Holy arc blow batman...

Finally had a dry weekend where I could finish building my heavy duty scarifier for the 3 pt. hitch. It's made out of 14" wide flange that's somewhere around 105lbs./ft and has 15 backhoe teeth adapters welded on. Welding the adapters on had no problems other than they were made for a 1" edge and the beam I had was only 3/4". I had a gap to fill and used 2 passes of 3/16" 7018 after filling the gap. I cranked the heat (amps) up and they welded really easy.

Fast forward to welding the 3 pt. mounts on. They are the ones cut on a $250,000+ CNC plasma table. First I had to use a die grinder to ream the holes a little for the pins to fit. Then I prefabbed the uprights with a 2" spacer separating them. I had to grind the edges of the spacer flat because it had about 5 deg. angle on the cuts. The uprights also had an angle on the cut and made it a pain to line everything up. I got it lined up but after tacking all the mounts in place, I took out the 3/16" rods and proceeded to weld them on. I put the ground right on the mounts but sure got a lot of arc blow. The rods started off great but on just about every pass, they would act up about 3/4 of the way to the end. I'd start off with a normal 15 deg. rod angle and have to change to about a 15 deg. push angle to counteract the arc blow. I've had arc blow before but never like this. Usually after you get the first pas in, the second pass goes pretty smooth. What's puzzling is that I didn't have any problems with arc blow welding the adapters on and I used more heat. 4th gear at about 85/90 on a SA200. Maybe if I had the rods in an oven and wrapped the ground cable around the beam would have helped? It's never going to break so I didn't experiment too much but luckily I had a sharp chisel to clean the spatter when it acted up.

I've never used a whole lot of 3/16 7018, but remember one job in the tank shop I worked in, where it was specified. Had to weld the lifting ring on this tank, the ring was 4” x 8” flatbar rolled to the outside circumference of the tank. Had to make 1 7/8” fillet weld top and bottom of this ring. Don't remember too much arc blow for the flat welding, but the overhead was an adventure!
Over the last couple years I've really noticed different brands of 6010, and 7018 like to burn off to one side. Not really arc blow, but like something is wrong with the flux. :?

Stick Welding, post some pictures.

Hello stick weld,
1/4 IN. rod is even more apt to blow!
Having dry rods is very critical when you are
running 3/16 rod or bigger. I ran some 1/4" 7018 and they only worked 100% right out of the package. Then, even out of the oven, they were really not 100% and had a tendency to blow some. The nature of the beast! Weld puddle and rod angle become more critical as well.
It has been too long to remember much more.
Guido.

Change the location of your ground.

The reason the the plasma table left the holes tapered, and the edges had a bevel is because the processor for the computer needs to be changed. Hypertherm recommends replacing their processors every six months. We just had the one at work replaced (pretty costly by the way) and it now cuts true.

I did try the ground in different places. If I would have tried to weld it with 1/4" rods, I'd still be cleaning it up! Never had arc blow that bad before. I know for years Lincoln were the only 6010's that didn't fingernail and that's why they're still so popular. I have seen some bad 7018 rods that the coating wasn't a consistent thickness all around the rods but these seemed like good rods.

If you are using DC uncoil all of your cable instead of just the length you need. AC doesn't matter.

An old-timer told me about this years ago when I was having the same problem. If you have a lot of cable spooled up the magnetic field this creates can cause problems with the arc. When you lay it out on the floor try not to cross the cable over itself too. Sometimes you don't have to do this but if I have arc blow that's the first thing I do and most of the time it stops arc blow.

I've heard that some of the rods that are coming from china and elswhere over seas can sometimes be real poor quality. I haven't seen any yet, but I always try to buy American if I can.

We have had some Lincoln Excalibur rods that were rusty if you knocked the flux off. We had several hundred lbs.returned to Lincoln. That was a couple of years ago.

(quoted from post at 00:31:52 09/10/12)

[color=blue:5c4237082c] I've had arc blow before but never like this.[/color:5c4237082c]

Click to expand...

My goodness, Dave!!
Just take that old AC buzzbox you've been using as a door stop, and "Git 'er done".
[b:5c4237082c][i:5c4237082c][u:5c4237082c]No more arc blow. :wink: [/u:5c4237082c][/i:5c4237082c][/b:5c4237082c]