[Old Stan Man]

I fabricate and build a lot of junk and stuff so an arc welder is a must for steel joining. I have an old Miller AC Thunderbolt Buzz box and in my old age sometimes don't have the steadiest hand when welding with AC, so I decided to convert it to AC/DC by adding a bridge rectifier. I had done this years ago to an old Monkey Wards welder my dad gave me, with huge diodes mounted on an insulated board and wired new recepts for the DC leads.

These days full wave bridge rectifiers capable of 300 amps and 1600 volts are redially available on Ebay or Amazon for just over 30 bucks. I converted mine and replaced all the plug in receps to the same type, 5' of welding cable, 8 copper cable ends, all for about $70-80 bucks. All the wiring and rectification is inside the welding cabinet and stays cool with the fan. I added a block of aluminum under the rectifier as a heat sink.

I now have AC if I need it, or DC with reverse polarity if needed, all using the the same leads. DC seems to work considerably easier when striking the arc and quality of the bead looks better. Probably not everyones desire to tackle this conversion, but it was another fun project. I will post photos later.

Not sure why the photo is sideways, but if I click on it it rotates upright.

[NMKawierider]

Nice idea. Please post. I have been arc welding sense I was 9 years old when building my first mini bike in my dads shop using his then new Lincoln Cracker Box 225. I actually have that very welder in my shop today. Always used A/C stick welders throughout all my ventures in life but just before retiring tried my hand at a small flux core wire feed. Just didn't get a handle on that and wanted to do those pretty welds everyone else was doing. Just hadn't got around to doing that yet because I can still weld about anything with that old stick welder. But I hear DC is the way to go and would be interested in this project because it sounds like its' a lit less money then a 500+ dollar wire feed.

[Richl]

I am intrigued  by your post.
I currently have no need to weld something but I am interested in learning. Would taking a welding class be of beneficial use for me.

Total newbie to the welding world.

 

[Old Stan Man]

I forgot to take photos during the conversion but maybe I can take the cover off and show the install of the components, and some explaination. There are a number of conversions on youtube but most are with the Lincoln Tombstone welders. They show the basic idea of converting, but I don't think any went to the extext that I did to keep the AC mode and add the DC mode. I like the idea of having both AC and DC capabilities. Easy as switching the cables to your choice of welding. Ill also make sure the photo is rotated.

I also bought one of the $100 Harbor Freight flux core mig wire welders and did not have much success either. It is stuck back on a shelf collecting dust. There are several Youtube videos on those as well, even converting them and some neat tricks and tips to improve them.

As for the other question Richl about welding, you sure can take an instructional course and many high schools still have welding shops and some offer evening adult educational programs for the trades. You might check with the local schools to see if those are available. Also check with your local welding supply business and they may have some ideas for you.
I like to weld and it isn't as hard to do as it might appear, but the more your practice, the better you weld. Most are better than me at it and many videos are available to show you the basic theory and technique.

I had welded for many years before I decided to build a wood burning stove back in the 70's. I figured it might be a good idea to get some instruction on welding for a project that would be in my house. The local highschool welding teacher coached me and offered suggestions. I eventually built 4 stoves for myself and family.

I will add more input in a day or so with better photos. It is a fairly easy conversion and worthwhile.

[Old Stan Man]

At the bottom are some photo's of the components I bought from Amazon for the conversion. No matter the welder you plan on converting and the extent that you want to modify it, you'll definately need the rectifier. This one is about 4" square and can handle 300 Amps, and 1600 volts. You can find them as low as $26-$27. The plugs and recepts are about $10 a pair, terminals about $1.00 ea., and cable about $3.00 a foot.

All you do is feed the rectifier from the AC terminals (in my case that was AC high and AC work) and out comes DC+ and DC- on the other two terminals of the bridge rectifier. Now just feed the DC+ and DC-to receptacles that you install in the front of the cabinet.

For my Miller welder, I paralled the feeds to the rectifier from the AC high and AC work receptacles. I did that internally along with mounting the rectifier and added a heat sink (not sure if I needed that but decided this was the time to do it in case.). I changed all the plugs and receptacles in order to be able to swith between AC and DC modes with one set of cables.

If you want to simplify the conversion to just a DC welder, you can do everything outside of the cabinet as did the guy in the following Youtube video link. You simply cut your leads and run them to the AC terminals (top terminals) on the rectifier, and take the cut cables and hook them to the DC terminals (bottom terminals). That is quick and easy. If I did it this way however, I would put some sort of cover over those terminals for safety sake in case you might short them out by touching with the ground clamp or chipping hammer. Just my opinion. Hope this helps.

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[murdo]

Nice work there. I have often thought of doing this for my small AC welder to be able to weld cast iron and stainless better, but now I have a 200amp TIG I usually use it instead of the stick.