Metric? Is it the way to go?

Michael Kellough said:
Can you believe we fought a war to get out of the Imperial domain?

Can you imagine how the Teaparty people in Congress would react if the Senate passed a bill to go metric?
Maybe that would distract them from their anger over millions of people finally getting health insurance...

Really? You're gonna drag the Tea Party and healthcare into what has been a reasonable discussion on metric in the US? Next we'll hear it's all Bush's fault  ::)
 
Paul G said:
Kev said:
I can't imagine the US weather on your TV being broadcast in Celsius. Teach metric solidly in schools now and it'll probably still be two generations before the US could realistically be comprehensively metric.

Was metric ever "sold" to the US population? Being the consumer driven society that it is, I don't believe there'd be enthusiastic adoption without a good sales pitch [wink]

I was taught metric in grade school, it's obviously not hard, it's the transition that is hard. Forget about the weather, just changing road signs will be an imense undertaking. Not just the speed limit signs (which will create a safety hazard when a 60 zone becomes a 100 zone) but every sign that says "Main street 3" or "San Francisco 35". Also we're dealing with Fed, State, County and City jurisdictions. The feds are not in charge everywhere in spite of what the big wigs in WDC pontificate. We've got 50 states, over 3,000 counties and probably 20-30,000 cities and all their governors, commissioners, mayors and legislative bodies will all get to weigh in. In the context of our overall societal problems, metric changeover is at the bottom of the list.
The UK went metric starting in 1965 with the majority of the process finishing in 1980 however distance and speed are still measured in miles.

So there is your answer. Don't change the signs or speed limits as they have little impact on trade or buisness.
 
Jerome said:
Paul G said:
Kev said:
I can't imagine the US weather on your TV being broadcast in Celsius. Teach metric solidly in schools now and it'll probably still be two generations before the US could realistically be comprehensively metric.

Was metric ever "sold" to the US population? Being the consumer driven society that it is, I don't believe there'd be enthusiastic adoption without a good sales pitch [wink]

I was taught metric in grade school, it's obviously not hard, it's the transition that is hard. Forget about the weather, just changing road signs will be an imense undertaking. Not just the speed limit signs (which will create a safety hazard when a 60 zone becomes a 100 zone) but every sign that says "Main street 3" or "San Francisco 35". Also we're dealing with Fed, State, County and City jurisdictions. The feds are not in charge everywhere in spite of what the big wigs in WDC pontificate. We've got 50 states, over 3,000 counties and probably 20-30,000 cities and all their governors, commissioners, mayors and legislative bodies will all get to weigh in. In the context of our overall societal problems, metric changeover is at the bottom of the list.
The UK went metric starting in 1965 with the majority of the process finishing in 1980 however distance and speed are still measured in miles.

So there is your answer. Don't change the signs or speed limits as they have little impact on trade or buisness.

If the UK is still using miles then I'm not understanding how the metric changover is finished ???
 
Paul G said:
If the UK is still using miles then I'm not understanding how the metric changover is finished ???
I didn't say it was.

But it is finished enough for now.

All vehicles sold in the UK have dual marked speedometers.
At some time in the future we may change the speed/distance units however they have no or almost no impact on trade or business so there is no immediate need.
 
morts10n said:
I had this conversation with another cabinet guy recently. He uses both systems, but maintains that metric is the better one.  I asked " Quick, what is a 1/4 of 35mm??"  He pointed out to me that in the metric system you are only dividing by 10, but in the imperial system you are dividing by (the arbitrary) 16.
Point taken!

He dodged the question. He wouldn't have that luxury when calculating the length of a fractional wavelength antenna.
 
Jerome said:
Paul G said:
If the UK is still using miles then I'm not understanding how the metric changover is finished ???
I didn't say it was.

But it is finished enough for now.

All vehicles sold in the UK have dual marked speedometers.
At some time in the future we may change the speed/distance units however they have no or almost no impact on trade or business so there is no immediate need.

Yes I misread, thought you said it was finished in the 80's. Cars here also have a dual gauge, the ones on my vehicles the metric is harder to read but at least its there if/when there is a sign change.
 
The clothing industry seems to be dragging the chain in Oz. Not only do we have the mix of metric and imperial, we've got relative sizing that seems to vary based on brand source ... and what is it with shoes - look inside and you see UK, US and Euro sizing.

Don't know that we'll ever escape the inch ... even on the most modern tech we still refer to screen sizes in inches, though you'll notice they're typically decimal inches, with no reference to feet (42 inch, 13.3 inch, 4.5 inch, etc). We could have marketing to blame for this though as "big" inches are used to describe panel sizes, but the "tiny" grams are used to describe the weight [blink]
 
I learned metric and imperial in school.  Every science class was based in metric and the research lab I worked in is all metric. 

I don't think I will change over to metric when building stuff.  I can't visualize 1390mm and would have to undo a lifetime of imperial associations. I just don't think the benefits outweigh the effort to switch over for me. 
 
As someone that is very fluent in both systems, I'm a little surprised how energetic the discussion is about the two.

The reason why the US stopped pushing the metric system so strongly is because the average person won't necessarily see any net benefit in their daily lives. The soccer mom taking the kids to school doesn't care whether the speed limit is posted in miles per hour or kilometers per hour. She doesn’t need to convert that to some other units. To him/her, it is just a number on the side of the road.

The same is true for the person planning a picnic. They don’t care whether the temperature is 75 degrees F or 24 degrees C. It's just a number and they know what range of numbers are comfortable. As a matter of fact, temperature is even a case where to the average non-scientist, Fahrenheit is actually a little more convenient than Celsius. That's because the range of temperature numbers in Fahrenheit is almost twice that as Celsius. Celsius is just as arbitrary as Fahrenheit. Kelvin is absolute, but it is still based on the divisions chosen from Celsius.

Many people mention the base-10 aspects of the metric system, but that is actually fairly trivial in the grand scheme of things. That benefit comes into play only when you are converting like-units from one range to another. For non-scientists, this is most often brought up in terms of dealing with units of length.

But let's take the very first example above--kilometers per hour. The standard unit of speed to a scientist is meters per second. Oops! That's not a base-10 transformation to go from km/h to m/s. Time is still based on 365.242 days/yr, 24 hours/day, 60 minutes/hr, 60 seconds/minute. So even a scientist working in the metric system still needs to go through calculations to make conversions.

The metric system is based on the various states of water at Standard Temperature and Pressure. But unless you are dealing with water, they are still arbitrary units. Temperature, length, volume, and weight are all based on water, but still nevertheless arbitrary in that foundation.

Those people that benefit from metric have already been using it for decades (including myself). But to the average person, the benefit is not quite worth the hype that it once had back in the 1970's.

Let's not forget woodworking here. If non-U.S. countries were truly metric, would nominal plywood thickness be 19 mm? No, it would be an even number like 20 mm. (The actual value is closer to 18.5 mm.) How about the 32-mm system? Why is it 32 mm (1.25") instead of a simpler number such as 30 mm?
 
Great read Rick. I need to read it again in the morning. 

I am going to browse homedepot.com, my brain just hurts. :)
 
Rick Christopherson said:
How about the 32-mm system? Why is it 32 mm (1.25") instead of a simpler number such as 30 mm?
Because 32mm was the smallest distance posible in economic terms to have counter rotating line boring machines built when the system was developed. Its importance is that it became the standard. If the spindles of the multi-head hole boring equipment of the day could have been set to 30mm then that would have become the standard.
 
Rick Christopherson said:
Let's not forget woodworking here. If non-U.S. countries were truly metric, would nominal plywood thickness be 19 mm? No, it would be an even number like 20 mm. (The actual value is closer to 18.5 mm.) How about the 32-mm system? Why is it 32 mm (1.25") instead of a simpler number such as 30 mm?

In the past four decades, I've run across plywood thickness from 17.5 mm all the way up to 19.5 mm. These various thicknesses all wavering around the 3/4" mark suggests to me that all plywood producers have been creating product that tries to meet both markets at the same time. Even your 32 mm system is a measurement that's trying to fill both markets at the same time. If the US was to suddenly switch over entirely to metric, I'm betting the rest of those non-US countries would go over completely to a total metric system.
 
jobsworth said:
Since I got into using festools, I began using the metric system. Still in the learning phase. I bought a construction calc for my Iphone. its very useful. I use it to convert imperial to metric . It makes life a whole lot easier for me.

Not taking any issues with anything that has been said, and really don't care about miles vs kilometers etc...

But the premise that I found more than interesting was the ability to add and subtract metric measurements so much easier.

Not even considering converting imperial to metric.

Just that once the outside dimensions (of a cabinet let's say) are established in imperial, then any inner pieces, like rail and style, panels, etc. could be measured in metric, rather than er.... 2-9/16" for example. So much easier to convert to mm and make the piece 65 mm.

Ever so slight a difference, and nobody would know looking at the end product, but so much less complicated in the math department.

 
Upscale said:
Rick Christopherson said:
Let's not forget woodworking here. If non-U.S. countries were truly metric, would nominal plywood thickness be 19 mm? No, it would be an even number like 20 mm. (The actual value is closer to 18.5 mm.) How about the 32-mm system? Why is it 32 mm (1.25") instead of a simpler number such as 30 mm?

In the past four decades, I've run across plywood thickness from 17.5 mm all the way up to 19.5 mm. These various thicknesses all wavering around the 3/4" mark suggests to me that all plywood producers have been creating product that tries to meet both markets at the same time. Even your 32 mm system is a measurement that's trying to fill both markets at the same time. If the US was to suddenly switch over entirely to metric, I'm betting the rest of those non-US countries would go over completely to a total metric system.

Back when the company I've referenced decided to convert their products over to "hard" metric we found that of the 37 different steel plate grades & thicknesses in use (1/8" to 9-1/2" thick) in about 9 grades there were only I think 5 of those that fell outside of the mill tolerances for metric plate.  The use of those were re-designed to use other grades/thicknesses.

There are far reaching effects for most companies that make the decision to change over to metric -- I recall one of the consultants I worked with using Otis Elevator Company as an example, the typical life cycle of their elevators is ~100 years so they are forced to maintain both imperial and metric repair parts, fasteners, etc. until the product is removed from service.
 
RonWen said:
Upscale said:
Rick Christopherson said:
Let's not forget woodworking here. If non-U.S. countries were truly metric, would nominal plywood thickness be 19 mm? No, it would be an even number like 20 mm. (The actual value is closer to 18.5 mm.) How about the 32-mm system? Why is it 32 mm (1.25") instead of a simpler number such as 30 mm?

In the past four decades, I've run across plywood thickness from 17.5 mm all the way up to 19.5 mm. These various thicknesses all wavering around the 3/4" mark suggests to me that all plywood producers have been creating product that tries to meet both markets at the same time. Even your 32 mm system is a measurement that's trying to fill both markets at the same time. If the US was to suddenly switch over entirely to metric, I'm betting the rest of those non-US countries would go over completely to a total metric system.

Back when the company I've referenced decided to convert their products over to "hard" metric we found that of the 37 different steel plate grades & thicknesses in use (1/8" to 9-1/2" thick) in about 9 grades there were only I think 5 of those that fell outside of the mill tolerances for metric plate.  The use of those were re-designed to use other grades/thicknesses.

There are far reaching effects for most companies that make the decision to change over to metric -- I recall one of the consultants I worked with using Otis Elevator Company as an example, the typical life cycle of their elevators is ~100 years so they are forced to maintain both imperial and metric repair parts, fasteners, etc. until the product is removed from service.

I've worked in printing for many years, label printing specifically and the printing presses even from Europe use a 1/8" gear increment, any print cylinder supplier has to make that size. And we're certainly not going to toss a plant full of $1.5 million presses to appease the metric zealots. And even if we went metric in house, all our clients order labels measured in inches, trying to force them to change for our sake would result in many sourcing their needs elsewhere. Just another example of the challenges of transition.
 
Jerome said:
Because 32mm was the smallest distance posible in economic terms to have counter rotating line boring machines built when the system was developed. Its importance is that it became the standard. If the spindles of the multi-head hole boring equipment of the day could have been set to 30mm then that would have become the standard.

Line boring machines weren't created in the stone age. The only thing limiting spindle spacing is the diameter of the gears. They could even get a lot closer than 30 mm.

Making a gear with a 15 mm radius (30 mm diameter) is pretty easy to do. It doesn't even take a lot of calculating (especially with a whole number gear module). You can use a metric gear module of 1 and 30 teeth, or a gear module of 2 and 15 teeth. Either way you end up with a metric gear with a 30 mm diameter. The 15 mm radius means two gears, when mated, would be 30 mm apart. It didn't even require fractional/decimal gear module values.  

You mentioned "economically". That could very well be true. It could be that a 1.25" gear was more common and therefore cheaper than a 30 mm gear. But then that was exactly the point I was making previously. The same situation occurs with chains (except in reverse). A metric chain is cheaper than a near identical imperial chain because metric chains are more readily available.
 
Part of the USA has already converted to the Metric system:

The medical industry

The US military
 
It is all politics!  Politicians maintain status quo, so they can be re elected.

Change causes people out of the comfort zone, and the politicians don't want that.  that is the reason is not adopted. 

I came to USA knowing and using the metric system, I learned to use the imperial and I went back to metric recently.
 
Rick Christopherson said:
Jerome said:
Because 32mm was the smallest distance posible in economic terms to have counter rotating line boring machines built when the system was developed. Its importance is that it became the standard. If the spindles of the multi-head hole boring equipment of the day could have been set to 30mm then that would have become the standard.

Line boring machines weren't created in the stone age. The only thing limiting spindle spacing is the diameter of the gears. They could even get a lot closer than 30 mm.

Making a gear with a 15 mm radius (30 mm diameter) is pretty easy to do. It doesn't even take a lot of calculating (especially with a whole number gear module). You can use a metric gear module of 1 and 30 teeth, or a gear module of 2 and 15 teeth. Either way you end up with a metric gear with a 30 mm diameter. The 15 mm radius means two gears, when mated, would be 30 mm apart. It didn't even require fractional/decimal gear module values.  

You mentioned "economically". That could very well be true. It could be that a 1.25" gear was more common and therefore cheaper than a 30 mm gear. But then that was exactly the point I was making previously. The same situation occurs with chains (except in reverse). A metric chain is cheaper than a near identical imperial chain because metric chains are more readily available.
the problem is that you are talking about today's tech and building new plant. And the 32mm system was established just after the war when existing tech and machines had to be used. The reason was because of the huge need due to the destruction caused by the war together with the lack of money and resources to build new plant. And that tech was capable of reliably and economically spacing no closer than 32mm QED
 
Jerome said:
the problem is that you are talking about today's tech and building new plant. And the 32mm system was established just after the war when existing tech and machines had to be used. The reason was because of the huge need due to the destruction caused by the war together with the lack of money and resources to build new plant. And that tech was capable of reliably and economically spacing no closer than 32mm QED

Gears haven't just been around for several decades. They have been around for many centuries. If 32 mm was a minimum achievable pre-WWII size, then that would make for a rather bulky pocket watch. Wouldn't it?  [big grin]

The module of a gear is what dictates the geometry of the teeth. Two gears of different diameter will mate as long as they have the same module. That is not a 20th century invention, nor are the mathematics anything new.

So the only difference between a 30mm gear and a 32mm gear, when both have a module of 1 (or even 2), is the number of teeth cut. Each tooth has the same shape, and that is why they will mesh. But one gear would be rotated 1/32 of a revolution per tooth (for a module of 1) while the other would be rotated 1/30 of a revolution per tooth, and of course the net diameter of the gear would be 32mm versus 30mm.

So the very same equipment that could make a 32 mm gear with a specific module (assume 1) with 32 teeth, would also make a 30 mm gear with 30 teeth (or even a 12 mm gear with 12 teeth). As long as the module of the gear stays the same, the geometry of the teeth stays the same, and the only thing that varies is the diameter and number of teeth. The ratio of those two parameters is in fact the module of the gear. That is why it is such a critical parameter in gear design.

Edit: If you look at the image below, you will see that the size, shape, and spacing of the teeth are the same. The only thing that varies is the diameter and number of teeth.

gear_ratio_anim.gif
 
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