Harbor Freight Flux Core: DC Conversion and Testing

well folks out here in the garage again messing around with the 125 amp flux core welder from Harbor Freight I've already done some videos showing some testing of this welder and I talked about the AC output and how I think that's holding it back quite a bit so in this video I'm going to see how much better it does if you convert it to a DC output in basically the simplest way possible now a lot of people have converted this machine over to DC output and some of them will put capacitors in there or chokes or things like that to try and smooth out the arc and you know just get the best results they can but today I'm going to be doing it in basically the simplest way possible I'm just going to install a simple rectifier bridge full wave rectifier to convert the AC from the transformer into DC output and that's it I'm not going to put anything else in there and then I'll do some test welds cut match and just kind of see what results we get just so that we can see how much this Walter can be improved with just basically the bare minimum of DC conversion now a lot of people talk about using either a hundred or a hundred and twenty eight rectifiers and I think that's mostly for the 90 amp version of this welder but as I've said in my other videos the 125 amp welder is essentially the same it has the same 90 amp rated output an 125 amp max output specification they just put a different number on the box and sure enough I saw you know reports of the one hundred and hundred and twenty amp DC rectifiers burnin out in some cases that people have used so I definitely wanted to go higher than that and also as my testing has shown with this welder it can put out 140 amps plus under the right conditions so I certainly wouldn't go with anything less than 150 amp rectifier but I just went ahead and went with the next step up which is a 200 amp just so that in theory at least this should be plenty but we'll find out and just a note if you are going to be doing this conversion or you want to you know convert your welds with DC make sure you factor in all the little odds and ends you're going to have to have for the conversion before you make up your mind on whether or not it's worth doing it hopefully we find out that we get satisfactory results with just the rectifier and we don't have to put extra capacitors and all that in there but even if that's the case you know this is only you know 18 to 25 dollars depending on where you find it but you're still gonna want you know some pieces of wire you're gonna want some terminals some hardware to bolt this down you know some little odds and ends of tools and supplies so if you already have all that and great but if you don't just you know bear in mind there are a few other little things that you'll need other than just the rectifier and most of that stuff doesn't amount to much but you know depending on where you can actually find it and all that it can add up a little bit so just make sure you factor everything in for me all I really bought was the rectifier some ring terminals to connect to the rectifier and some wire that I'll be using inside now I'm not really intending for this video to be you know an in-depth how-to as far as this conversion process mostly I just want to do the testing after the conversion to see how much performance we gain or if we gain any performance after the conversion but it is fairly simple on the rectifier you just have a seat irma NAL's on the one side and your DC output terminals on the other side and they are labeled negative and positive and all you really have to do is put this in series with the output so here we have the output from the transformer that goes to the work clamp and here we have the output of the transformer that goes to the mid gun that powers up the contact tip so all you really have to do is just basically cut these wires hook the two outputs from the transformer to the AC side of the rectifier and then hook the work clamp to the positive side of the rectifier and the wire feed side to the negative terminal of the rectifier so I'll get started doing that I'll show you what I come up with and then I will put the welder back together and do some testing and see what kind of results we get okay so I got all the wire splicing done on this side and the wire up here from the transformer that feeds the big gun I have that cut and spliced with the two wires again that go over to the rectifier I got those soldered together with some heat shrink tubing on the joint and I'm actually going to mount the rectifier over on the other side a little bit more room over there also these little wires that go up to the controls those come directly off of the output of the transformer so you definitely want to make your splices after those wires or basically either way just make sure that these wires end up at the end on the AC side and on this side once again I got the wires all soldered and heat shrink tubing onto the terminals and I've only got the AC side landed so far I'm actually going to have the rectifier mounted right here it's going to be bolted to this side panel so basically I'll screw it to the side panel and then just slip the side panel in place and screw it in now these rectifiers do have a metal plate on the back and that is essentially a heatsink this will get hot and that's how the diodes inside will actually dissipate heat is through this plate now depending on you know duty cycle and how close you're running to the diodes capability that kind of thing they may build up more or less heat but it's still a good idea to have these bolted to something metal that can pull that heat away you know heat sink is technically ideal but in this case I'm just gonna have it bolted to the side panel which is metal and will kind of help dissipate the heat also the airflow from the fan will be kind of blowing through that panel all the time so hopefully that should be enough heat sink if I find that it's getting too hot you know maybe I'll do something about it but with it bolted directly to that panel you know I can check with my temp gun after I use it and just make sure that that's not getting too hot but at this point we're just about ready to go I just have to get the wires kind of arranged how I want to go so that I can get the rectifier in there drill some holes in the side panel get that mounted and then we can fire this thing up and do some testing okay so I'm all finished up you can probably just barely see the rectifier there kind of behind all those wires it is just screwed to the side panel back there so everything's wired up and ready to go I just have to put this last side panel on the welder and I will fire it up and do some testing see how it does okay so I got the machine together and did some welding with it and I have a couple of sample joints here that I will go over in a second but I just want to say that the way I did this conversion was the simplest possible pretty crude all I did was put a rectifier in it so it doesn't run okay but you get a little bit of stutter at the starts and the arc is pretty rough it's not very smooth or anything so hey you know it's definitely the simplest crudest way to do it because you know this is a cheap welder and you know just the cost and the simplicity this welder is what makes it popular so while they're definitely more things you could do to make the arc better but I just wanted to see what kind of results I could get with just the simplest DC conversion also that rectifier bridge does get pretty warm I do have it bolded to that side plate of the case so that does give me some heat transfer and as long as I didn't do you know just back-to-back long runs the temperature stayed okay I didn't get any hotter than about 140 degrees or so but if I had a big project where I was doing a lot of continuous welds I would probably want a an actual dedicated heatsink on that so there again you know just something to keep in mind you know for as far as complexity and cost and stuff if you're actually going to do this you might just want to keep an eye on those temps or just get a dedicated heatsink for that but now let's take a look at the results first off this is a joint that I did with the welder in stock form I cut niche this for the last video but this was done with the the welder with AC output and sorry it's starting to kind of corrode because the stuff I put on there to etch it has been sitting on there for a while so it's kind of corroded but you can still get a good idea of the weld really kind of NotI and right at the toe super high crowned bead not a whole lot of penetration there's actually a hole down here at the root and then a lid just a very little bit of penetration on this upright portion but really not a lot of penetration and this was actually the best penetration on 3/16 material I was able to get with the welder in its stock form with AC output and on this side you can see this was with the welder turned down just a little bit and in this case definitely didn't get down into the root virtually no tie-in on this bottom piece and only the tiniest bit on this vertical section so again this is how the welder did originally with AC output really high crowned welds not a lot of penetration not getting down into the root like I said this was about the best I got on 3/16 material with the welder stock after installing the rectifier and converting to DC you can see a pretty different story now this was with the welder maxed out and this was with it turned down just a little bit to get just a little bit smoother arc and a little bit flatter bead and you can see in both cases I got pretty decent penetration again this was with the welder turned down a little bit not super deep penetration but it is tied in all the way along and all the way right to the toe on both sections it is tied in right to the toes not super far into the root but you know but it does it does go down in there you know there might be a little bit of a lack of tie in right there so maybe not super deep down into the root but not too bad so even even turn down a little bit for a flatter bead profile we are getting a lot better penetration than we did with any kind of settings or travel speed or anything like that when the welder had AC output now over here the welder was maxed out and I do have a little bit higher crown of a bead but not too bad certainly not as bad as we had on AC with a lot of the welds but you can see pretty darn good penetration the penetration right here at this toe is very shallow but I don't think there's a total lack of fusion there in fact if I kind of draw a line there you can see you know it is tied in all the way to the toe there so not a ton of penetration but it is tied in all the way to the toe definitely tied in all the way to the toe here and I flipped the part because of the way my light was but you can see definitely getting down into that root with the welder maxed out so after converting to DC definitely a lot better penetration not quite as good as you know a factory DC output welder or probably not as good as you could get if you put a little bit more time a little bit more components into fully converting this welder but it just goes to show that even with the crudest form of DC output on this welder there pretty significant difference in the penetration and weld profiles so that's pretty much it I'm not going to do a ton of testing in this video but either way now you have at least one piece of data to know what kind of a difference it will actually make in the end so if you have any questions post them up down below as always thank you for watching take care

Channel: bigtb1717

Views: 39,823

Keywords: harbor freight, hf 125a, harbor freight flux core, hf flux 125, hf 90a flux core, harbor freight flux core dc conversion, harbor freight flux core dc mod, dc mod testing, harbor freight welder dc mod testing, hf welder dc conversion, harbor freight welder, welder dc mod

Id: 87sHpMX8M4E

Length: 10min 45sec (645 seconds)

Published: Mon Feb 04 2019