.120 Mild Steel Tubing Help

[vegaslightsss]

Hi All, I am a 50 year old Boy rediscovering my Childhood,with my Kids (lots of Fun). Back In the Early 80s I build a Single Seat VW Desert Rail,out of .095 for the Chassis,and .120 for the Cage or "Top Half " of the Car,I had a Miller 200 which was almost new at the time and the car never cracked,bent,had a failed weld or otherwise and looked clean. Turn the Clock forward 28 years or so and I now have a Millermatic 175 loaded with .030 ER70S Wire with a 75%Argon/25% C02 Mix, I have a Nice JD2 Model 3 Bender,A JD2 Notchmaster Notcher,an OXy.Acetylene Rig,A Cheapie Chicago 130Amp TIG (never even turned it on),and every kind of CutOff,Sawing,Grinding Tool ,one could possibly want. I am trying to pass on some of my Welding Skills that I have developed over the years (some self taught/some Instructor Learned),I dont remember having such a hard time producing a consistent good looking weld. All of my joints are super good before welding.I am running 45 Voltage and 50ish wire speed with about 15 lbs. of gas. The machine sounds like it is happy,but my welds have a higher "crown" I guess you would call it than Looks good,the penetration is there obviously by looking at the tube afterwards.What do I need to do to "flatten down the bead,am I moving too slowly? I don't like to have to grind my beads down but they are just plain ugly if I do not. Everything I am welding is .095 Round Mild Steel Tubing. It kind of feels like the machine is pushing me too fast to get around the tube.How much time approx. should it take to MIG halfway around a 1.5 tube with an airtight notch? I only spent 30 minutes today,after at least 10 years off from welding before becoming frustrated,I am in Vegas and it's 116 today in the garage which does not help,I don't have any fans or anything blowing my Shield away,and it sounds like a happy weld,no popping or anything.I did run out of .030 tips so I was welding with an .035 tip on .030 wire,would that cause a problem. Thanks for listening and any advice in advance,I have been reading through all of the tube related forums,I am not lazy and ignoring the questions already asked many times to the best of my knowledge.Thanks Again In Advance for anyone who might have an Obsevation or suggestion,Vegas

[strictlycarved]

Im no expert but i had the same trouble with bead appearance a few weeks back and someone had changed the tip on me, so that might be your problem. Try that and hope it works for you. Im a vegas local too, Post pics of the project im sure everyone would love to see them.

[vegaslightsss]

Here is a Pic of the bumper I am working on now,I was welding the "ladder pipes today between the 2 long pipes,after I was tacked ,I clamped it to the bench at a 45 so that the welds would be close to flat and I would be a comfortable as possible,I will post a pic of the welds tomorrow so you can see what I am talking about. Thanks,Vegas

[strictlycarved]

hey looks good like i said though change that tip it will really screw you up, for critical appearance welding with the mig. Just my two cents someone please correct me if im wrong. just my experiences.

[turboglenn]

Well this is a long shot and ASSumes everything else is set correctly, but besides the tip have you tried using a "pulling" technique instead of pushing the bead? It will penetrate deeper and have a lower profile bead compared to pushing it. And it is just like it sounds, instead of walking the cup/gun forward over the bead you're welding, work it backwards and away from the bead as you weld. I've heard there's a few more benefits such as longer shieling exposure to the cooling weld but i can't think of the others :P

Also you may just have the wire speed too high or be moving too slowly, then depending on the toes of the bead you can determine how you are sitting as far as volts/amps

[urch55]

Vegas: you have some great suggestions to choose from. I would think you need to slow up your wire speed.

[vegaslightsss]

ZigZag Bead or Straight Pull and different Miller MIG Wire Tip Threads?

Thanks All,I will Back the Wire Speed Down and Pull ,I had an instructor, "A guy that works for "Lincoln" at the SEMA Show,tell me Not to "move the tip in a slight ZigZag between the two pcs being welding when running the Bead,that I should move in a straight line with a good fitted joint.When He asked why I continued to do that,I told him it was a habit that I have developed over the years and it was my understanding that it distributes the HEat and Penetration more evenly and I think it looks better (the nice even puddle over/underlap that are on nearly everything I see being welded that is not robotic. He went on to say,if he was testing me for Cert. that he would fail me for doing it,reguardless of the Weld Quality,Penetration,ect.,,that is is not needed and a very Bad habit,I think the Guy was Hungover and Had a Bad night at the Tables on the Strip,followed by Having to look Happy and Chipper standing in the Lincoln Booth at SEMA all day,It would seem that the bead would have less of a crown using that method,but is the penetration on a thin wall tubing joint as good that way?? Thanks for any Opinions. Also I need to get the right wire Size Tip,I am running a really Beat up .035 on .030 wire when I started welding yesterday,I purchased a Package of 10 .030 "Universal Miller MIG Tips" and they do not screw on properly.I am heading over to the "Home Depot" as I just got off work and all the Welding Supply Stores are closed already. The Tips for my MIG gun on the MM175 that I have are the type that have about 3-4 threads and then the tip has a skinny short smooth section and then widens out to the normal Tip size,as Opposed to the type that are threaded and the tip stays the same OD the entire length. The Only tips HomeDepot has are "Lincoln" they don't carry Miller ,Does anyone know if the Lincoln tips will fit the Miller Gun,They do have Both thread styles.they are 10 to a Pack and you can't open them to Check them.Thanks,Vegas

[Broccoli1]

The Lincoln dude is correct

[SundownIII]

Pushing the bead will result in a flatter crown with less penetration.

Pulling the bead will result in a more "humped" crown with more penetration.

That's my experience, and it can be confirmed in nearly any welding reference.

I agree with you though, that a slight weave will tend to flatten the bead. Penetration on .120 material should be a non-issue assuming your other parameters are set correctly.

[Ultrachop]

Kevin,

This may sound stupid, it sounds like you and I are about the same age and like you I quite welding for a "lot" of years, took up Tig about 8 months ago and as well bought a new MM252 and darned if I didn't have a lot of the same frustration as what you describe? I got a lot of great advice (all good) from the pros here and yet thought I was loosing it!! (what I used to be pretty good at in terms of doing what ever it took to make a good sound and esthetically pleasing to look at weld. I FOUND THAT AGE HAD CAUGHT UP TO MY EYES!!! I was not able to see as clearly as I used to and so I was forcing myself to slow down? With my new found passion for Tig I was getting to much heat to the metal and with my new Migger I was getting much like yourself to high a crown on the bead (I actually took my hood "elite digital" into the eye doc and said "what heck is going on"? Well to conclude, if I was welding out of position I needed to have a lot more cheater then what I could buy at the LWS and I also found that I had to keep my head a lot steadier then the old days when I could move in/out and all over the place and still see the edge/top of my bead clearly? (I think they call it "field of focus" or something like that??
With that said I now have a couple pairs of prescription cheaters, and or my bifocals and two or three different hoods. I STILL THINK I AM A KID AND LOVING LIFE!!
Best of success to you friend!

Tim---'if I knew I was going to live this long I would have taken better care of myself when younger"

[turboglenn]

Pushing the bead will result in a flatter crown with less penetration.

Pulling the bead will result in a more "humped" crown with more penetration.

That's my experience, and it can be confirmed in nearly any welding reference.

I agree with you though, that a slight weave will tend to flatten the bead. Penetration on .120 material should be a non-issue assuming your other parameters are set correctly.

Hmmm... I always get less of a crown with the pull so i had to check some references and alhough it does give better penetration (as stated by you, I and references i have found) the pull technique has always given me a lower profile and less rounded bead. Now i'm not argueing as there's too many variables that can be user/operator related, but just stating that i get lower profile beads with the pull technique when all other settings are the same on the machine and on the same material and joint type.

Sitting here thinking about it I would guess that the reason i get flatter beads is from the amount of stickout I end up running based on the technique i'm using at the time ( i tend to have more stickout when pushing)

As far as the rep telling you not to weave the bead from one part to another, I can't speak from a structural integrity standpoint but i do NOT weave when butt welding thin materials or working with tubing joints. I just use small bursts traveling in a forwad direction to avoid burn through. I should also add that i'm not nearly the weldor that 90% of the members here are, I'm more of a fab guy that welds, so i'm just speaking of what tends to work best for me.

[strictlycarved]

As for the weaving im not certified for anything structural with a wire feed. I use a stick for that. But i weave very little usually not at all but i use a wire feed for building gates and building some buggy cages. Never had a weld fail with the technique that i use.

[hotsparks]

from a hobby welder

I've read on this forum, others and in books that to flatten a mig welding bead increase the voltage or reduce the wire speed.

It works for me.

John

[SundownIII]

Turboglen,

Not going to retype the whole passage, but if you're interested, I refer you to page 46 of the Miller GMAW handbook. This section deals with Direction of Travel-Type of Technique.

This manual can be downloaded or ordered in hardcopy as part of the Miller Student Pack ($25 including postage). The student pack, not only includes the GMAW handbook, but also an excellent TIG Handbook, along with a bunch of other goodies. Best $25 you can spend in welding.

Be careful of those "short bursts". Each one of them has the potential for a "cold start". A push technique is often used to reduce burnthru as the penetration is less.

When pulling the gun, the arc/heat is directed at an already molten puddle (preheated if you will), whereas with with a push the arc is directed at solid material. Think about it.

I use both techniques, just depends on what I'm trying to accomplish.

[KarateBoy]

I am a little confused.

I always PULL on thin metals to get LESS penetration. My thinking is that I am moving AWAY from the heat.