Diode options

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So I trying to figure out what diodes/bridge rectifier to add dc ability to my recently acquired ad thunderbolt. My main question is about how to wire stud type diodes for said operation (I'm doing it on the low side just FYI.) My secondary question is would it be better to use a bridge rectifier I have been looking at those Chinese single phase 300a 1600v bridge rectifiers and was wondering if that would be better or easier or cheaper. I have also seen people use a bunch of bridge rectifiers wired together to do what I'm thinking.I do plan on being able to switch between AC and DC tig and stick with just a few wire changes and probably make a cover that the inside is easily accessible to make the changes.Any help is appreciated.Sent from my XT1080 using Tapatalk
Reply:I just bought a Lincoln Idealarc AC/DC off craigslist for $100. My suggestion is to be patient and look for a deal on an ac/dc machine. Then sell your ac only machine. I also just sold my AC225S for $100. Total cost to upgrade was many hours searching craigslist and a few gallons of diesel fuel to pick up the new welder.Eventual master of the obvious, practitioner of "stream of consciousness fabrication".  P.S. I edit almost every post because because I'm posting from my phone and my fingers sometimes move faster than my brain.
Reply:I have to agree with sedanman, 200 amp diodes are $50.00 or more each. A decent rectifier should have four diodes, total cost $200.00 just for the diodes plus shipping. It doesn't make sense to try to build a rectifier with so many good deals on CL. Three weeks ago I bought a Century 250 amp stick welder for a $100.00 with 50 foot stinger and ground.
Reply:If you mod your own machine you can run cool options like more or less and no inductance settings, have on demand arc softening for easy restarts on difficult rods and improved cooling.With typical machines you get AC and DC and that's it. And on the Lincoln 225 amp DC machine you get 125 amps, on the Hobart you get 160DCA.If you build your own machine you can have from 90% to the full AC amperage on your DC side like I do.Being able to burn three 18 inch long 3/16 inch diameter 7024 at 230 amps in a row, reverse polarity with no inductance is kind of cool."Single phase bridge rectifier" means it already has the 4 diodes inside it.Where a 3 phase bridge rectifier has 6 diodes.Last edited by mad welder 4; 05-15-2016 at 10:45 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:I agree with mad welder 4 not because I'm being stubborn but I got the welder for free and it has no leads or plug so I doubt I'll get much for it and it wouldn't offset buying one vary much. I am planning on doing things to it anyway such as scratch start tig (maybe a high freq box who but knows that's another topic) so might as well start on a machine I got for free, if I bought it that would be a different story.I asked for advice on the medium of taking AC to DC that would be best to do that not whether it's worth it besides I think I can get neat features maybe for less maybe not but in reality it's about the experience and gaining knowledge isn't it?Sent from my XT1080 using TapatalkLast edited by nerdrage88; 05-15-2016 at 11:24 PM.
Reply:I turned my 100 amp AC only craftsman stick welder to an AC/DC stick machine then converted it to scratch start tig. Now I have the ability to attempt to weld aluminum with my HF box, but only because I want to try to weld aluminum. You can add in a foot switch to do momentary HF start for everything else. Scratch start wears out the tips really fast.If you only want to weld steel then you don't have to have an HF box.You also need to take your AC only machine and set it up so it can be reverted back to use AC if you think you might want to try aluminum.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:I built my DC converter in its own box.I use it with 2 AC welders.It has fans to cool the diodes.I wound a reactor with some fiberglass insulated wire.4 diodes cost $39.I had most of the parts on hand.Final cost was $100.Building the converter takes much knowledge of electronics.A bunch of small bridge rectifiersl wont work,one may carry the load and overheat.Stud diodes have to be mounted on aluminum heat sinks.You need a large capacitor to filter the DC plus bypass caps on each diode.Much better to buy a welder that is AC/DC.Building a converter will cost more than a used welder.
Reply:Well you did help a little but.....did you not read my last post? I'm guessing not....like I said I got the welder for free so I can build what I want on the clean slate that I got. For me it's not about the money, It's about knowledge and knowing how to fix it if it brakes instead of just buying another. Not to mention the cost of the other things like gas and rods and whatnot it's just expensive stuff anyway so there is no getting around that so I might as well learn something and do it on my own instead of relying on the engineering of a guy who is bound by corporate desires, marketing and profit. Oh and the work I have been doing that ended up getting said welder isn't for my profits, I'm doing it to hep out some people to make their lives easier and expand my knowledge and they don't mind the expense.So please I'm not interested in buying I want to build. Anyways off my soapbox. I have a general understanding of the conversion I am looking for specific components that have been found to work and not work to add DC to my AC machine (that was free) then I'll think about adding TIG stuff and increase duty cycle and whatnot. Sent from my XT1080 using Tapatalk
Reply:Settle down son and re read the post you just tore up. The man said he built a seperate box that does what you are looking to add to your welder. The advantage of doing it this way is that it  works with any welder and requires no permanent modification to your machine. Google  "DC cheater" to see an example of a stand alone rectifier.Eventual master of the obvious, practitioner of "stream of consciousness fabrication".  P.S. I edit almost every post because because I'm posting from my phone and my fingers sometimes move faster than my brain.
Reply:Originally Posted by SedanmanI just bought a Lincoln Idealarc AC/DC off craigslist for $100. My suggestion is to be patient and look for a deal on an ac/dc machine. Then sell your ac only machine. I also just sold my AC225S for $100. Total cost to upgrade was many hours searching craigslist and a few gallons of diesel fuel to pick up the new welder.
Reply:I apologize I'm just tired of reading people suggesting just buy (new or used) different form what they got especially when the question had nothing to do with buy a whole different item. And it wasn't just his sorry if it seemed it was entirely directed to that one. As I said it did help but ultimately he suggested it would be better to buy a different machine that already had ad/dc. I will bee checking out this DC cheater. I don't mind not having all this stuff not contained in one unit.Sent from my XT1080 using Tapatalk
Reply:If you Google "Welder DC Cheater" there are lots of builds out there.  I'm looking at doing the same to my AC only welder.  Unfortunately, you can't touch a used AC/DC machine in my area for under about $350.  I can buy all the needed parts brand new for the DC cheater for under $100.Plus I like understanding how things work.  I'm the guy that takes brand new stuff apart just to see what makes it tick.  Guess that's what I get for being raised by an engineer...
Reply:And that's my main point with this project (plus many others) that I will attempt. Even if it fails I learned something. Look up Jamie manzel he is inspiration to being inspired.  Sent from my XT1080 using Tapatalk
Reply:Oh and I wanted to be an mechanical engineer but ultimately decided against it because I didn't want to be bound by a corporations desires. Sent from my XT1080 using Tapatalk
Reply:Also consider packaging. An ac/dc welder needs more than just a few diodes to be a truly good dc welder. Good ones have a capacitor and an inductor (looks like a smaller transformer but functions differently).  A nice stand alone rectifier could be built in an old battery charger case, it's on wheels, typically is fan cooled, has a power cord, and has room inside for all of the components.Eventual master of the obvious, practitioner of "stream of consciousness fabrication".  P.S. I edit almost every post because because I'm posting from my phone and my fingers sometimes move faster than my brain.
Reply:Hmmmm so I could, theoretically, attach another case to one side of the welder (we all know that the thunderbolt is a nice rectangle)  that has the DC stuff in it and maybe squeeze the HF stuff in there. Maybe that would be hard to cool though. I could have a space under the capacitor/s and inductor just like the welder is already and have the fans on the side where the fresh air intake (louvers)  on the right side of the welder and the left side of the DC side, an then the air travels upward thus cooling both sides. I think I'm going to refer the sections as the AC side, the DC side and the HF which, as of writing this, I already have an idea of how it my way to make this a semi compact unit. I might have to make a diagram to show what I'm thinking. Off topic but I also plan to make a lathe because I am not satisfied in what I see with ones that are commercially available so I'll make one and yes I plan to make a furnace to melt iron to pour it into shapes. Ultimate goal is to (again experience) and have all capabilities I want because usually they come with some that I want but not others and design it to be ultra rigid that again some lack. I bring this up because that is another reason why I rathe rebuild than buy that I'll ultimately modify anyway. Sent from my XT1080 using Tapatalk
Reply:So I discovered an HF box isn't hard to do so I think I may just make a side box to the thunderbolt containing the DC stuff and HF. Then internally connect the wires between them and have all the switches and connections on the original front panel. This is the page showing the HF box home built,http://www.casano.com/projects/hfstart/Sent from my XT1080 using Tapatalk
Reply:Thunderbolts have a DC option so why not just GOOGLE that, look at the photo's of the front, study the drawings of the inside then build it.Somewhere at home I have some BIG 200 amp stud mount and some NOT so Big 150(?)'s that need a good home.
Reply:I have....in case you were wondering my original question was about what diodes to use but since has gotten derailed. To many people worried about my money.Sent from my XT1080 using Tapatalk
Reply:If you use the HF booster you linked to, don't forget to add a bypass capacitor.
Reply:Oh since we are on the subject can someone point me to a wiring diagram for a ac/DC thunderbolt to aid in my researchSent from my XT1080 using Tapatalk
Reply:Originally Posted by nerdrage88Oh since we are on the subject can someone point me to a wiring diagram for a ac/DC thunderbolt to aid in my researchSent from my XT1080 using Tapatalk
Reply:Sounds like you'd rather be building a welder, than welding. Nothing wrong with that! Just pointing out that you're reinventing the wheel. You'll still have a noisy buzzbox, choppy DC, tied to 220v, when you could get a dual voltage inverter, new , with a warranty, and a tig rig for under $300. Just add Argon, and you're tigging! I know that doesn't address your question, but I think it may be relevant. Just my 2cents.
Reply:Originally Posted by ForneycatorSounds like you'd rather be building a welder, than welding. Nothing wrong with that! Just pointing out that you're reinventing the wheel. You'll still have a noisy buzzbox, choppy DC, tied to 220v, when you could get a dual voltage inverter, new , with a warranty, and a tig rig for under $300. Just add Argon, and you're tigging! I know that doesn't address your question, but I think it may be relevant. Just my 2cents.
Reply:Thanks for the PDF in normally I look myself I figured by now someone had it already.Sent from my XT1080 using TapatalkJust use Miller receptacles and plugs to attach leads to the machine. I use then on everything welding related.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:I was planning on using them for the + and - where I would put them idk for sure. I would like them on the original front panel. I have looked back at some pics of AC/DC thunderbolts and the inductor is where my fan is. I will replace the fan for a side mounted one, at least the diodes (or bridge rectifier I think I'll go for one of those 300a 1600v deals so if it goes it's an easy swap and I think there like $60 bucks) capacitors and inductor will fit. I figured it wouldn't be to much more work to add a tig after I get the stick worked out. Maybe not but it doesn't seem too complicated. I mean let's be honest a car is more complicated just electrically let alone the other systems that depend on the electrical system. Don't even get me started on tucks.....way more electrical, air, abs...oh boy........bla blaSent from my XT1080 using TapatalkLast edited by nerdrage88; 05-16-2016 at 09:17 PM.
Reply:Adding tig is easy.Get a WP-17V torch, cut the ring lug off and replace it with a miller plug (if that is what you are using) and connect the gas hose to argon."converting to tig" sounds impressive, but once you already have DC putting the tig torch on is the easiest part of the whole process.You will also need to put the diode bridge on a big heat sink with a fan.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:In guessing adding hf is easy also if I build it would be the hardest part.Sent from my XT1080 using Tapatalk