#111
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Bottle holder
On 5/24/2019 7:21 PM, John B. wrote:
On Fri, 24 May 2019 07:55:44 -0500, AMuzi wrote: On 5/23/2019 10:33 PM, John B. Slocomb wrote: On Thu, 23 May 2019 18:17:29 -0500, AMuzi wrote: On 5/23/2019 6:04 PM, John B. Slocomb wrote: On Thu, 23 May 2019 06:56:28 -0700, sms wrote: On 5/23/2019 3:34 AM, John B. Slocomb wrote: snip No, sorry, they didn't teach us about stress concentrations when drilling holes, primarily because any hole is a stress concentration, at least to some extent. And it is illogical to think that one can change "fatigue life" by drilling a hole in some special manner. It is not illogical at all. It is a fact. There is just no way that any course in machining would not teach about how to reduce stress concentration of holes drilled into metal. You might want to ask for a partial refund if that school is still in existence. Well, I can only comment that in my career I drilled holes in just about everything that flew and much of that was specified in either manufacturer's designs and/or specifications from people who had been assigned to design and document a modification and I cannot remember ever seeing any specifications, or directions, or other data intended to tell me how to change "fatigue life" by drilling a hole in some specific manner. So kindly teach me. But before you get off your podium please remember that we are not talking about designing a hole, or placing a hole or any other fuzzy example that you may care to elaborate on. We are discussing the drilling, or boring of a cylindrical passageway through a base material. We just had a spectacular example of the result of improper drilling of holes in steel beams in San Francisco, but these were not drilled by journeyman machinists. I assume that you are referring to the following https://www.nbcbayarea.com/investiga...494862071.html If so than once again you demonstrate that you simply do not know what you are talking about and apparently haven't even bothered to take the time to "read up" on what you are trying to say. The "holes you are talking about aren't drilled, i.e. cylindrical, holes but are , apparently, cut "holes" as described in the article, that you obviously didn't read, which says, "It's not a good structural element, says mechanical engineer Bernard Cuzzillo, referring to rectangular notches clearly cut in the four-inch thick steel at the bottom of the 85-foot long I-beam used to support the terminal deck across Fremont Street. Please note, "RECTANGULAR NOTCHES" not drilled holes. Unless, of course, you anticipate cutting rectangular holes to install the cylindrical revnuts. For God's Sake! They even had a video that clearly showed the cut, angular, holes... and you didn't even bother to watch the movie. Square apertures like a DeHavilland Comet? What could go wrong? I'm working from memory now (an always hazardous undertaking) but I think that the problem with the Comet wasn't so much the window shape so much as the fuselage expanding and contracting when pressurized. Apparently that had never been a problem with previous aircraft. After all, more modern airplanes have essentially square windows :-) Huh? That's not right. https://media.cntraveller.in/wp-cont...x-8-window.jpg I don't think there are any, not in the last 40 years anyway. Hmmm... a bit of face saving is in order :-) See https://www.youtube.com/watch?v=2ZZ0qyXNOV4 or even https://tinyurl.com/y3tgdhrw Good point, thanks. I was thinking of the passenger rows where the stresses are probably different from the front windows. In theory: https://siemensplm.i.lithium.com/t5/...564EFDF2?v=1.0 and in practice: https://www.telegraph.co.uk/culture/...-4-review.html -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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#112
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Bottle holder
On Fri, 24 May 2019 18:42:37 -0500, AMuzi wrote:
On 5/24/2019 6:18 PM, John B. wrote: On Fri, 24 May 2019 02:24:00 -0700, sms wrote: On 5/24/2019 1:28 AM, John B. wrote: snip Back in the day, we were taught to deburr everything we did and most machinists kept a flat, single cut, file and a triangular scrapper in the top of his box and before you took the piece out of the machine you hit every shoulder with the file and the edges of every hole with the scrapper. Well even without going to machinists school, deburring edges and holes is a pretty obvious thing that most people know to do. I see... and you think that "most people" have a flat file and a triangular scrapper right there in their tool box? Among those with a Kennedy tool box, yes and yes. Love this little Israeli deburr: http://www.bartsupply.com/gallery/pr...haviv_tool.jpg I just had a look at Amazon and a Kennedy "machining's tool box is almost $600 :-( Back when I was working at the trade my whole box, tools and apron didn't cost that much and we had to supply our own 1" and 2" micrometers and they had to be either Starret or Brown & Sharp. and a couple of Diamond Debs too. That said, "most people" probably have a crappy claw hammer, a screwdriver with flat/Phillips #2 flipover from the $1 table and a can opener. They don't know how to use the can opener. This is based on my research of being asked to help out with various household problems at various households. Based on those experiences, "no" is usually the best response. Or, "I charge $10 an hour" :-) Or, as I remember seeing somewhere, "$10 an hour and if you tried to fix it first than $20 an hour". -- cheers, John B. |
#113
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Bottle holder
On 5/24/2019 8:08 PM, John B. wrote:
On Fri, 24 May 2019 18:42:37 -0500, AMuzi wrote: On 5/24/2019 6:18 PM, John B. wrote: On Fri, 24 May 2019 02:24:00 -0700, sms wrote: On 5/24/2019 1:28 AM, John B. wrote: snip Back in the day, we were taught to deburr everything we did and most machinists kept a flat, single cut, file and a triangular scrapper in the top of his box and before you took the piece out of the machine you hit every shoulder with the file and the edges of every hole with the scrapper. Well even without going to machinists school, deburring edges and holes is a pretty obvious thing that most people know to do. I see... and you think that "most people" have a flat file and a triangular scrapper right there in their tool box? Among those with a Kennedy tool box, yes and yes. Love this little Israeli deburr: http://www.bartsupply.com/gallery/pr...haviv_tool.jpg I just had a look at Amazon and a Kennedy "machining's tool box is almost $600 :-( Back when I was working at the trade my whole box, tools and apron didn't cost that much and we had to supply our own 1" and 2" micrometers and they had to be either Starret or Brown & Sharp. and a couple of Diamond Debs too. That said, "most people" probably have a crappy claw hammer, a screwdriver with flat/Phillips #2 flipover from the $1 table and a can opener. They don't know how to use the can opener. This is based on my research of being asked to help out with various household problems at various households. Based on those experiences, "no" is usually the best response. Or, "I charge $10 an hour" :-) Or, as I remember seeing somewhere, "$10 an hour and if you tried to fix it first than $20 an hour". Mine was a hundred, about the same as a midprice race frame at the time (less than a Masi, more than a Gitane). Good value IMHO. My Starret micrometer set was a gift from a retired machinist. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#114
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Bottle holder
On Fri, 24 May 2019 18:33:34 -0500, AMuzi wrote:
On 5/24/2019 6:16 PM, John B. wrote: On Fri, 24 May 2019 02:19:37 -0700, sms wrote: On 5/24/2019 1:05 AM, John B. wrote: snip Further to Jobst's comments. I'm afraid I know many people who see no problems what so ever in drilling holes in frames - literally every custom frame builder I have ever been in contact with will put as many bottle cages on your new bike as you ask for. And every cage requires two holes to mount. Hopefully you realize the difference between a custom frame builder drilling a frame for cage mounts and the owner of a Huffy doing the same. Well, tell us, oh great pundit. Do the frame builders, who often know very little about the metals that they work with, buy special tubes to allow them to drill holes in them? Does Columbus, for example, manufacturer special frame tubes for those who wish to mount bottle cages? Or does Huffy buy special tubes that are specified by the maker NOT to be drilled? In another post I believe you made a statement that you posted about things that you knew about, so please tell us when and when not to drill holes to mount bottle cages. The former almost certainly has jigs for the task and is able to put in the mounts prior to assembling and painting the frame. If it's a steel or titanium frame, which is much more likely to be the case for a custom frame builder, then they're probably brazing on the mounts, not using Rivnuts. Actually, I wonder if you know what you are talking about? Titanium is a rather difficult metal to work with and at elevated temperatures reacts with air by bursting into flame. It can be welded using MIG with sufficient gas flow but cannot be welded with an open flame... Let me give you some information from https://www.thefabricator.com/articl...ou-can-weld-it Any time the metal reaches a temperature of 900 to 1,000 degrees F, brittle oxygen-stabilized alpha phase (or \u03b1-case) can form not only on the weld surface and its back side, but also on grinding tools2. Frictional heat, especially from aluminum oxide (Al2O3) wheels, can create high enough temperatures to embrittle the surface. Carbide-grit wheels are better because they have no aluminum to contaminate the weld. A gentle touch is best, because titanium has a low thermal conductivity and needs to be kept below the 500 degree F mark, where scaling begins. ---------- Note that most brazing done on bicycle frames is done with either silver solder - melting point in the 450 F degree region - or brass - ~850 F - which is hot enough to cause very significant changes in a titanium parent metal. So, yes, one can braze titanium but only if it is done in an inert atmosphere. I doubt and many, if any, frame maker has an inert atmosphere box large enough to hold a bicycle and thus probably brazed fittings on a titanium bicycle frame are rare enough the be non existent. -- cheers, John B. The first several years of titanium frames were indeed welded in inert-gas booths. Not very different from a bicycle frame glass bead booth really. Modern shielded-arc systems with inert gas flowing inside the tubes is the standard practice now. I think I've mentioned that. The last time I certified (U.S.A.F.) I got my stainless and aluminum samples done and passed and had to wait for another day for the guy I came with to finish and tried welding in a box. Surprisingly I "passed" with my second sample. Some time later I visited a friend who was a civilian working at an A.F. Base and was (sort of) bragging about how I passed my certification for Titanium and he says, Oh Yes. We weld it all the time here with just a MIG torch and backing gas. Oh and I think you mistyped silver braze temps, usually 1100F &up, and brazing temps roughly 1600F and up. 450 degrees F is in the cookie-baking zone, even below my lead work. Yes. 450 degrees is awfully low for silver brazing :-( I once came across some "silver solder" rod with a liquid temperature in the 600 degree range and used it to braze some brake posts on a frame I had. I later found that this low temp stuff was NOT recommended for ferrous metals :-( Apparently it has a high cadmium content and that is bad. Rather then try to remove the posts and all the traces of the cadmium containing "solder" I just left them and so far... maybe 6 or 7 years later they are still there. -- cheers, John B. |
#115
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Bottle holder
On 5/24/2019 8:35 PM, John B. wrote:
On Fri, 24 May 2019 18:33:34 -0500, AMuzi wrote: On 5/24/2019 6:16 PM, John B. wrote: On Fri, 24 May 2019 02:19:37 -0700, sms wrote: On 5/24/2019 1:05 AM, John B. wrote: snip Further to Jobst's comments. I'm afraid I know many people who see no problems what so ever in drilling holes in frames - literally every custom frame builder I have ever been in contact with will put as many bottle cages on your new bike as you ask for. And every cage requires two holes to mount. Hopefully you realize the difference between a custom frame builder drilling a frame for cage mounts and the owner of a Huffy doing the same. Well, tell us, oh great pundit. Do the frame builders, who often know very little about the metals that they work with, buy special tubes to allow them to drill holes in them? Does Columbus, for example, manufacturer special frame tubes for those who wish to mount bottle cages? Or does Huffy buy special tubes that are specified by the maker NOT to be drilled? In another post I believe you made a statement that you posted about things that you knew about, so please tell us when and when not to drill holes to mount bottle cages. The former almost certainly has jigs for the task and is able to put in the mounts prior to assembling and painting the frame. If it's a steel or titanium frame, which is much more likely to be the case for a custom frame builder, then they're probably brazing on the mounts, not using Rivnuts. Actually, I wonder if you know what you are talking about? Titanium is a rather difficult metal to work with and at elevated temperatures reacts with air by bursting into flame. It can be welded using MIG with sufficient gas flow but cannot be welded with an open flame... Let me give you some information from https://www.thefabricator.com/articl...ou-can-weld-it Any time the metal reaches a temperature of 900 to 1,000 degrees F, brittle oxygen-stabilized alpha phase (or \u03b1-case) can form not only on the weld surface and its back side, but also on grinding tools2. Frictional heat, especially from aluminum oxide (Al2O3) wheels, can create high enough temperatures to embrittle the surface. Carbide-grit wheels are better because they have no aluminum to contaminate the weld. A gentle touch is best, because titanium has a low thermal conductivity and needs to be kept below the 500 degree F mark, where scaling begins. ---------- Note that most brazing done on bicycle frames is done with either silver solder - melting point in the 450 F degree region - or brass - ~850 F - which is hot enough to cause very significant changes in a titanium parent metal. So, yes, one can braze titanium but only if it is done in an inert atmosphere. I doubt and many, if any, frame maker has an inert atmosphere box large enough to hold a bicycle and thus probably brazed fittings on a titanium bicycle frame are rare enough the be non existent. -- cheers, John B. The first several years of titanium frames were indeed welded in inert-gas booths. Not very different from a bicycle frame glass bead booth really. Modern shielded-arc systems with inert gas flowing inside the tubes is the standard practice now. I think I've mentioned that. The last time I certified (U.S.A.F.) I got my stainless and aluminum samples done and passed and had to wait for another day for the guy I came with to finish and tried welding in a box. Surprisingly I "passed" with my second sample. Some time later I visited a friend who was a civilian working at an A.F. Base and was (sort of) bragging about how I passed my certification for Titanium and he says, Oh Yes. We weld it all the time here with just a MIG torch and backing gas. Oh and I think you mistyped silver braze temps, usually 1100F &up, and brazing temps roughly 1600F and up. 450 degrees F is in the cookie-baking zone, even below my lead work. Yes. 450 degrees is awfully low for silver brazing :-( I once came across some "silver solder" rod with a liquid temperature in the 600 degree range and used it to braze some brake posts on a frame I had. I later found that this low temp stuff was NOT recommended for ferrous metals :-( Apparently it has a high cadmium content and that is bad. Rather then try to remove the posts and all the traces of the cadmium containing "solder" I just left them and so far... maybe 6 or 7 years later they are still there. I just wandered around the InterWebs a bit and the high (50%+) silver content with cadmium super-low-temp products are indicated for joining silver and also copper electrical connectors at just under 600C (not F). I have no experience with those. My 45% silver braze, no cad, is 1150F = 620C. Same temp range different product entirely. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#116
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Bottle holder
On Fri, 24 May 2019 20:06:02 -0500, AMuzi wrote:
On 5/24/2019 7:21 PM, John B. wrote: On Fri, 24 May 2019 07:55:44 -0500, AMuzi wrote: On 5/23/2019 10:33 PM, John B. Slocomb wrote: On Thu, 23 May 2019 18:17:29 -0500, AMuzi wrote: On 5/23/2019 6:04 PM, John B. Slocomb wrote: On Thu, 23 May 2019 06:56:28 -0700, sms wrote: On 5/23/2019 3:34 AM, John B. Slocomb wrote: snip No, sorry, they didn't teach us about stress concentrations when drilling holes, primarily because any hole is a stress concentration, at least to some extent. And it is illogical to think that one can change "fatigue life" by drilling a hole in some special manner. It is not illogical at all. It is a fact. There is just no way that any course in machining would not teach about how to reduce stress concentration of holes drilled into metal. You might want to ask for a partial refund if that school is still in existence. Well, I can only comment that in my career I drilled holes in just about everything that flew and much of that was specified in either manufacturer's designs and/or specifications from people who had been assigned to design and document a modification and I cannot remember ever seeing any specifications, or directions, or other data intended to tell me how to change "fatigue life" by drilling a hole in some specific manner. So kindly teach me. But before you get off your podium please remember that we are not talking about designing a hole, or placing a hole or any other fuzzy example that you may care to elaborate on. We are discussing the drilling, or boring of a cylindrical passageway through a base material. We just had a spectacular example of the result of improper drilling of holes in steel beams in San Francisco, but these were not drilled by journeyman machinists. I assume that you are referring to the following https://www.nbcbayarea.com/investiga...494862071.html If so than once again you demonstrate that you simply do not know what you are talking about and apparently haven't even bothered to take the time to "read up" on what you are trying to say. The "holes you are talking about aren't drilled, i.e. cylindrical, holes but are , apparently, cut "holes" as described in the article, that you obviously didn't read, which says, "It's not a good structural element, says mechanical engineer Bernard Cuzzillo, referring to rectangular notches clearly cut in the four-inch thick steel at the bottom of the 85-foot long I-beam used to support the terminal deck across Fremont Street. Please note, "RECTANGULAR NOTCHES" not drilled holes. Unless, of course, you anticipate cutting rectangular holes to install the cylindrical revnuts. For God's Sake! They even had a video that clearly showed the cut, angular, holes... and you didn't even bother to watch the movie. Square apertures like a DeHavilland Comet? What could go wrong? I'm working from memory now (an always hazardous undertaking) but I think that the problem with the Comet wasn't so much the window shape so much as the fuselage expanding and contracting when pressurized. Apparently that had never been a problem with previous aircraft. After all, more modern airplanes have essentially square windows :-) Huh? That's not right. https://media.cntraveller.in/wp-cont...x-8-window.jpg I don't think there are any, not in the last 40 years anyway. Hmmm... a bit of face saving is in order :-) See https://www.youtube.com/watch?v=2ZZ0qyXNOV4 or even https://tinyurl.com/y3tgdhrw Good point, thanks. I was thinking of the passenger rows where the stresses are probably different from the front windows. In theory: https://siemensplm.i.lithium.com/t5/...564EFDF2?v=1.0 and in practice: https://www.telegraph.co.uk/culture/...-4-review.html If you want some detailed studies originating from the water tank testing see https://aerospaceengineeringblog.com...d-comet-crash/ The design modifications are a bit more complicated than simply rounding window corners and included "crack-stoppers are now placed between frame-cutouts that take the shape of circumferential stiffeners that break-up the fuselage into multiple sections and thus prevent the crack from propagating from one window to the next". The most important change was said to be the change over from a " SAFE-LIFE, which means that the structure was designed to sustain the required fatigue life with no initial damage and no accumulation of damage during service" to a "FAIL-SAFE design philosophy was developed in the late 1950's. All materials are assumed to contain a finite initial defect size before entering service that may grow due to fatigue loading in-service." -- cheers, John B. |
#117
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Bottle holder
On Fri, 24 May 2019 20:34:19 -0500, AMuzi wrote:
On 5/24/2019 8:08 PM, John B. wrote: On Fri, 24 May 2019 18:42:37 -0500, AMuzi wrote: On 5/24/2019 6:18 PM, John B. wrote: On Fri, 24 May 2019 02:24:00 -0700, sms wrote: On 5/24/2019 1:28 AM, John B. wrote: snip Back in the day, we were taught to deburr everything we did and most machinists kept a flat, single cut, file and a triangular scrapper in the top of his box and before you took the piece out of the machine you hit every shoulder with the file and the edges of every hole with the scrapper. Well even without going to machinists school, deburring edges and holes is a pretty obvious thing that most people know to do. I see... and you think that "most people" have a flat file and a triangular scrapper right there in their tool box? Among those with a Kennedy tool box, yes and yes. Love this little Israeli deburr: http://www.bartsupply.com/gallery/pr...haviv_tool.jpg I just had a look at Amazon and a Kennedy "machining's tool box is almost $600 :-( Back when I was working at the trade my whole box, tools and apron didn't cost that much and we had to supply our own 1" and 2" micrometers and they had to be either Starret or Brown & Sharp. and a couple of Diamond Debs too. That said, "most people" probably have a crappy claw hammer, a screwdriver with flat/Phillips #2 flipover from the $1 table and a can opener. They don't know how to use the can opener. This is based on my research of being asked to help out with various household problems at various households. Based on those experiences, "no" is usually the best response. Or, "I charge $10 an hour" :-) Or, as I remember seeing somewhere, "$10 an hour and if you tried to fix it first than $20 an hour". Mine was a hundred, about the same as a midprice race frame at the time (less than a Masi, more than a Gitane). Good value IMHO. My Starret micrometer set was a gift from a retired machinist. I had an antique, I guess you'd call it, wooden Kennedy box given to me. I was always afraid to actually use it for a tool box as I was afraid of damaging it. So it just sat in the garage looking pretty :-) -- cheers, John B. |
#118
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Bottle holder
On Fri, 24 May 2019 15:22:12 +0700, John B. wrote:
On Fri, 24 May 2019 04:40:50 -0000 (UTC), news18 wrote: On Fri, 24 May 2019 10:46:42 +0700, John B. Slocomb wrote: On Thu, 23 May 2019 18:14:40 -0500, AMuzi wrote: Geez. Who can't sharpen a drill bit?? Apparently someone that posts here as I remember the implication and sharp drills were only found in machine shops :-) Yep, YMMV, but I've always found it cheaper to just buy a new drill set or collection of drills than fuzing around trying to sharpen them. OTOH, I don't earn my living drilling holes and it rapidly became obvious that as far as "drill sharpening devices" went one size/type/style didn't fit all and apart from a pileof files, that's enough. I'll go as far as touching up a chain saw every cut on dry redgum or yellow box(realraiway sleepers), but life is too short to touch up a drill for every hole. Different strokes for different folks, I guess. But sharpening drills is just two passes across the grinding wheel and a chain saw has a multitude of teeth :-) If you have a shop, then I guess you're bound to have a grinding wheel or three, but no shop here. Nor do i have a vice standing by with a groove to hold drills so I can rub a file over them. Then there is the fact that I just can't file a flat surface for the life of me. |
#119
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Bottle holder
On Sat, 25 May 2019 08:08:37 +0700, John B.
wrote: I just had a look at Amazon and a Kennedy "machining's tool box is almost $600 :-( I paid $35 for my first one in about 1970. I currently have 3 of them, including one copy my father made from mahogany. They can be had used on eBay for $100 to $150 including shipping: https://www.ebay.com/sch/i.html?_nkw=kennedy+520+machinist+tool+box or new from various sources for $300 to $400: https://www.google.com/search?tbm=shop&q=kennedy+machinist+tool+box+520 I'll reply to accusations of ineptitude for failing to deburr the hose clamp later. Verrry bizzeee for a few daze. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#120
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Bottle holder
On 5/24/2019 8:24 PM, John B. wrote:
On Fri, 24 May 2019 11:16:37 -0400, Joy Beeson wrote: On Fri, 24 May 2019 15:18:59 +0700, John B. wrote: One of the A.F. machine shops I was assigned to had no drill sharpening "utensils" what so ever as the Shop Chief, a grizzled old fellow that did his apprenticeship at Morse Twist Drill, I believe, said that sharpening a drill was such a basic skill that everybody must know how to do it. :-) Reminds me of the time I bought a booklet called something like "Tools and their Uses". Since it was intended for Navy inductees who didn't know anything, I figured it would tell me how to sharpen a pocket knife. All it said about pocket knives was that they should be kept sharp. Good Lord! And you a married woman? and you don't know how to sharpen a knife? You just say, "Honey, this knife is sooo dull that I can't cut this steak meat... would you like hamburger for supper? :-) -- - Frank Krygowski |
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