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#51
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torque wrench issues
wrote in message ... On Sun, 30 Apr 2017 21:30:36 +0100, "Ian Field" wrote: "AMuzi" wrote in message news On 4/30/2017 12:01 PM, Ian Field wrote: wrote in message ... On Sat, 29 Apr 2017 19:53:16 +0100, "Ian Field" wrote: wrote in message ... On Tue, 25 Apr 2017 20:16:22 +0100, "Benderthe.evilrobot" wrote: "John B Slocomb" wrote in message ... On Mon, 24 Apr 2017 22:17:14 -0400, wrote: On Tue, 25 Apr 2017 07:42:21 +0700, John B Slocomb wrote: On Mon, 24 Apr 2017 19:51:41 +0100, "Benderthe.evilrobot" wrote: wrote in message ... On Sun, 23 Apr 2017 22:06:05 +0100, "Benderthe.evilrobot" wrote: "Emanuel Berg" wrote in message ... I finally got the 1/2" torque wrench, 28-210 Nm, not even made in China, but in Taiwan! Eh... I guess it depends who you ask if that is China or not It has a locking screw, a torque setting handle, a scale (Nm as well as "FT-LB", some English unit I take it?) - it also as a locking lever on top just like an ordinary ratchet, so it can go both ways, clockwise and anti-clockwise. The torques only work in the clockwise direction. So if the locking (ratchet) lever is set the other way, it is just a ratchet, right? Well, in the manual it says: Note: Never use the torque wrench to undo nuts, bolts or other fasteners as this will damage the ratchet mechanism and the calibrated settings. So how does that add up? Is it only OK to use the anti-clockwise pull to insert things, which would require a left thread? (And it would be just a long shaft, with the torque not in effect.) As for me, I don't plan using it for anything but as a torque, because I have other, less expensive ratchets and spanners to do the everyday stuff. But of course, I'd like to know what it means. It also came with a certificate with data on the calibration and in the manual it says it should be recalibrated at least every 12 months. Calibration is irrelevant if you don't follow the rules to the letter. Most torque settings I've seen were for dry threads - any stray lubricant and you might even twist the end off at the correct torque. --- This email has been checked for viruses by AVG. http://www.avg.com Torque specs vary considerably by application. Some are given as clean and dry, some are given as lubricated with oil - some are given cold, and others hot. That said, I personally have never run across a torque spec that was so "close to the edge" that torqing with "stray lubrication" would cause immediate failure of the bolt by twisting off the end. However, that said, most of my wrenching has not been on bicycles but on automobiles and agricultural and construction equipment which may be slightly more "overengineered" or "overbuilt" Bicycles tend to have less things you can twist the end off. Its common on motorcycles, but mainly pulling the threads out of alloy castings. Its pretty rare to strip an engine down so far that you can put the castings in degreasing plant - torquing the engine case bolts with oil left in the holes is a very good chance of stripping the threads. As for stripping engine bolts, the Honda factory used to install fasteners so tight that a normal person couldn't get them out without an"impact driver". A tool that I never even saw before the Japanese invasion. The lock washers were very effective where used, and the Phipips style bolts were incapable of delivering enough torque to breat them loose without camming out - the Hammer Impact driver solved that problem I believe I've read that the "Phillips" headed screws in a Japanese motorcycle are not actually "Phillips" but some Japanese standard that didn't quite match the screwdrivers we had in the U.S. Which probably didn't help either :-) That's the *whole* cause - just grind a tiny bit off the point of the screwdriver bit and it fits just right. The bits on my Impact driver fit perfectly without grinding. Note I said Philips "style" (I know, I mis-spelled it) bolts. Some of the early Jap stuff didn't use Cadmium plated bolts either - W10 imploded and I had to start over with a replacement news account. So back to old name. The japs were the worst of the lot for cadmium plated fasteners. The very toxic cadmium rubs off on your hands and is cumulative in the body - it causes such acute osteoporosis; you can end up fracturing ribs just by coughing. In the UK - nickel plated fasteners became fashionable about the 80s. They didn't do much about cadmium plated chassis in electronic equipment until RoHS. AFAIK: cadmium batteries are exempt from RoHS - but they've more or less vanished from the shops anyway. Cadmium is very nasty - wash your hands after handling anything plated with it! from Cadmium, A Health Hazard Surface Treatment C. Rehm ESG Einsteinstr. 174 D-81675 Munich, Germany An object containing cadmium is not especially injurious to health on its own. No risk is involved simply by touching it. A potential hazard occurs, however, when such objects are processed and high temperatures are generated. Cadmium plating rubs off on your hands whenever you handle cadmium plated parts and assemblies. Many years ago they even used it on electronic component leads to prevent oxidation - they used more aggressive fluxes in those days. Welding cad plated sheet steel is particularly dangerous - the cadmium is vapourised and becomes airborne. Usually the osteoporosis takes decades to start crippling the sufferer - but I've heard of a repair technician dropping dead after a couple of years from fumes using low melting point cadmium based solder. The specific mode of death wasn't announced. The Japanese know all about it, they discharged industrial effluent containing cadmium into heavily fished costal waters. They even have a name for the disease - itai itai byo. apparently its the noise sufferers make in their death throes. As I mentioned previously - bones become so weak and brittle, you can fracture ribs just by coughing. Well then avoid it as you wish. Many of us recognize the difference between metals and reactive metallic organic compounds. Zinc rich tablets are popular for symptoms of herpes simplex and yet no one welds galvanize steel a second time. Zinc can't be that toxic - its a usual ingredient of baby powder. Never heard of any warnings against welding zinc passivated steel - only know of cadmium plating being very dangerous. You will only weld or braze galvanized steel in a poorly ventilated space ONCE unless you are REALLY stupid. I have never become aware of the dire consequences of welding zinc plated that are being spouted here. "galvanised" can be plated with *ANY* metal that has a higher galvanic affinity than the host metal. Including cadmium and various other toxic heavy metals. Cadmium poisoning is cumulative and has various routes into the body - its a long slow painful journey to a Darwin award. For a few years I worked assembling electronic equipment on cadmium plated chassis - I've seen with my own eyes the extent to which the plating rubs off on your hands. But if you're too stupid to take it from someone who's been there - Darwin awaits you with outstretched arms. |
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#52
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torque wrench issues
"John B Slocomb" wrote in message ... On Sun, 30 Apr 2017 18:01:20 +0100, "Ian Field" wrote: wrote in message . .. On Sat, 29 Apr 2017 19:53:16 +0100, "Ian Field" wrote: wrote in message m... On Tue, 25 Apr 2017 20:16:22 +0100, "Benderthe.evilrobot" wrote: "John B Slocomb" wrote in message news:schtfc5i6qshna502vhg4pv5f918haa426@4ax. com... On Mon, 24 Apr 2017 22:17:14 -0400, wrote: On Tue, 25 Apr 2017 07:42:21 +0700, John B Slocomb wrote: On Mon, 24 Apr 2017 19:51:41 +0100, "Benderthe.evilrobot" wrote: wrote in message news:vmfqfc17u3012cn5jrkkk4r335ol6r5s8a@ 4ax.com... On Sun, 23 Apr 2017 22:06:05 +0100, "Benderthe.evilrobot" wrote: "Emanuel Berg" wrote in message ... I finally got the 1/2" torque wrench, 28-210 Nm, not even made in China, but in Taiwan! Eh... I guess it depends who you ask if that is China or not It has a locking screw, a torque setting handle, a scale (Nm as well as "FT-LB", some English unit I take it?) - it also as a locking lever on top just like an ordinary ratchet, so it can go both ways, clockwise and anti-clockwise. The torques only work in the clockwise direction. So if the locking (ratchet) lever is set the other way, it is just a ratchet, right? Well, in the manual it says: Note: Never use the torque wrench to undo nuts, bolts or other fasteners as this will damage the ratchet mechanism and the calibrated settings. So how does that add up? Is it only OK to use the anti-clockwise pull to insert things, which would require a left thread? (And it would be just a long shaft, with the torque not in effect.) As for me, I don't plan using it for anything but as a torque, because I have other, less expensive ratchets and spanners to do the everyday stuff. But of course, I'd like to know what it means. It also came with a certificate with data on the calibration and in the manual it says it should be recalibrated at least every 12 months. Calibration is irrelevant if you don't follow the rules to the letter. Most torque settings I've seen were for dry threads - any stray lubricant and you might even twist the end off at the correct torque. --- This email has been checked for viruses by AVG. http://www.avg.com Torque specs vary considerably by application. Some are given as clean and dry, some are given as lubricated with oil - some are given cold, and others hot. That said, I personally have never run across a torque spec that was so "close to the edge" that torqing with "stray lubrication" would cause immediate failure of the bolt by twisting off the end. However, that said, most of my wrenching has not been on bicycles but on automobiles and agricultural and construction equipment which may be slightly more "overengineered" or "overbuilt" Bicycles tend to have less things you can twist the end off. Its common on motorcycles, but mainly pulling the threads out of alloy castings. Its pretty rare to strip an engine down so far that you can put the castings in degreasing plant - torquing the engine case bolts with oil left in the holes is a very good chance of stripping the threads. As for stripping engine bolts, the Honda factory used to install fasteners so tight that a normal person couldn't get them out without an"impact driver". A tool that I never even saw before the Japanese invasion. The lock washers were very effective where used, and the Phipips style bolts were incapable of delivering enough torque to breat them loose without camming out - the Hammer Impact driver solved that problem I believe I've read that the "Phillips" headed screws in a Japanese motorcycle are not actually "Phillips" but some Japanese standard that didn't quite match the screwdrivers we had in the U.S. Which probably didn't help either :-) That's the *whole* cause - just grind a tiny bit off the point of the screwdriver bit and it fits just right. The bits on my Impact driver fit perfectly without grinding. Note I said Philips "style" (I know, I mis-spelled it) bolts. Some of the early Jap stuff didn't use Cadmium plated bolts either - W10 imploded and I had to start over with a replacement news account. So back to old name. The japs were the worst of the lot for cadmium plated fasteners. The very toxic cadmium rubs off on your hands and is cumulative in the body - it causes such acute osteoporosis; you can end up fracturing ribs just by coughing. In the UK - nickel plated fasteners became fashionable about the 80s. They didn't do much about cadmium plated chassis in electronic equipment until RoHS. AFAIK: cadmium batteries are exempt from RoHS - but they've more or less vanished from the shops anyway. Cadmium is very nasty - wash your hands after handling anything plated with it! from Cadmium, A Health Hazard Surface Treatment C. Rehm ESG Einsteinstr. 174 D-81675 Munich, Germany An object containing cadmium is not especially injurious to health on its own. No risk is involved simply by touching it. A potential hazard occurs, however, when such objects are processed and high temperatures are generated. Cadmium plating rubs off on your hands whenever you handle cadmium plated parts and assemblies. Many years ago they even used it on electronic component leads to prevent oxidation - they used more aggressive fluxes in those days. Welding cad plated sheet steel is particularly dangerous - the cadmium is vapourised and becomes airborne. Usually the osteoporosis takes decades to start crippling the sufferer - but I've heard of a repair technician dropping dead after a couple of years from fumes using low melting point cadmium based solder. The specific mode of death wasn't announced. The Japanese know all about it, they discharged industrial effluent containing cadmium into heavily fished costal waters. They even have a name for the disease - itai itai byo. apparently its the noise sufferers make in their death throes. As I mentioned previously - bones become so weak and brittle, you can fracture ribs just by coughing. I hate to disillusion you but the Japanese word "itai" can be translated into English as "ouch" and is commonly used in everyday conversation. Secondly, the cadmium poisoning you are referring to was specific to mining in Toyama Prefecture. Not to industry per si. Sophistry doesn't magically make you right. |
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torque wrench issues
On Monday, May 1, 2017 at 11:34:12 AM UTC-7, Ian Field wrote:
The people who made the RoHS list don't seem very keen on cadmium - like most battery systems; the cadmium ones got an exemption. However - most battery manufacturers seem to have voluntarily dropped cadmium. You can still get them for specialist applications like security systems, but general types have pretty much vanished from the shops. I'm not aware of any restrictions on zinc - zinc/air hearing aid batteries have if anything, increased in popularity. Because they need air to work - they're not fully sealed. I think that you would find that no one "voluntarily" ceased production because of health concerns but because Lithium Ion batteries are taking over the market. Cadmium is not a very strong health hazard as a plating material. Zinc is poisonous if a large enough dose is given. Cadmium ends up remaining in your liver and kidneys while I believe that Zinc can pass safely outside of it. Remember that nitrogen is harmful if you don't get enough oxygen with it. So you have to draw a line between harmful and poisonous. |
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torque wrench issues
On Mon, 01 May 2017 15:08:31 +0700, John B Slocomb
wrote: SNIPPED The usually suggested preparation for welding or brazing galvanized materials is to grind all the galvanizing off! ACTUALLY, stripping the zinc with acid is much more effective. Hydrochloric acid makes short work of zinc and produces zinc chloride, which can be used as soldering flux - - - While prepping the base metal will remove the majority of the zinc from the surface of the metal, the possibility of some galvanizing while welding may occur. A common sign of galvanizing is the appearance of yellowish-green smoke. Other signs are a white powdery particles in the air, and a white residue around the weld. If exposure to large quantities of the yellowish-green zinc oxide fumes occur, you may experience galvanize poisoning, or metal fume fever as it is sometimes called. The severity of your symptoms depends on the amount of time of exposure to the harmful fumes. Galvanize Poisoning Symptoms of galvanize poisoning can be similar to flu symptoms. The onset of symptoms typically begin shortly after exposure to zinc oxide and may include a mild headache and nausea. If you have a more severe case of exposure, your symptoms will be consistent to those you experience when you have the flu. A moderate case of exposure will result in symptoms including chills, shaking, a slight fever, vomiting and cold sweats. If you begin to experience any of these symptoms you should immediately stop working and get some fresh air. In severe cases the symptoms may be so bad that you will have to go home until they subside. The most severe cases of galvanize poisoning can result in death. If you feel that your symptoms are worse than ever before, you should seek medical attention at once. Galvanize poisoning is often short and your symptoms should begin to lessen within four hours of exposure. You should be completely symptom free within twenty four hours. If you experience a stronger exposure, you may still be experiencing symptoms up to forty-eight hours later. We recommend upon exposure that you drink milk in order to quicken your recovery. The calcium in milk helps remove the zinc build-up from your body. AND Avoiding “Fume Fever” Feb 09, 2011 by bakersgas in Uncategorized Imagine you just finished up a day on the job, welding Galvanized Steel. You head home, shower up, and grab a beer as you settle in to watch the game on the tube. But then you start to feel kind of gross. Your legs start to ache, you become really thirsty with a blazing dry throat, and you start coughing and become congested, shivering all over. Things get worse from there as you spike a fever, feel nauseous and start throwing up. At the height of this two-day nightmare ride, you even hallucinate and experience convulsions. Is this the worse flu ever? Nope—you’ve just been hit by Fume Fever. It’s pretty nasty stuff, but totally preventable and fortunately, it’s not currently linked to any long-term health problems. Galvanized Steel is coated with a thin layer of zinc, and zinc melts at a much lower rate than steel, so when you’re welding Galvanized Steel, the zinc coating is vaporized and turns into zinc oxide. When you breath-in zinc oxide fumes, you develop what is commonly known as Fume Fever. This usually happens 1-4 hours after exposure and typically lasts for 1-2 days. The good news is these nasty side-effects are totally preventable. •Proper ventilation in your work area is the first, and most effective way to prevent the inhalation of zinc oxide fumes. Most shops and industrial complexes have effective ventilation and air filtration systems in-place, and outdoor job sites are generally not a problem, as fumes dissipate naturally outside. •If you’re working in a confined or unventilated work area, wear an approved respirator. Varying types of respirators are available, and the level of fumes you’re exposed to will dictate the type of respirator you need for a particular job. **Never eat, drink or smoke in an area contaminated by zinc oxide or any welding fumes. ***Always wash your hands thoroughly after you finish welding, and definitely before you eat—zinc oxide can be extremely poisonous if ingested |
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torque wrench issues
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torque wrench issues
wrote in message ... On Monday, May 1, 2017 at 11:34:12 AM UTC-7, Ian Field wrote: The people who made the RoHS list don't seem very keen on cadmium - like most battery systems; the cadmium ones got an exemption. However - most battery manufacturers seem to have voluntarily dropped cadmium. You can still get them for specialist applications like security systems, but general types have pretty much vanished from the shops. I'm not aware of any restrictions on zinc - zinc/air hearing aid batteries have if anything, increased in popularity. Because they need air to work - they're not fully sealed. I think that you would find that no one "voluntarily" ceased production because of health concerns but because Lithium Ion batteries are taking over the market. Its difficult to make lithium cells that deliver 1.5V - so not much use for the standard sizes. I have seen some, but not recently - and they were very expensive and not rechargeable. Ni-Mh has largely replaced Ni-Cd and have around 2 - 3x the Ah capacity - but they can't deliver the instantaneous current draw. Ni-Cd, size for size have comparable instantaneous current to lead-acid - I've used a Ni-Cd pack on a motorcycle with electric starter. When the Ni=Cd battery in my rechargeable shaver gave up, I couldn't get a replacement for the original, so I tried a Ni-MH - despite 3x the Ah capacity, it only ran as long as the knackered one it replaced. I noticed the battery was getting pretty warm - that's where the missing energy was ending up. |
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torque wrench issues
On Mon, 1 May 2017 19:49:36 +0100, "Ian Field"
wrote: I have never become aware of the dire consequences of welding zinc plated that are being spouted here. "galvanised" can be plated with *ANY* metal that has a higher galvanic affinity than the host metal. Including cadmium and various other toxic heavy metals. Cadmium poisoning is cumulative and has various routes into the body - its a long slow painful journey to a Darwin award. For a few years I worked assembling electronic equipment on cadmium plated chassis - I've seen with my own eyes the extent to which the plating rubs off on your hands. But if you're too stupid to take it from someone who's been there - Darwin awaits you with outstretched arms. Whenever working with ANY metals, or ANY chemicals, you should wash your hands well before eating, and never eat in the contaminated working area. Unless you have breaks in your skin, you are unlikely to absorb significant amounts of Cadmium From the CDC: The principal factor determining how much cadmium is absorbed is the route of exposure. Once exposed, how much cadmium is absorbed depends on many factors: age, gender, smoking, and nutritional status. As a cumulative toxin, cadmium body burden increases with age. Women have been shown to have higher blood levels of cadmium than men. Typically women, with lower iron status, are believed to be at risk for greater absorption of cadmium after oral exposure (Olsson et al. 2002). Inhalation Once in the lungs, from 10% to 50% of an inhaled dose is absorbed, depending on particle size, solubility of the specific cadmium compound inhaled, and duration of exposure (Jarup 2002). Absorption is least for large (greater than 10 micrometers [µm]) and water-insoluble particles, and greatest for particles that are small (less than 0.1 µm) and water soluble. A high proportion of cadmium in cigarette smoke is absorbed because the cadmium particles found in that type of smoke are very small (ATSDR 1999). Ingestion Most orally ingested cadmium passes through the gastrointestinal tract unchanged as normal individuals absorb only about 6% of ingested cadmium, but up to 9% may be absorbed in those with iron deficiency (ATSDR 1999). Also, cadmium in water is more easily absorbed than cadmium in food (5% in water versus 2.5% in food) (IRIS 2006). The presence of elevated zinc or chromium in the diet decreases cadmium uptake. Dermal Absorption through the skin is not a significant route of cadmium entry; only about 0.5% of cadmium is absorbed by the skin (ATSDR 1999). |
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torque wrench issues
wrote in message ... On Mon, 1 May 2017 07:06:39 -0700 (PDT), wrote: Whenever you are working with galvanized steel it is important that you take the necessary steps when prepping the metal before welding. If you have properly prepped your metal before welding, you will help reduce your exposure to zinc oxide fumes. The usually suggested preparation for welding or brazing galvanized materials is to grind all the galvanizing off! Welding a joint with zinc still on the area would weaken the weld but who am I to suggest that you're right? Smokers have very high amounts of cadmium in their bodies. If you've smoked for 50 years you probably have the maximum allowable amount of cadmium in your body. You can get cadmium in your body by touching it. The amount into your plasma is as high as 0.07%. The half-life of cadmium in the body is about 10 years if memory serves. But both zinc and cadmium would normally only accumulate to dangerous levels at a rate that wouldn't harm you until long after you're dead unless you're a smoker. Or a careless welder. Brazing spelter containing cadmium can make you sicker than a dog in short order if you are breathing the fumes - as can the fumes from welding galvanized steel. It only takes a few minutes to get you wretching and puking and aching to the point you almost wish you could die. "galvanised" is galvanic protection - which can include any of several toxic heavy metals. Some people here seem to think it can only mean zinc. The toxic dose of zinc is really quite large. |
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torque wrench issues
wrote in message ... On Mon, 1 May 2017 19:25:05 +0100, "Ian Field" wrote: "John B Slocomb" wrote in message . .. On Sun, 30 Apr 2017 23:14:27 -0400, wrote: On Sun, 30 Apr 2017 22:10:43 +0100, "Ian Field" wrote: "AMuzi" wrote in message news On 4/30/2017 3:30 PM, Ian Field wrote: "AMuzi" wrote in message news On 4/30/2017 12:01 PM, Ian Field wrote: wrote in message ... On Sat, 29 Apr 2017 19:53:16 +0100, "Ian Field" wrote: wrote in message ... On Tue, 25 Apr 2017 20:16:22 +0100, "Benderthe.evilrobot" wrote: "John B Slocomb" wrote in message ... On Mon, 24 Apr 2017 22:17:14 -0400, wrote: On Tue, 25 Apr 2017 07:42:21 +0700, John B Slocomb wrote: On Mon, 24 Apr 2017 19:51:41 +0100, "Benderthe.evilrobot" wrote: wrote in message ... On Sun, 23 Apr 2017 22:06:05 +0100, "Benderthe.evilrobot" wrote: "Emanuel Berg" wrote in message ... I finally got the 1/2" torque wrench, 28-210 Nm, not even made in China, but in Taiwan! Eh... I guess it depends who you ask if that is China or not It has a locking screw, a torque setting handle, a scale (Nm as well as "FT-LB", some English unit I take it?) - it also as a locking lever on top just like an ordinary ratchet, so it can go both ways, clockwise and anti-clockwise. The torques only work in the clockwise direction. So if the locking (ratchet) lever is set the other way, it is just a ratchet, right? Well, in the manual it says: Note: Never use the torque wrench to undo nuts, bolts or other fasteners as this will damage the ratchet mechanism and the calibrated settings. So how does that add up? Is it only OK to use the anti-clockwise pull to insert things, which would require a left thread? (And it would be just a long shaft, with the torque not in effect.) As for me, I don't plan using it for anything but as a torque, because I have other, less expensive ratchets and spanners to do the everyday stuff. But of course, I'd like to know what it means. It also came with a certificate with data on the calibration and in the manual it says it should be recalibrated at least every 12 months. Calibration is irrelevant if you don't follow the rules to the letter. Most torque settings I've seen were for dry threads - any stray lubricant and you might even twist the end off at the correct torque. --- This email has been checked for viruses by AVG. http://www.avg.com Torque specs vary considerably by application. Some are given as clean and dry, some are given as lubricated with oil - some are given cold, and others hot. That said, I personally have never run across a torque spec that was so "close to the edge" that torqing with "stray lubrication" would cause immediate failure of the bolt by twisting off the end. However, that said, most of my wrenching has not been on bicycles but on automobiles and agricultural and construction equipment which may be slightly more "overengineered" or "overbuilt" Bicycles tend to have less things you can twist the end off. Its common on motorcycles, but mainly pulling the threads out of alloy castings. Its pretty rare to strip an engine down so far that you can put the castings in degreasing plant - torquing the engine case bolts with oil left in the holes is a very good chance of stripping the threads. As for stripping engine bolts, the Honda factory used to install fasteners so tight that a normal person couldn't get them out without an"impact driver". A tool that I never even saw before the Japanese invasion. The lock washers were very effective where used, and the Phipips style bolts were incapable of delivering enough torque to breat them loose without camming out - the Hammer Impact driver solved that problem I believe I've read that the "Phillips" headed screws in a Japanese motorcycle are not actually "Phillips" but some Japanese standard that didn't quite match the screwdrivers we had in the U.S. Which probably didn't help either :-) That's the *whole* cause - just grind a tiny bit off the point of the screwdriver bit and it fits just right. The bits on my Impact driver fit perfectly without grinding. Note I said Philips "style" (I know, I mis-spelled it) bolts. Some of the early Jap stuff didn't use Cadmium plated bolts either - W10 imploded and I had to start over with a replacement news account. So back to old name. The japs were the worst of the lot for cadmium plated fasteners. The very toxic cadmium rubs off on your hands and is cumulative in the body - it causes such acute osteoporosis; you can end up fracturing ribs just by coughing. In the UK - nickel plated fasteners became fashionable about the 80s. They didn't do much about cadmium plated chassis in electronic equipment until RoHS. AFAIK: cadmium batteries are exempt from RoHS - but they've more or less vanished from the shops anyway. Cadmium is very nasty - wash your hands after handling anything plated with it! from Cadmium, A Health Hazard Surface Treatment C. Rehm ESG Einsteinstr. 174 D-81675 Munich, Germany An object containing cadmium is not especially injurious to health on its own. No risk is involved simply by touching it. A potential hazard occurs, however, when such objects are processed and high temperatures are generated. Cadmium plating rubs off on your hands whenever you handle cadmium plated parts and assemblies. Many years ago they even used it on electronic component leads to prevent oxidation - they used more aggressive fluxes in those days. Welding cad plated sheet steel is particularly dangerous - the cadmium is vapourised and becomes airborne. Usually the osteoporosis takes decades to start crippling the sufferer - but I've heard of a repair technician dropping dead after a couple of years from fumes using low melting point cadmium based solder. The specific mode of death wasn't announced. The Japanese know all about it, they discharged industrial effluent containing cadmium into heavily fished costal waters. They even have a name for the disease - itai itai byo. apparently its the noise sufferers make in their death throes. As I mentioned previously - bones become so weak and brittle, you can fracture ribs just by coughing. Well then avoid it as you wish. Many of us recognize the difference between metals and reactive metallic organic compounds. Zinc rich tablets are popular for symptoms of herpes simplex and yet no one welds galvanize steel a second time. Zinc can't be that toxic - its a usual ingredient of baby powder. Never heard of any warnings against welding zinc passivated steel - only know of cadmium plating being very dangerous. Fumes of burning zinc make your knees go soft as you vomit on the way down. Don't try this at home. When I was a kid, I liked throwing zinc batteries on the bonfire to watch them explode - no such effect was ever observed. Even one single exhausted battery would have more zinc than a pretty big sheet of zinc plated steel - and would dwarf the amount of zinc vapourised by a weld run. Whenever you are working with galvanized steel it is important that you take the necessary steps when prepping the metal before welding. If you have properly prepped your metal before welding, you will help reduce your exposure to zinc oxide fumes. The usually suggested preparation for welding or brazing galvanized materials is to grind all the galvanizing off! Genius!!! - you've invented a way to breathe it as dust instead of fumes. Darwin must be biding his time with you............................... Metallic sinc is not anywhere near as dangerous as the zinc oxide fumes from over-heated zinc Zinc oxide is the usual filler in heat transfer paste on heatsinks for power semiconductor devices. Total burnouts aren't as rare as most people would like - I've never heard of any casualties from those events. |
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