When I worked offshore in the Gulf of Mexico, I got to try my hand at Oxy/Acetylene and Arc welding on little projects around the construction barge I was working on. I've always remembered that someone mentioned there was a special certification for welding aircraft structures, with some more stringent inspection standards. Is that the case? I would really like to take a class to learn to do this properly for future projects.

Aside from good old stick arc welding, MIG is hands down the easiest method. I feel like I can do no wrong with my Millermatic 175. Good setup is key but the settings are made easy by the reference card on the inside of the access door. Good clean wire, lubed pads on the feeder, clean tip, correct working pressure on the gas bottle, clean work-- all these things contribute to a good weld but the wire feed takes that coordination of the filler rod dipping out of the equation. I've found that holding the trigger and running a little wire out before the first weld helps to prime the hose with gas, making the first contact cleaner.

I find O/A a little more challenging, mostly because I end up chasing heat settings for different material thicknesses. TIG is by far my favorite just for the cleanliness factor and the flexibility to run AC on aluminum. No splatter. I'm still a noob but having fun getting better.

Say you spot a poor quality weld on your airframe: would you fix it? If so how? File out all the filler you could and redo it, go over it again with the TIG and add filler as necessary to fill in the voids, get out the O/A rig and go over it adding the same filler used before, or ??? Yeah, there are a few welds on the Bearhawk I'd like to fix.

whee wrote:Say you spot a poor quality weld on your airframe: would you fix it? If so how?

If the filler is ok, then gas is a fast way to reflow and penetrate a sketchy bead on thin stuff. It generally puts more distributed heat into the work piece than electric welding,and may be undesirable for warpage in a weldment. TIG is a nice way to re-work beads. MIG may require more grinding to avoid excessive filler. If a larger gap is present that needs filling, pulse welding is super handy and easy to use.

I'm with lesuther. But post heat the cluster. If porosity is present? Grind to fresh shinny metal, then weld.

A weld has to be really bad to be unsafe. Are you not happy with the appearance or do you believe strength has been compromised ? Sounds like you better go ahead and fix it to your satisfaction as you will always think about it as long as you own it. If you think there is porosity you can find it with patience and the tig torch. Obviously try to make it better than when you started. I've seen this go the other direction.

Kevin wrote:A weld has to be really bad to be unsafe. Are you not happy with the appearance or do you believe strength has been compromised ? Sounds like you better go ahead and fix it to your satisfaction as you will always think about it as long as you own it. If you think there is porosity you can find it with patience and the tig torch. Obviously try to make it better than when you started. I've seen this go the other direction.

So true. Ive seen airframe and engine mounts that looked like they were welded with a coat hanger and a worn out Chinese battery as a power supply, yet these machines seem to hold up fine. When it comes down to it, the basis of airframe construction is the truss, an amazingly strong geometry, that deals with the forces or tension, compression and shear, in a very efficient manner. In my opinion, ya can't beat the steel airframe. It's light and strong and quite forgiving of workmanship.

I agree with the robustness and tolerance of workmanship but there are a couple welds I'm not sure I can leave alone. The A&P that looked the airframe over said to leave it alone but I just can't.

Here is one of the welds I want to fix:

I just had a crack in my crane sub base repaired by a buddy who's been a pro welder and fabricator forever. 1/4" thick steel, the first thing he did was "chase the crack" with a skinny wheel, until he "got it all out". Then he welded the resulting fissure back up and I ended up with a flush repair.

Speaking of welding and metal fab in general, I am pulling the trigger tomorrow on another crane, to replace the one I just sold. What sold me on this 2006 National was the owner, here's what he does for a living (he is the company owner and founder of the family run biz): http://www.leescfi.com/ So much so that I am buying it sight unseen It has a custom bed (a job he seems more then qualified to handle) and lot's of trick features only a guy with his metal working ability and equipment could do, as opposed to all the plain jane stock units I've looked at. I saw this rig the same day I came from my welder friends shop, and as always I was super impressed with his all around workmanship and what a great shop setup he has, (I built it for him a few years back) my crane seller appears to be cut from the same cloth. During our initial conversation, while he starting to expound on the cranes unique features, I cut him short, telling him I had been on his biz's website, and that told me all I need to know about the crane, in a sideways kind of way. He bought a new 50 ton, his biz is that good, another selling point for me. I am really looking forward to meeting this guy, and my "new" crane!

Whee: I would keep in mind whether the part was in compression or tension, or both. Obviously all welds being perfect is desired, but if the part is only ever loaded in compression, may not be a biggy.

You could paint over that and it would probably be fine but I don't blame you for wanting to make it better. Obviously with all the porosity on top you can't expect underneath it to be much better. From looking at the pic it looks like a die grinder with narrow stones or cutters are going to be needed making sure not to scar the tubing. If that was just one little pocket of porosity a patient welder could go back over that cluster and "boil" out the bad stuff and correct it with some additional filler. That's not the case in the picture. Once you get that area in question dressed out and re welded it will not have that stack of dimes look but it can be better. One of the nice things about tig welding in this era is equipment is affordable for a home shop guy. One of the downsides is not everybody is a tig welder.
Edit: I'm repairing a Stinson 108 right now and as many know Stinson stick welded their fuselages. There are clusters on the Stinson that look kind of like this.

Thanks Kevin. My TIG welding is getting much better but it still doesn't look like stacked dimes. I don't really care about the look I just want the airframe solid and built to last.

6 years ago I decided that I wanted to weld and fabricate. So I bought a cheap mig welder from Home Depot. I watched some youtube videos and just started practicing and trying things. Then I decided I wanted to tig weld so I bought an AC/DC tig welder and used the same process that I used to teach my self tig. I also had a friend that lived in NY that was a welder so I would call him if I had questions that I couldn't find online. I was driven by shear determination.

Practice is the only thing that will truly make you better. The one thing I wish I had was someone looking over my shoulder and telling me what I was doing wrong, beacuse I had no basis as to what was wrong or right and how things should look. I now own a performance motorsports fabrication business in Portland Oregon where I offer Precision welding, CNC cutting, CNC forming, CNC machining, 3d cad Design, and Manufacturing consultation.

Beautiful examples of the kind of work we would all like to produce.

Steve

I will mention a few things, hopefully the op has been welding all year and learned this already.

Clean material and fit well. A good pipefitter makes the welder's job way easier.

Get a gas lens on your TIG torch - google it. Also learn your equipment and decide if you like a foot control or fingertip control best. Foot for me.

Got wind? Your TIG welds will suck. Gas is way more forgiving.

Get a GOOD helmet, like an Optrel and learn how to adjust it, get a cheater lens if needed. TIG is the ultimate weld if you have the time, with the right equipment you can see the weld as if forms into your base metal one excruciatingly slow bead at a time.

Whee, you can re-flow those welds and they will look better, but they won't be stronger by any meaningful amount. Most any weld is going to hold in our application - on a crane maybe not so much. Still they look pretty rough, if lots of folks are going to be looking at that you will feel better about re-flowing them.

MIG on an airframe? Sure, if you keep it clean, fit it tight and have some skills - I wouldn't shy away from a migged airframe. I'll TIG mine though.

I have some welding equipment, but I gave away my stick welder about ten years ago - never looked back.

http://www.northerntool.com/shop/tools/ ... _200631881

I got turned on to this machine after our weld shop foreman got called by a buddy of his to set this up for him. This guy is an absolutely awesome welder and has been welding his entire working career (35 yrs). I have been welding quality control most of my entire working career and the quality control manager for the last 10 years. I do know a little something about welding using all processes and materials.

Back to the point. So the welder set up this machine for his buddy and then came back to work and told me how smooth it ran using all processes. He tried to trip it out on duty cycle by cranking the heat up and hogging the metal to the plates. He could not trip it out or find any fault in it. He was so impressed with it he sold his 4000.00 miller and bought one of these. Well not to be outdone I had to buy one too. The tig unit for it is another 80 bucks, but it comes with a spool gun for aluminum, the built in wire feed to run the larger spools of wire and the lead for stick welding.

The tig torch is a mini rig so its nice for getting into tubing clusters and will handle any aircraft welding job you need to do. The ONLY draw back to this unit is you cant do AC tig for welding aluminum, but you have the spool gun for that. To step up to a machine that will run AC on the tig torch you are gonna spend some money. Bottom line, for a machine that only weighs 35 pounds this is a GREAT unit. I have welded up my aluminum snowmachine trailer, various steel trailers etc. as well as the 4130 tubes and it runs SUPER smooth!

This unit is cheap enough that one or two small welding jobs and its paid for itself. Learning to use it is really pretty easy, youtube the process and you will get tons of hit that teach you how to "walk the cup" etc to get those beautiful welds you are wanting to make. It really does not take that much time to get the hang of it. Learning to feed the wire smoothly with your off hand is probably one of the hardest things to learn. They make a "pen" with a roller on it and a hole in the middle that you can just roll the wheel to feed the tig wire and a lot of people find that easier than learning to feed it with your fingers and thumb.

My current project, all MIG welded. 10' x 20' steel racks for solar arrays, my own design, I have about 35 of them up now. A bit over 3 KW per array.Some as high as 60'! Most 10 or 12'. They weigh about 1400 lbs, and 4 of them on one big pipe seems to be working well, though most are singles, with a few doubles. I pre fab them in the home shop, and then truck them to the job site, really keeping my time spent there to a minimum. I can do these as cheap as a "store bought" one, but with all local materials, delivered, and installed. They are built to be picked with a crane, good thing I have one. This 4 array system, installed last year, will be doubled in size with another 4 array rack, that's what I'm building now. The customer drives a Tesla, and put 59 K miles on it the first 6 months he owned it.

Strictly a self taught welder here, but with a all around construction background "when in doubt, use a gusset", is my motto. And, when able to buy buy used pipe "use larger dia. then you think you need, it's still pretty cheap". Keeping them square is the trick, ( the usual carpentry lay out skills come in real handy) I have my system down now to the point that when finished, they come out within 1/4" square, some perfect. One was an inch out, over the diagonal, but still easy enough to correct when installing panels, just like a good carpenter building on a bad foundation can make it work. Fun stuff, I really like working with steel, after being a nail bender most of my life!

That tow bar on the Rav4 knocked a deer down the other day, if I would have been in the Yaris, it would have ended up in my lap. No harm to to the 4 or the deer, that bar has been on 5 different rigs over the last 25 years, guess i built it right.

So.... the other day I'm doing a crane job at a semi retired well drillers place, unloading a big water tank off a trailer, and I happen to notice a pile of misc. pipe., some large enough dia. (24" and up), to be just what I need for the main vert support pipe for the 4 solar arrays I delivered yesterday. See his boneyard at the upper right? Tonight I called him up and said I have cash money for the right pipe, and is he going to be around tomorrow AM?

He is a 40 minute drive from me, on a busy 2 lane highway, but only a 10 minute flight (unless i get distracted) down the ridge line. And, I took this picture a few days earlier, showing that landing right there won't be any problem.




I mentioned that I could drive over, or just jump in the plane, and he readily agreed that flying over (fun) made more sense, once we strike a deal I'll drive over with the one ton and trailer (boring). I reminded him that I had sold his nephews across the highway an ultralight about 30 years ago, back when I was peddling them, so was quite familiar with the area. No need, he was readily agreeable, no problemo, come on down! What a country (and county/state)! I'll post tomorrow on how it went

And.... done! I landed upslope (hard to tell from pic) over the short trees, and parked, with the parking brake ON, at about the 3:00 area in the previous pic. Right behind the big blue shop, where you can see the gap in the junk piled there. I then called the house, and his wife said he was in the shop. I walked around to the front, the big door was open, and there he was, HE HADN'T HEARD MY APPROACH,LANDING, OR TAXI UPHILL That's how frigging quiet my bird is, just saying. I was a little concerned over the alfalfa height, it being hard to ascertain from above, but it was OK. My place is on the range to the right and up a ways around the corner.



Another trick I use, when landing off airport like this at a new site, and of course wanting to eyeball it good but at the same time, not attract a lot of attention, is to have a little altitude in the bank, and then make two or three descending, well throttled back, 360's while figuring out the LZ. This game plan goes back more then 30 years for me, as I used to refuel exclusively at truck stops and gas station when going XC in my Pterodactyl ultralight. Being sneaky and quiet is just a habit now.

He had exactly what I was looking for, a 20'+ length of 28" pipe, (I need to match the other array, it's vert pipe is also a salvaged/pre owned 28"er) schedule 80 no less! Sure it was scabbed together but welded right, and was straight other then one end being mushroomed a bit, that end will go in the 10' deep hole with 6 yards of concrete around it so no problem. Plus, using my new concrete bucket I just bought for the crane, this pipe will not only be IN the concrete, but will have concrete INSIDE it, so, hell for stout. $300.00, a great deal for him and I saved about the same, considering a new piece would be about $600 or more. The last thing I needed was 24' of 14" pipe, he didn't have any so we went across the road to his brother's boneyard, who also didn't have any. Bummer, as they sell it in 21' lengths when bought new, so I was looking at 2 lengths to end up with 24'. But then I spotted a short piece in the weeds that looked about right. The only piece of 14" we could find, and it was 38", so now I can buy 1 length of new, and have 24'+, a very productive and cost effective morning.

35 miles later, at the job site, I rolled the 28" pipe off the trailer, next step is to cope the top out for the 14", and then plant it in the concrete. Sorry for the thread drift, this is a welding thread after all, but as usual sooner or later whatever I do seems to involve the airplane. The tall grass and a tailwind made reversing my landing for takeoff a little iffy, so I taxied up along the blue shop and blasted off into the wind on the field with the small pivot system, it being out of the way. The well driller got 300 bucks and a 10x12 photo of his spread, and he had zero problem with me flying in and out, liked it in fact.