The more I think about it, the more I get the idea that it may be better to build a seperate, portable MIG welder that can run on 120V/20amps and save the space I left in the Arc welder for a future TIG attachment. Fortunately, this change of plans will not result in wasted time/effort.
Reasoning:
1.) The constant current of the arc welder is exactly what you need for TIG anyways.
2.) I could add a variable current footpedal easily to the arc welder for TIG.
3.) TIG uses different gas (argon) on things that TIG is good for (aluminum), so would need another bottle for gas anyways.
4.) Having a portable MIG would be sweet.
5.) I didn't build a spot for the gas canister on the arc welder. Yet.
6.) The arc welder is effin heavy.
7.) Being able to run a MIG on 120V would be really, really nice.
8.) There's easily enough room in the arc welder for an arcstarter, also essential for TIG.
9.) I can wind the trannies for the MIG at the exact voltages I need.
10.) Its soooo easy to convert ATX power supplies to work for what I need on the MIG, but retrofitting the arc welder would be a pain in the ass.
11.) The MIG would be much smaller/lighter, and I can make completely from metal easily.
The only real disadvantage is that I need to scrounge at least 3 more MOTs. I got one today, so..
MIG Welder: part 2
After building my ATX lab supply, I used it to test out my MIG wire speed controller setup.
I think I'll go ahead and use another ATX supply as the accessories supply for my welder.. its just so easy to do.
Seems to be working, the voltages and motor operation seem right when either arc voltage or target voltage is varied. Won't really know though until its installed and tested in the entire MIG welder application.
I think I'll go ahead and use another ATX supply as the accessories supply for my welder.. its just so easy to do.
Seems to be working, the voltages and motor operation seem right when either arc voltage or target voltage is varied. Won't really know though until its installed and tested in the entire MIG welder application.
ATX Power supply into a cheap lab power supply
This is old hat by now and is covered in some web articles. Why build it? I needed the +/-12V to test my welder wire speed control.
Basically an ATX supply scavenged form an old computer, cut off all the wires, install a load resistor, and an LED power on indicator + switch. Good source of ~1 foot lengths of 16 gauge wire as well.
You get +12V, -12V, +5V, -5V, and +3.3V from this supply. The 5V is at ridiculous current - usually 25 amps or more. 12V is usually 15 amps+!
Super easy to do, surely the cheapest way to get a fairly capable lab power supply.
I used terminal strips - most people use binding posts. It's all I had on hand. The REALLY nice thing about this ATX supply I later found out is that the fan speed is temperature controlled - which means most of the time this thing is almost silent.
Basically an ATX supply scavenged form an old computer, cut off all the wires, install a load resistor, and an LED power on indicator + switch. Good source of ~1 foot lengths of 16 gauge wire as well.
You get +12V, -12V, +5V, -5V, and +3.3V from this supply. The 5V is at ridiculous current - usually 25 amps or more. 12V is usually 15 amps+!
Super easy to do, surely the cheapest way to get a fairly capable lab power supply.
I used terminal strips - most people use binding posts. It's all I had on hand. The REALLY nice thing about this ATX supply I later found out is that the fan speed is temperature controlled - which means most of the time this thing is almost silent.
High Voltage DC Power Supply
This circuit generates 10-20kVDC depending on the input voltage using a rectified flyback transformer typically found in Computer CRT monitors. It is suitable for driving HV loads such as Marx Generators and Lifters.
Here is a video of me testing the HV supply - notice that I am only using one hand!! This is good practice even though the current in this case is too low to kill me.
The basic circuit is a 555 timer running astable around 17-18kHz, wired to a Power MOSFET which chops the supply voltage wired to the primary of the transformer.The power MOSFET is a low resistance type (IRFP450) to keep heat dissipation to a minimum. This will reduce the heatsink requirements substantially.
Here is a video of me testing the HV supply - notice that I am only using one hand!! This is good practice even though the current in this case is too low to kill me.
The basic circuit is a 555 timer running astable around 17-18kHz, wired to a Power MOSFET which chops the supply voltage wired to the primary of the transformer.The power MOSFET is a low resistance type (IRFP450) to keep heat dissipation to a minimum. This will reduce the heatsink requirements substantially.
