1970's Miller Thuderbolt 225 restoration

[T_Texan254]

Howdy!

I have a Thunderbolt 225 that my grandfather bought in the early 70's and I doubt has burned 20lbs of rods; he got sick in '75 and it sat for about 20 years before I got it and it's been sitting in the barn pretty much since then. Last weekend I pulled the amp control wheel off of it and sprayed a little WD-40 on the threads of the shunt block. It turns fairly easy but I'm wondering whether or not I should buff the rust off the sides of the shunt... remember this thing hasn't been turned on in over 20 years. I need to hook up an air hose and blow the whole thing out, as I removed a double handful of mud dobber nests from the bottom floor of the welder. What should I do to make sure I don't burn it up the first time I plug it in? I have other welders, so I'm not completely ignorant of mechanical workings, but given the sentimental value of this machine to me, I'd like to keep it around and working as intended. Any ideas, thought, suggestions, and/or advice is most welcome- and thanks in advance for your attention.

PS- my machine is similar to the one attached here, but instead of a silver adjusting wheel as pictured, mine has a black one. Everything else is nearly identical.

[H80N]

Those old Thunderbolts are pretty bulletproof.... and simple design... without any control electronics

If you cannot detect any visible damage after a close inspection

I would be tempted to plug it in and run it

[Can You Weld This For Me?]

Blow it out, plug it in and use it. If it's not broke don't screw with it until it is.

[Miller Welders]

It may be beneficial to have the machine checked out at a service station to verify that wire insulation is still intact. You will want to keep the unit clean from dust and occasionally inspect the cables and wires for any damage or age/use-related breakdown. If you'd like to speak to a Service Technician directly about restoration, send us a direct message and we'll get you connected.

[aametalmaster]

Those plastic sockets are known to burn up or break if the cable lug gets melted to them. Doubt if yours are just sayin. I have the AC/DC version just a few years newer...Bob

[T_Texan254]

Just to update, this little welder works like a champ! I know my grandfather must have looked down the afternoon I turned it on and smiled. I burned about six 6011 rods and laid the prettiest bead... just like it's supposed to do! The high output lug was melted to the nut, but I got it off and the front of the machine sanded and repainted, then reinstalled it. I can't see where it would hurt anything: it had to be my braindead cousin who melted it years ago by not knowing what he was doing. But thank you to all who've chimed in! I appreciate the input.

[Aeronca41]

Congrats on getting the old machine working. When they have sentimental value it's a real treat. I still on occasion lay aside my fancy self-darkening hood and put on my Dad's old Jackson from the 60's just to remember how he did it for 40+ years. Still have his O-A outfit but I'm afraid to connect the regulators to bottles. The old Purox torch still works just fine. Hope you get a lot of use and enjoyment along with some nostalgia out of the old Thunderbolt

[ryanjones2150]

My thunderbolt was my first welding machine. Given to me by a handicapped gentleman that was no long able to weld. I call it my frankenwelder...its...uh...interesting...I try to use it as often as I can and I refuse to sell it, even though I don't need it. What's it worth? Couple hundred bucks at most? It's worth more than that to me sitting there and keeping the dust off that part of the shop floor.