Fixing Welding Holes

snipped-for-privacy@invalid.com fired this volley in news: snipped-for-privacy@4ax.com:

The single event that revolutionized my stick welding was the time a guy scrapped me about 100' of #2.

I didn't have to pay for it, but knowing what I do now about how it eased my chore, I'd go pay the big bucks out of my own pocket if I had to.

I immediately did the same thing to the feed side of my MIG with similar results in my shop. Not fighting the stinger makes for a much easier life. Keeping the welder "home" and still being able to work over in the middle bay of the barn is a joy. ('course, the mig is portable)

LLoyd

With my Lincoln 225AC "crackerbox" I created a DC machine. I found some huge diodes, mil surplus, and wired in a full wave bridge rectifier. Changed my internal wiring adding sockets to the box, changed to plugs on the leads. Now I just plug in for AC or DC as needed.

Since the factory Lincoln 225 AC/DC uses a half wave rectifier (or so I am told, don't know for sure) you only get half the current when on DC but with my homebrew machine I get a full 225 amps when on DC. Burns

3/16 7018 real easy, has a nice sizzle to it.

George

I doubt that the spot adds much to overall strength, but it seems like it works well for you.

i

Sounds good.

Where would I go to look for these diodes (online or other)? Do theey need to be 225A diodes or what? I know what a bridge rectifier is.

Thanks

I found mine in a pile of scrap, about to be burned by a friend who buys and resells mil surplus. They are rated at 400 amps each. May not need that much current rating but I used what I found. Probably you could get by with 250 amp diodes, thinking in terms of sticking an electrode with the setting on 225, need a margin of safety?

They are made on a plate of 1/4 inch steel about four inches square with a tab sticking up in the center of the round potted mass of smaller diodes. They now occupy the open area in the top of the Lincoln 225 cabinet. Bent the cabinet metal to enclose the area instead of leaving it open (safety issue). I used welder cable with tabs soldered on for my interconnect wiring in the bridge, cleaned everything and bolted it together with clean bolts. Used some huge standoff insulators to hold it in place, just bolted through the top of the cabinet. Looks OK for the shop.

George

Burning a hole in a highly stressed piece and then welding in a bolt of unknown composition to fill the hole most likely severely weakens the part, first from the excessive HAZ that created the hole, then from the unknown metallurgy filling the hole area and then from probable stress concentration points in that area.

My best recommendation to the OP:

1) Invest in a decent auto-dark welding helmet, they really help infrequent welders.

2) Take a welding class at a local tech school and note your typical welding needs to the instructor.

3) Be willing to invest a bit more in the equipment recommended by your instructor, likely a 240V MIG, or an AC/DC stick machine.

4) Visit a metal supplier and get some pieces (cutoffs) of 1/4" plate so you have suitable material to reinforce areas where you have welded up cracks.

snipped-for-privacy@invalid.com wrote in news:qfc1p3d0e4tp1nv60rh2dblknhqeutjpck@

4ax.com:

They're commonly called Auto Darkening Helmets and I agree with the sliced bread statement. Nothing like being able to see the area I'm welding right up to the point I strike arc.

Bill

Kinda overkill when you can buy a used Crackerbox AC DC for fifty bucks. But that's just me.

Steve

Sounds like you get your firebrick a whole lot hotter than I do...

Relative humidity is affected by temperature. A given amount of water in the air can be really low humidity when it's warm, but high enough humidity to get condensation when it's cold. So the rod will deteriorate faster in an unheated garage -- if you go through it fast enough, it won't matter.

Auto-darkening. I got a cheap one on ebay for $30; terrible, flimsy construction; darkness adjustment inside the helmet instead of outside -- but meets my needs just fine.

That's thick. I frequently did 1.5mm with stick.

Nick

Chris,

You were suppose to answer that little oops that you were using an Oxy-acetylene torch ;-)

Well, lets see, the machine was already paid for, the diodes cost me nothing, the cable cost me nothing, and the whole process took just less than one hour. And I gained knowledge and ability in the process. And my machine now can use cables of any length, just so long as they have plugs on them.

Seems overkill to some, seems thrifty, fun, and cost effective to others....

I vote with the home brew fix, and it was fun. YMMV

George

That's what I thought, Steve. Which polarity is more common? I only use AC myself.

Best wishes,

Chris

Some rods have the capability of absorbing a very large percentage of water because of the nature of their coatings. This vaporizes when the temperature rises instantaneously and greatly affects weld properties.

Steve

So, weld me up some metal and don't burn a hole and you pass the course.

Steve

As a guess, I would say that reverse polarity with stinger positive is more common, with there being more heavy gauge welding than thin welding. Just a guess, though. I personally do not use rod on thin materials, but use MIG. I use 6010 and 7018 on thick material with reverse polarity, stinger positive.

YMMV.

Steve

You're right, Letterman. Just build a bridge rectifier with big diodes. I made one out of a Miller Thunderbolt and I love it.

j/b

Not unless you're ona 30 Hz power line. It would be 120 times per second with a 60 Hz supply.