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Another 4130 question?

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  • Another 4130 question?

    Still working on that motor stand.......

    Question is. What if any problems come about from welding mild steel to 4130? What filler would be best (TIG)?

    In the effort to save a couple bucks on the deal, I was thinking about using mild steel to make some sleeves and bungs that I will need from mild steel rather than pop for 4130. There will only be a few so weight will not be an issue and strength isn't nessecarily a factor either, unless the welds on the bungs will be overly prone to failure. The welds on the sleeves will see no stress, but the bungs will be in tension.

    Thanks in advance.


  • #2
    Mild Steel and 4130 are welded together quite often in older aircraft designs. Filler rod of choice then was either #7 or #1 when using O/A. For the guys who Tig repairs ER70s-2 is normally reccomended. Same precautions go as for welding all 4130.


    • #3
      I doubt they will be "overly prone" and this is a metallurgical question so that part of it is over my head but am curious. First, from sheer experience when we were kids we repair dirt bikes. Damage of all types, a fair share caused by loose bolts and the kind of stresses all the fuss over alloy steel is about. Places with marginal design and hi vibes, most fixes with simple welding rod, a lot of it just weld over cracks etc. and it worked well. This type of thing obviously wouldn't be acceptable on a commercial airliner.
      They use mild steel in NASCAR cages. Likely maintenance and repair are part of the issues and I assume (to some extent) we don't want metal so highly engineered that it makes every joint critical. We would need Aero and the slide rule gang involved at every step, wouldn't be able to do this work with relatively simple codes and acceptable welds from a MIG would do, and to top it off there is a certain amount of pieces required by geometry where eliminating weight might be a great gain by changing the materials and processes. This is a simple version, not meant to be exact, not meant to be debatable at every word.
      Now more of the same, one of the reasons to use alloy is to save weight but not just due to the fact that the material is lighter but thru engineered design the builder may be able to use less material, this is usually where the weight savings come from. It isn't just that one tube is lighter than the other. If you copy this from a general design and just replace the tubing likely all this is moot and likely no real gains were made and it added to the complexity and all the QC issues possibly creating more problems than it solves. To take advantage and avoid catastrophic error we need the calculator crew and experienced builders familiar with the issues and forensics as well as codes to oversee every detail, design the connections, even OK minor changes.
      The reason the "backwoods with the buzz box" was brought up was they were the originals, way it was with a lot of stuff including racing but power has increased speeds and competition, increased the stresses, they need better design to go with better materials, as was brought up in another thread, 300 mph vs 330 isn't 10% but 21. Most home build projects or even hobby stuff are not running at these margins and the builder isn't capable of refining design requirements at this level.
      When I have a difference of opinion with Aero (for example) it isn't because I figure I know more, quite the contrary, its usually some kind of perspective issue rather than a technical one. Look at the motor mount thread, no one thought it a good idea to saw relief for the header in a souped up sports car without some kind of legitimate evaluation, different context than "Can I splice a roll bar install in my 87 mud truck, especially since he was willing to put some kind of sleeve and reasonable locate the work so it didn't substantially add liability. Also toss in some other reasonable factors being that the owner is about 25 times as apt to injure ones self while working on such truck as driving it or exposes himself to other commonly accepted hazards, one primarily being on the hi-way to and from such an event or possibly greater riding a motorcycle as a hobby.
      I tend to evaluate on general condition, some electrical threads don't get a lot of help just due to the general tone of things, different than if we are talking to someone with decent general skills, willing to make some investment in parts, easy for me to spot people that can learn or grasp with explanation, in general I find most guys on the forums a pretty smart bunch. A fine example is trailers, most end up overbuilt in comparison to mass produced, lots of stuff like that where the owner replaces a stamped rusted sheet with a piece of structural angle. etc. No amount of welding will make up for poor design while properly engineered there is only a handful of connections that matter, most of which can be welded flat, nearly flat or horizontal. Most of that is moot compared to the risk if a guy drives like a bat out of **** with poorly located, poorly secured loads.


      • #4
        I had that up this morning and miss Aero's post before I hit the button. Back to the point of that ramble anyway, I would be somewhat interested in pics and wonder what the design work is based on.


        • #5
          I saw some airplane tanks from alum I am sure Aero would have had issues with. The guy built the airplane called a Barracuda and was on the cover of Air Progress at one of the fly-ins I think, about 25 yrs ago. It was a copied design, mostly wood with 300 hp Lyc in it, I guess one of a handful in the world.
          2 tanks out of light sheet with econo tig I recall, he was a pipe welder but this was about the first tig out the gate and this guy works like a maniac. It was all functional and pass inspection, he had some buds with papers but he was doing engine and I happen to pick up a new piston, sheet, I could feel the difference. I ask, aren't you going to fix the weight? He figures Lyc wouldn't send it that way if it wasn't alright. Me personally wouldn't find an ounce difference in one of 6 acceptable especially when the rest were within a gram. This plane eventually collapsed a landing gear and I don't know if the tanks ever leak or not, at least there were 2 of them and he was good about not flying on empty. I am a risky enough guy it don't bother me to take a spin but I always thought about the potential for fire with this unit. No amount of licensing, inspection, etc is going to stand in this guys way and it wont make up for decent craftsmanship. Big ole half inch bead on .060 alum sheet.


          • #6
            Here is a question for our engineer, could you get to the ground fast enough if one of these tanks rupture, catch this bomb of African Birch or whatever it was combined with a gob of fiberglass resin?


            • #7
              Originally posted by Sberry View Post
              Here is a question for our engineer, could you get to the ground fast enough if one of these tanks rupture, catch this bomb of African Birch or whatever it was combined with a gob of fiberglass resin?
              Thats what the 'chute is for
              As to quote a famous book "The best laid plans.....". An organization can do only do much, and in most cases wont outline a specific process, but the methodology used to determine if a process is appropriate for a given application, and the documentation therof. However that leaves the level of craftsmanship up to the actual person doing the work, and the acceptability of the work up to who "signed off" the part or repair. Ive seen my share of bad workmanship, some downright scary. Whats even more scary, is that someone actually "signed off" that part as being safe....luckliy that decision follows them....forever. It always comes down to the individual in some form or another. No form of process, paperwork, chain of command, or anything of that sort, is a replacement for the intellegence of the individual. Thats why I have always felt, that the best method of promoting safety, was by education, and not by control. But how do you stop those that dont want to be educated, but still dive into something over their head? Control. You will always have those renegades, that think they know better then everyone else, and usually dont like having to prove, by engineering, a process they want to use....usually because they cant.
              And im not even talking about formal education, the best engineers and designers I know, are the ones that had the drive and desire to learn on their own, they pounded the books for the love of it, not for a career.


              • #8
                My lack of formal academic education is a drawback. Lots of stuff that I just don't have the ability to figure out, many of them so far removed I plain don't bother, I am not really interested that much to tell you the truth.
                And I'm not even talking about formal education, the best engineers and designers I know, are the ones that had the drive and desire to learn on their own, they pounded the books for the love of it, not for a career.
                Absolutely no disagreement there. My own motivation is slightly different. I need to know how it works, my electrical experience is an example. I really could care less what happens or why one electron bumps another one, don't really understand it at an instinctual level of the truly gifted anyway. I am very self serving, I learn basically because I have to and I want to use it, need to service or be able to make a safe functional legal install especially related to the type of equipment I use. 95% of electrical is basic mechanical anyway and on the occasion I am faced with something over my head I do some research or have developed means or other spe******ts to consult.
                Some of the code stuff I know the details as good as sparky and better than my genius engineer. He don't care about like I don't care about igbts or even a diode beyond,,, well whatever, the guy can live from a simple extension cord, can does and will. My inclination in life is to run a circuit to have to avoid green acres wiring but for him its safe, the kitchen counter top may not have 2 circuits like code but he know enough not to run the micro, toaster and coffee pot on all at once.
                My interest isn't the how, why, or the curiosity of it all its in making the utilities and machinery, manpower all available at the time and place they are needed. An example, I got another 200 ft of pipe for a couple additional water hydrants, everyone else is content or resigned to using a couple long hoses and inconvenient valves. Its a big energy eater over several years and since I am not a rocket scientist I become willing to bite the bullet once up front for the materials and time, so hence I need to know how to size the right pipe to deliver the service while being economical for the installation. Could care less about understanding coefficients of friction etc. My real thing is production. Welding doesn't particularly interest me, taking the effort to become the finest welder I can be is way down my list of self improvement issues. The usefulness of welding interests me, how to make, save, reduce, expand, the convenience, the options the problem solving, the list could go on in that respect.
                I don't fundamentally care how my welder or generator works is another example, my time spent learning the how and why which I may never have the capacity to learn well anyway would be frustrating at best and the end result of knowing wouldn't replace the simple effort to be prepared with it, did I value it enough to acquire it, do I have fuel and the needed cords or connections to utilize it should the need arise.


                • #9
                  My electronics guy is an example, knows nearly everything there is to know about the inside of a welder and on the circuit boards, doesn't even own a machine, really doesn't need to, but I know nothing past setting a couple knobs and have 10 machines, go figure?


                  • #10
                    I don't think you'd go wrong using ER80S-D2 .


                    • #11
                      Btw some of you guys get WAY off topic , dude's question was about what filler metal people would recommend . I also get bored but jeez .


                      • #12
                        It does slide off topic but a simple answer would have killed this thread and my angle/question is how close is it that one follows exacting weld design parameters and when? My personal view as to what might be acceptable changes with the type of project. Just some general observation, I might be able to make the actual weld just fine but it doesn't make me qualified to do the work or give advice on air frame, engineered crash protection, etc. The filler may be a tip of the issue so therefore where is the work being done is part of the equation.
                        BTW, I saw another NASCAR thing the other day and the welding work was far superior to the last one I see. They both must have passed inspection but the skill level was better in the second.


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