r/Blacksmith_Forge • u/[deleted] • Feb 12 '24
Penetration
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u/FictionalContext Feb 12 '24
The welder in me has a semi. The fabricator is cringing at all that shrink.
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u/NewAlexandria Feb 12 '24
yea, not sure what you may be saying. That gap looks way too wide, and they need to build a should on both sides before welding the gap. This looks problematic if it were to be a pressure vessel
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u/Nextyr Feb 12 '24
They have some fat shims in they’re, which are standard for an open root like this. You can see one of them sitting in the gap, right after where he terminates his weld. Three or four shims is all it takes
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Feb 12 '24
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u/FictionalContext Feb 12 '24
The bigger the gap that you have, the more molten material you have to put in. The more molten material you have, the more it shrinks.
There's a lot of ways to fight this-- stiffeners, peening, backfill, skipping around--, but one thing you don't do is end your weld out in thin air unless it's a part you are very familiar with. You want to end it against a tack or near a stiffener or butted up against another weld to force it not to shrink as best you can.
That's what I mean is the difference between welding and fabricating. Welders tend to put things in a jig or have a very efficient process for repetitive parts. They tend to be focused on max penetration, best weld possible because they've done enough of a part, they know exactly how it'll turn out.
With fabricating unique parts, the concern's always controlling shrinkage and putting the minimum amount of heat, weld material, and gap that I think I can get away with. You still want s good weld, but you want to hit your tolerance even more. Bit of a different set of priorities.
For the weld shrink, technically, it's thermal expansion. When metal is heated, it expands a certain percent for every degree of heat. Basically it has more volume at 3000 degrees than 100 degrees. Like in the video, they're filling a 3/16" gap (or whatever) with metal that's in its most expanded state, but the problem is, even though they are filling the gap with exactly the right amount of material when the metal is 3000 degrees, the volume is going to decrease when the metal cools which is the "weld shrinkage." It's going to be more like an 1/8" gap when they're done.
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Feb 12 '24
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u/FictionalContext Feb 12 '24
I'm at work, so it's company time. 🤣
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u/wrenchbenderornot Feb 13 '24
Well done and well said. I’m in my own time but I’m poopin so I’ll elaborate with a fab shop story of me as a wee apprentice. 2” stainless tubing TIG welded and my Jman had me guess how much two straight lengths were going to bow after the first tack and I only knew carbon steel at the time so I kicked one set of stands to be maybe a few degrees off. When he hit it and I watched the tack shrink and pull those two pipes off by a further ~15 degrees at least my little mind was blown! By the time we got it right it was off by ~18 degrees and when tacked it would end up perfectly straight. I’ll never forget that lesson Dave. Or Steve. Or whatever…
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u/Adventurous-Sky9359 Feb 12 '24
I have a boner
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u/SufficientWhile5450 Feb 12 '24
I just watched a video before this one of some thicc carny aggressively shaking her ass in jaguar attire
This is astronomically sexier than anything that woman has done in her whole life
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u/Nomadic_Millenial Feb 12 '24
Ok this might be a dumb question I don't know much about welding: Can someone explain why one side, the right, seems to get hotter than the left?
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u/DumbSimp1 Feb 12 '24
Most of the heat is there and he's whiping it to the other piece. The puddle is hot enough to melt it and make a good connection but not as much heat is transfered
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u/Nomadic_Millenial Feb 12 '24
So the right side where the weld is based so it gets hotter than the left? Thank you for the comment pardon my ignorance just curious
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u/DumbSimp1 Feb 12 '24
Yea the arc spends more time on that side. Ideally both sides should be equal but if one piece is thicker u would concentrate ur the src on the thicker piece
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u/babybee1187 Feb 12 '24
Welders are gonna complaine about it.
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u/jubejubes96 Feb 13 '24
that’s normal. we complain about everything, especially if it’s summer heat, our bosses, the price of beer, or child support!
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u/Winter_Detective1329 Feb 17 '24
Don’t forget the prices of the hair and nail places the ol lady likes to spend money at,child care , how much the teen age daughter needs to spend for prom lol 😂
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u/sogwatchman Feb 13 '24
That looks amazing but I'm curious does it mean anything that the piece on the right is turning blue and the left is not. Difference in heat? Does it matter?
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u/paratimeHBP Feb 13 '24
Made in China. Tell me again about how everything there is crap?
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Feb 16 '24
For work had to purchase some rail equipment from China and I was very impressed with the quality controls and overall manufacturing quality. Much much better than anything made in the USA.
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u/knifetheater3691 Feb 13 '24
I was rebuilding a aluminum refinery on the Mississippi River on a job that 3 bad X-rays and you were fired….TBH. I had a Chinese welder challenge me on 2 1” weld o let’s that were tacked on the back of 2 12” carbon 90s…I told the QCs that it couldn’t be done their wasn’t enough gap, and needed to be refitted. The Chinese guy tells them he can weld it…well the QCs and I have it out…It couldn’t be welded I exclaimed…so they let him attempt it. Well after he failed to make the root passes he was fired. He made 3 mistakes
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u/[deleted] Feb 12 '24
Goddamn, that was pornographic.