I have A Harbor Freight Mig-100, same as Harbor Freight Welder 90 amp welder item # 44567, I try to modify it. My question is why DC is better than AC?
Converting a welder from AC to DC
http://www.blinkenbyte.org/welder_co...onversion.html
Harbor Freight Welder 90 amp welder modification results
https://www.youtube.com/watch?v=FEkxQ4PVGLE
I did the modifications that Matt Heere suggested in his YouTube videos and wow, what a difference it makes to this little welder. Once I get some time back at the stick and get some good techniques built up again I have no issues with the idea of welding 3/16" soft steel. Check out the video, then check out Matt's two 9 session series on modification to the H/F 90 amp flux wire fed welder. It makes the cheap little (as low as $80 on special sales) into one heck of a welder. Doing a crappy weld, and then pounding on the weak side with a hammer in a vice, and nothing, didn't even bend the weld. Amazing.
https://youtu.be/NoYN4vx1WU8?list=PLd...
Update: Last night I ground the weld down and had to grind a ways into the original metal to get the weld to finally break. I did a T weld next, all the way around the base where the one bar set on the bottom bar. I set it on its side and pounded on the weld with a 4 Lbs. hammer. The bar bent! The weld held strong.
Update: I've been watching a lot of YouTube video's on how to weld with a flux core and MIG welder. That certainly helped because the weld on the T looked so much better, almost dime stacking look, and the weld is apparently strong. On about half of the You Tube video's the welder was adamant about cleaning the metal before welding and cleaning the slag after welding before doing a second pass if needed. The other half of the video's the welder would weld, stop, start welding again without cleaning the slag off. I learned really quick that it's MUCH better to clean the metal before welding, after welding, and certainly in between welds. The welds look so much better and appear to be stronger. I will have to curb the urge to just keep welding and instead, take my time, clean the metal and slag, and then continue welding.
Update: As mentioned below in a conversation with another Youtube viewer, I welded a very long bead and the 100 amp bridge rectifier couldn't handle it, and burn up. At first I thought that my HF 90 welder had died, but no, it's just fine. A new 200 amp bridge rectifier was installed, big ... heat sink and fan. Shouldn't have problems with overheating anymore. This isn't the issue with the bridge itself. As Matt mentioned in his video's he's had no problems with the 100 amp bridge, but he welds in short bursts, allowing the 100 amp bridge to cool. That's a problem with wire feed welders, once you get going and the bead is looking good you have a tendency to just keep going - bad for the bridge! The 200 amp bridge should resolve that issue, along with me taking more breaks and just simply slowing down.
Update: Adding a bleeder resistor - To determine what size bleeder resistor you may want to use to safely discharge the capacitor on your HF 90 DC modification, I found a nice Excel spreadsheet on Digi-Key's website.
The URL is: https://www.digikey.com/Web%20Export/...
Open the spreadsheet. It's pretty self-explanatory but in a nutshell you enter the capacitor value, the maximum voltage the cap will be charged to (we know this to be around 45 volts from Matt's comment in his videos – you can use the cap max if you wish for extra safety), and we need to know what the safety threshold voltage of the cap is. I used .1 volts just to see what it would take to get to that point (pretty much as close to full discharge as possible). My values are 56000uf for the cap, 45 volts' initial charge, and 0.1 safety threshold with a 2000-ohm resistor. The calculator revealed that it will take about 11 ½ minutes for the cap to discharge. The more important part is that the resistor will dissipate at 1 .6 watts. I picked a 10-watt resistor so it'll pretty much last forever and I can live with the 11 ½ minutes for discharge. I always treat the welder as hot because in the older versions of the HF 90, the tip is always hot when the power is on. Within a ¼ of an hour after power off the welder should be plenty safe. Now let's change the value for the resistor to 150 ohms. The power dissipation by the resistor will need to be 13.5 watts – that's going to go past my resistors capability and pretty quickly burn up the resistor, not to mention that while the welder is running that resistor is putting out 13.5 watts of heat continually! That's power that could be going into my weld and that resistor is going to be very hot, which presents another danger. On the positive side, the cap would be discharged in just over 51 seconds. The choice is yours for how quickly you wish the cap to discharge and how much power you wish to be dissipated by the resistor while your welder is running.
Can I use Plasma TVs diode?. How can I use IGBTs do current regulator?
I try to do a little bit improvement of his welder. My budget is $10.00....................
#374 Harbor Freight 90A "MIG" welder upgrades
https://www.youtube.com/watch?v=ozjFq5KXm1U
Converting a welder from AC to DC
http://www.blinkenbyte.org/welder_co...onversion.html
Harbor Freight Welder 90 amp welder modification results
https://www.youtube.com/watch?v=FEkxQ4PVGLE
I did the modifications that Matt Heere suggested in his YouTube videos and wow, what a difference it makes to this little welder. Once I get some time back at the stick and get some good techniques built up again I have no issues with the idea of welding 3/16" soft steel. Check out the video, then check out Matt's two 9 session series on modification to the H/F 90 amp flux wire fed welder. It makes the cheap little (as low as $80 on special sales) into one heck of a welder. Doing a crappy weld, and then pounding on the weak side with a hammer in a vice, and nothing, didn't even bend the weld. Amazing.
https://youtu.be/NoYN4vx1WU8?list=PLd...
Update: Last night I ground the weld down and had to grind a ways into the original metal to get the weld to finally break. I did a T weld next, all the way around the base where the one bar set on the bottom bar. I set it on its side and pounded on the weld with a 4 Lbs. hammer. The bar bent! The weld held strong.
Update: I've been watching a lot of YouTube video's on how to weld with a flux core and MIG welder. That certainly helped because the weld on the T looked so much better, almost dime stacking look, and the weld is apparently strong. On about half of the You Tube video's the welder was adamant about cleaning the metal before welding and cleaning the slag after welding before doing a second pass if needed. The other half of the video's the welder would weld, stop, start welding again without cleaning the slag off. I learned really quick that it's MUCH better to clean the metal before welding, after welding, and certainly in between welds. The welds look so much better and appear to be stronger. I will have to curb the urge to just keep welding and instead, take my time, clean the metal and slag, and then continue welding.
Update: As mentioned below in a conversation with another Youtube viewer, I welded a very long bead and the 100 amp bridge rectifier couldn't handle it, and burn up. At first I thought that my HF 90 welder had died, but no, it's just fine. A new 200 amp bridge rectifier was installed, big ... heat sink and fan. Shouldn't have problems with overheating anymore. This isn't the issue with the bridge itself. As Matt mentioned in his video's he's had no problems with the 100 amp bridge, but he welds in short bursts, allowing the 100 amp bridge to cool. That's a problem with wire feed welders, once you get going and the bead is looking good you have a tendency to just keep going - bad for the bridge! The 200 amp bridge should resolve that issue, along with me taking more breaks and just simply slowing down.
Update: Adding a bleeder resistor - To determine what size bleeder resistor you may want to use to safely discharge the capacitor on your HF 90 DC modification, I found a nice Excel spreadsheet on Digi-Key's website.
The URL is: https://www.digikey.com/Web%20Export/...
Open the spreadsheet. It's pretty self-explanatory but in a nutshell you enter the capacitor value, the maximum voltage the cap will be charged to (we know this to be around 45 volts from Matt's comment in his videos – you can use the cap max if you wish for extra safety), and we need to know what the safety threshold voltage of the cap is. I used .1 volts just to see what it would take to get to that point (pretty much as close to full discharge as possible). My values are 56000uf for the cap, 45 volts' initial charge, and 0.1 safety threshold with a 2000-ohm resistor. The calculator revealed that it will take about 11 ½ minutes for the cap to discharge. The more important part is that the resistor will dissipate at 1 .6 watts. I picked a 10-watt resistor so it'll pretty much last forever and I can live with the 11 ½ minutes for discharge. I always treat the welder as hot because in the older versions of the HF 90, the tip is always hot when the power is on. Within a ¼ of an hour after power off the welder should be plenty safe. Now let's change the value for the resistor to 150 ohms. The power dissipation by the resistor will need to be 13.5 watts – that's going to go past my resistors capability and pretty quickly burn up the resistor, not to mention that while the welder is running that resistor is putting out 13.5 watts of heat continually! That's power that could be going into my weld and that resistor is going to be very hot, which presents another danger. On the positive side, the cap would be discharged in just over 51 seconds. The choice is yours for how quickly you wish the cap to discharge and how much power you wish to be dissipated by the resistor while your welder is running.
Can I use Plasma TVs diode?. How can I use IGBTs do current regulator?
I try to do a little bit improvement of his welder. My budget is $10.00....................
#374 Harbor Freight 90A "MIG" welder upgrades
https://www.youtube.com/watch?v=ozjFq5KXm1U
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