pfrederi 17,893 #1 Posted February 22, 2022 I have a Miller AC/DC Thunderbolt ($35 at auction didn't work well...was wired for 440 fixed that works fine). Bought a Miller 140 MIG welder. But I am not good at welding and welding thin sheet metal has not gone well at all. Picked up a massive Miller 33 Spot welder at auction for $15 (came with a Dayton 1HP electric motor that worked. The auction went 10 hours and these were at the end. I used Proxy Bid) Been sitting for a few months the power cord on the welder looked positively dangerous, so I never tried it. Found a manual on line and it became apparent that it had been modified. Originally it had a timer (dial in the rear) so you could replicate your weld more accurately than counting to yourself. it was missing couldn't find a replacement part...Not surprising since it used 4 Vacuum Tubes (anyone remember pulling them out of TVs and testing them on a big tester some where??) Guess this is old machine.... The timer was gone and there was big mercury solenoid installed. Worked on it for a bit and got the wiring replaced. Had it apart on the bench plugged it in and it tried to weld instantly. I had the solenoid lying down, turns out that when you tip a mercury solenoid beyond a certain point it triggers. Not a great idea for tool you might use at an angle. Picked up a 30amp solenoid for $10 probably won't last as long but I don't weld much and for $10... repair by replacement ...better that having it trigger unexpectedly . Got it together this afternoon did a couple test welds on sheet metal. (in one of the pics) Not bad. Have to get used to timing how long you depress the button. (Now I can work on the GT14 hood) The thing weighs a ton note the length of the straight welding arms that came with it.... 8 4 Share this post Link to post Share on other sites
Maxwell-8 4,310 #2 Posted February 22, 2022 3 minutes ago, pfrederi said: I have a Miller AC/DC Thunderbolt ($35 at auction didn't work well...was wired for 440 fixed that works fine). Bought a Miller 140 MIG welder. But I am not good at welding and welding thin sheet metal has not gone well at all. Picked up a massive Miller 33 Spot welder at auction for $15 (came with a Dayton 1HP electric motor that worked. The auction went 10 hours and these were at the end. I used Proxy Bid) Been sitting for a few months the power cord on the welder looked positively dangerous, so I never tried it. Found a manual on line and it became apparent that it had been modified. Originally it had a timer (dial in the rear) so you could replicate your weld more accurately than counting to yourself. it was missing couldn't find a replacement part...Not surprising since it used 4 Vacuum Tubes (anyone remember pulling them out of TVs and testing them on a big tester some where??) Guess this is old machine.... The timer was gone and there was big mercury solenoid installed. Worked on it for a bit and got the wiring replaced. Had it apart on the bench plugged it in and it tried to weld instantly. I had the solenoid lying down, turns out that when you tip a mercury solenoid beyond a certain point it triggers. Not a great idea for tool you might use at an angle. Picked up a 30amp solenoid for $10 probably won't last as long but I don't weld much and for $10... repair by replacement ...better that having it trigger unexpectedly . Got it together this afternoon did a couple test welds on sheet metal. (in one of the pics) Not bad. Have to get used to timing how long you depress the button. (Now I can work on the GT14 hood) The thing weighs a ton note the length of the straight welding arms that came with it.... Nice machine, could use one to reweld my C141 hood. they are welded that way 1 Share this post Link to post Share on other sites
Achto 27,818 #3 Posted February 23, 2022 4 hours ago, Maxwell-8 said: could use one to reweld my C141 hood. they are welded that way If you have a wire feed welder you can use some blind welds to put that back together. Drill 8mm holes through the old spot welds on the inner piece. Clamp the parts together and weld through the holes that you drilled. I use this method quite frequently. 4 1 1 Share this post Link to post Share on other sites
Jeff-C175 7,203 #4 Posted February 23, 2022 (edited) 1 hour ago, Achto said: Clamp the parts together If ya can't clamp them, clamps not big enough, etc... you can nut and bolt every other hole with some 8 or 10 hardware, even self drilling sheet metal screws work, then weld the open holes, remove the hardware and then weld those holes. Done this myself a few times and it worked pretty good. I used less than 8mm holes though, as I recall, 1/8" Edited February 23, 2022 by Jeff-C175 1 2 Share this post Link to post Share on other sites
