| Electronics > Projects, Designs, and Technical Stuff |
| Homemade IGBT MIG welder with ATX PSU parts. [blown yet again][blown count: 5] |
| << < (14/32) > >> |
| Refrigerator:
Finished the wire speed controller, I had some 555's laying around somewhere but couldn't find them. No big deal because i found a neat little LM393 PWM controller schematic on google and made the speed controller with that. Drew the traces with a permanent marker and etched the board, soldered everything on top because i couldn't be bothered to mirror the layout on the other side and drill the holes. I put dots around the circuit with my marker, those dots are there in case i ever wanted to experiment with feedback so that i'd have pads to solder to. Planned to use a TO-220 MOSFET but the only ones i had were IRF640 and IRF614, which would get way too hot, so i bodged in a NTD70N03R that i pulled from a dell motherboard. My PWM is tuned to 30kHz and the MOSFET stays ice cold. For my wire feed i'm using a VW windshield wiper motor, which seems to have some good torque so the open loop speed control might not be as bad as i had anticipated. |
| strawberry:
is it posible to use TL494 as PWM controller more detailed info for TL494:http://www.ti.com/lit/an/slva001e/slva001e.pdf |
| mikerj:
--- Quote from: Refrigerator on July 02, 2019, 05:35:44 pm ---For my wire feed i'm using a VW windshield wiper motor, which seems to have some good torque so the open loop speed control might not be as bad as i had anticipated. --- End quote --- That going to be a very heavy duty wire feed, but it's a nice choice for an easily found/cheap part to repurpose. Getting/making suitable rollers and assembling then in an accurate, mechanically rigid assembly is key to a decent wire feed, and typically is where all the cheap MIG welders have problems (flexible plastic rubbish held together with self tapping screws). |
| Refrigerator:
--- Quote from: strawberry on July 02, 2019, 06:07:20 pm ---is it posible to use TL494 as PWM controller more detailed info for TL494:http://www.ti.com/lit/an/slva001e/slva001e.pdf --- End quote --- Yeah i saw that but the LM393 circuit is much simpler. --- Quote from: mikerj on July 02, 2019, 06:59:45 pm --- --- Quote from: Refrigerator on July 02, 2019, 05:35:44 pm ---For my wire feed i'm using a VW windshield wiper motor, which seems to have some good torque so the open loop speed control might not be as bad as i had anticipated. --- End quote --- That going to be a very heavy duty wire feed, but it's a nice choice for an easily found/cheap part to repurpose. Getting/making suitable rollers and assembling then in an accurate, mechanically rigid assembly is key to a decent wire feed, and typically is where all the cheap MIG welders have problems (flexible plastic rubbish held together with self tapping screws). --- End quote --- While i was looking up wire feed mechanisms on the internet i found quite a few that use a 24V windshield wiper motors in them. The roller problem was sorted with the help of a cheap skateboard bearing that i welded shut to keep it from spinning, this one will be mounted to the windshield wiper motor and will function as the drive roller. One problem that i came into though is that the bearing is so cheap that the races are not even hard, my dull file bites pretty well into it. I might try quench hardening to see if it helps because as i assume a soft metal drive roller won't last long. |
| tautech:
--- Quote from: Refrigerator on July 02, 2019, 08:27:55 pm ---While i was looking up wire feed mechanisms on the internet i found quite a few that use a 24V windshield wiper motors in them. --- End quote --- Yes because the 24V wiper motor is a good match for MIG welding voltages and simple speed control circuits are needed as the motor is only energised when the handpiece trigger is pulled. --- Quote from: Refrigerator on July 02, 2019, 08:27:55 pm ---One problem that i came into though is that the bearing is so cheap that the races are not even hard, my dull file bites pretty well into it. --- End quote --- More likely you annealed the hardening from it by welding it. |
| Navigation |
| Message Index |
| Next page |
| Previous page |