Welding, Part One: Gear Selection

I've only tried welding twice in my life and it was with a TIG welder (Miller 225 and Lincoln 225). I have to say, after a 5 minute introduction I was on my way making what the instructor called very good welds.

I haven't tried Stick or MIG yet, but I think I'm gonna skip them alltogether and go the TIG route.

My only issue is that TIG welders are not cheap. A good, solid entry level one can run you up to $2000. There's no such thing as a cheap TIG welder (it just wont work or last).

So I'm trying to save up a little cash :-)

This was great breakdown of your welding process. It's also good to see how you've developed your welding skills and gear over time. It looks like you have a nice set up in your shop, so I was curious as to what sort of plan you used to organize your workspace to fit your welding projects?

Gladiatorgw.com

MIG is like a hot glue gun, but with metal. It's super easy.

I TIG'ed pressure vessels for years. A really good book is "How to Weld Damn Near Anything" by Jessie James. Read it before you buy a welder so you can understand what the different types of welding are for.

Cool article. Ive been welding for over 6 years now, with over 3 years TIG welding aluminum and stainless steel professionally. I find that while TIG is the most difficult to master, it is very satisfying when you lay down that perfect bead. Only thing I find dissatisfying is getting shocked when you accidentally feed the filler wire into the electrode!

blaxpear wrote: "There's no such thing as a cheap TIG welder (it just wont work or last)."

I have to disagree, at least from the DIY POV.
For professional daily use of course, you would want a Miller or Lincoln, and pay over $1000.

I've taught myself to TIG weld to fabricate go kart racing parts and to restore or modify frames, and have been doing it for about a year.

I bought a new 'Hutai' (cheap Chinese) 220v TIG machine on eBay, which is pretty basic. It's DC only, (ie can't weld Al,) and doesn't have provision for a foot pedal, but it was only $350, it does have pushbutton (HF) arc start, rudimentary pulse features, and a current/gas ramp up/down delay control, and I find it quite adequate. Knowing it's Chinese "junk," I baby it, and NEVER leave it outdoors or in the (unheated) garage overnight. You'd want to bring your consumables (filler, tungstens) indoors overnight anyway.

I do plan to get a better (smaller) swivel torch, but being retired I doubt I'll ever be able to afford a "good" welder.
Do I miss Al capacity and a foot pedal current control while welding? Sure. But it works quite well for steel, and IMO was a huge bargain. You just have to choose VERY carefully and educate yourself RIDICULOUSLY well before buying. Remember you will pay and pay for consumables (like gas, and tungstens, which you'll burn a lot when learning,) with TIG - but it's worth it as the process is incredibly versatile and controllable. You can make a neat weld on anything from the thinnest sheet (tin can) or tiny firearm parts, to 9/16" 4130 steel -as long as they're clean, and not contaminated (say, with bronze brazing,) or cast iron, which WILL NOT weld.

I got one of those chin strap-controlled hoods and (not ever having acquired the "neck nod" technique for flipping down a manual hood,) find that jaw control convenient. A weldor who has acquired other hood habits would find it difficult to adjust to, even annoying (as they also would hate the pushbutton type torch,) but having known only this, I like it.

Ony thing I would never try is buying a cheap MIG unit. Too mechanically delicate to do on the cheap. A MIG welder must have a well designed, very high quality, precise and durable wire feed mechanism, or it would be unusably annoying and waste lots of wire. It would tangle MOST of the time. And I would never do without the shielding gas function. There are many "flux wire only" MIG welders being sold out there for less. I'd steer far clear of those - even if they were "good" brands (like TS's Hobart.) Flux (gasless)welding is just too messy for me after seeing TIG, which is so clean and safe you can do it on the dining room table (as long as it's heat protected, LOL. Your 'work' will still get RED hot...just no sparks.)

As for interim price, "quasi-good" brands, check out HTP. Sometimes their sales produce decent intermediate pricing, and their support (something that's nonexistent with a Chinese welder) has a good rep.

A cheap TIG is actually a MUCH better choice an a fluuuux wire MIG, though you'll have to put in your time practicing to get good with TIG. Personal instruction would be great if you live where it's available.

Be VERY careful with eBay. Make absoilutely sure you tal to the supplier and establish a DOA return policy you (somehow....?) trust. I was lucky I guess. But MANY Chinese welders are either shoddily assembled, and/or almost all are mistreated in shipping (welders are HEAVY and can destroy themselves through their own weight in shipping. The Chinese do NOT pack well, and you can expect what you would, of cheap labor in assembly.)

Uh, oh....

The original post forgot a very important type of welding, the earliest, from which all else (including cutting) was developed -flammable Gas (as opposed to MIG/TIG's inert gas shielding,) or "oxy-acetylene" welding.

My mentor (who, being an experienced pro, has always been right except for his "cheap welder" prejudice) keeps telling me I WILL want a torch setup as well as the TIG I use.

He insists there are times you just need to heat metal (VERY hot, not just "propane hot,") to bend it, or to cut lots of it fast and rough. And yes, I have seen the wisdom of that statement recently. He also claims there's nothing like it for lighting BBQ charcoal ;)

Anyway, for oxy-acetylene welding, you need the two gas tanks, ling hoses, and a safe torch setup (with the proper flashback valves and different tips for heating, cutting and welding - which is somewhat like TIG, but not as clean.) I still avoid it, as keeping high pressure 02 around is IMO prohibitively dangerous for sporadic use (and TWO MORE gas tanks, with regulators, are expensive to buy and keep full.)

My mentor of course pooh-poohs that, but he uses it often, has a huge shop space, and has transported tanks to and from jobs all his life (and even witnessed and survived a number of fires.)

NEW TECHNIQUE FOR RESIDUAL STRESS MEASUREMENT NDT

Introduction

This type of non-destructive method NDT provides the possibility to measure residual stress and the effect of the service load with an impact device and a vibration measurement sensor.Internal stresses are to be considered as the following: 1) Operational strains referring to loads that the material is subject and calculated 2) Residual stresses in the material caused by heat treatments or stresses caused by welding, forging, casting, etc. The new technique is able to measure the applied load and residual stress that are balanced on the surface of the material, and in a relatively large volume, at times even the same size as the entire structures. This stress is part of the metal’s elasticity field and has a three axis spatial orientation. The system works through the accelerometer mounted with a magnetic base to generate the acceleration value of the vibrations created by the device impacting on the metal surface. The acceleration value, in combination with other parameters, permits obtaining the exact value of the residual stress or load applied in the desired point. This value will appear on the display directly in N / mm ². For non-magnetic metals, wax or gel will be used to mount the accelerometer.
This new system, for buildings, bridges steel inspection is very simple for to use , portable ,measure exact values of residual stress due to welding and the applied loads. After many years of research and tests, and between e discover about elastics behavior in field of metal steel now is very practice inspection point to point building and bridge constructions. This new system, for buildings, bridges steel inspection is very simple for to use , portable ,measure exact values of residual stress due to welding and the applied loads.
Internal stresses are to be considered as the following: 1) Operational strains referring to loads that the material is subject and calculated 2) Residual stresses in the material caused by heat treatments or stresses caused by welding, forging, casting, etc. The new technique is able to measure the applied load and residual stress that are balanced on the surface of the material, and in a relatively large volume, at times even the same size as the entire structures. This stress is part of the metal’s elasticity field and has a three axis spatial orientation.

Description

Elastic oscillations (also called vibrations) of an elastic material consisting of elementary masses alternately moving around their respective balance positions; these movements cause a transformation of the potential energy into kinetic energy. This phenomenon takes place due to reactions (elastic forces) that the aforementioned masses produce in opposition to elastic movements; these reactions are proportional according to Hooke’s Law to the same movements. The elastic waves that are produced propagate according to a fixed speed that depends on how rapidly the elemental masses begin to oscillate.
Elastic waves of this type are called “permanently progressive”, and they propagate at a constant speed which is absolutely independent of the speed with which the elemental masses move during the oscillating motion, and therefore also their respective oscillations. It is easy to verify that the elastic oscillations, from a material point P (in which the elemental mass m is supposedly concentrated) are harmonic. In reality, due to the fact that in any moment the elastic force that is applied to P is proportional to the distance x of the point from its position of balance 0, P acceleration (caused by the proportionality between the forces and the corresponding accelerations) is also proportional to x; this is demonstrated in the harmonic movement. The impulse creates in the metallic mass a harmonic oscillation (vibration) which is characterized by a specific frequency ù² and by a width equal to dx (movement of the relative mass). If a constant impulse is produced in the metallic material, the elastic oscillation generated in the P point will also produce a sinusoidal wave with specific width, acceleration, speed and period values. This wave is longitudinal when the direction of the vibration is equal to the P point movement, or is transversal, and in both cases the values of the results are identical; the only difference is the ¼ delay of the phase.

Analyze impact energies

Impact with the metallic surface results an elastic deformation energy.

Ed = Ei – ( Ek + Ep )

Ei = Impact energy Ek = Kinetic energy

Ed = elastic deformation energy Ep = plastic deformation energy + lost energy

Ed = ½ K dx² = ½ m ω² dx² K = constant elastic material (stiffness)

Conclusion

Application of this type of non-destructive method NDT provides the possibility to measure residual stress and the effect of the service load in a very rapid and simple way on any point of the metallic surface. The testing method requires smooth surfaces free of oxides, paint, lubricants and oil. Precision depends on the roughness of the surface.
This technology has demonstrated its validity over years of mechanical experimentation and has confirmed its theoretical basis.

About residual stresses

The residual stress in a metal doesn’t depend on its hardness, but from the elasticity module or Young module and from its chemical composition. The hardness of a metal indicates its ability to absorb elastic or plastic energy, but through it not possible to determine the value of residual stress. In a metal with the same hardness we will have different values of this stress. The residual stresses tend to equilibrate themselves in the surface of the material. The measurement made with all the major methods, X-ray, string gauge (destructive), optical etc. the residual stress is determined between the measuring the displacement of the equilibrium point the reticule crystalline. The method discovered analyzes the value of frequency and vibratory acceleration generated by an impulse with the subsequent reaction elastic (elastic field) from the metal.

You will realize the convenience of this technique.
1) Portable system easy to use and very swift.
2) NDT non-destructive test.
3) Repeatable in unlimited number of points.
4) All metals type (a-magnetic) and surface and inclination.
5) Don’t expensive. Effective for welding, hardened treatments, vessels control,
bridges, pipes line, aeronautics, NDT inspection for every metal types.

p.i Ennio Curto.