You can see from the example welds that the DC conversion makes a world of difference on the quality of the welds. New fan holes were made in the case, in retrospect I should have removed the back panel and punched them on my Roper Whitney #218 press, but went the quicker route of drilling the holes. The cooling fan had to be moved down to make room for the rectifier. Also made a sheet metal bracket to mount the capacitor next to the transformer. I chose to mount the rectifier on the back of the case, just looks cleaner to me. I guess that’s probably how Harbor Freight would do it. They mounted the capacitor by drilling a couple of holes in the case and tie strapped in down. All of the examples had the rectifier mounted on the side of the case. One thing I didn’t care for on the on-line conversions is how they mounted the rectifier and capacitor. The weld gun is tied to the capacitor’s – Negative lead. So, the welder’s ground clamp lead is tied to the capacitor’s + Positive lead. For flux-core wire, the welder ground clamp should be DC positive. Those leads run to the appropriate terminals on the capacitor. The rectifier has two output leads + positive and – negative. The transformer output leads each have a small lead that runs to the welder’s circuit board, so the splicing takes place downstream from that point. The conversion is pretty simple cut the output leads from the welder’s transformer and jump them to the AC side of the rectifier. The capacitor I found had a shunt resistor already there, drains the cap in about 3 seconds. The resistor drains the capacitor after welding, otherwise the wire is still grounded and your ground clamp is still hot! Some guys on their conversion discharged the capacitor by touching the wire to the ground clamp expect a nice spark. Found a Siemens electrolytic cap rated at 40V and 47,000 uF for $25 delivered.Īnother important component is a shunt resistor across the two leads of the capacitor. I found a number of eBay sources for the rectifier rated at 1000V and 100A for $10. The videos I watched recommended a minimum 47,000 uF electrolytic capacitor with 30V minimum rating (welder outputs 28V). The capacitor smooths out the “hills” to a relatively straight line or DC output. ![]() The rectifier takes the sine wave AC and flips the negative wave to the positive side so the output looks like “hills” running from 0V to peak voltage and back down, then back up again. The two pieces of hardware needed are a full-wave rectifier and an electrolytic filter capacitor. I did a little web research, watched a few YouTube videos and found that it’s fairly easy to convert these units from AC to DC. All other HF wire feed welders are DC if that tells you anything. ![]() Current flows back & forth from the puddle to the wire which causes the flux-core wire to spatter even more than DC flux-core wire welding. Problem with the stock welder is it’s AC output, not DC. Penetration is poor and there is a lot of spatter. But as my dad constantly told me as a kid “you get what you pay for”.īottom line is the welds look terrible. They’re probably not a bad deal for the occasional weekend welding project, plus the 110V portability is nice. ![]() I have to admit to looking at them too, especially when they go on sale for under $90. I have a buddy who impulse bought a Harbor Freight 90A flux-core wire feed welder.
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