|
Leperflesh posted:Always wear eye protection, kids. Ye old leather apron is awesome if your working with steel wire brushes in grinders on a regular basis- I've got one thats a few years old now and it looks like a god drat echidna.
|
#
?
May 19, 2012 03:20
|
|
|
|
| # ? May 23, 2024 10:49 |
|
|
thecobra posted:I don't really see why you'd need one for aluminum and one for steel. Here's two reasons: Because if you go and grind aluminium with wheels that aren't made for it they tend to explode. Aluminium flows under pressure, and it ends up smeared all over (embedded into) the surface of your abrasive. Then the heat from this aluminium rubbing on the workpiece causes the resin binding the wheel together to soften and weaken the wheel - which eventually fails. Disks made for, and used on steel end up with small particles of iron in them, if you use them on aluminium, the iron can get embedded in the surface of the metal, and fucks up its resistance to corrosion.
|
|
#
?
May 19, 2012 06:55
|
|
|
Here's another (albeit a pretty unlikely scenario): Who can tell me what you call a mixture of powdered aluminum and powdered iron oxide?
|
|
#
?
May 19, 2012 08:06
|
|
|
Leperflesh posted:Here's another (albeit a pretty unlikely scenario): Deflagration!
|
|
#
?
May 19, 2012 12:48
|
|
|
Leperflesh posted:Here's another (albeit a pretty unlikely scenario): I don't think that's actually even a scenario that requires consideration. Aluminum tends to oxidize when heated, it oxidizes faster the greater the surface area, a grinding wheel will both increase the surface area of the aluminum and oxidize it. Aluminum based thermite is a mixture of aluminum powder (non-oxide) and iron oxide- it won't work if both materials are oxides. Even if the Aluminum somehow did not get fully oxidized, but the iron did, the initial combustion temperature required for thermite is immense (start it with an arc welder, or burning magnesium; not with a lighter or a hot piece of ground metal).
|
|
#
?
May 19, 2012 16:01
|
|
|
Iskariot posted:Why not? It's slow rotation that's really dangerous. A grinder at 10 000 RPM will not take hold of a glove. It will cut it. Any glove is peanuts compared to steel. Even the axle won't catch a garment at that speed. http://www.youtube.com/watch?v=y0ehJlL0Ydk Gloves are dumb. I know its kids taking a shredded glove to it but yes, it can suck up a glove.
|
|
#
?
May 22, 2012 15:22
|
|
|
Linux Assassin posted:I don't think that's actually even a scenario that requires consideration. Aluminum tends to oxidize when heated, it oxidizes faster the greater the surface area, a grinding wheel will both increase the surface area of the aluminum and oxidize it. Aluminum based thermite is a mixture of aluminum powder (non-oxide) and iron oxide- it won't work if both materials are oxides. Even if the Aluminum somehow did not get fully oxidized, but the iron did, the initial combustion temperature required for thermite is immense (start it with an arc welder, or burning magnesium; not with a lighter or a hot piece of ground metal). You are mostly right, of course, although I have heard of starting up thermite using just bright sparks. Wikipedia claims it can be lit with a "regular flint spark lighter" as well as with a sparkler. One source of a flint spark is a gas welding torch igniter... and I happen to have one in the garage. So the main thing is the unlikliness of producing the right amount and type of aluminum powder, as well as getting it into the right mix with iron oxide powder, which I agree is pretty unlikely indeed. Won't stop me from being a bit anal about sweeping up around the grinders though.
|
|
#
?
May 22, 2012 18:38
|
|
|
I just breathe in all the dust and clean my shop's air with my post shower nasal clearing. It's as gross as it sounds.
|
|
#
?
May 22, 2012 21:18
|
|
|
Not an Anthem posted:http://www.youtube.com/watch?v=y0ehJlL0Ydk You insert stuff with more mass into grinders all the time as that's their primary task. They don't all get gobbled up for a variety of reasons, the primary ones being sheer weight and mass. Trying to cut or grind cotton would probably resemble the video. A welders glove will resemble more like your finger. If the glove catches, so would your finger. But, as your example shows, don't be stupid with what gloves you wear.
|
|
#
?
May 23, 2012 10:29
|
|
|
There's a reason OSHA requires the rest be adjusted to within 1/8" of the wheel and it's not ease of use. A grinder can suck up anything that comes close to fitting in between the wheel and guards. The issue with gloves is twofold. One, the fabric or leather is thinner than any part of your hand and can get pulled into a narrower gap. Two, the tensile strength of most gloves is significantly higher than human skin, so a bump that would tear your skin would instead yank the whole glove in.
|
|
#
?
May 24, 2012 02:32
|
|
|
Harbor Freight question: Is there any reason why I should get this more expensive MIG/Flux welder instead of this one that is $100 cheaper?oxbrain posted:the tensile strength of most gloves is significantly higher than human skin, so a bump that would tear your skin would instead yank the whole glove in. (  The answer is always yes )
|
|
#
?
May 24, 2012 07:36
|
|
|
Fire Storm posted:Harbor Freight question: Is there any reason why I should get this more expensive MIG/Flux welder instead of this one that is $100 cheaper? Wahahahaha nooo mmm chicken wings (gloves and grinders dont mix!) I was going to link tests done with tablesaws and gloves but figured you'd poo-poo that as too low rpm, but yeah, whole gloves get sucked in and eventually stop the blade. After yknow, the whole glove is sucked through a zero clearance insert.
|
|
#
?
May 24, 2012 16:14
|
|
|
Not an Anthem posted:Wahahahaha nooo mmm chicken wings (gloves and grinders dont mix!) That injury is caused by a piece of jewlery getting caught in something, not a glove. The (mangled) ring in question is circled at the lower right. Canadian Centre for Occupational Health and Safety posted:
Which contradicts "Don't wear gloves when using a bench grinder."
|
|
#
?
May 25, 2012 01:13
|
|
|
When I was in repair school doing our safety training, they showed us pictures of a guy who didn't wear glasses when using a steel wire brush. There was a 2 inch strand of steel wire in his eyeball. I always ALWAYS wear my eye protection now.
|
|
#
?
May 26, 2012 12:32
|
|
|
I fired up the old grill for the first time this year and found out that the pull out drawer under the grill was filled with water and of course sheets of rust. The inside of the grill isn't doing too much better. Does anyone have any experience with Krylon High Heat & Radiator and BBQ/Stove Paints or Rust-Oleum Bar-B-Que Black paints? Or does anyone have a better suggestion as to how I could protect the surface after cleaning the hell out of it? I'd like to get at least a few more years out of it before I have to replace the main grill body with stainless (not too much of a joke, that would be nice!) EDIT: The worst parts are at about 3-4 sockingtons (inside of the drawer), but most of the grill is a 0. Just the drawer and some of the inner grill area (a 1 or 2 really) are showing rust. A lot of the visible metal is actually stainless (doors, lid of grill). Fire Storm fucked around with this message at 01:00 on May 27, 2012 |
|
#
?
May 27, 2012 00:52
|
|
|
Fire Storm posted:I fired up the old grill for the first time this year and found out that the pull out drawer under the grill was filled with water and of course sheets of rust. The inside of the grill isn't doing too much better. Does anyone have any experience with Krylon High Heat & Radiator and BBQ/Stove Paints or Rust-Oleum Bar-B-Que Black paints? Or does anyone have a better suggestion as to how I could protect the surface after cleaning the hell out of it? Well don't paint the inside, of course. Look for coal yards in your local yellow pages, go to them and ask for some furnace paint. That poo poo rocks.
|
|
#
?
May 27, 2012 00:58
|
|
|
Sponge! posted:Well don't paint the inside, of course. Look for coal yards in your local yellow pages, go to them and ask for some furnace paint. That poo poo rocks. Speaking of stainless, I've been reading some pages on it and some stuff is confusing. Can I seriously use 100% CO2 for stainless (MIG at least)? If I have a bottle of argon and a bottle of CO2, is there any easy way to mix it to 95/5? I'll probably try TIG stainless before I even consider MIG stainless. Looking on Miller's website, they list a few replacements for thoriated electrodes. Any personal recommendations? Should I have separate electrodes for stainless vs mild steel? My machine is straight DC (no pulses), or at least I'm pretty sure it's pulseless. Am I reading pages right that I can't use the same wheels (grinding and wire) for stainless that I use for mild steel? Fire Storm fucked around with this message at 02:20 on May 27, 2012 |
|
#
?
May 27, 2012 02:00
|
|
|
Fire Storm posted:Thanks! Yes, I believe you can weld stainless with 100% co2 on GMAW. I can look into some of my handbooks for more info if you're interested. I would assume it would produce a weld with some high oxidation. For GTAW, you can't use co2. Co2 will oxidize your electrode. You'll need argon/helium or a mix. If you want to make a quick gas mixture, you can set the flowrate of each cylinder to the required ratio for the mix, and hook them up to a Y-hose. Is there a specific reason you want to switch from a Th electrode? It's not terribly common to use other alloyed electrodes, and an EWTh-2 will be suitable for any welding you want to do. No need to have seperate ones for different steels. For your wheels, it depends on whether contamination is an issue for you.
|
|
#
?
May 28, 2012 04:46
|
|
|
thecobra posted:Yes, I believe you can weld stainless with 100% co2 on GMAW. I can look into some of my handbooks for more info if you're interested. I would assume it would produce a weld with some high oxidation. #1 reason I was thinking of a non-Th electrode is because I remember my instructor saying that Th was being phased out of electrodes (but lots of stockpiles remain). I STRONGLY remember him saying that the radiation risks were absolutely minimal, esp if you have ventilation.
|
|
#
?
May 28, 2012 19:08
|
|
|
Fire Storm posted:Na, no need to look it up, it just sounded like crazy talk to me (I never even thought of CO2 as a shield gas because I thought oxidation would be an issue.) Wet wheel only. Its an alpha emitter, which is mostly safe as long as the dust doesn't get inside your lungs/digestive-tract...
|
|
#
?
May 28, 2012 19:14
|
|
|
I've never used a wet wheel on them. As far as I know they are the industry standard right now, and most places won't even have an alternative around. The danger would be exposure time. I suppose if your job is to grind them all day (??) you would have a problem. Similar to SAW flux. It's not recommended you breathe it, but minimal exposure is of no ill consequence. CO2 is an extremely common shielding gas, more so in mixes with Argon. Standard mixes are 5C, 8-10C, 25C, or just 100%C. Each mix will produce different effects on your weld, and you have to consider your process, mode, and filler metal.
|
|
#
?
May 28, 2012 21:24
|
|
|
thecobra posted:I've never used a wet wheel on them. As far as I know they are the industry standard right now, and most places won't even have an alternative around. The danger would be exposure time. I suppose if your job is to grind them all day (??) you would have a problem. Do you at least wash your hands and wipe your face after grinding them? Maybe a respirator? THOX isn't exactly harmless. On the one hand you could powder your  and ballsack with the grinding dust and not have much of an issue at all because it will rinse off, but I wouldn't like to think of the many ways it can gently caress up things like your corneas, sinuses, larynx, and alveolar functions. Once it is inside your body, there is no natural process to excrete it. And since Thorium 232 has a half life that is nearly 200 MILLION times your total life expectancy, its a lot like herpes. Can't get rid of it, but you can live with it if you have to.I'd rather snort a pinch of powdered Lead than lick a freshly ground but un-rinsed Thoriated tungsten... For the most part, Ceriated Tungstens will do the job just fine. Now if you're welding submarines or space hardware, then yes sometimes only Thorium will do. Edit: You used the phrase "the danger would be exposure time" which is almost, but not entirely incorrect. If it gets into your lungs or intestines, the exposure time essentially becomes infinity. Double Edit for fact checking: See section 7. https://www.airgas.com/documents/pdf/004014.pdf Sponge! fucked around with this message at 22:09 on May 28, 2012 |
|
#
?
May 28, 2012 22:03
|
|
|
I picked up a book on chasing and repousse a coupla days ago and have been devouring it ever since. I happened upon a technique that seems like a real neat approach to a project i've been wanting to do for forever and a day- make a really ballin' flask. It's called Masonite die-pressing: you build a 'die' by cutting the desired outline out of a sheet of hard Masonite drilled at the corners (bolting additional identically-cut-out sheets of plywood under the Masonite if you need additional height), and then bolt a sheet of ductile annealed metal to the face of the die (via holes you drill in the metal sheet itself). Then you dish out the general form with soft hammers and mallets, moving up to punches for greater detail, before dissassembling the die and cutting the formed object out. The whole point of this is to create hollow forms with identical borders that still have unique/non-mass-produced craftsmanship, for the purpose of assembly. Hence my flask- it solves the finicky problem of shaping two halves freehand and expecting them to fit together worth a drat if you're not good at what you're doing. Now the thoughts/questions/etc!! 1) What metal should I use? Priorities are 1) foodsafe 2) ductile and cooperative with the forming process 3) strength. Originally I wanted to go with tinplate, but it's impossible to find in less-than-1-ton quantities, and tinplating the steel after it's been formed is possible but a pain. Then I was considering copper/brass/bronze, because they're way prettier and better for die-forming, but they'd still have to be tinplated. Now I figure aluminium's the best bet, I'd prefer silver but lmao @ the price of precious metals nowadays, and silverplating nickel silver or tinplating the inner surface of copper/alloys is a whole ball-game I'm not playin yet, so aluminium seems like the best compromise. 2) How can I best join the two halves? I don't know a goddamn thing about welding/brazing aluminium, it's weird finicky metal I don't really do much with. Make that just brazing because I don't really have proper welding equipment beyond a tankless oxy-acetylene rig and a tiny baby anaemic stick welder.
|
|
#
?
May 29, 2012 02:38
|
|
|
Ambrose Burnside posted:I picked up a book on chasing and repousse a coupla days ago and have been devouring it ever since. I happened upon a technique that seems like a real neat approach to a project i've been wanting to do for forever and a day- make a really ballin' flask. It's called Masonite die-pressing: you build a 'die' by cutting the desired outline out of a sheet of hard Masonite drilled at the corners (bolting additional identically-cut-out sheets of plywood under the Masonite if you need additional height), and then bolt a sheet of ductile annealed metal to the face of the die (via holes you drill in the metal sheet itself). Then you dish out the general form with soft hammers and mallets, moving up to punches for greater detail, before dissassembling the die and cutting the formed object out. Have you considered flatware grade(food-safe) pewter sheets? Aluminum is going to be a bitch to make two become one... And at least you can braze/silver-solder pewter together without much ado.
|
|
#
?
May 29, 2012 03:32
|
|
|
Sponge! posted:Have you considered flatware grade(food-safe) pewter sheets? Aluminum is going to be a bitch to make two become one... And at least you can braze/silver-solder pewter together without much ado. Pewter rocks to work with, I've already done a lot of farting-around practise stuff with it, but it's absurdly expensive to get nice clean sheets of. I'm not making an heirloom or anything, I'm not good enough (nor can I afford) to warrant dropping 50 bucks on materials for one specific vanity project. If I had a rolling mill, even a lil one, I'd roll myself All The Sheet Pewter from the still-expensive-but-much-more-reasonable chopped-up/melted down pewter ingots. Working with tinplate/tin-plated on one side at least metal is supposed to be nice because it solders together incredibly effortlessly well, which is why I was leaning towards it originally. I could repousse/chase a design into one or both sides of the flask and then mask the outside (minus where it'll be soldered) and tinplate it in one of those jury-rigged lil electroplating bath thingies.
|
|
#
?
May 29, 2012 03:47
|
|
|
Ambrose Burnside posted:Pewter rocks to work with, I've already done a lot of farting-around practise stuff with it, but it's absurdly expensive to get nice clean sheets of. I'm not making an heirloom or anything, I'm not good enough (nor can I afford) to warrant dropping 50 bucks on materials for one specific vanity project. If I had a rolling mill, even a lil one, I'd roll myself All The Sheet Pewter from the still-expensive-but-much-more-reasonable chopped-up/melted down pewter ingots. I still say rock out with the pewter. http://www.ebay.com/itm/Vintage-WIL...22881%26ps%3D54 I'm sure you could come drat close to getting a flask out of that.
|
|
#
?
May 29, 2012 04:09
|
|
|
Sponge! posted:Do you at least wash your hands and wipe your face after grinding them? Maybe a respirator? I understand your concern for the radioactive material, completely, but I was just saying. Anybody in any shop should be wearing their safety googles like a good boy. On top of that, I can't think of a time when I have been welding and decided to see what my fingers taste like. For the exposure time, I see where you are coming from, but like I put it, I meant you want to worry about your respiratory tract if you are constantly exposing yourself to the dust, not what it will do inside you. All I'm saying is that Thoriated electrodes are still extremely common, and I have never seen anybody use any sort of face protection. quote:Oh my. This sounds serious. quote:So there are no effects whatsoever? I do consider your information valid, however it really isn't enough to make me take any sort of precaution there. If anybody wants to ensure their health and safety, go ahead, I won't argue with that.
|
|
#
?
May 29, 2012 04:10
|
|
|
'Cause we talkin bout pewter;     Forging rings as opposed to casting 'em is neato. Can't really control for final ring size much, though.
|
|
#
?
May 30, 2012 02:55
|
|
|
Ambrose Burnside posted:2) How can I best join the two halves? I don't know a goddamn thing about welding/brazing aluminium, it's weird finicky metal I don't really do much with. Make that just brazing because I don't really have proper welding equipment beyond a tankless oxy-acetylene rig and a tiny baby anaemic stick welder. I did a bit of research into this before, you can weld aluminium with Oxy/acetylene and the right fluxes, i imagine its pretty hard with very thin material though. http://www.youtube.com/watch?v=pjGip_StNGY http://www.youtube.com/watch?v=WMgYPFpGytY
|
|
#
?
May 30, 2012 03:18
|
|
|
Fire Storm posted:Thanks! Flux cored stainless should be able to be used with 100% CO2, but works best with Argon w/ 18% CO2. Solid wire stainless depends on the grade. Generally it's Argon with 2% CO2 for 300 series stainless (e.g. 307/308/316), and Tri-mix with added Oxygen/Helium for thick sections (above 8mm). Some Duplex grades can handle up to 10% CO2. 625 (Inconel?) is usually done with pure argon. If the CO2 content is too high, it binds up the chromium as chrome carbide leading to poor corrosion resistance, and cracking.
|
|
#
?
May 30, 2012 04:12
|
|
|
echomadman posted:I did a bit of research into this before, you can weld aluminium with Oxy/acetylene and the right fluxes, i imagine its pretty hard with very thin material though. Nah, it's easy: Front:  Back:  Bottom:  0.5mm Aluminium welded with OA, 2.4mm 4047 TIG wire, and Eutectic+Castolin 190 flux.  The trick is to use the thick filler rod as a heatsink, and to never hold the flame on the workpiece. Just keep passing it over then off of the joint, then once it's hot enough the flux melts, and your filler will just flash into the joint. Chalupa Joe fucked around with this message at 06:11 on May 30, 2012 |
|
#
?
May 30, 2012 06:08
|
|
|
0.5 milimetre aluminium, welded 
|
|
#
?
May 30, 2012 17:20
|
|
|
Chalupa Joe posted:Nah, it's easy: And just because I saw this video of welding and it looks good: Tig Welding Techniques and Welding Magnesium
|
|
#
?
May 30, 2012 19:11
|
|
|
^^^ Brazed, the 4047 has 12% Silicon, and has a melting point of 560ºC, approximately 85ºC lower than pure aluminium. There's a bunch of caveats on its use too: the colour won't match if you go and anodise afterwards, and it won't work at all if the magnesium content of the base metal is too high. The usual application is repairing aluminium radiators. I haven't tried Magnesium welding, using OA is as far as I'm aware limited to repairing castings, though one of our customers* TIG welds bike/kart frames from it. *The company I work for sells welding consumables, and Fronius welding equipment.
|
|
#
?
May 30, 2012 22:04
|
|
|
Chalupa Joe posted:Nah, it's easy:  Impressive.
|
|
#
?
May 31, 2012 02:29
|
|
|
A wild inlay appears!
|
|
#
?
Jun 6, 2012 23:39
|
|
|
Ambrose Burnside posted:A wild inlay appears!
|
|
#
?
Jun 6, 2012 23:51
|
|
|
Yeah. Originally I was just gonna try 16 ga. solid wire, but decided I could put in the 5 minutes to twist up some filigree. Started off round but flattened as I worked it into the groove. Went with pewter because it's so soft- real easy to use hammers/punches to drag over the edges of the filigree to trap it. The backside is dead-ugly, there's a hilarious ~1 cm gap where there's no inlay because the ring expanded as I worked it on the mandrel, stretching the gap where I welded it shut. Also the inlay wanders a lot; it started straight down the middle, but ended up meandering as I hammered on stuff and then aligned it all at the end. Its very blurrrghh, but I'm cuttin myself a huge slice-o-slack because I did work you'd normally do with a full set of jeweller's dapping punches with a single light ballpeen.
|
|
#
?
Jun 6, 2012 23:57
|
|
|
Slow motion magnified chip formation. Iscar Chip Formation https://www.youtube.com/watch?v=mRuSYQ5Npek Bogatyr fucked around with this message at 13:07 on Jun 12, 2012 |
|
#
?
Jun 12, 2012 13:02
|
|
|
|
| # ? May 23, 2024 10:49 |
|
|
Been makin rings. I weld em shut, which is finicky as hell on copper and with a cheapie-cheap brass torch head connected directly to the disposable propane cylinder. 
|
|
#
?
Jun 12, 2012 19:56
|
|