Welding

[jeff0520]

Hello all,
Does anyone have any wisdom to share with me on the topic of welding? I have a 90 amp flux wire welder. Some of my welds come out strong and serviceable, and some of them require only a gentle tug to break apart. The good welds and the bad welds look the same. I have not really isolated the factor that makes the weld good or bad.
I use a needle scaler, then a wire brush in a high speed drill to clean the area before I attempt to weld it, so I'm pretty sure it's not a matter of cleanliness. I just don't see what I'm doing differently between the good welds and the bad ones

Thanks

[KCStudly]

Take a look at O'Shell's "Standy Widget" build here http://www.tnttt.com/viewtopic.php?f=50&t=50100. He started out with a big dbl axle TT frame that needed some work and I have given him a bunch of welding advice on his thread. He has some welding training in his background and a suitable welding machine for the task.

90 amps is probably not enough to properly weld the gauges that are needed for a proper trailer frame. And I'm not a big fan of flux core (unless it is windy...even then, not so much). If you are stringing your welder out to your work area with a long skinny extension cord, that will wreak havoc on your ability to weld. You may also be running up against the duty cycle of your machine. The inexpensive entry level welding machines have dismal duty cycles (the time that you can weld versus the time that the machine needs to recover inbetween welding).

Another thing, If you are able to pull any of your welds apart by hand (except for little itty bitty one sided tacks) then your other welds are also very suspect. Just because you can't pull them apart by hand does not mean that they are up to the task of sustaining even modest loads in service. A loaded trailer bouncing down the road sees a lot more dynamic load than you could ever hope to apply by hand...even with a lever.

Make an honest assessment of your welding ability, both personal and equipment wise. If you really want to do it yourself, seek out more training, practice on scrap, and consider an equipment upgrade. If you just want to get it done and over with for a minimum of money and time outlaid, it sounds to me like you should be considering the services of someone with more experience.

Please don't be offended. I am not trying to discourage you. I have yours and other's best interest in mind. You will never be happy and will always be worried about immanent failure if you are not 100% confident in your work. You can thank me later after you have had time to think it over.

[CARS]

I absolutely agree with the above post.

Maybe an option for you is to use your little welder to tack it together and haul it to a welder for final welding? Should give you the satisfaction of doing it yourself and the safety of a welder that is certified.

[kirkman]

What they said

[jeff0520]

Makes sense. In the shop right now I also have a 200 amp Lincoln stick welder with a 100% duty cycle when used at 100 amps or less. I have the wire on hand to put in an outlet to run it. I guess I need to trot down to the big box store and get the big breaker and receptacle for it. The flux wire welder is just so darned self contained and handy I really WANTED it to work .

[CarlLaFong]

Flux core wire gets a bad rap from those who don't know how to use it. I am a certified welder and have run miles of flux core on high rise office towers, the Los Angeles Metro system, bridges, water projects, etc. Stick, flux core and sub arc are the only three processes that are pre approved for structural work. The fact that it is popular with the cheap Harbor Fright welders has led quite a few people to believe it is a Mickey Mouse process, but nothing could be further from the truth. That being said, a 90 amp machine, with a questionable duty cycle may not give the best results. Polarity needs to be correct. MIG is electrode positive, Flux is electrode negative. It makes a huge difference. Straight polarity (electrode -) runs much hotter. I have welded, at home, 3/8-1/4 mild steel with my old 110V Hobart handler many times with no problems or failures. I upgraded to a larger 220V machine a few years ago, but I worked that little machine to death (literally) for quite a few years

[Shadow Catcher]

I am level III NDE and weld inspector and did inspections on FCAW including welds such as Carl mentioned. Yes a competent welder can do very well with flux core and I learned ho to weld with it, but my goal was to learn how to make mistakes and what they look like ultrasonically. I would NOT trust one of my welds for a critical application, I do not get the practice necessary. Have some one competent do it for you. Stick is fine but I can tell you I have seen lots of really really bad welds.

[Dale M.]

Also its "penetration" you may not be holding arc long enough on one side or the other that is why weld may look good but fails... Its all about heat and metal flow...

With Gas you can use the push technique to draw bead, with flux core its recommended you pull (drag) your bead, also angle you hold MIG torch to work will make a lot of difference on how good your weld is... Also get you head over to side so you can "see" what you are doing.... MIG torch actually blocks most critical area from your view...

http://www.hobartwelders.com/elearning/
http://www.millerwelds.com/resources/
http://www.lincolnelectric.com/en-us/ed ... enter.aspx

Dale

[tonyj]

Just another hobbiest welder adding my observation . . .
Learned a long time ago to not trust a wire brusher surface--I always use a grinder or flap sander. You want the metal shiny and clean, clean, clean.

And what the others said.

[jeff0520]

Thanks everybody. I'm not welding the frame though. I'm just trying to tack the fender brackets on in a different spot than the trailer manufacturer intended. I went with a pre-manufactured trailer kit just to avoid having to do any structural welding. I know my limits

[Treeview]

Instead of starting a new thread I figured I ask here.

Using an auto-darkening helmet sure makes welding easier. It's time for me to buy my own. Up til now I've got plain ol' large screen helmets. Too often I jiggle around an loose my starting point.

How do I make a good choice? There are times when HF/China-made is 'good enough' but not with life-critcal things like this.

I have no idea what criteria to use to make a decision. any recommendations?

Thanks,

Tom

[jeff0520]

I'm very happy with my HF auto-darkening helmet. That is the one thing in my quest to learn how to weld that has worked like a charm.

[KCStudly]

I've been welding for almost 30 years, since before auto darkening hoods existed. I've tried them and every time I have, I have been flashed in one form or another. Now that's not to say that I have not been flashed by std hoods when my timing was off, etc. The thing with auto darkening is that it is not within your control. If the battery is dead (on the earlier models) or the sensor is blocked due to an awkward position you will be flashed.

Big Daddy Don Garlits shunned auto darkening helmets and that is good enough for me, despite my own experiences that tend to independently agree with his assessment.

Std hoods become second nature, like when you reach to take your glasses off before taking your shirt off, even tho you are not wearing your glasses; you still nod your head before you strike an arc, even if you are wearing an auto darkening hood.

I don't like them. In thirty + years of welding I have been flashed every time I have tried an auto darkening hood; a much higher percentage than the number of times I have been flashed with a std hood.

[LarryJ]

How do I make a good choice? There are times when HF/China-made is 'good enough' but not with life-critcal things like this.

I have no idea what criteria to use to make a decision. any recommendations?

I found Summit Racing has good prices on welding helmets. Purchased mine through them 4 or 5 years ago and it still works great.

[doug hodder]

Hello all,
Does anyone have any wisdom to share with me on the topic of welding? I have a 90 amp flux wire welder. Some of my welds come out strong and serviceable, and some of them require only a gentle tug to break apart. The good welds and the bad welds look the same. I have not really isolated the factor that makes the weld good or bad.
I use a needle scaler, then a wire brush in a high speed drill to clean the area before I attempt to weld it, so I'm pretty sure it's not a matter of cleanliness. I just don't see what I'm doing differently between the good welds and the bad ones

Thanks

The difference between good and bad welds is practice and knowledge. Get some scrap material and do some practice welds. A wirefeed welder hates dirty iron, so either grind all the paint and rust off, or use new materials. Play around with the settings on it. See just how easy it is to burn through if your up on the heat and wire feed. You really need to play with the welder and get a feel of what it can and can't do, and what you can and can't do. Try welding thicker material to a thin piece, learn where you need to place the heat and how to move the stinger. You need to learn what to look for when looking through the hood in terms of what is good penetration and what is cold lapped. Just my .02. Doug