Welding Tips and Tricks

This Forum saved my bacon when starting out on MiG and now it seems, on TiG too. Got the basics of Mig pretty much down - happily. Today I am learning TIG, I learned here at weldingtipsandtricks.com that If your tungsten melts, you need to change polarity!. Thought I followed owner's manual but, maybe not? Torch is now on neg ( house wiring reversed?) ground is on pos. Bottom line, no more melted tungsten !!!

Anyways, I never TIG welded before today, I have a new machine and, am essentially clueless. TIG looks easy when somebody who knows what they're doing is showing how its done- on this day, that was not me.
So, this afternoon I sharpened then promptly melted the 3/32 tungsten 10 or more times. Came in and searched this site for "melting tungsten" and WHA LA.... post says to change polarity. Before this fix, I melted tungsten, cooked a ceramic cup (the thing tuned to dust and is in the trash) and, popped 115 VAC, 15A breaker. Oh yeah, I sweated my tail off as its about 100 F in the garage. After changing polarity I have a concave weld bead -it looks like coral but hey- I'm good with it. It is concave baby! Tungsten is still sharp, not all balled up. Dam, life is good again- whoo hoo!!

Never had a similar issue with MIG. With MIG, you work the settings right, get the sound right and bam, you're producing a good weld. All my MIG welds convex. They look like tooth paste squeezed from a tube.

I'm learning that TIG on the other hand is more demanding, more costly and, needs more infrastructure, From what I've seen though, it offers way, way more control of the desired weld.

Next step, turn that coral into dimes!

Thanks Welding Tips and Tricks users!

It sounds like you have identified the learning curve and are sorting your way through things OK.

One thing I can say is that reversed polarity has absolutely nothing to do with your house wiring. Polarity all starts and ends with which way you connect your torch and earth cables to the power source (welder).

In the real world, electricity flows from negative to positive, it's called Electron Flow. That's why your torch should (normally) be negative.

You may not have enough shielding gas flowing either. What flow settings do you have?

And you didn't mention other important settings such as material thickness and type, amps etc

A photo can really help others to quickly identify problem areas and assist you faster too.

And importantly: welcome aboard! This is a great forum.

if you can post some pictures and setting several very talented welders
will get you going in the right direction.

TRACKRANGER wrote: In the real world, electricity flows from negative to positive, it's called Electron Flow. That's why your torch should (normally) be negative.

You'd be surprised how many people still think its the other way around man, or will argue with you when you say that. (Not in reference to the original poster, just saying)

Good point Sam.

When electricity was first discovered / invented, the scientists recognized that one terminal had a higher potential to the other. Without any means of measuring the direction that the electrons were flowing, they presumed they went from the terminal with the higher potential to the other, so they called the terminal with the higher potential 'Positive'. This method is aka 'Conventional Current Flow'.

Later they found out that electrons actually travel towards the positive terminal.

Without any knowledge of electricity, it's understandable why one can easily make the same presumption as our forefathers, and not be correct.

Trev

I'm probably wrong here, feel free to tell me so if you explain. I was taught that electrons at an early time in Ben Franklyn's research were arbitrarily labeled positive in the sense that other fluids, (as Ben believed electricity to be) flowed from positive pressure to negative pressure. When it was later learned that electrons flowed the opposite direction, his corrected drawings showed only the change in direction with "negatively charged" ions flowing to positive.
Electrons being negative, and protons being positive is an arbitrary designation showing them to be opposite. Ben had a 50% chance of guessing correctly, the fact that he didn't has doomed us to forever be confused.

So going by this, the machine (when hooked up dcep) already flips the polarity from the feed power, and power is flowing from the + lead to the -?


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79jasper wrote:So going by this, the machine (when hooked up dcep) already flips the polarity from the feed power, and power is flowing from the + lead to the -?

Not quite understood I fear.

Electrons ALWAYS flow from Negative to Positive.

Reversing leads from DCEN to DCEP doesn't mean that power is now flowing from the + lead to the - lead. It means that electrons are flowing from the Work to the Electrode, instead of the electrode to the work.

Understand the difference?

Trev

Der. I was looking at it wrong.

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TRACKRANGER wrote: One thing I can say is that reversed polarity has absolutely nothing to do with your house wiring. Polarity all starts and ends with which way you connect your torch and earth cables to the power source (welder).

To add to this a bit, the AC that comes from the mains changes polarity multiple times a second (60 in the States for household wiring). That's rectified in the welder's power supply, and depending on the welder and settings output as DC or AC. The only thing that matters is the welder and apparatus as Ranger says.

Bill Beauregard wrote:I'm probably wrong here, feel free to tell me so if you explain. I was taught that electrons at an early time in Ben Franklyn's research were arbitrarily labeled positive in the sense that other fluids, (as Ben believed electricity to be) flowed from positive pressure to negative pressure. When it was later learned that electrons flowed the opposite direction, his corrected drawings showed only the change in direction with "negatively charged" ions flowing to positive.
Electrons being negative, and protons being positive is an arbitrary designation showing them to be opposite. Ben had a 50% chance of guessing correctly, the fact that he didn't has doomed us to forever be confused.

It's debatable - there are a handful of reasons that conventional current sticks around. The obvious one is that we've got tons of textbooks and formulas that are based on it. More importantly, using conventional current, we can use the hydraulic analogy to help people understand how electricity works. I'd argue that knowing which way the electrons are flowing only really makes a difference in areas like semiconductors. Not terribly helpful at the macro level.

Deepak wrote:
... I'd argue that knowing which way the electrons are flowing only really makes a difference in areas like semiconductors. Not terribly helpful at the macro level.

Not True! Knowing which way the electrons are flowing is critically important for Welding Too! The very subject matter of this thread.

Ranger.

There are numerous reasons to know which direction electricity flows. In welding, the majority of heat flows the direction the electrons flow. In EP TIG we easily overheat the tungsten, and get shallow penetration. In stick welding we use EP to melt the electrode for fast deposition, working with very thin metal we choose EN to limit penetration and deposition rates.

I read the Everlast dv200 manual again and yep, electrode - torch - negative for DC TIG. I connected the electrode - torch - positive just like my HTPMig200. Won't do that again. It is great to see the dialogue from the Welding Tips and Tricks user community. Interesting bit on electron flow. If you've ever seen high speed video of lightening, you will see that it originates from the ground ("negative") and travel up to the cloud.


Gas flow very fist pass. Worked on gas flow setting at the regulator, for the preflow and postweld and will post a snap. I didn't use any rod here, just trying to 'wash' metal from the upper part edge into a puddle.
I'm using the 2t switch and 110VAC for now. Once I quit wrecking the electrode so often and get a feel for how to feed the rod, I will hook up the pedal and have at it. 2t will be good to use laying on my back under the jeep so it is a necessary skill.


TIG and MIG stack up. My jeep better look out

Soon2GetIt wrote: After changing polarity I have a concave weld bead -it looks like coral but hey- I'm good with it. It is concave baby! Tungsten is still sharp, not all balled up. Dam, life is good again- whoo hoo!!

Concave is not neccessarily a great thing.

An excerpt from the linked article:
"In the shipyard, we were making fillet welds, so we will start by discussing fillets. As the molten weld metal begins to solidify, grains grow from the base metal to which the weld is being applied. The grains continue to grow as thermal energy is conducted away from the weld, with the general direction of growth being toward the center of the bead. The last portion of the weld to solidify is the center of the bead, near the surface.

While the weld is cooling, it is also volumetrically shrinking. The resultant contraction pulls on the surface of the weld. For convex beads, the shrinkage puts the surface into compression. For concave beads, however, the shrinkage puts the surface into tension. These contraction forces caused the welds made with the E6020 electrodes to crack"

http://m.weldingdesign.com/blodgett/con ... cking-0709

Too much convexity is also bad as it creates a notch effect at the toes.

Summary:
Too concave - bad
Too convex - bad
Very close to flat - good

Soon2GetIt wrote:I read the Everlast dv200 manual again and yep, electrode - torch - negative for DC TIG. I connected the electrode - torch - positive just like my HTPMig200. Won't do that again. It is great to see the dialogue from the Welding Tips and Tricks user community. Interesting bit on electron flow. If you've ever seen high speed video of lightening, you will see that it originates from the ground ("negative") and travel up to the cloud.


Gas flow very fist pass. Worked on gas flow setting at the regulator, for the preflow and postweld and will post a snap. I didn't use any rod here, just trying to 'wash' metal from the upper part edge into a puddle.
I'm using the 2t switch and 110VAC for now. Once I quit wrecking the electrode so often and get a feel for how to feed the rod, I will hook up the pedal and have at it. 2t will be good to use laying on my back under the jeep so it is a necessary skill.


TIG and MIG stack up. My jeep better look out

The book I read on the subject I believe was written by a recognized expert in the field. He says cloud to ground lightning begins as a surplus of electrons in the cloud. As numbers and concentration of excess electrons grow, enormous voltage, or electrical pressure builds. Air being a very poor conductor, it must be ionized, (put in a state of imbalance of electrons and protons), to become a good conductor. Vast numbers of electrons will rush to the bottom of a "step leader" until sufficient numbers of electrons are present to again ionize another step. The process repeats until the leader is close enough to the ground to exert significant attraction to the earth where at that instant positive ions are drawn from the earth to rise and meet the negatively charged bolt. Although the human eye isn't fast enough to see it, a bolt of lightning is made up of a large number of steps, combined they take a small fraction of a second.

quote: Concave is not necessarily a great thing.

Good put, many thanks.

It is interesting that in aircraft, bead blasting is used to ensure metallic part surfaces are in compression from the start. Ship building industry builds big flexy stuff too so the details are a big deal. The input on this board is soo great.

TIG is taking some calories to get my arms around. I'm now practicing feeding the rod with my fingers while watching tv. One of my cold weather microfiber motorcycle liner gloves is now seeing duty on my torch hand under my MIG glove- helps a lot. I've cut my tungsten rods in half to sharpen both ends so I don't have to go sharpen dirty tips so often. In my weld photo, it shows that I'm practicing on ~.08 thick mild steel. I am still running beads across the same 4 x 4 square of steel. Have been gradually increasing amps since blowing the fuse on day one. Will try about 80-85 amps tomorrow. Used 70 amps today and the .060 filler rod was a bit sticky.

Hi SoonToGetIt:

Everybody here of course supports one and other, and we all look out for each other too. Your enthusiasm is commendable, and like all things, practice is the key to ultimate success. There's always something new to learn.

You also mentioned: 'My jeep better look out'

I think it's fair to just say that making non-structural, non-engineering gadgets for your Jeep is a commendable thing to do. I'm not sure what your plans are, but out of courtesy, just a reminder that structural / engineering changes are a different story, and generally require accreditation, for safety reasons.

Keep at it. Looks like you are getting yourself a nice collection of equipment

Cheers

Trevor








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