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Submitted via IRC for Bytram
Grind Your Welds With Pride, If That's The Way You Do It
To grind or not to grind? What a question! It all depends on what you’re really trying to show, and in the case of welded joints, I often want to prove the integrity of the weld.
Recently, I wrote a piece in which I talked about my cheap inverter welder and others like it. As part of it I did a lower-current weld on a piece of thin tube and before snapping a picture of the weld I ground it back flat. It turns out that some people prefer to see a picture of the weld bead instead — the neatness of the external appearance of the weld — to allow judgment on its quality. Oddly I believe the exact opposite, that the quality of my weld can only be judged by a closer look inside it, and it’s this point I’d like to explore.
So dear soylentils, do you even weld and if you do, do you grind your welds?
(Score: 3, Interesting) by hemocyanin on Wednesday October 23 2019, @06:07PM (7 children)
I weld badly). I have a cheap wire feed MIG (*) welder that I use every now and then to fix something not worth an expert's expense, or to make something where beauty and great structural integrity are not required but commercial options are either non-existent or very expensive. I know I'm a crappy welder so I don't apply my skills to anything that could fail dangerously, but I will say, even low grade skills such as mine are pretty handy to have.
(*) This is like the "hello world" of welding equipment. Example equipment: https://www.northerntool.com/shop/tools/product_200632003_200632003 [northerntool.com]
(Score: 1, Funny) by Anonymous Coward on Wednesday October 23 2019, @06:32PM (6 children)
I tried to come up with a way to break this to you gently, but you know that's not a MIG welder, right?
(Score: 2) by The Mighty Buzzard on Wednesday October 23 2019, @06:56PM (4 children)
S'true. Flux-core ain't the same as MIG. Now plenty of welders can do both but if you check down at the bottom you see that this isn't one of them.
My rights don't end where your fear begins.
(Score: 0) by Anonymous Coward on Wednesday October 23 2019, @07:05PM (3 children)
And plenty of welders can't / won't stick-weld at all, I've only ever seen a couple of people who were any good at it.
(Score: 3, Informative) by The Mighty Buzzard on Wednesday October 23 2019, @11:54PM (2 children)
Yeah, start out on wire feed and you're probably never going to be anything but shitty with stick, same as automatic and manual transmission. Thankfully, I started on stick in both cases.
My rights don't end where your fear begins.
(Score: 3, Interesting) by Anonymous Coward on Thursday October 24 2019, @12:55AM (1 child)
A dilettante's history:
In middle school, assembled some Archer and Heath kits, followed the instructions for soft soldering and everything seemed pretty easy. With very clean parts the solder flows nicely.
Started with gas welding about 10th grade where I was once good enough to make cosmetically pretty welds, if the work was in a good position. Never tried to pass a test, I'm sure I would have needed more instruction to be pro quality. Tried stick in the high school shop and could make pretty welds after a very short time--oxy-acetelyne was good initial training. About 5 years later I tried a friend's big Miller tig with pedal, that was a really neat experience, so many things that were difficult or slow with gas became magic.
Never had a proper forge, but using the gas torch to heat the steel, I've also done a bit of hammer/forge welding. Lots of fun pounding on red hot metal.
At the big Oshkosh EAA show I watched an old hand weld aluminum with oxy-hydrogen. His butt welds sagged just enough that the bead looked the same on both sides, after one pass! This is the way aircraft fuel tanks used to be made, before tig. Went home, rented an H2 tank and practiced for awhile, turns out it wasn't that hard when using the correct rose colored (really!) glasses--the tint was called didymium pink and it lets you look through the soft hydrogen flame to see the solidus phase of the aluminum.
Later I started working on bicycles and learned how they do "bronze welding" in the UK. This adds a pressure canister to the acetylene hose and the gas bubbles through a liquid flux solution. A mixing valve on the "gas-flux" tank adjusts the quantity of flux. When properly tuned up, brazed joints on thin alloy steel tubing (1 mm wall or thinner) come out as perfectly smooth fillets. No filing needed and cleanup is a quick wipe with a wet rag. This is another "magic" process...if you learned brazing like I did by dipping hot brass rod into powered filler and generally making a mess. Later I happened to find out that some large industrial heat exchangers are also assembled by gas-flux brazing.
Don't know much about spot welding, but I do have an electric band saw blade welder, bzzzz-zap! Met a craftsman once who worked out how to spot weld tiny pieces of stainless. He was building architectural models and after much trial and error was able to make nearly invisible, but strong, welds in 1/8" and 1/16" square bar stock and also tack even thinner stainless sheets to the little bars.
Never asked to try, but a good friend was early in the game of tig welding Ti bicycles, without using a glove box. Starting with very clean parts the tube ends are corked or otherwise plupged and purged with inert gas. The tig torch is set up with a large (about 1" / 25mm) diameter cup and welds are done a half inch at a time (the radius of the cup). The weld zone is allowed to cool below the temperature that would make TiO2 and then the next half inch is welded.
Had a plant tour of a precision machine building company once, they were making machines for friction stir welding. From memory this process is now being used to assemble parts of Spacex boosters. A *very* hard pin is spun and translated along the joint with extreme force/pressure, mixing the metal at relatively low temperature.
There must be many other metal joining techniques, I feel fortunate to have experienced quite a few of them.
(Score: 4, Interesting) by The Mighty Buzzard on Thursday October 24 2019, @03:19AM
Yes. Yes, it most certainly is. I've heated rebar up with a torch and beat it with a shop hammer for no other reason than the sheer enjoyment before.
Unfortunately my oxy rig is still in storage back in OK because I won't have room for it until we get into the church we're turning into a big damn house. Never had a proper forge or a steel furnace but I do have an aluminum furnace and a lead pot that I use for casting random doodads and fishing weights.
Brazing and cutting with a torch are the things I could pass as professional at. Mostly because I used to be a professional at them. A year or so back in the 90s I worked as a lot hand at a used car lot during the day then made oil well drill bits (the smaller, triangle-shaped ones not the big, multi-head ones) for the car lot owner's side business on nights and weekends. Slap a jig on the blank, mark it, two cuts with a torch (complex angle, done by eyeball and experience, had to be as perfect as possible to avoid getting chewed out by the grinding guy), then braze on the tungsten carbide cutting edges, and stack them up for the guy who ground and painted them.
Brazing was never difficult for me though. I had to learn to solder copper line back in the army on account of part of the 52C MOS was repairing air conditioners. Brazing's largely the same but slightly easier as your materials don't heat or cool as fast.
My rights don't end where your fear begins.
(Score: 2) by hemocyanin on Wednesday October 23 2019, @09:03PM
I suspected as much -- as I said -- LOW SKILLED. Low knowledge even. ;-)