Sabtu, 23 Februari 2013

Arc Welding Project

Why did this simple job turn into an arc welding project?
Normally, Mig welding is the choice for fabrication jobs like this one.
It was a simple stand for a bender. A stick of 3 1/2" tubing with a flange plate welded on one end and a mounting base plate welded to the other...simple as they come.
So why Stick weld, when mig welding would be faster and easier?
Well...
My buddy tack welded one of the flanges with a tig welder and the tacks were so jacked up, so oxidized, so ugly, it was either cut the thing off, grind all the weld off and start over....
..or just whip out the stick rods and weld right over all the junk and call it good.
Sometimes, good enough really is good enough.
A 7018 stick rod burned in nice and hot will definitely hold till the cows come home on a stand for a tubing bender. I dont care if a 6 foot cheater bar is used for bending, these welds aint gonna give.
So instead of all that extra work for nothing, I decided to Stick weld this job.
Not only would the 7018 Stick rods burn thru all the crud better...but My pal didnt even have a mig welder hooked up at his shop...I would have had to haul one for a 30 minute job. ( actually, because I filmed it, it was more like 2 hours)
Anyway, The Everlast Powerpro 256 tig, stick, plasma combo welder was already there, hooked up and ready to rumble. I keep it set up for tig welding at my machinist friends shop. But swapping it over for stick welding only takes a few seconds...so thats what I did.
All I had to do was unhook the tig torch and plug in the stick leads.
The square tubing my friend wanted to use for this arc welding project was 3 1/2" x 3/16" wall and the flange mounting plates were 1/4" thick.
In this arc welding project video, I show how to center the tubing, tack weld, get it square, along with some arc welding tips for how to weld it without a bunch of stops and starts ...except on the corners.
I also show a tip for another way to prop for arc welding using a tig finger.
One thing every welder needs to know is how much tack welds draw...how much they will pull a piece out of square. Knowing how much the tack welds pull lets you pre position a piece to allow for that and lets you get things square and plumb without cutting tacks loose and reworking. Thats what you wind up doing if you dont allow for the tack welds drawing.
I can tolerate certain things not being perfect but things being out of square and out of plumb...drives me to distraction...I hate it.

Arc Force and Arc Control

What is the Arc Force / ARc control knob and what does it do?
The arc force/control lets you adjust whether you have a soft buttery arc or a digging arc.
Arc voltage drops as the arc gets tighter.
When you set the arc force knob high , the machine makes the arc dig more by sensing a drop in voltage when the rod is about to stick...an arc welding machine with arc force control compensates when the rod is about to stick by increasing the arc voltage. You can literally jam the rod in as tight as you like without sticking if you have it hot enough with the arc control set high.
Setting the arc force knob low, gives a soft buttery arc.If you were hardfacing backhoe bucket teeth, a soft arc might come in handy to prevent that hardface rod from diluting too much with the softer base metal.
Who wants to pay an arm and a leg for hardface rod only to have it turn out soft because too much base metal was melted?
Today , for this arc welding project, I set the arc force to dig because the 7018 rods I was using were old and had been sitting out in the air for like 2 years. I knew they would have a tendency to stick if I didnt set the machine for a digging arc.

Sabtu, 09 Februari 2013

Aluminum Welding Training

Aluminum Welding - Tig welding Aluminum. That is the way. If Yoda was a welding instructor he would have all his Jedi masters tig welding aluminum to make them strong in the force.
This is starting to sound like a line of BS so I better get to the point. What I am saying is that aluminum welding will make you a better welder of all metals....not just aluminum.
Why?
here are just a few reasons:
With Aluminum welding, You have to feed more rod...your rod feeder hand will have to get better and faster and that will help on all metals.
Conductivity...aluminum will make you pay more attention to your foot pedal amperage control because the heat changes a lot more than stainless or carbon steel
Seat Time/ Arc Time...practice like I outline here and you get lots more seat time.... you spend your time welding and not cleaning and wire brushing.
Getting a piece of aluminum about 1/8” thick and stacking beads on it is the best tig welding practice there is.
That’s a pretty strong statement but here is why its true:
Aluminum cools quickly and doesn’t form a grey oxide film like carbon steel does so you can stack beads , one on top of the other and the puddle will flow the same bead after bead…well , almost.
Aluminum conducts heat rapidly so you have to get used to working the foot pedal remote amperage. You cant get lazy and just leave your amperage in one place like you can with steel. Aluminum exaggerates everything that can go wrong with steel.
For example, too much arc length, too much torch angle, not enough amperage, too much amperage….all will cause problems and make you think more about how to fix your technique.
Aluminum has a big attraction for your tungsten electrode and wants to jump on it at every opportunity…(at least it seems that way.)
When ..not if, but when your electrode gets crapped up with aluminum, stop and clean it off with a sander. You can get away with a tiny bit of contamination when you are tig welding steel. Not so with tig welding aluminum...unless you like welding aluminum inside a big cloud of black soot.
With just one scrap piece of aluminum sheet, you can stack bead after bead practicing spacing your ripples, keeping your bead width consistent, welding fast, slow, medium.
The piece I welded for this page was 4” x 8” x .125” thick 3003 aluminum. It does not matter what grade you use… . whatever you can get your hands on will do.
I recommend welding a bead all around the edges first. That is really good practice controlling amperage…too much amperage and you roll the edge off and the bead gets fat and ropey. Too little amperage and you don’t even melt the rod without it just balling up.
Once you get an edge weld all around, practice just running beads and stacking them evenly. Not just running random beads, but practice with purpose. Purposefully stack beads as straight as you can.
Practice Welding right handed, left handed, weld fast , weld slow, add rod every 1/8”, try adding rod every 1/16” too.
Pay attention to the difference.
Which ripple spacing do you like better? Sometimes its just a matter of preference. Do you like the stack of dimes look? Or do you like tightly spaced ripples better?
Practice stacking beads diagonally too. When you are building up a big lug on an aluminum transmission case, you need to vary the direction of beads to spread the shrinkage stresses. That can actually help prevent distortion and cracking.
The time to get good at stacking beads is on a scrap piece of aluminum. Not on the actual job.