The Old Buzz Box needs work

After learning the basics of welding from my friend Bob, I needed to decide how to restore a Craftsman Welder. I needed practice. Welding concepts are simple, physical skills are hard. Bob anticipated this and offered to send his Dad’s old Craftsman welder home with me. It was generous  — giving me a tool that his dad used a lot, and saving the cost of  a welder before I’ve established my skills. A real jump-start.

It hadn’t been used on decades. One might say it was well-loved, but in need of some work. Also, it’s a simple A/C welder, similar to the old Lincoln buzz box my grandfather had on the farm. Perfectly serviceable, but bare-bones by today’s standards. Nevertheless, I saw possibilities and was thrilled. I wanted to learn welding at its most basic and stick-welding with a buzzbox was it

I’ve been looking at welding  videos on YouTube for months now, and there was one upgrade I could make easily. Turning the buzz box welder into a D/C machine. It would involve a big honkin’ rectifier bridge, and some additional connections on the front panel. Also, new cables and a stinger were needed. The insulation on the  old cables was brittle and cracking off and the stinger was worn.

How to restore a Craftsman Welder

Cleaning was first to remove decades of funk. I removed the cover to expose — surprisingly little. These welders are simple and consist mainly of a big transformer, switches to select the welding current and — well, that’s about it. I also removed the A/C power switch. It had been bypassed, and I wanted to make sure there were no issues with it. Liberal application of Simple Green  and a scrub brush, followed by a rinse made a big difference. Left in the sun, it was dry in a few minutes.

We can make it better!

Studying the interior wiring, it was clear that the amperage switch selected between two ranges. They allowed welding currents from 25 to 140 amps. Final selection of either the “A” or “B” range was done by plugging the “hot” welding cable into either the “A” or “B” jack. Pretty simple. In theory, the addition of a high-current rectifier bridge would convert the A/C current into D/C. Welding with D/C current was preferred on most on the YouTube videos I had watched. Also, Bob’s welder (that I had just learned to basics on) was set to D/C. Hard to argue with a pro’s choice.

I decided to keep A/C current as a choice and add the D/C capability. This meant I would need to install two sets of new output connections — one pair for A/C and another for D/C. The rectifier would be connected between them. At the same time, I wanted to preserve the amperage switch and “A” and “B” range selection. Putting it all together, I came up with the following diagram.

We’ll need a few parts

This provides the most choices. A/C and D/C either Positive or Negative polarity by simply plugging the welding cables into the correct jacks. Some parts were needed:

• 25 feet of 2 gauge black and red welding cable (total of 50 feet)
• Single phase 300 amp diode bridge rectifier
• Welding cable panel connectors
• 2 gauge copper welding cable lugs
• 240 VAC @ 30 amp primary power cable

Let’s build it!

Parts in hand, it was time for assembly. The 300-amp bridge rectifier was first bolted to the front panel. Because the bridge will generate some heat, I coated the back of the bridge with silicone thermal compound to help transfer heat  to the front panel.

The welding cable connector sockets were next. I made four notched holes in the front panel. The holes are large, and a step drill was really helpful. A small triangular file made the notches, and Voilà — we were done.

Now the fun part. Connecting all the parts. Normally, this wouldn’t be so bad, but when working with high current, large wire is needed. In this case, #2 AWG stranded copper. About as big as my little finger, it doesn’t bend easily, and tight bends are needed in tight quarters. Also, each jumper has a copper lug swaged on. A hammer lug crimper is really handy for this purpose. The lug is fitted on the cable end and placed into the lug crimper. A stout hammer-blow or two, and the two are as one. Ready to carry some current! Large pliers or even a vise are helpful for making the wire bends.

With the secondary wiring done, a new power cord was needed. The old cord was worn, and didn’t fit the 240-volt outlet in my shop. A new dryer cord did the trick. The final refinement was a furniture dolly to roll the welder around the shop. It’s heavier than a single person can lift easily. Plugged in and turned-on, everything seems right. The fan runs and appropriate voltage is present on the A/C and D/C jacks.

It works.

I came back from Omaha with accessories. A new auto-darkening helmet and cotton cap, welding gauntlets, chipping hammer and wire brush. I was even able to get +1.5 optical correction for the helmet. Some scrap from a local metal crafter and a welding table completed the welding suite. Now I just need to practice!