I made my Miller Thunderbolt AC into an AC/DC

Tue, 31 Aug 2021 15:04:27 GMT

go to see Welding Machine for I made my Miller Thunderbolt AC into an AC/DC

My friend gave me 4 big diodes and two aluminum heat sinks, so I looked up how to convert my early 80s Miller Thunderbolt's AC output to DC.  For a while, I had the hardware in a box next to the welder, but I decided to buy some tapered Miller receptacles on the internet, and put it all inside the machine and make it look factory made.Here are most of the parts I put in the machine.  The diodes are attached to a heat sink, which is bolted to some angle iron.   That is attached to some cutting board material and then to the bottom of the welder.  I used 6 gauge wire, which is probably fine for me.  Someone else might need thicker wire.Here is a diagram I drew for reference.  I used the little symbols that were on the diodes.  Basically, each heat sink had the same direction diode, was connected to both "work" and "low" (you can see I wrote that on the heat sink), and then was connected to one of the new DC receptacles.Here's how the inside looks.  Pretty crowded. I cut holes for the new receptacle with a $300 ebay plasma cutter/tig/stick.  Works great.  I had to wrap electrical tape around a few things to keep them from shorting.And it's done.  I need to come up with some clean way to indicate which receptacle is pos and which is neg.It works good.  DCEP has less sparks flying, which will be good for my t-shirts.  Maybe adding a capacitor or an inductor would make it real smooth.Peregrine FisherCave Junction, Oregon1981 Miller Thunderbolt 225VOxy/AcetyleneSome broken shovels and rakes
Reply:Originally Posted by PeregrineI need to come up with some clean way to indicate which receptacle is pos and which is neg.It works good.
Reply:If you have 2 diodes with a neg base and 2 with a positive base,you can use 2 heat sinks. If you have 4 diodes with a negative mounting base, you will need 3 heat sinks Attached Images
Reply:Hi you will most definately need an inductor to smooth the DC pulses from the rectified AC wave form.It may be rectified, but it still has a ripple on the waveform.I posted elsewhere about the inductor design, but in case it isn't apparent I'll post the pics again.Core has a few ferrite rods making 3" diam covered with plastic tube and 10 coils of 1/2" diam copper rod wound round the outside.Ian. Attached Images
Reply:Miller made a DC adapter for the Thunderbolts."Never mistake education for intelligence."AIRCO Oxy/AccMiller Thunderbolt
Reply:Yeh, but i'm not sure they make it anymore.
Reply:That's a really nice job.  Mine is still hanging off the front of the machine and no choke.  Works awesome. Great for stainless.
Reply:You can always wrap a weld lead around a metal table leg until you get the arc you want.Or even a piece of round stock. Then tie it in place so it does not move. Just keep the wraps tight.
Reply:Originally Posted by ccawgcYou can always wrap a weld lead around a metal table leg until you get the arc you want.Or even a piece of round stock. Then tie it in place so it does not move. Just keep the wraps tight.
Reply:Originally Posted by ccawgcYou can always wrap a weld lead around a metal table leg until you get the arc you want.Or even a piece of round stock. Then tie it in place so it does not move. Just keep the wraps tight.

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