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| John NW Ia - 3/2/2013 11:22
I find it hilarious (could it be ironic?) that the definition of a meter is a fraction.
That's the point, the hard work is done upfront, you don't need fractions anymore when actually using metrics. |
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| 247farmer - 3/2/2013 13:49
For the third time I have no issues understanding. Just trying to point out the ease of use and efficiency of the metric system. If I sir am a whiner then you sir are a fool for thinking those two examples are equally logical. :) Enough of this as we have resorted to name calling. Have a nice day, Im going to go play some poker.
Best of luck on your poker game. Hopefully the game not being based on multiples of ten won't prove too cumbersome. :) |
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Southeast Wyoming | I didn't read much of your editorial. It simply has no basis in fact. Only in the past few years has NASA been looking to metrics and they are seeing problems with going to the use of metrics.
If I recall correctly, in the past decade there was some mission that went bad because some country provided a device that was designed using the metric system and it would not match up the the imperial measurements used in the system it was supposed to have been manufactured to match up with. So yes, we will have to dumb down so the non-thinking people do not have to adapt to a system that has worked to bring our nation to lead the world.
And you were the first I noticed in this thread to bring up fractions as if they were some how endemic to the imperial system. WOW! |
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Germany | http://en.wikipedia.org/wiki/Gimli_Glider the "fuel meter" of the plane was defective and they checked the fuel with a dipstick. Then the did a mistake converting the volume into weight, by mixing up the conversion factors for imperial and metric units... like in most accidents, a chain of things that went wrong. A german pilot landed gliding in Vienna in 2000, he went out of fuel at the attempt to reach Germany coming from Greece with the landing gear out, probably to save repair cost and for "passenger convenience". http://en.wikipedia.org/wiki/Hapag-Lloyd_Flight_3378 |
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| In metric you still have some confusion, because a cc is only a gram with pure water. Any other solution the density is different from 1.000000000000 and measuring by cc doesn't give the same result as measuring in grams.
Gerald J. |
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| US and old Imperial threads are defined in threads per inch, usually whole threads per inch giving often odd pitches, inches per thread. Metric threads are defined as pitches, usually (except for BA threads) using integer mm, 1/2, or 1/4 mm steps for pitch.
Thread cutting on metal lathes can be mixed metric and fractional in several ways. Generally if you shift the change gears from US to metric throwing in a factor of 2.54 or 1.27 (classically a 100 to 127 gear pair) the threads per inch now become threads per centimeter and if the quick change gear box is very well equipped some are useful. Like 10 threads per inch becomes 10 threads per cm or 1mm pitch. Sometimes the quick change selection has been cobbled to give 12.5 threads per inch which fits no standard US screw but with the change gears shifted becomes 1.25 mm pitch.
Most US metal lathes stack the selecting gears 8 through 15 teeth per gear (driven gears) on the shaft coupled to the lead screw, and change ranges in factors of 2 on the input side of the quick change gear box. A pure metric lathe has those 8 through 15 teeth gears on the driving side with the factors of 2 change on either side of the quick change box, just the selections within a range change integer pitches, not integer threads per inch.
Some metric/US thread quick change boxes have two sets of fine gears. Inputs driving for metric, outputs driven for US. And with the magic of the 127/100 gear pair its possible to get US threads from a pure metric quick change gear box with a few extra none metric selections.
Some western Pacific combination lathes take care of the lead screw pretty well, but on the cross feed make it a compromise between .1" per turn and 2.54 mm per turn, but show only 25 divisions on the dial so for one its always a little wrong. Either the thread of the cross feed is .1" and 2.54 mm per turn or its 2.5 mm and .098425" per turn. So in the first case when you depend on the dial for cutting to size, it works out for inches, but is undersize for metric, or safer with the second version and the metric feed screw it cuts right for metric but leaves the work oversize with US which you learn with your final micrometer check that the part is oversize, so you have to cut another pass.
Without a quick change gear box, my lathe is most versatile (but very inconvenient), there are many possible sets of gears for most every thread, metric or US though its handy to have that 100 to 127 ratio for the metric threads, but with the collection of gears there are often several, up to a dozen, different gear trains that will get an approximation of the desired thread. Just depends which one you use if you have the right gears and how picky you are about the accuracy of the resulting thread. Years ago I found a windoze program on line that will show the possible combinations given the available gears and the threading lead screw thread and show the error of each. Its not in this computer. I've not looked for something like it lately, probably there's a web page and a dozen apps for that.
Gerald J. |
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Agent Orange: Friendly fire that keeps on burning. | My lathe uses a 127 tooth gear to very closely approximate many metric thread pitches. A guy needs to forget about using the threading dial when doing so though.
Threading is very much complicated when you need to keep the half-nuts always closed as opposed to having the luxury of a threading dial. |
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WC Saskatchewan | I find it funny that my John Deere combine has metric bolts (built in the US) and my Mac Don header has imperial bolts (built in Canada).
Its one of them things like, which side of the road should we drive on? Neither is right or wrong, the world should just pick one, and make it standard. |
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| Yah metric often means keep the half nut closed unless the lead screw is metric. Then is when you wish for a hand crank on the spindle for a few turns or a good quick drive clutch in a gear head lathe so you can sneak up and easily back up.
Friend of mine has a sturdy Italian lathe that has US style quick change box, but shows all kinds of pitches US, Metric, modular for cutting worm gears, and about 5 others set up by changing the manual change gears and it never has had a threading dial. Just has a quick clutch and gear head to get really slow. It has a separate shaft out of that gear box for the manual change gear drive the turns the same as the hollow spindle.
On my little lathe I made a hand crank to fit in the outside of the spindle hollow shaft. I used a flat piece of steel with a knob on the side, and an expanding concrete anchor bolt in the hollow shaft. It mounts and comes out fairly easily, really handy when cutting a short coarse thread. Like a 2"-4 thread for a spare water cap for my camper that has to stop three or four turns in against the inside of the cap.
Sometimes that crank needs to be on the lead screw instead of the spindle where the pitch is large, like fewer than four to the inch because the change gears and the quick change gear box are often turning the lead screw faster than the spindle and they can't hack that and cut steel with the rapid feed too. Also in that situation the hand crank is easier to turn on the right hand end of the lead screw than on the spindle.
The 50 or 100 to 127 gears are exact. There are other odd ratios that are not as close but close enough.
Gerald J.
Edited by Gerald J. 3/2/2013 21:53
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Near-north Ontario, French River | Except for the fact that the US doesn't use the ENGLISH(imperial) system. Yes there is some overlap, ie a lb is a lb, a mile is a mile etc in both systems BUT the US pint is different from the Imperial pint, same goes for fluid ounces, ounces etc |
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Near-north Ontario, French River | Skipper the problem is you( the US) DID refuse to buy anything metric way back when, and that's what's gotten you into the mess you are in now. The rest of the world has changed around you, its just the US and 2 small countries, that have held out. While the rest of the world has embraced Metric and moved on, the US continues to complain about wrench sizes and having to convert. Having said that, if ya'll want to be different and hold out, more power to you . |
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Near-north Ontario, French River | Grain at the farm gate level , and elevator counter level is talked about in bushels, I can all but guarantee you that at the commercial level they talk about grain in TONNES. At the elevator level, where counter staff talks to growers, the conversion is done because that's what growers are used to. Our local co-op is in an interesting area. We are very close to the US border but operate in a relative large area of Ontario. Few years ago the grain division of the Co-op changed their statements and settlements. They were responding to requests from a lot of customers to have settlements in Metric tonnes, seemed reasonable enough because that's how grain with in dealt with at the commercial level. Well you couldn't hear yourself think above all the complaints from a lot of guys that farmed closer to the US border, they wanted BUSHELS. Can't please everyone LOL.. FWIW when I talk yields I talk about bushels/ac,,, but yields are reported to crop insurance in METRIC tonnes . It's a real mix mash around here. We drive km/h , buy fuel by the litre, drive distances in km but measure fuel economy in MPG. Anything sold is sold in metric units though, usually Metric tonnes or Litres. |
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Near-north Ontario, French River | Lots of interesting tie-ins in the metric system. Pure water is one of the standards in the metric system. A Metric tonne is the weight of a "cube" of water with the dimensions of 1M x 1M x 1M. |
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thumb of michigan | Thud - 3/3/2013 14:44
Lots of interesting tie-ins in the metric system. Pure water is one of the standards in the metric system. A Metric tonne is the weight of a "cube" of water with the dimensions of 1M x 1M x 1M.
fresh or saltwater ? |
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Near-north Ontario, French River | PURE water,,, salt water isn't pure. |
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| Distilled and at a particular temperature, probably 1 or 2C where the density is greatest.
And one meter cubed is a million centimeters cubed, so a gram is 1 cubic centimeter of that distilled water. There are 1 million grams per metric tonne, 1000 kilograms per metric tonne.
Of course in the US we have long tons and short tons, the long ton being closer to a metric ton than a short ton. Long ton is 2240 pounds, 1.12 short tons and 1016.05 Kg.
Gerald J. |
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thumb of michigan | Gerald J. - 3/4/2013 16:04
Distilled and at a particular temperature, probably 1 or 2C where the density is greatest.
And one meter cubed is a million centimeters cubed, so a gram is 1 cubic centimeter of that distilled water. There are 1 million grams per metric tonne, 1000 kilograms per metric tonne.
Of course in the US we have long tons and short tons, the long ton being closer to a metric ton than a short ton. Long ton is 2240 pounds, 1.12 short tons and 1016.05 Kg.
Gerald J.
Usually it is considered a mole I think? A certain temperature etc. like 70 F.? |
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Lantry, SD | mennoboy - 3/1/2013 16:20
The part of that story that I find interesting is that they had trouble judging how fast to come in for the landing because the distance was a bit of an unknown. The pilot realized he was coming in too fast and did a manouvre that sounded like he put the plane somewhat sideways while gliding to increase the drag. He had apparantly learned the manouvre in pilot's training on a small plane years before and pulled it off in a big jet.
I believe it was a bunch of drag racers that were using the runway at Gimili.
The manuever that he did would most likely have been a slip, which is basically rolling the plane on one side and applying opposite rudder to raise the nose of the aircraft even more in relation to the ground. It feels like you are dropping like a rock when you do this, but your airspeed doesn't increase.
Edited by dnkag 3/4/2013 17:01
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NE Indiana | Thud - 3/3/2013 14:44
Lots of interesting tie-ins in the metric system. Pure water is one of the standards in the metric system. A Metric tonne is the weight of a "cube" of water with the dimensions of 1M x 1M x 1M.
Actually it's not. A kilogram weighs just slightly less than a liter of water. 1 liter of water at 3.98 degrees C at sea level weighs 1.000028 kg.
Edited by cz4586 3/4/2013 17:37
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Units of measure
