Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Ending the Era of the U.S. Survey Foot

nist.gov

Post reply on HN
Print view View original

91–100 of 163 posts

Re: Ending the Era of the U.S. Survey Foot

#91

Post by beerandt »

big_chungus wrote: post #76
analog31 wrote: post #71

Earlier quoted context omitted.

We are. All of the US standards are based on metric units. A large number of the products that we buy are made from metric components such as screws. CAD software and machine tools can switch effortlessly between unit standards. There are some standards that are so unique that they might as well be arbitrary, such as spark plug threads. Some building materials still have US dimensions, but if you measure plywood care…

> the "2 x 4" has never been 2 x 4 inches. Well, it used to be pretty close, until lumber manufacturers and builders cheaped out. They've been gradually "shrinkflating" by reducing the thickness, conveniently requiring less wood. This went along with the switch to fast-growing garbage pine. I lived for a long time in an early-fifties house, and the quality of the wood was vastly superior to what you'd find today. Tho…

While i don't doubt they're cheating it a bit, the dimensions originally refered to rough cut, pre-dried lumber. Most of the difference came from finish cuts and drying.

Re: Ending the Era of the U.S. Survey Foot

#92

Post by opwieurposiu »

function_seven wrote: post #54
opwieurposiu wrote: post #10

Earlier quoted context omitted.

Sometimes the benchmark for northing/easting/elev is many miles away from the actual site. This is especially true with gps surveys. It only takes a few inches to wind up with a substantial drainage problem.

Wouldn't the elevation difference between benchmark and site be the important bit here? If so, then the difference would rarely be more than a mile, and the resulting error would be at most an 1/8"

It has been 20 years since I worked in this area so likely I have some details wrong. If elevation is distance to the center of the earth 1/8" per mile is 40 feet!

From the link below you can see the noaa benchmark is using both elevation in feet above sea level and in meters from the center of the earth.

https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=aa3449

Re: Ending the Era of the U.S. Survey Foot

#93

Post by beerandt »

p1mrx wrote: post #55

> In 1959, the relationship of the foot to the meter was officially refined as 1 foot = 0.304 8 meter exactly. We can thank one man for this: Carl Edvard Johansson from Sweden. When making gauge blocks, he decided to round off the inch to exactly 25.4mm, and people around the world used his blocks to manufacture everything. The 1959 change just reflected what industry was already doing. - http://mitutoyo.com/wp-conte…

For reference, a US survey foot is legally defined as 1200⁄3937 meters, which is ~0.304801 meters.

The difference is usually written as 2ppm, for practical purposes. (To match units for survey equipment accuracy.)

Re: Ending the Era of the U.S. Survey Foot

#94

Post by samatman »

p1mrx wrote: post #55

> In 1959, the relationship of the foot to the meter was officially refined as 1 foot = 0.304 8 meter exactly. We can thank one man for this: Carl Edvard Johansson from Sweden. When making gauge blocks, he decided to round off the inch to exactly 25.4mm, and people around the world used his blocks to manufacture everything. The 1959 change just reflected what industry was already doing. - http://mitutoyo.com/wp-conte…

It frustrates my sense of aesthetics to no end that the inch isn't defined as 25.6 mm.

That would make the imperial system a base-two variant of the SI system.

This would have made the mile around 42 (current) feet longer, which is a non-starter; I just wish the foot had been a little longer, somehow.

Re: Ending the Era of the U.S. Survey Foot

#95

Post by a2tech »

beerandt wrote: post #91
big_chungus wrote: post #76

Earlier quoted context omitted.

> the "2 x 4" has never been 2 x 4 inches. Well, it used to be pretty close, until lumber manufacturers and builders cheaped out. They've been gradually "shrinkflating" by reducing the thickness, conveniently requiring less wood. This went along with the switch to fast-growing garbage pine. I lived for a long time in an early-fifties house, and the quality of the wood was vastly superior to what you'd find today. Tho…

While i don't doubt they're cheating it a bit, the dimensions originally refered to rough cut, pre-dried lumber. Most of the difference came from finish cuts and drying.

My house was built in 1860. The 2x4s are basically 2x4.

Re: Ending the Era of the U.S. Survey Foot

#96

Post by analog31 »

a2tech wrote: post #95
beerandt wrote: post #91

Earlier quoted context omitted.

While i don't doubt they're cheating it a bit, the dimensions originally refered to rough cut, pre-dried lumber. Most of the difference came from finish cuts and drying.

My house was built in 1860. The 2x4s are basically 2x4.

My house was built in 1962, and there were some exposed studs, and spares made into things like garage shelves. The old 2x4's are bigger than new 2x4's.

Re: Ending the Era of the U.S. Survey Foot

#97

Post by beerandt »

opwieurposiu wrote: post #92
function_seven wrote: post #54

Earlier quoted context omitted.

Wouldn't the elevation difference between benchmark and site be the important bit here? If so, then the difference would rarely be more than a mile, and the resulting error would be at most an 1/8"

It has been 20 years since I worked in this area so likely I have some details wrong. If elevation is distance to the center of the earth 1/8" per mile is 40 feet! From the link below you can see the noaa benchmark is using both elevation in feet above sea level and in meters from the center of the earth. https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=aa3449

If you're not converting H (gps orthometric height) to E (local elevation datum to "sea level") first, you're doing it wrong, for a number of practical reasons.

Usually there's not even a reason to use H directly anymore, since elevations should reference a local benchmark.

GPS has changed things, but surveyors are still obscenely practical when it comes to procedures for eliminating systematic error.

Re: Ending the Era of the U.S. Survey Foot

#98

Post by irrational »

Taniwha wrote: post #82
irrational wrote: post #48

Earlier quoted context omitted.

Yeah, woodworking is so much easier when using feet and inches. It's so incredibly useful to be able to divide a foot into half, thirds, quarters, sixths, and twelfths.

nah, a mm is an incredibly useful unit for woodworking, it's a little less than the width of a saw cut, it's just about the right precision for most woodworking

It's not the precision. It's the divisibility. 10 can only be divided in half. It can't be divided into thirds, quarters, sixths or twelfths evenly and that ability is invaluable.

This is the same reason why, in the old days of grid layouts, grids were 12 columns wide and not 10.

Re: Ending the Era of the U.S. Survey Foot

#99

Post by beerandt »

a2tech wrote: post #95
beerandt wrote: post #91

Earlier quoted context omitted.

While i don't doubt they're cheating it a bit, the dimensions originally refered to rough cut, pre-dried lumber. Most of the difference came from finish cuts and drying.

My house was built in 1860. The 2x4s are basically 2x4.

Yeah, I went through a remodel and dealt with the same thing, trying to get drywall to line up on old (1970) and new walls. There's more to it than that, but it's the quick version.

On the other hand, if you find a smaller mill, usually the ones specializing in hardwood, you can still get "full size" cuts, usually without even asking.

Re: Ending the Era of the U.S. Survey Foot

#100

Post by beerandt »

thrower123 wrote: post #74
kibwen wrote: post #19

Earlier quoted context omitted.

I suppose it depends on what your goals are; despite being officially metric, my Canadian and British friends still seem to exhibit a melange of imperial and metric in everyday life.

Some metric units work well, and are scaled to human everyday measurements, and some are not.

But the time thing goes to show the absurdity of people's frame of reference. The same people that judgingly ask why the US hasn't gone full metric will say how absurd the idea of base 10 time is.
Post reply on HN