Rough NASA welding

[Richard.]

like dale said if it’s a mock up. A demo piece in which case what does it matter.
I know nothing about the item, what it does and what it’s done. What I do know is what a decent weld looks like from a defect inspection POV. I also have a firm understanding of typical criteria on welding defects and there allowances. Zero tolerance isn’t always practical so there are allowable tolerances on defects and craters on aluminium are typically a max depth with No limit on diameter last time I looked at a criteria spec on them which was for a company making scaffolding braces with tig.
Yes it’s quite a bit more tricky if you don’t have facilities to slope off. As you can’t control solidifying times. You would then need to do a patch up with low current re strikes and touching up with thin fillers. A bit more of a ball ache.
My 06 fireblade had Short weld on the swing arm that cracked 2/3 of the way across. It looked to of started from a small crater. In fairness with the rest of the design in the swing arm that weld could of failed completely and not caused any ill effect. I still re welded it mind. To me a crater shows laziness and laziness is something I’ve never really tolerated so the defect has a little grind on me when I see them because it’s like leaving something unfinished. Open box section on fabs pees me off in much the same way

 

[mechman]

The picture's from wikipedia and it says it's a 1960's vintage Mercury-Atlas motor, so probably not bad considering it was made 50 odd years ago!!

I was in MAN in Augsburg a few years ago and there is an Arianne rocket in their museum (MAN made/make lot of the rocket motor parts, I'll try and dig out the pics) - that was similar with lots of rough looking parts but I'd guess it was either a pre production mock up, used for proving a manufacturing process or used for training etc with no intention of ever flying.

A little bit off topic but there was a documentary a few years back(think it was ch 4)called the cold engine, very very interesting, watching it the west wouldn't have been where they are without the discovery of abandonment of eastern technology

 

[daleyd]

A little bit off topic but there was a documentary a few years back(think it was ch 4)called the cold engine, very very interesting, watching it the west wouldn't have been where they are without the discovery of abandonment of eastern technology

Yeah, the American space prgrwmmae was headed up by Werner Von Braun who they smuggled out of Germany after the war, without him and the technology from the nazis they would have been years behind.

There was another good programme about how the Russians actually won the space race, the amount of firsts they had was amazing considering their technology was quite antiquated and agricultural compared to the American effort!

 

[postie jon]

Ah ,with plenty of underseal and a blast of shutz it'll sail through the Mot...

 

[zeppelin builder]

End craters are one of those things that can have no effect or can crack under any amount of pressure. They are also one of the easiest things to fix on the job. Putting it into the field and saying it’s fine cos it survived doesn’t mean the next one will.
I wouldnt be bothered about the rest of it looking a tad un tidy but any alu tig welder worth there salt wouldn’t leave a crater on the end of a run let alone 3 that I can see.

Absolutely it wouldnt even get passed a visual in my mind its also a stress raiser
Look at most of the production welds on mcycle frames and they all have it there are ways to alleviate this even with basic machines with no slope off crater fill

 

[zeppelin builder]

Bare in mind some transformers would not have had slope 50 years ago.

Dont need it they had pedals mostly . there is another method too we used it all the time on cunifer pipes which is realy hard to stop abruptly without pin holing

 

[Richard.]

Dont need it they had pedals mostly . there is another method too we used it all the time on cunifer pipes which is realy hard to stop abruptly without pin holing

What was the method you used Zep

 

[daleyd]

Would this have even been classed as a defect 50 odd years ago (A genuine question) ?? It’s easy to look at stuff through today’s eyes and criticise but everything needs some context.

Things move on so quickly, bear in mind at around the time this was made they only just started to discover about metal fatigue when dehavilland comets started falling out of the sky...

 

[Richard.]

Would this have even been classed as a defect 50 odd years ago

Probably yes but the criteria could of changed.
Thing is dale it might not even be classed as a failing defect now mate. With weld defects you have a criteria to work to. That is set by what the welding engineer deems as acceptable or not depending on lots of things. With craters it’s all about design. If that crater exists but hasn’t cracked immediately after welding which a lot of them do then it comes down to the fact of how is that part designed. What stresses are those welds under. If the stresses are purely on the structure and the welds are simply holding it together then the criteria could well be all craters are acceptable if there is no cracks.
As someone that knows nothing about that part apart from looking at the picture. I have no criteria on it so I’d have to play on the side of caution and say those welds are failures based on end craters being present. I’d measure them and from my own experience let go any thing shallower than 0.5 mm as this is more a sink in the run rather than a crater. It’s all theories though. Without knowing the ins and outs you can never really know.
My problem with craters steps out side of an inspection POV (probably less professional) but there is an increase in risk by leaving one than by not. It’s probably one of the only weld defects that can be sorted out without weld metal removal and it’s one of those defects that can be addressed with minimum skill. I’ve taught people how to eliminate them in 30 mins. On this basis it’s not so much a question of are they really a problem but more of a question why are we leaving them.

 

[zeppelin builder]

What was the method you used Zep

As you are about to finish you lean the torch back and feed abit more wire in there it leaves a pronounced raised bump a rub with a file will reveal the crater which is now above the regular cap metal and should be filed out
Accelerate before stopping leaves a progressive taper out on cap you should be familiar with this on scratch type set ups
Flash torch off on off on rapidly . works with old viper units with no slope down
You will be amazed how deep them craters can be
My favourite way to check alloy tanks is to put some water soluble dye penetrant inside then watch
It will seek out even the tiniest defect

 

[Richiew]

I expect that has never left the NASA labs work bench. Most stuff that NASA sends up never returns at all or burns up on re-entry. I watched the Heavy Falcon launch the other day and really enjoyed it. Just compare the Saturn V rocket going up with the Apollo earth landing system splashing back down. The return is absolutely minimal. Shoddy welds are probably fine for proof of concept,whatever it did.

 

[penfold]

Not welded by NASA; NASA shuffle paper, train astronauts and write cheques; Grumman, Martin Marietta, Lockheed, Aerojet, Morton Thiokol, Pratt & Whitney, Rocketdyne, North American Aviation, Rockwell etc, did/do the fabricating bit.

 

[mike os]

Could be a prototype, failed part or a single use part...... later mocked up for display.

As a single use part would cracking be an issue?

Did they x ray or ultrasound the welds?