metric v. inches

[bill-e]

Gary,

I don't want to switch either and hadn't seriously considered it until using the Domino.  But since in order to center the mortises on the thickness you have to measure your work and set the Domino using metric, it seems to me that I might finally have to make the switch...at least for the small measurements anyway.  As for the Router, I've been still using imperial and setting it with gauge blocks so that hasn't been an issue but it would be nice to be able to use the built in scales.

My mind still thinks and reasons in imperial and even as of this second I don't really know, or cant picture even, how big a millimeter is.  So how can I use the vernier depth adjustment on the OF1400 without making the transition?

 

[Gary K]

:-\  I don't know Bill....I really admire this Festool Co. and like alot of their tools, but I wouldn't change my way of measuring for just one tool that may be some kind of blip on the radar screen in the future. Now, before someone gets their dander up over the last statement I just made, remember that alot of people would have laughed at me if I said that most biscuit joiners would be gathering dust in the future when they were the latest "have to have, tool"
    I know alot of guys who haven't used the biscuit joiner in many years. Even if this isn't a fad, I heard there are ways to use it without using the metric system. Don't they have accesories so you don't need any scales?
    Gary K.

 

[Michael Kellough]

Gary,
....
I don't really know, or cant picture even, how big a millimeter is...

A millimeter is pretty much right in between a 1/16th and a 1/32nd.

 

[richard.selwyn]

I sympathise with US Festoolies struggling with metric - I was brought up with both at school in England and thought I'd have an easy life when I moved to France.  Not so.
Firstly: Some equipment I can only find in the US - I regularly use Kreg pocket screws for instance -  so have had to make a Metric/Imperial conversion chart. 
Secondly: Looking at the conversions made me understand something that had been baffling me ever since I moved here (I'm easily baffled!).  I now understand why most materials I buy here are such stupid dimensions - they're largely still based on imperial dimensions!  You buy an panel of plywood and its often something like 2.44m x 1.22 - an 8'x4'!! - and "so called" 12mm, 13mm, 18mm, 19mm, 22mm panel thicknesses - I'd always wondered why they weren't 10, 15, 20 etc still I saw that 3/4 inches is 19.05mm etc.

According to Wikipedia: " As of 2005 only three countries, the United States, Liberia, and Myanmar (Burma) had not completed the changeover (to metric)........On January 8, 2007, that NASA decided to use the metric system for all operations regarding the moon.[1] "
I hope that's all you leftponders have in common with the other two

But why do we still have nautical miles??

 

[greg mann]

Nautical miles are based on degrees, and minutes around the Earth. I think I am right in saying a nautical mile is equal to one minute of distance as measured at the Equator. This was especially useful for Seafarers as they could only use measurements in degrees with a sextant. 360 degrees X 60 minutes per degree = 21,600 increments (or nautical miles) as opposed to roughly 25,000 statute miles around the Earth. I could be all wet on the particulars and any real sailor is welcome to correct any misinformation in my response but this is at least close. In short, a nautical mile is or was directly useful to the only measuring system available to sailors.

 

[Forrest Anderson]

For those of you who are having difficulty in visualising millimeters, I have created a chart which shows how millimeters relate to fractions of an inch:

Notice how 19mm is approx 3/4", 12.7mm is 1/2" and 6.35mm is 1/4".

Larger versions of the file in various formats can be downloaded and printed out on Letter or A4 size paper:

JPG Format (176KB)
PDF Format (297KB)
AI format (260KB). This format allows you to edit the chart in Adobe illustrator.

I don't think there are any errors, but if anyone sees something wrong, then just let me know and I'll alter it.

I hope it proves useful!

Forrest

 

[greg mann]

Forrest,

This is a very useful chart for fractional conversions. IMO, I believe fractions are the biggest stumbling block to moving to metric from imperial. Anyone that might like to make the switch should at least start out by going to decimals. At that point, you are in a base ten system (of sorts). Even in metric one is not always working in whole numbers, but far more work will be done in whole numbers for sure, and then using 3.5mm or 3.75mm becomes much more natural after weaning yourself off fractions. It is common knowledge that three out of every two people have trouble with fractions.

Another little conversion that is useful for woodworkers is that .25mm equals .010". Not exactly, but certainly close enough for woodworking. Anything closer is really now about fit rather than size. So, FRACTIONALLY, a mm can be divided into four segments (quarters) that are for all practical purposes: .010,.020,.030,.040 inch. These are increments smaller than 1/64, or the smallest increment on a fractional imperial scale. Any woodworking to closer dimensions will need to be measured with a caliper and now you are back to quality of fit rather than size. If one really feels the need at this point to work in fractions the only ones they will need are 1/4, 1/2, 3/4 mm. I suppose you could add 1/10mm (.004 inch or 1/250  :) as that is the increment on the adjusters for depth (router) and width (guiderails and fences).

 

[fcraven]

The problem with changing a measurement system is that it's like learning a different alphabet for your own language. You may know the words but that funny letter that looks like a cross between a an H and a "10" is pronounced "you" ? Huh?

If you are familiar with the size of something (like a 35mm hole) then it doesn't really matter that it's in millimeters or inches, it's just what it is. The problem for me is that I know how tall a 6' man is. But 1.8m is just weird to me. Likewise, I know how far 30 miles feels like, but what's 48km? Nevertheless, one metric measure I do know is "2 liters". I'm also quite familiar with 750ml (wine, some ale), and 500ml (the bottle size of my favorite beer and ale). I like 0ºc for freezing, but 100ºF is a good organic number for "I'm hot" (afterall, it was based on the inside human, normal temperature).

In a former life I was a scale model rocket builder (even won a national championship once). ALL the dimensions on the blue prints were in inches. Needless, to say my scale model was also in inches. Fortunately I was able to borrow some marvelously accurate dial calipers. BUT, although I was using the inch as my standard for measurement, everthing was written in decimals, e.g. .03125" not 1/32". I thought of it as "metric-inches". Base 10 is simply easier for my brain to compute then base 12 (although I've gotten better at base 16, but I digress)

You know, when I was a kid, I was with Jimmy Carter.
I really liked the idea of going metric. Too bad id didn't stick then.

It would be nice if the scales on Festool tools had metric AND imperial marks, but I wouldn't want to remove the metric. It would be nice if they offered drill bits in US standards too.

In the mean time I'm working on a project that involves "two by fours" that are actually 1.5" x3.5"...

 

[Dan Clark]

While working on your projects, don't forget to get pour yourself a nice Coke from the two liter bottle!  ;D

 

[ohkipp]

I started using MM four years ago when i started using Blum products. I really fought it at first ( old guy mentality ) but now I just grab one of several steel rules or tapes that have MM on them. Back then it was a little harder to find anything with Mm  on it but now its everywhere. i still use my old rules as well but only in certain situations. Kinda like me explaining to my younger staff why I detest those large clumsy carpenter pencils. I need a nice sharp small line and sometimes I need a really small increment of measurement

 

[Michael Kellough]

........On January 8, 2007, that NASA decided to use the metric system for all operations regarding the moon.[1] "
I hope that's all you leftponders have in common with the other two

But why do we still have nautical miles??

Oct. 1, 1999

"In an embarrassingly simple mistake, NASA officials said yesterday, the spacecraft burned up on impact with the thin Martian atmosphere because two navigation teams and their computers had confused English and metric units.

After flying more than 415 million miles over nine months, the spacecraft was about to enter its first orbit around the Red Planet last Thursday when it accidentally flew too low toward Mars, mission engineers said at the time.

But yesterday the engineers said they had found the cause: It turned out that Lockheed Martin engineers in Colorado, who built the spacecraft and are responsible for its health, transmitted the orbiter's final course and velocity to Pasadena using the English term of pounds per second of force.

But the spacecraft's navigation team at JPL Mission Control in Pasadena --like almost all space scientists and engineers -- always use the metric system in their work. Their computers used the metric term newtons, or grams per second of force, to send final course and velocity commands to the Mars-bound spacecraft.

The ship flew just a hair too close and disintegrated in the Martian atmosphere.

"We're talking about velocities in millimeters per second,'' said Tom Gavin, deputy director of the laboratory's space and Earth sciences programs. "We had multiple systems of checks and balances, but they just didn't catch it," he said.

Gavin said previous Mars missions always used metric measurements.

Lockheed officials are reviewing contracts to see whether the space agency specified the units of measurement, said Noel Hinners, vice president of flight systems for Lockheed, Martin Astronautics in Denver. "We should have had them in metric units," he said.

The bad numbers had been used since the spacecraft's launch last December, but the effect was so small it went unnoticed The difference added up over the months as the spacecraft jouneyed toward Mars."

From here;
http://www.welchco.com/02/14/01/60/99/10/0101.HTM#0001

 

[Ned]

...I need a nice sharp small line and sometimes I need a really small increment of measurement

Hey Kip, have you seen the Incra rules?  Rockler sells them, but not the metric ones.  Look at Incra's website for the full line including metric.  Small sharp lines down to 0.5 mm.  I'm not on commission, honest.

Ned

 

[Dave Rudy]

Michael, What a perfectly appropriate story.  It's not which one is better -- it's the undeniable fact that there are two of them to get confused over.

I am half-converted to metric which seems so much easier and better a system to work in.  But I am in danger of confusion all the time -- and it is hard enough for me to keep the measurements straight when I'm only working in one language.  UGH!!!

Dave

 

[T. Michael]

Then there are Bobs; 1/24th of an inch.  A cogent argument for something inbetween inches and metric.  But if you thought it was hard to change to metric; imagine convincing many people to go with Bobs. 

This is serious, and has a pretty good rational.  Here's some in part.....

How can the ruler, an age old measuring device for woodworkers, possibly be improved upon? Read on to find out!

THE PROBLEM: Neither the familiar system of Feet and Inches nor the Metric system of meters and millimeters are suited to the type of measurement and calculation woodworkers and other craftspeople use day in day out.

THE SOLUTION: A system of measurement that retains Feet and Inches and then divides the Inch into 24 parts.

THE ARGUMENT: The Metric system excels at smaller measurement while Feet and Inches are better suited to larger. Because of these innate characteristics I have always used both, often in awkward combination. The Metric system’s only real asset is the particular size of the millimeter. This happens to be an ideal “small” unit of measure. Smaller than a 1/16" and larger than a 1/32", it can be distinguished easily without reading glasses while at the same time is fine enough to be a basic increment of woodworking precision.

In every other respect the Metric system is inadequate. There can be no rational argument in favor of a system that divides and multiplies by tens. It is perhaps not surprising that we break the day into 24 hours rather than 20, the hour into 60 minutes rather than 100 and so on. By the same token we divide the circle into 360 degrees rather than 100 or 1000. It is because the basic building block of twelve is vastly more versatile than ten, whose capacity for easy division by five and multiplication by ten is a talent I cannot remember ever having needed in 25 years of woodworking.

Feet and Inches supply a manageable series of larger increments. Feet and Inches break up what in the Metric system tend to be long easily corrupted numbers into readily recalled chunks. For example a Metric length of 2286mm equals 7 feet 6 inches. While 2286 might easily become 2268 in our fallible memories, it is hard to not notice 7 feet 6 inches becoming 6 feet 7 inches. The inspired division of the foot into 12 inches rather than 10 allows easy division into halves, thirds and quarters.

For more, seehttp://www.bobsrule.com/index_frame.htm

Mike

 

[VictorL]

It’s not a reply to any specific person in this conversation. It is just conversation to myself. 
Metric system is absolutely scalable. Just use millimeters in machinery and small projects. When you work with bigger object - use meters. Length of cruise ship is 528 meters nobody will say 528.000 millimeters (it’s still right).  When you measure furniture you go with centimeters 88cm by 120cm or 0,88 m by 1,2 m (Cheap IKEA?  Hmm. 35 mm European hinges? 32 mm European shelf spacing? Cross dowel with  M5 bolts? Slides. Who cares about this foreign crap!) Use kilometers for distance. When you work with semiconductors or smaller object use micrometers or nanometers. Simple. The same units, different order.
1km=1000m=100.000cm=1.000.000mm. Simple again. Can you recall how many yards, feet and inches in one mile? Why my odometer shows 0.4 miles?  But my in law said make a left turn in 800 feet. Are we there yet?!
where is anybody?!
I need directions!
I’ll buy GPS.
Soon.
Immediately after New Year.
2012
or 2020.
Whatever.
Do I want to call her to clarify directions?
Not really.
I’ll make my math.  ;D

When you work with stock its marked 1x3, but… it’s really 3/4x2.5. And what about 1x10? Is it 3/4x9.5? Nope, it’s ¾ x 9.1/ 4. Oops again! It’s a little bigger than ¾, so adjust your dado or make 2 passes with your ¾ router bit. I bought a plywood in Home Depot, guess what? It’s undersized! Hurray!  I don’t need ¾ bits anymore; I’ll use ½ instead.
In two passes.
Metric system is a really system. (Just like our adorable Festool  ) 1 liter is 1kg of fresh water. Sorry, what is one liter again? It’s a cube 10cm x10cm x 10cm. How many oz in one lb? And what about liquid oz in gallon?  What is one ton? It’s exactly 1000kg. No more, no less. How many lbs in 1 ton? Let me think…  2202.64 lbs! Sounds much better then just one tiny ton. One milliliter? It’s precisely equal 1cc. You don’t buy pharmacy by lb or oz – only by milligrams.
Try to mark 7 equal spaces on 10 feet board? It’s hard to do. You have to deal with fractions. I’m not so well in math, but it keeps my brain busy. Now try to do the same in metric. It’s much more simpler! What about drill bits? Which one is bigger 13/16 or 15/32?  Now compare to 5,5 mm and 6,0 mm.
25,41 mm sounds funny! 1mm is 1/25th of inch.1/10th is 1/250th of inch, 1/100 is 1/2500th of inch. Yes!!! We can provide space rocket technology precision on bare wood!  Now I have to keep my cabinet in special camera with constant temperature and humidity. Can you notice difference between 25mm an 25,4 mm? Really?
How many SAE bolts and nuts are in “American” car? Not so much, most of them are assembled in Canada or Mexico. “European” or “Japanese” cars – have none, but they were assembled on US soil. Its' metric again. I have to keep two sets of wrenches and heads just for this purpose. It’s really convenient, trust me. Two nice boxe$ of really nice chrome-vanadium big boys’ toy$ in two drawer$.
Try to explain to European what is 5/16” bolt. OK? Why its better then M8? OK, Can you use it outside US? Yes, but only in our equipment. Fine!  It was simple questionnaire. Now try to explain what is 1x12x8 piece of lumber. Do you succeed? Yes! Now question: why it is not the same as 4 boards 1x3x8? Because, because it’s a tradition… And I missed something: 1”x3”x8’ Inches, feet.  Now calculate one board 300mm x 18 mm x 2500 mm or 4 boards 75mm x 18 mm x 2500 mm boards. (75mm approx. equal 3”) Is it still really hard work with decimal numbers? What? REAL woodworkers don’t buy milled wood? Sure.
How many people live in US? More than 300 millions! And we are using wonderful Imperial system for some applications! How many people live outside US? Just a little bit less than 6 billions, and they are using useless and inconvenient metric system.
PLease don’t ask why 12PM goes before 1PM, I don’t know.
Yes, it’s hard to accept metric system, but it’s matter of time when we’ll use it.  :-\
Good luck everybody! 

 

[Ned]

Thanks, Victor.  Feels like this grin will last for hours.

 

[Jesse Cloud]

??? Now you guys have done it.  Inquiring minds want to know.  Is there such a thing as a board-meter instead of a board foot?  If so, what are the dimensions?

 

[Dave Rudy]

Do you mean a bored meeter?  I think so.

Dave

 

[Ned]

Do you mean a bored meeter?  I think so.

Dave

Works at Wal-Mart.

 

[sherbin18]

I was thinking of converting to metric for various reasons, Festools not the least.

However, I generally use story poles and such for most of my measuring so units are really secondary. Anyhow, some company at a recent wood show handed out neat little charts (one of which I keep in my apron) having inches to metric and metric to inches. It also has inches and fractions to decimal inches.

Really, if you think about it, the fractions of inches aren't that tough if you convert them to decimal ( 1/8" = .125").

--Steve.