku, please keep us posted on your conversion.  If possible, can you take pictures of the internals when you've  installed all of the components?  Also, where did you find the majority of the necessary components for your "DC upgrade"?  Thanks. Attached ImagesLincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member
Reply:Originally Posted by SuperArcSince we're on this topic, any idea why Lincoln's AC/DC-225 only puts out 125 DC amps, while the Thunderbolt's is 150 on the older model and 160 now on the new models?  Is it that much more difficult or expensive for Lincoln to bump up their DC output to 150?  I don't understand that. Are they not basically the same machines, minus tapped vs continuous settings?
Reply:Originally Posted by InsanerideThis may not answer your question but, keep in mind that the DC (RMS) average is the square root of 2 divided by 2 or 0.707 times the measured AC voltage. Its like if you had a big boob and the tip is the AC peak but if you stick your face on it , it squishes and the peak drops but you get the RMS or 0.707 percent average. Something like that
Reply:Originally Posted by MinnesotaDaveActually, I think that's how bra sizes are determined
Reply:Originally Posted by freckuI poured all over the AC/DC (older) welders and found that the AC component might be up to 225 Amps but the DC is always off the lower leg and maxes out at 150 Amps.Even the Miller equivalent AC/DC unit clearly shows this on page 21 of this manual :http://www.millerwelds.com/om/o316_mil.pdfhttp://www.millerwelds.com/om/o316_mil.pdf:
Reply:Originally Posted by InsanerideActually, its how to get you to pay attentionJust think of how much better kids could learn gaussian distribution if it was called a Boob curve instead of a Bell curve.
Reply:Originally Posted by Insaneride DC (RMS) average is the square root of 2 divided by 2 or 0.707 times the measured AC voltage.
Reply:Originally Posted by MinnesotaDaveI see some math teacher long ago forced your skull to continue thinking in terms of rationalized denominators Because of calculators and computers nearly eliminating simplification by hand, the equation would now be written:(I used amps instead of voltage)Since they are both equal to each other, neither is more correct - unless it's a testing day - then simplification is required
Reply:Originally Posted by InsanerideYou are correct MDave, I complicated it but if I wanted it simple, I could just say : multiply times 0.707 to get RMS. Its the same as dividing by square root of 2.
Reply:I dont use an Iphone anymore. Expensive cell phones are deliqut.  Thanks for the info on Selenium diodes.
Reply:dodis & SuperArc, Good pic's and great ideas on your hand truck/welding cart. I've been trying to think of ways of making my machine more mobile.Thanks guys.
Reply:Maybe some dilithium crystals Scotty for full power. So you can achieve warp drive.Miller Dailarc HF 250 Hobart 140
Reply:Originally Posted by Warroad140Maybe some dilithium crystals Scotty for full power. So you can achieve warp drive.
Reply:For $230.00 shipped you can do this.....  http://www.proto-power.com/dc_cheater.htmlMiller 211Hypertherm PM 451961 Lincoln Idealarc 250HTP 221  True Wisdom only comes from Pain.Originally Posted by Warroad140Maybe some dilithium crystals Scotty for full power. So you can achieve warp drive.
Reply:Heres an example of AC peak voltage vs. RMS DC equivalent voltage (root mean square) . Notice how V peak looks like a boob and RMS is flattened out.
Reply:I was hoping for all the parts to get here and have the build this week-end, unfortunately no go. I will most certainly post my project when I start.It will be an exact duplication of of the build I made to my Lincoln 225. As one post mentioned the space in the Miller Thunderbolt is very limited, it will take a lot of moving to cram all the parts in, it is worth it though. I love the great bif nfan as opposed to the tiny on on the Lincoln 225.I did come across this link  too :http://www.proto-power.com/dc_cheater.html In my mind the greatest disadvantage other than the $230 is the 110V cord, now you have to deal with two extension cords.
Reply:I thought about making a cheater box but went with an internal dc rig because my big craftsman has a ton of unused internal space. And like you said it would require an extension cord too.
Reply:In the mean time here is a link to my Lincoln 225 DC build while I wait for the Miller parts :http://weldingweb.com/vbb/showthread.php...nversion-to-DC
Reply:SuperArc,I have mine bolted in as well, used some pipe clips wrapped around the uprights and bolted through at the top of the welder, can barely see them in the pic. Used 5/8" round bar to make a new axle, located low enough to match the casters on the front, also makes it easier to tip the cart back for big moves, with some solid 10" wheels from 'China' Freight. To mount the HF unit, I plan to move the center cable hanger up to make room for a shelf for the HF unit.I got lucky on the diodes, our radio/electronics guy at work (now retired) had a bunch in his spare parts bin, he gave them to me as long as he can have use of the welder when needed. I don't have pics but the threaded portion for the mount is at least 3/4" dia., so I don't think I need to worry about burning these up. Probably melt down the windings first!  And have been gathering aluminum plate scraps to build the bridge/heatsink on.Then, I run eBay seraches now and then and found the inductor coil for a Miller AC/DC machine (new), got that for $100. Radio guy checked it out of curiosity, 2.56 Henrys.Then, another recent eBay search and landed a Craftsman high-frequency box for $78 shipped! Now all I need are the fans, probably shoot for some good size muffin fans, mount one on each side outside the louvers pushing in. And of course, the time to do all this... Family matters and hospice to deal with first.Mike "Dodis"Century 135 MIGMiller Thunderbolt XL AC (working on DC converter) (SCORE! got a H/F box off eBay for this one too) now gotta get busy!!! Harbor Freight 130 TIGOxy/Propane Victor Torch
Reply:Getting ready to post the Miller 225V Thunderbolt conversion this week-end. Unfortunately postman decided to deliver my parts package to someone else, so much for trackig, it says it is delivered..........
Reply:I am ready to type the conversion build, since this tread is getting rather long should I open a new post ?
Reply:Originally Posted by SuperArcSince we're on this topic, any idea why Lincoln's AC/DC-225 only puts out 125 DC amps, while the Thunderbolt's is 150 on the older model and 160 now on the new models?  Is it that much more difficult or expensive for Lincoln to bump up their DC output to 150?  I don't understand that. Are they not basically the same machines, minus tapped vs continuous settings?
Reply:I was doing vertical and overhead today with AC. Why cheat?   Arcblow will bite you anyway.What I need is an insulated, LP/electric, rod oven. edit, missed page 2,Last edited by tanglediver; 01-31-2014 at 10:57 PM.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:Conversion part one...First the transformer, obviously make sure it will fit, you have to remove the core, a saws-all works great.Once the ends are cut off punch out the core in on single block, if you punch out a piece at a time the glue or lacquer holds the strands against the walls  making it a pain.Here is the final product ready for winding.End of part one............
Reply:Part two.............The original front of the Miller Thunderbolt 225V,the top of the welder with the adjustment shaft,the bottom part, I got a new motor , the original worked but was on its last legs, rattled a lot. What this picture fails to show is how close the blades come to the terminals, it is really 1/4"By the way they bend really easy, remove the motor when doing the install. I tried to go around it and constantly bent the blades.The first terminal post is the ground, second is the low, last is the high, you can see two copper rings.And the new front plate, DC terminals on the right with red being +pos.end of part two..........
Reply:part three...........Building the frame holder for the six bridge rectifiers, they have to be close together, the cables also have to be of exact same length.Zip ties make it more manageable, at the ends I have #2 connectors that tie in to a #2 automotive battery cable, the ends are #1 lug nuts with 1/2" eye. Of course everything is heat shrunk to prevent short.end of part three...........
Reply:part four..........I decided to wind my own arc current smoothing reactor/choke/inductor on a used microwave oven transformer core. I also decided to omit any type of arc voltage smoothing capacitor because I figured the inductor would be sufficient on its own and much cheaper. I wound it with 2 AWG stranded automotive cable.One leg goes down to the DC +pos terminal, the other to the bridge rectifiers.another angle, ready for the bridge rectifier frame.Now finally the #2 cables that bring all this together :top lug DC +poslower lug DC -negfirst inline lug groundsecond lug low rangethird lug high rangeI am pulling the power from the second lug, low range. notice the big loop on the cable, this is intentional, it will reach the third lug, high range. If I need more power I will simply move the cable over.other angle securing DC +pos up leg to choke,and finally all put together, it still looks spacious but there is really very little space because of the fan, I would have liked to put on the right but there was no way to avoid the blades hitting the cables.end of part four..............
Reply:part five............another picture of the terminals, I tried to take a picture while on of the spinning fan blades to show how close they came to the terminals, all I got is frame freeze, the reading is OCV DC at 75 Amps.Finally a table of OCV at LOW/HIGH range, the numbers in red represent the DC leg. Tested and all works well, I would definately recommend this project if you pick up a cheap AC only welder.Exact same principles were used in converting my Lincoln 225.http://weldingweb.com/vbb/showthread.php...nversion-to-DCend of part five..........final post
Reply:Great work, Frecku!Though I already have an AC/DC Thunderbolt I appreciate you documenting these conversions and sharing the information. It shows some folks how "unscary" electricity is with some knowledge and some research to fill in the gaps.GravelThe difference between theory and practice is that in theory there is no difference.
Reply:Another job well done - were did you get the transformerThe main thing is not to panic or get excited Bobcat 250, X-Treme 12VS,  MM211Meltabo, Milwaukee,Porter Cable,Dewalt,MakitaVictor O/A, Ingersoll-RandEvolution Rage2, 40 amp PlasmaLincoln 225 AC/DC
Reply:The transformer I got from Ebay only because I could not find any on Craigslist, size is 4 x 2 1/2 x 3 1/2 high, found this one on the side of the street on garbage day,, wire harness will com in handy too.
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Reply:Do the rectifiers get hot?
Reply:They will but they are close to the fan and on a heat sink. Of course it depends on Amps and duration of weld. I guess I could take off the skin and take an infrared reeding.
Reply:Originally Posted by freckuI decided to wind my own arc current smoothing reactor/choke/inductor on a used microwave oven transformer core. I also decided to omit any type of arc voltage smoothing capacitor because I figured the inductor would be sufficient on its own and much cheaper. I wound it with 2 AWG stranded
Reply:Originally Posted by hildstromfrecku,Please don't use ideas from my project, ask for my help in numerous emails, and then copy text verbatim from my web page without providing any sort of credit, attribution, or link. You did a good job on your conversion, but presenting the ideas and work of others as your own is very disrespectful. Also, it may be helpful to others if you would share the various sources that inspired and influenced your project. This one comes to mind:http://hildstrom.com/projects/ac-225/index.html
Reply:I have tried 4 to 5 loops of 2ga, it wont do squat.I recomend doing 2 out puts, one with inductance so you can run 7018 and especially for 6010. And one receptacle with out inductance for stuff like 7024, 7014, 6011 and other rods that run great on AC.The choppy rough pulsations of AC or rough unrefined DC agitate the weld puddle more and bring stuff you dont want in the filler to the surface better.   To make an effective inductor you need at least 20 turns, even then dont expect 6010 to run that well. Realistically you need something wit h about 50 turns.You absolutely want to use a laminated core of some kind. You can use multiple high number turn inductors in parallel. I used 6 inductors with 48 turns each wrapped with 12ga wire in parallel. They work great and barely heat up at all running 5/32 inch 7018.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:You could cut the cross piece off of two oven transformers and mate the cut ends if you have room.It would give you more room for windings.You could also wrap the windings around the outer shell legs and hook them in series.