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ArtistCeleste posted:From my limited experiences in welding aluminum I know that the material oxidizes and becomes more like a ceramic. I believe you can tell when aluminum is oxidized because it is less refractive in appearance. When welding you brush or clean the top layer off to remove the oxidized layer. When forging I ended up discarding oxidized pieces because the finished product looked bad. Yep. Aluminum that is exposed to oxygen passivates itself and forms a layer of aluminum oxide that is much, much harder than the base metal. That's why you (usually) have to use an AC TIG to weld it -- the repeated strikes help blast off the oxide coating so that the current can flow smoothly. The oxide's melting point is also about twice that of elemental aluminum, so you usually have to ramp the power way up to get a pool going, then quickly back off so that you don't blow right through. Brushing the metal helps establish the arc quite a lot. Unoxidized aluminum is usually slightly duller and whiter than the passivated stuff (which is what you mostly see). Until you melt it -- then it suddenly goes really shiny (the only indication that it's liquid) and stays that way for a couple of hours as the weld cools and the oxide regenerates. I greatly enjoy TIG welding 
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Feb 12, 2013 04:33
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| # ¿ May 11, 2024 11:32 |
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A good rule of thumb, I have found, is "you shouldn't breathe anything that isn't air." Are there even (commonly available) respirator cartridges that work for metallic fumes? Or do you have to go with a full-on enclosed oxygen hood if you want to work around a crucible of molten cadmium?
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Feb 16, 2013 19:05
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Any time something is a liquid it is offgassing at some rate that depends on the temperature, air pressure and general molecular structure of the compound. I don't know what the vapor pressure is for cadmium around its melting point, but if you've got it in a molten state there will be cadmium molecules drifting around. Who knows how bad that actually is, but better safe than sorry. Heavy metal poisoning is not a joke.
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Feb 17, 2013 08:40
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oxbrain posted:Nope, P is for oil proof, R is for oil resistant(8 hour lifespan when exposed to oil), and N is for no oil. All are for particulate. Whoever came up with that system is an rear end in a top hat. How large does a particle have to be in order to get stuck in the filter, though? Monatomic helium is technically a "particle", for instance, but it's also a gas and passes through any filter that also passes air. So unless your filter is working on an atomic radius scale, any monatomic metal particles produced by offgassing are also going to go through. That's why I think you need some chemical treatment to adsorb the metals, or a closed hood. Or is there research somewhere showing that all metallic fumes form particles large enough to be caught in a regular P100?
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Feb 20, 2013 23:00
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I know that lead, cadmium and zinc (and probably many other metals too) are adsorbed by activated carbon, though, regardless of particle size. So tossing one of those into the cartridge probably couldn't hurt.
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Feb 23, 2013 19:35
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Yeah I was gonna say. It didn't sound that interesting, but then I clicked it and it was a very pro click. Went straight in my "cool techy stuff" bookmarks folder.
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Mar 11, 2013 06:26
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I worked for a company that makes audio equipment once. Did you know that on a volume knob, the little line that indicates where it's pointed is called the "vein?" I did a lot of work with veiny knobs.
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Mar 12, 2013 03:32
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Ambrose Burnside posted:Can anyone speak to welding training and certification in Canada, or in general I suppose? What's worth getting training in, how the system actually works and how much 'havin yer ticket' actually matters, etc- I don't know a whole lot. Hardly anyone (e: in the first world) working as a professional welder uses oxyacetylene any more, except for cutting. Any welding you could do with a torch you can do faster and better with a TIG. A ticket is 100% necessary if you're going to do anything structural, like bridges or pipelines. You don't need one to weld up exhaust pipes but you also don't make the big bucks doing that. If you want a ticket, you basically train for it and then go and do the test for certification. They have you demonstrate your skills in a specific technique, position and metal. Your welds will be analyzed with acid or x-ray, so you have to learn to consistently make strong, reliable welds -- no porosity allowed. Besides making a good weld of your own, it's also important that you be able to feather your welds into an existing one for repairs, and continue existing beads with no temporary loss of strength. Changing up what you tested on means you need a new ticket. So you can't go and train in steel with a MIG and then go and start TIG welding nickel alloy turbine blades, for instance. Most of the introductory courses at a community college will teach you SMAW, MIG and some TIG. From there you basically decide where you want to go. If you're aiming to be a professional welder, I'd say focus on the SMAW and TIG. If you're aiming to weld on the side or do quick assembly work here and there go for the MIG. Sagebrush fucked around with this message at 04:31 on Mar 26, 2013 |
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Mar 26, 2013 04:29
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AbsentMindedWelder posted:Edit: So I go to Advanced Auto today ... This happened to me when I went to AutoZone and asked if they had a socket for an H4 headlamp bulb. The guy wordlessly punched in "HUMMER" and then informed me that no, they didn't carry anything like that. 
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Mar 27, 2013 04:28
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I have a motorcycle luggage rack that I want to modify. I found this tiny image of it online: I need to shorten the two legs about two inches each. Since it's just thin steel tubing, I was going to just bandsaw them off, cut out the length I need and weld them back together. I can handle TIG welding thin tubes like that but my problem is it's chrome-plated, and I've got no idea what to do in this case. Obviously I need to strip off the chrome around the joint, but I'm concerned about the incredible toxicity of any chromium compounds that might be evolved while welding. Also, I understand that chrome-plating process requires a nickel and copper coat underneath; will that cause any specific problems?
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Mar 29, 2013 18:44
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AbsentMindedWelder posted:I measured my old belt today and it came in at 61.75". goons.txt No but seriously your lathe is quite awesome. We have an old South Bend in the shop here and it's a peach. Despite decades of use by untrained students, all you need to do is feed it some ATF every so often and it just keeps on trucking away.
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Apr 1, 2013 05:24
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Aircraft remover is the best chemical for taking paint off of things. It's basically 95% jellied dichloromethane with a little bit of methanol and caustic base thrown in for good measure. It will bubble off the paint like Xenomorph blood eating through the hull of a spacecraft. It will also burn your skin so wear gloves, and it's highly toxic so don't do this to anything you intend to eat out of later. If you can find a place that supplies pure dichloromethane (also called methylene chloride), you can use that as well, but aircraft remover is easier to find. Failing that, most chemical paint strippers you can find at Lowe's will have the same general compounds in them. Avoid the ones with sissy names like "low toxicity" or "environmentally friendly" if you want the good stuff  That said, now that I've tried soda-blasting I don't think I'm ever going to try stripping paint any other way again. That poo poo is magic, and it's cheap and completely non-toxic to boot. Can't beat that combination. e: hah, the first google result for "aircraft remover" is a youtube video of somethingawful's own Boomerjinks demonstrating it on one of his movie car replicas. Sagebrush fucked around with this message at 07:35 on Apr 2, 2013 |
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Apr 2, 2013 07:32
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Bad Munki posted:Pretty sure that's still not going to work the way you hope. Anything "plastic" is generally going to cure as a hard material, which of course won't work in a belt, since it needs to constantly flex. Yeah, was gonna say, that's not going to work very well under load. Just get some of the alligator belt-zipper things that were posted up the page; they're designed for this purpose. VVVVV then just sew it together with strong thread, or lace it with a narrow leather strip. Sagebrush fucked around with this message at 23:42 on Apr 2, 2013 |
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Apr 2, 2013 21:58
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Fire Storm posted:TIG welding question: What would happen if I used stainless filler rod on non-stainless metal? I need to repair my eyeglasses and I've had very bad luck fixing glasses like this with JBweld, tape or heat shrink tubing. Worst case, I am due to get new glasses anyway and I have safety glasses I can use until then. Do you know what the metal is, though? You're going to be making such a tiny weld, it can't be too expensive to just buy a little bit of appropriate wire or something.
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Apr 4, 2013 21:27
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rotor posted:poke fun if you must, but if you've got a better way to set up a flood coolant system I'd like to hear it. Do the work in your swimming pool, obviously. Much more thermal mass that way. 
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Apr 16, 2013 22:49
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Pff "everywhere", whatever. I also promptly googled 12L14 and read that same website 
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Apr 16, 2013 22:51
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I can do it without even visiting your shop: abrasive blasting. Your choice of soda, walnut shells or glass beads. Goddamn is it amazing. Looks great though.
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May 5, 2013 02:37
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Soda blasting won't touch aluminum, let alone steel like those ways. It won't remove deep rust but it does a phenomenal job with paint and grease 
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May 5, 2013 03:11
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I use waterstones to sharpen my knives -- they don't last as long as oilstones, but they cut faster and are cleaner because you can clean up with water. Sushi chefs will keep a waterstone on the counter and sharpen the knife rapidly before every sequence of cuts (note, I am not a weeaboo). Remember to soak the stones in water for half an hour before you use them, and it's good to also have a flat piece of granite or glass or something you can lap them against when they get hollowed.
Sagebrush fucked around with this message at 23:53 on May 13, 2013 |
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May 13, 2013 23:51
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When she does, can I have that thing?
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May 24, 2013 23:46
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Lanolin sounds like a great solution. Don't they use hog fat in steel mills as a lubricant and rust inhibitor?
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Jun 5, 2013 18:23
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Top. Men.
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Jun 8, 2013 21:35
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When I learned to weld they started everyone out drawing beads with a stick. I think it definitely gives you the best understanding of what's going on at the weld site with the relationship of speed, feed and arc length. Also it's super cheap to get started with.
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Jun 24, 2013 21:51
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Yeah, never wear gloves with any power tool that moves, and especially ones that spin. An angle grinder would be particularly nasty to get caught in, but OSHA has plenty of stories of people who lost fingers to gloves that got wound up in drill presses and the like. Not to say I haven't run skilsaws and the like while wearing workgloves, but it's a bad bad idea.
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Jun 26, 2013 01:51
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Well, yeah. You're supposed to hold the grinder with both hands, and the workpiece with your thighs. Like a man.
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Jun 26, 2013 02:22
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Yeah, if this is going to be anything involving anything that humans put inside them you should go pick up a bag of lead-free shot instead. Some of the tungsten/iron/bismuth stuff is just as dense, though quite a lot more expensive.
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Jun 26, 2013 06:31
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I think people write that at the end of their craigslist ads specifically to attract the kind of people like us who will go "oh, I can't bear to see that thing thrown out!" and hopefully force a quick sale. I've seen ads like that go up over and over again when they clearly didn't get any bites the first time around. A good indication for whether the person is actually going to scrap it is how far the asking price is above the going scrap value for the metal. If they're asking $1200 for something that's only got $400 of steel in it, they clearly aren't *that* prepared to just throw it away.
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Jul 5, 2013 22:22
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There's a ton of magnetite/hematite sand on the beach where my family spends the summers along the Ottawa river. The river waves naturally separate the sand by density so all along the whole length there's this strip of pure magnetic iron-bearing sand. See the dark line in the middle of the beach? http://goo.gl/maps/wyVYo It's very hot to walk across in the summer and it annoyingly sticks to everything that's even the slightest bit magnetic (say a knife blade that was recently sharpened) but I'd imagine it's pretty ideal for smelting. So maybe looking for something like that on Google Maps would be a start?
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Aug 14, 2013 01:47
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Hard to say definitively -- that could just be wet sand -- but it seems to be the right color and general arrangement. If you get there and find that it's extremely fine sand (about the same grit as the fine oceanic sand in Florida, but denser -- definitely finer than your average rocky beach sand), and it's a very dark reddish-brown color, I would say you're on the right track. Obviously the easiest way to test is just to bring along a magnet though. Roll it around in the sand for a few seconds and see what sticks. Every beach should have a few particles sticking to a magnet here and there; in that strip of sand up on the Ottawa river, the entire magnet will be coated in like a quarter inch of black fur. Sagebrush fucked around with this message at 01:58 on Aug 14, 2013 |
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Aug 14, 2013 01:55
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It's a pretty narrow tolerance for a student who isn't allowed to use anything but a hand file.
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Aug 19, 2013 02:02
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Can you take a course at a community college? That's only $450 or so and will get you professional instruction and lots of practice with good machines on all the material you could want.
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Aug 21, 2013 05:23
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Back and forth along the line of the bead, or perpendicular to it? If you're just doing regular stick welding in the flat position you should be tilting the electrode about 5-10 degrees in the direction of travel and moving slowly forwards, never going back. If you're right-handed, that means holding the electrode in the right hand, tilting it 10 degrees to the right, starting on the left of the joint and moving smoothly rightwards. Sweeping up and down to widen the joint ("weaving") is not needed if you're just starting to practice and working with thin material. Take one of your sheets of 1/4" plate, cut it to about 5"x7" and just cover the entire surface with overlapping beads to practice. You should be focusing on smooth movement and keeping a steady arc length. Miller actually has a lot of helpful information on their site: http://www.millerwelds.com/resources/articles/smaw-stick-arc-welding-tips-techniques/
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Aug 27, 2013 08:38
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I have come into a crapload of scrap aluminum, mostly extrusions but also some cast stuff and several buckets of milling swarf, that I'm going to melt down and recycle. I am not sure what alloys I've got specifically but it's almost certainly a mix of different things. What's a decent flux to use in this case?
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Sep 28, 2013 20:13
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At work we have a small gas-fired foundry furnace from some ancient era that is still plumbed and completely functional, but which hardly sees any use these days. We fired it up the other day and managed to melt maybe 10 lbs. of the aluminum and pour a couple of small ingots, but there was a huge amount of dross to skim off. I'm just interested in recovering as much of the metal as possible. e: oh, well that's neat. The second post of the thread is a huge mega-post from AbsentMindedWelder explaining everything about casting aluminum. I should really go back and check these things sometimes. Sweet! Sagebrush fucked around with this message at 22:25 on Sep 28, 2013 |
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Sep 28, 2013 22:03
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Oh, no, I don't mean recycling like selling the metal for money -- I mean recycling it myself into a usable form. We have an entire sand-casting setup here that, again, hasn't seen use in many years, but somewhere down the line I'd like to start screwing around with it. Making a bunch of practice ingots seemed like a good way to start that also generates a supply of raw material for later.
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Sep 28, 2013 23:13
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The waterjet places I know of charge a flat fee for setup, plus a rate per minute for cutting because of the power it uses. So if you have one piece it's going to be dominated by the setup fee, but if you have fifty the average price goes down a lot because it's mostly just based on the time.
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Oct 11, 2013 19:07
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Leperflesh posted:It also uses powdered garnet, I believe. And yes, that's basically what I was getting at; there's an up-front cost that makes it prohibitive for a single small job, but overall it can be reasonable or even cheap if you're doing a lot of cuts. It does, but the abrasive is generally recoverable. You'd have to replace it eventually but the system I'm familiar with has a filtration unit that can recycle both the water and the abrasive at least over some number of hours/days.
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Oct 13, 2013 01:15
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jvick posted:mig welding is hands down a much easier and cleaner way to weld. Spoken like someone who's never tried a TIG  I can't deny that MIG is like fifty times faster, but ugh you just get so spoiled by those shiny little bubbles of metal and the sheer precision of the tungsten arc. Everything else just seems so brutish in comparison. It's an elegant weld for a more civilized age. On that note, I just tried lanthanated electrodes for the first time a couple weeks ago and it's blowing my mind. You mean you can have the arc control of a sharpened electrode...while doing AC?  My aluminum welds are going to look so good
Sagebrush fucked around with this message at 04:26 on Oct 30, 2013 |
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Oct 30, 2013 04:23
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I have no particular problem with oxyacetylene welding. It's the same technique as TIG and makes the same lovely shiny welds, except TIG is a hell of a lot faster and you don't need to go to the gas place as often. Plus, acetylene kind of scares me in principle. Nasty squat little containers just waiting to blow themselves up.
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Oct 30, 2013 06:32
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| # ¿ May 11, 2024 11:32 |
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https://www.youtube.com/watch?v=wrz-E_QuM3E I mean, think of how much steel you could cut through with all the gas in a full tank, and then think how much energy you're applying to melt all that steel, and then realize that all that energy is always there inside the tank just waiting to get out. 
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Oct 31, 2013 04:34
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