Take heart, there is a lot of welding and sanding between these fun bits..

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Nope, I'm too busy welding together my thunderdome.

Flux core would remove any slight oxidation between deposits on a continuous weld, or a media blast nozzle in front of the weld zone.
I agree with you if they intend to use it for load bearing structures, but it wouldn't be difficult. Just a loose seal around the work area and positive gas flow keeping oxygen out, problem solved.
The downside I see is cost. It's expensive to 'make metal' with a mig....or any welder. Electrodes/wire aren't cheap, and then there's the electricity. Bending or milling sheets, castings, or blocks is almost always going to be cheaper. This will be useful for designs that require complex interior shapes impossible to do conventionally, but not much else, imo.

There has to be a downside to weld-additive construction. They'd have to do this in a vacuum or inert gas filled chamber to avoid oxidisation between layers.

I know you can't weld aluminium like this. Aluminium Oxide has a much higher melting point than aluminium, which is the main point of failure with aluminium welding.

That is actually what this video is about: how people thought cold welding was a problem in space but it turns out it hardly ever is. That wouldn't make a terribly catchy title though.

A few more references would've been nice.

Since I quite enjoyed the talk I'm willing to overlook that fact He did also have some good examples of actual cold welding.

NASA has an interesting lessons learned article about the Galileo high gain antenna failure, which also seems to be more nuanced than "it was cold welding" - http://llis.nasa.gov/lesson/492

p.s. I got curious about the reference to Gemini, and I'm not 100% sure but I think it might come from a 1991 paper "On-Orbit Coldwelding Fact or Friction?" by Dursch, H. & Spear, S. (Bibliographic Code: 1991NASCP3134.1565D) or else it's from the paper it references as ref 5 (I. Stambler "Surface Effects in Space", Space/Aeronautics, Vol 45 No. 2, 1966 pp. 63-67).

That paper gives the opposite impression to the start of Derek's talk, rather than cold welding being discovered around the time of Gemini, it was often thought to be a problem around that time but as he says later was subsequently found to be quite rare (Dursch and Spear found no actual cases of cold welding causing spacecraft issues, they were usually friction issues due to fretting or galling caused by loss of lubricants, but still recommended taking precautions to avoid coldwelding).

Wait...

Uses an example of cold-welding to set the premise for the talk.
Psych! - Example was not actually cold-welding.

His second example, the Galileo Jupiter mission, didn't explain why we *thought* cold-welding was a result of a malfunction, and I've no idea how that information would come about because the craft never returned to earth.

wtf? Are these shows really getting so bad? I had more respect for this guy.

They aren't wrapped in wood, but if this is uncoated pipe, some will lightly tack weld a ridge or piece of scrap barstock to the OD of the pipe to keep it from rolling when building the stack; they aren't there to prevent this type of major rolling action. At around 1:33 you can see one of these going over the edge. Just guessing, but these look to be in the 20" to 30" diameter range with plenty of length, so they're just really small ships with the ends cut off and will float for a bit until well flooded - lots of surface area there for some buoyancy, and I've seen 40 foot joints of 20" diameter casing float near the surface for 30 seconds or so when a bubble gets trapped temporarily inside before burping out and sinking to the bottom. At around 2:15 you can see the big reddish block with the vertical groove right on the corner of the load platform about 1/4 of the way up the frame. That's where normal humans stab the stake or pipe to help contain the load (so, the vertical pipe or solid stake goes in the hole, the load is built, and no rolling can occur - momentum is the killer here, so if you keep things from rolling, life is good. This was an excellent example of how not to load pipe on a barge / ship.

They've sure come a long way... we used to use our old chain driven potato harvester to dig up carrots after a slight modification. With potatoes sitting in a hill and the tops killed with spray before you harvest, it's a little easier as the front blade just cuts through the hill and you sift out the taters with a series of metal belts and a shaker tray, with one or two folks standing on the sideboards tossing out the rocks, dead animals and rotten ones. To do the carrots, we welded a modified ridging plough blade ahead of the scoop to break the land and free up the carrots, and up the conveyor they'd come. Had to move along a bit slower because the tops sometimes got snagged or bunched, but it worked pretty well, and was easier on the back. The potato harvester we had was built in 1928, lots of cast iron parts but held together for at least 46 years.

Actually blade thickness has a lot to do with cutting power. Having a nice sharp edge at a good angle helps with the bite of the blade - and a host of medieval and ancient swords had that - but blade thickness impacts how deeply a cut can go, the thicker the blade the harder the hit will have to be.

It's why your kitchen knives are measured in milometers. Beyond that thickness of a blade has a large impact on its weight (katanas are a shorter blade but heavier than most longer swords), how long the hilt needs to be (and katana hilts were significantly longer than the remakes of today) and more.

One might think the thickness is there for durability and certainly the blades were durable, it's why there are still some of the originals around today, but the real reason is Japanese steel wasn't very good and full of impurities while at the same time the Europeans were mass producing steel of a significant higher quality. I hear the Japanese folding process vaunted as the height of sword-making but the real reason they folded the steel wasn't because it was a superior process - it wasn't, pattern-welding was and it was used in Europe as far back as a millennium earlier - but because it helped spread those impurities throughout the steel. That extra thickness helped keep the impurities from ruining the blade as well.

The katana... it's beautiful, fun to wield, unique looking, has a treasured past but it just.. isn't.. a very... good.. sword.

Yes, and I still can't understand how someone can possibly be a doctor and still hold the naïve beliefs he holds.

Perhaps it is mean to judge her, but I think she wasn't actually asking a question, but she was regurgitating a specific phrasing of a statement as a question, right?
"Why should we base the validity of all of our life's beliefs on a theory?" by which she really means 'We should not base our beliefs on an unproven theory, we should defer to the 'proof' of the bible'...at least that's how I hear it, because I've heard it before and that's what was meant.
First, it more than implies that we all hold immutable 'beliefs', rather than fluid ideas, and second it conflates "scientific theory" with the English word "theory", showing a complete lack of understanding (or more often the case, an intentional misstatement and/or intentional conflagration of disparate terms) of science and it's processes and terminology.
If I thought she was actually ASKING, rather than just slightly rudely interjecting her incredulity in the form of a 'question', I would agree with you. I wish more people would actually ask this kind of question. Sadly, I've seen this all too often, and invariably those asking this 'question' aren't listening to the answer, because this 'question' is their answer.

Unfortunately, I'm not rich enough, or able enough (twice broken back) to qualify to immigrate to NZ (although I am trained in the correct field, welding, to qualify the last time I looked). If I was qualified and could convince the wife, I can see no reason not to move there tomorrow, even if all Americans got their act together tonight. Have you seen NZ?!?

My guess....that car is totaled. Every electronic device in it is fried beyond repair now, and the wiring is probably also shot. Cars are not designed to survive this. I noticed the car shut down instantly.
I wouldn't be surprised to find out that some things had welded to each other as well. It looked like the front wheel at least was locked up, but that could be the driver breaking hard. I hope for their sake that the doors didn't weld shut!

Whelp, apparently working with linear friction welding gives you a serial killer face...

insane, back when I was in highschool there was no cops/guards/etc

We even had a smoking section, and guns could be brought on campus.

For smoking section you just needed a letter from parents that they knew you smoked. and on recess the smokers all hung out there.

To bring gun to school, it was during any hunting season. You had to have note from parents that they know. The gun had to be visible, either gun rack in back window of truck or in passenger seat. Rifles and Shotguns only no pistols.

You had to have your Hunter's Safety Course card, Your Hunting License both on you to give copies at office.

You had to leave your vehicle keys with the front office and submit to random vehicle search of the hunter's vehicles only.

So while everyone could go to their cars at recess, or if you had extra empty elective, some of us juniors would drive up to Hardees before lunch and grab fast food then be back before 4th period started, but the hunters had to leave their keys with front office and they could not retrieve them until end of school.

So much more freedom.

Smoking was banned on campus for students only my 10th grade year, but Teachers had the smoking lounge in building. There was a teacher's lounge on each hall, the back hall F where weight lifting, welding, home ec, and vocational classes were was where the teacher's smoking lounge was. Most students friendly with teachers could sneak in there and smoke anyhow.

crazy times.

I had a 84 Camaro and kept a flare gun under seat my dad owned a boat and had couple extra flare guns. So I had that for some crazy reason thinking if someone attacked me, at point blank range I'd put on a huge firework show


Then there was the stereotypes that were proven right not wrong.

The jocks hung out together, the headbangers/smokers hung out together, the nerds, the band folks like me as my senior year I was drum major
and the blacks stayed together all in separate cliques at lunch and recess and before/after school.

stereotypes even went further.

the only highschool girls with babies (during time I was there I stress) were black girls, they had to build a daycare from the old mechanic shop behind the highschool for them. And even though this was the early 90s in the south, you'd hear over the Intercom every 6 months "All Black female students to gym at this time please" where they'd get lectured on abstinence, or condom use, and std's and such.

the only time rest of the student body went through that was in 10th grade they'd take the boys one day, and girls the next day.

We had a blast though as the guys, the protection/std talk was given by one of the football coaches, and during the talk with the guys and showing various "shock images" of std's on penis on the TV, when he got to the "sex ed" portion, he flipped in a Nina Hartley porn intro where a nude Nina Hartley showed the correct way to place a condom on. haha was hilarious looking back before "political correctness" went out of control.

I loved highschool and college.

Graduated high school in 94, got associates in 96, took year off then got bachelors in computer science in 99.

But 89-94 (our highschool here in the deep south is 8th through 12th) most are 9-12, but not here. It's still 8-12th here. So it's nothing seeing 12th graders dating 8th graders. Freaky yea, but not unusual.


If you got into a fight, if a coach was around he'd let the fight finish, unless it got a bit too over the top then they'd break it up. You didn't get suspended, you lost recess privileges usually 3 days plus the starter of the fight got 10 licks of the paddle in principle office, the other only got 1 to 3, or if person was just dominated and got ass kicked you just got detention.


Kids didn't act up at all most times. And the reason was Corporal Punishment. Not private paddling either.


Once I was having a bad day, me and "highschool" sweetheart were having a bit of a spat. We sat next to each other so we were bickering a bit during class. Teacher had yelled at me to shut up and do the work. I sighed "Leave me the fuck alone"

bad move.

She called me to front of class and I got 5 licks of paddle in front of everyone. They'd stick finger in your belt loop and yank it up tight to put that extra sting on it. Embarrassing as hell! Even female older teachers who didn't paddle hard, it was just too embarrassing to get paddled, so kids behaved.


And of course if you refused paddling which you could but you'd take a zero for the day's work. few of those in a semester and no matter how hard you worked you were flunking that semester.


But the system worked.

It wasn't until they went crazy insane on political correctness, stopping corporal punishment, and putting cops/rent a cops/guards in schools and after the No Child Left Behind was signed into law, they severely dumbed down kids forcing the smartest to learn at the slowest kids pace. Doc's prescribing SSRI's like candy to kids in MASSIVE quantities, that schools in today's culture are crazy.