Author Topic: Metric measures  (Read 4641 times)

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Offline Drew Sanderson

  • Posts: 6
Metric measures
« on: April 03, 2019, 01:30 PM »
I do not have any metric measures and will be building the newest Ron Paulk workbench. His newest plans are only in metic. What specific metric measuring products would you suggest the not only cover this project, but will be nice to have I the future?

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Offline WoodworkTech

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Re: Metric measures
« Reply #1 on: April 03, 2019, 01:51 PM »
Fastcap tape measures come in metric.  Also like the woodpecker rules in metric.
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Offline demographic

  • Posts: 501
Re: Metric measures
« Reply #2 on: April 03, 2019, 04:46 PM »
Not an endorsement for any particular product, just a technique.
Ignore the existance of centimetres. Just use millimeters or metres for the building size stuff. Centimetres are for teachers and dressmakers and generally just confuse matters.

Offline jpmeunier

  • Posts: 80
Re: Metric measures
« Reply #3 on: April 03, 2019, 05:05 PM »
Fastcap true 32 for tape, Incra/Woodpeckers for other stuff....Be careful


Offline pixelated

  • Posts: 185
Re: Metric measures
« Reply #4 on: April 03, 2019, 05:26 PM »
I like folding rules like these from Lee Valley, but I also have a metric tape and a metric Woodpeckers rule.
A calculator that does conversions comes in handy too.




Offline rst

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Re: Metric measures
« Reply #5 on: April 03, 2019, 05:27 PM »
I use Hultafers tapes that I buy on Ebay...

Online DeformedTree

  • Posts: 561
Re: Metric measures
« Reply #6 on: April 03, 2019, 09:12 PM »
I've been buying various ones to try.

The Fastcap one from a mechanics standpoint is a bad tape measure, it sticks, the latch works poorly, etc. But it has one thing that makes it my go too. It's a mm Metric tape.  All the others I have bought are cm taps which makes them annoying as all heck. When you start working on something out beyond a meter, it's very easy to get yourself in the wrong place.  The fastcap has no cm markings, which makes it easy to use/read/etc.

I have others, a

Komelon 8m, mechanically nice, but is a cm unit.
Starrett 5m, the latch sucks, not the easiest to read, again a cm unit.

I have a hultafers tape that people mentioned here. I have it at work, it's very stabby, I've bleed on it a few times.  It's neat and has a function to measure diameters, still not great.

Really haven't found the end all.  But the fastcap definitively gets honors for being in mm and not cm.

Offline pettyconstruction

  • Posts: 526
Re: Metric measures
« Reply #7 on: April 03, 2019, 09:27 PM »
Fastcap also has one he reads MM and imperial .
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Offline infer

  • Posts: 66
Re: Metric measures
« Reply #8 on: April 04, 2019, 01:44 AM »
BMI VISO and BMI meter pocket tape are always in my pocket. Nothing compares.

Offline Reiska

  • Posts: 1171
  • Hackers build things, Crackers break them.
Re: Metric measures
« Reply #9 on: April 04, 2019, 07:20 AM »
Hultafors Talmeter is the best tape measure I have ever had, love the reverse locking of the tape (i.e. you press the lock to release and it holds the tape when not depressed). Also the marking tip is the best thing after sliced bread when you just need to quickly mark your measures on wood - just scratchmark with the tapemeasure's integrated scratch tip.

Other good household makes are Bahco-tools and ofc. the high-end Woopecker, Incra, etc. fancy expensive metric versions are obviously just as good as their imperial breathren.

As someone already mentioned above dimensioning and planning is always done in millimeters and never in centimetres unless you are talking on several meters worth where you don't need mm resolution. i.e. you would talk about 600mm doors (24") but you could use 450cm for say a wall lenght dimension in the floorplan.

I guess what it boils down to is to use the unit type your final dimension needs to accurate to all over.

I mean you don't want a +-1cm gap in a cupboard door so you would not define it's size as 60cm but rather you want a 1-2mm relief around the door so using 600mm +-1mm is acceptable.

In woodworking you NEVER need to go to ½mm resolution in anything so that's an metal engineering measuring equipment.
The sky's the limit in my workshop, literally. [big grin]

Offline Sanderxpander

  • Posts: 381
Re: Metric measures
« Reply #10 on: April 04, 2019, 12:01 PM »
I don't mean for anyone to take this the wrong way but as a born and raised metric person (The Netherlands) to hear the centimeter described as "confusing" (vs feet/inches/fractions) is a bit bizarre.

Offline demographic

  • Posts: 501
Re: Metric measures
« Reply #11 on: April 04, 2019, 12:29 PM »
I don't mean for anyone to take this the wrong way but as a born and raised metric person (The Netherlands) to hear the centimeter described as "confusing" (vs feet/inches/fractions) is a bit bizarre.

Raised metric here and for me cms just don't exist. They don't help and in engineering as well as building we dont use them. Metres and millimeters yes, cms? Naah.

4500 mms would also be 4.5 m. It's just how we do it over here.
The numbers work out so far different in scale that theres less possibility of confused sizes.
None of that 450 cms stuff and if anyone uses a decimal point in a measurement thats not come off a vernier caliper its a metres size.
Mms are small enough that I'm not playing with decimal points in general carpentry work

Offline Sanderxpander

  • Posts: 381
Re: Metric measures
« Reply #12 on: April 04, 2019, 02:34 PM »
I could never possibly confuse 15 cm with mm or meter for anything I'm doing because the order of magnitude is so different. At the same time, the calculation between them is so easy (add or remove a zero) that I don't get the fuss. It must be me. Feet and inches and fractions confuse the heck out of me, especially when adding or subtracting them.

By the way, I've never had or even seen any metric tape measure or ruler or combination square that didn't have centimeters on them as main distance markers. Hultafors, Incra, Starrett, all mentioned here, all centimeters. Fastcap is the only one I've heard of that's in millimeters.
« Last Edit: April 04, 2019, 04:39 PM by Sanderxpander »

Offline greg mann

  • Posts: 1866
Re: Metric measures
« Reply #13 on: April 04, 2019, 04:18 PM »
Not an endorsement for any particular product, just a technique.
Ignore the existance of centimetres. Just use millimeters or metres for the building size stuff. Centimetres are for teachers and dressmakers and generally just confuse matters.

And OB/GYNs
Greg Mann
Oakland, Michigan

Offline Reiska

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Re: Metric measures
« Reply #14 on: April 04, 2019, 04:57 PM »
By the way, I've never had or even seen any metric tape measure or ruler or combination square that didn't have centimeters on them as main distance markers. Hultafors, Incra, Starrett, all mentioned here, all centimeters. Fastcap is the only one I've heard of that's in millimeters.

Well, yes - one would use cm's for measuring devices just because each cm = 10mm and makes the numbers legible on a narrow tape. Having a 6m measuring tape would make the text quite small to try to squeeze in 6000mm at the end  [tongue]
The sky's the limit in my workshop, literally. [big grin]

Offline Jiggy Joiner

  • Posts: 750
Re: Metric measures
« Reply #15 on: April 04, 2019, 04:58 PM »
Millimetres have always been a favoured system, mainly for accuracy. As somebody that grew up with imperial, then because of our EE ties, we all had to learn metric. I can work in imperial, and everything in metric, millimetres, centimetres, metres and kilometres etc, etc.

We only work in millimetres in my company, and so do most of my associates in the building trade, simply because it’s quick and easy, just as others have said.

To the OP, if you’re serious about switching to metric, I would just get used to buying everything in metric. After a while, you won’t want to revert.

Offline justaguy

  • Posts: 201
Re: Metric measures
« Reply #16 on: April 04, 2019, 06:11 PM »
Go to that really big auction site and search for PEC metric.

There is one seller, taylortoolworks, that has a significant assortment posted. Some are perfect, some are seconds. The seconds are cosmetic blemishes not accuracy related. I have several items that I use for my daily work. I've held them up side by side with my Starrett's and on the mm and 64th scale they match perfectly. The materials on the Starrett are much nicer. However a Starrett 30mm square is $100 and a PEC is $33.

Offline Sanderxpander

  • Posts: 381
Re: Metric measures
« Reply #17 on: April 04, 2019, 06:18 PM »
By the way, I've never had or even seen any metric tape measure or ruler or combination square that didn't have centimeters on them as main distance markers. Hultafors, Incra, Starrett, all mentioned here, all centimeters. Fastcap is the only one I've heard of that's in millimeters.

Well, yes - one would use cm's for measuring devices just because each cm = 10mm and makes the numbers legible on a narrow tape. Having a 6m measuring tape would make the text quite small to try to squeeze in 6000mm at the end  [tongue]
And it's trivial to convert between the two which was my point.

Online DeformedTree

  • Posts: 561
Re: Metric measures
« Reply #18 on: April 04, 2019, 11:36 PM »
I don't mean for anyone to take this the wrong way but as a born and raised metric person (The Netherlands) to hear the centimeter described as "confusing" (vs feet/inches/fractions) is a bit bizarre.

CMS has basically been replaced by MGS globally.  From personal experience and from other discussions here, it's understood areas around the Netherlands do use cm a fair bit, but globally it's not the norm.  Centimeters don't work well with the rest of the system as they are a kilo, mega, etc 3 place shift.  Just like how decimeters are not used. In the US centimeters are often brought up when go over metric with kids, and tend to be spoken by people who don't use metric. For those who do use metric a lot, they are almost never used.  Often they can't be used because the field or contract simply won't allow them. Also tools (software) is default mm.  Engineering drawings if in metric are mm-kg-s.  As others mentioned, usage of cm is in general a casual usage thing, not something people would generally use operationally.   Not really any different than how Yards are perfectly valid in the inch system, but you don't use them on drawings, design, etc. But in casual usage for how far away something is, sure.

Centimeters defeat one of the primary benefits of metric over inch.  With mm, almost everything you do is whole units, not decimals. Needing less than 1mm is un-common, yet 1mm works out nice as a base thickness.  Even in engineering work it's nice as most all dimensions are whole mm numbers. Not many things get over 1m, and when they do mm still work fine up thru 10m. 1mm is ~.040" which is a classic big tolerance, and 0.1mm is a good tighter tolerance limit  .004" (aka about 1 sheet of paper).  So designing stuff you are always in mm, and only introduce a decimal on things where you have to like hole tolerancing, surfaces, profiles, etc. It just works out really well. We don't say 1cm bolt, or 1.8cm bolt or 0.6cm bolt, we say 6, 10, 18mm bolts, it's just so much cleaner/easier.  0.5mm pencil comes across much better than .05cm pencil. Centimeters mean you loose that and now have a decimal place all the time, now your back to the same headaches as inches.

Using cm and mm together gets real confusing. This is where the tape measures cause problem.  You got a number in your head say 1106mm,  you go to your cm tape and go past 100 (the 1 meter mark) to 106, make mark.  Now you just messed up, you are off by 46mm.  You ended up making your mark at 1060mm, not the 1106 mark you intended.  You have just killed the beauty of metric.

Since stuff when listed with it's proper metric designations are listed in mm,  introducing cm to the mix is a headache and its the very thing that causes people not to want to work in metric.  Almost universally those I find who hate metric or find it dumb speak of cm when pointing out the issues/flaws and to some degree they have a point.  Where those who do work in mm, almost never use/speak of  cm.  Tape measures are this strange thing where ones that are metric tend to be cm, which is just annoying since nothing else metric is listed in cm. Thankfully Festool doesn't recognize cm and sticks to mm (except when they ditch metric all together).

Offline Alex

  • Posts: 6079
Re: Metric measures
« Reply #19 on: April 05, 2019, 01:45 AM »
Using cm and mm together gets real confusing.

It's not.

Offline Bob D.

  • Posts: 1266
Re: Metric measures
« Reply #20 on: April 05, 2019, 06:06 AM »
Coincidentally Matthias Wandel showed a Metric/Imperial rule he created
just the other day in a YT video. Have a look.

-----
It's a table saw, do you know where your fingers are?

Offline Sanderxpander

  • Posts: 381
Re: Metric measures
« Reply #21 on: April 05, 2019, 06:25 AM »
It's obvious I'm not going to convince anyone and I don't even really have to, I'm fine using mm for dimensions and do so most of the time. But to say the conversion between mm and cm, which literally means shifting the decimal point one place right or left, "destroys" the advantage over the imperial system with twelve inch feet and lots of different fractions sounds really strange to me. Cm/mm is just a non-issue.
« Last Edit: April 05, 2019, 07:24 AM by Sanderxpander »

Offline Bob D.

  • Posts: 1266
Re: Metric measures
« Reply #22 on: April 05, 2019, 06:52 AM »
Agree, I'm in my 60s and back in grade school we were being taught the metric system because "it's right around the corner" and "the US will be on the Metric System by the time you graduate High School". Yeah, that never happened.

Anyway, I wish we (the USA) had 'converted' years ago. Maybe then I would not have 40 years worth of tooling in my home shop designed around the Imperial measurement system. Yes fractions seem daunting if you have not used them much but it's not too bad. It's not much different than learning a language I think.

Also, at work I'm stuck with drawings from the 60s, 70s, and 80s when the place was designed and built. Those will never be converted (too expensive, over 500,000 hand-drawn drawings, not CAD, so not easy to scan and convert to DXF or DWG) to metric so kinda stuck with Imperial there.

You can't work on your car or pickup with a set of metric tools for the last 20 years I'd say. Maybe in another century we'll catch up with the rest of the world. Hang in there, it will be here before you know it. :-)
-----
It's a table saw, do you know where your fingers are?

Offline Alex

  • Posts: 6079
Re: Metric measures
« Reply #23 on: April 05, 2019, 08:07 AM »
Centimeters defeat one of the primary benefits of metric over inch.  With mm, almost everything you do is whole units, not decimals. Needing less than 1mm is un-common, yet 1mm works out nice as a base thickness.  Even in engineering work it's nice as most all dimensions are whole mm numbers. Not many things get over 1m, and when they do mm still work fine up thru 10m. 1mm is ~.040" which is a classic big tolerance, and 0.1mm is a good tighter tolerance limit  .004" (aka about 1 sheet of paper).

Just re-read this, odd understanding of engineering you have, I must say.

I did the first year of engineering school, didn't finish my whole study because I got side tracked, but what we learned is that you have different tolerances for different applications.

And for working with metal, the standard tolerance is measured in thousands of a millimeter, 0,001 mm or micrometer. Engineers don't mind decimals, there is nothing wrong with decimals. They are very used to decimals.

Working with decimals is not the same as working with fractions. Want to add 0,123 + 0,456 ? That's simply 0,579.

But want to add 3/8 + 5/6? You'll have to convert to 1/24th! Very complicated to work with and you e.

"Not many things get over 1m, and when they do mm still work fine up thru 10m" - You know bridges and skyscrapers are also made by engineers, right? Trucks, tables, even a fridge is easily over 1 meter.  Engineers don't mind, they simply convert.

Offline waho6o9

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Re: Metric measures
« Reply #24 on: April 05, 2019, 11:57 AM »
Use a 5M folding ruler and enjoy the day.

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Offline Sanderxpander

  • Posts: 381
Re: Metric measures
« Reply #25 on: April 05, 2019, 12:39 PM »
It's in cm, that's too complicated, apparently.

On a more serious note, I would love to hear about high quality measuring devices that use millimeters exclusively. I'd probably try one out. My Starrett combo square, my incra ruler, my Bosch laser meter and my Stanley tapes and folding rulers all use centimeters.

Online DeformedTree

  • Posts: 561
Re: Metric measures
« Reply #26 on: April 05, 2019, 01:00 PM »
Centimeters defeat one of the primary benefits of metric over inch.  With mm, almost everything you do is whole units, not decimals. Needing less than 1mm is un-common, yet 1mm works out nice as a base thickness.  Even in engineering work it's nice as most all dimensions are whole mm numbers. Not many things get over 1m, and when they do mm still work fine up thru 10m. 1mm is ~.040" which is a classic big tolerance, and 0.1mm is a good tighter tolerance limit  .004" (aka about 1 sheet of paper).

Just re-read this, odd understanding of engineering you have, I must say.

I did the first year of engineering school, didn't finish my whole study because I got side tracked, but what we learned is that you have different tolerances for different applications.

And for working with metal, the standard tolerance is measured in thousands of a millimeter, 0,001 mm or micrometer. Engineers don't mind decimals, there is nothing wrong with decimals. They are very used to decimals.

Working with decimals is not the same as working with fractions. Want to add 0,123 + 0,456 ? That's simply 0,579.

But want to add 3/8 + 5/6? You'll have to convert to 1/24th! Very complicated to work with and you e.

"Not many things get over 1m, and when they do mm still work fine up thru 10m" - You know bridges and skyscrapers are also made by engineers, right? Trucks, tables, even a fridge is easily over 1 meter.  Engineers don't mind, they simply convert.

I'm not sure where you are going with this.  This isn't about fractions v decimal.  We don't use fractions, but sadly when working with inch stuff, even though you work with decimals, the values used are generally decimal fractions  (.125, .375, .750) The point I'm making along with others is that metric gives you a great system to work with, and jamming cm in there along with mm at the same time is just asking for mistakes, see my example above.  I know from previous discussions you use cm, that doesn't change the matter that globally when working in metric cm are not generally used.  The cm-kg-s system is obsoleted for m-kg-s and or mm-kg-s.

On tolerances, I'm not sure where you were taking issues.  Some of this may be a difference in how metric prints and inch based prints are generally toleranced.   Inch prints typically have a sheet tolerance block.  Tolerance in inch based world is based on places after the decimal.  So in the lower corner of a drawing there will be a block that looks something like this  :  .X  +-.1 , .XX +-.05  .XXX +-.025 .  (the actual values are up to the company to decided, and is generally based on what they build).   In the field of a drawing,  if  there is a dimension that is 12.5"  then it has a tolerance of +-.1  if it says 12.50" then it has a tolerance of +-.05".    if  .125  then +- .025".   The number of decimal places dictates the tolerance.  If you want to be different from the default, then you call it out in the field.   12.500 +- .004, this trumps the block.    You can do the same with metric, and update the values of things.  Of course in metric trailing zeros don't matter.    12.500 is the same as 12.5   also there are now leading zeros   0.5, not .5".  Metric drawings generally use range tolerances.  Something like  0-10mm +- something.  10-100mm +- something.  I'm not sure if that plays into your comment on tolerances. Handling of leading and trailing zeros in metric vs inch systems is completely different. With inch based stuff you almost always have decimals places in play because an inch is a big unit of size.  If you were to work in cm, you will still have the same annoyance as working in inches. But by working in mm, especially for doing something like house construction, you are never going to go into decimal places. Everything will be whole numbers, life is great.

With modern machining we can expect to hold sub .004"  (.1mm) all day.  So this is where working in mm is very nice.  Just call out dimensions in mm, and have sheet tolerance for no place to be something like +-1mm (.039", nice loose easy tolerance), and when you need tighter, you have .X tolerance as +-.1mm.  So it's a very convenient setup.   Of course GD&T changes it all, stuff is now basic, but that works great with mm too, again all whole numbers and you only see decimals in the Gtol block.

It comes down to things being the right scale, and that's why mm are so nice.   Far as when you shift to m from mm,  no idea what various industries do.  I know we stick to mm all around, and stuff we build gets rather large.  I've worked on stuff near 10m long, everything was still mm.  As needed a jump to meter from mm is easy enough. Certainly no need to jump to meter on a house, only extremes of the house get very big.

But there is no reason to use cm, we don't talk in cm, we don't design in cm, standards/specs for things aren't in cm.  So it comes down to why inject something in there for no reason.  Stuff is generally listed/talked about in  mm and m.   Long distances we will make the jump to km, and for things like surface finish um,  why toss cm in there?  If someone is making cabinets, it's 32mm cabinetry, the material is in mm thickness, the hardware/slides are in mm, Festool marks their tools in mm (parallel guides as a good example, and the tracks are designated in mm too), everything being done is in mm, so why would someone want to use a cm tape measure and risk the mistakes like I showed above?

switch to mass for a moment,  we work in grams and kilograms.   Sure kg may be a bit big of a unit for  some things, and gram may be a bit to small for things, but we stick to gram and kg,  we don't don't randomly decide to use centigrams.  If you bought a scale and it read out in centigrams, sure it works and yes you can convert easy enough. But will a person make mistakes, you bet and often.



Offline Sanderxpander

  • Posts: 381
Re: Metric measures
« Reply #27 on: April 05, 2019, 04:48 PM »
When I take a measurement of, say 62.6 cm on my tape measure, I write down 626. There's no chance I could ever think I might have meant 626 cm, same as you don't mistake 6 inches for 6 feet. When I have to use a tape measure again to transfer the measurement, I add in one decimal point and it's 62.6 again.

The simple fact is that millimeter based measuring devices are not common and often not practical for the kinds of distances we need (in the sense that the numbers won't fit in a sensible way). But you can easily read a cm based tape measure as a millimeter based one that just has numbers every tenth millimeter and a larger mark every fifth.

Offline DashZero

  • Posts: 100
Re: Metric measures
« Reply #28 on: April 05, 2019, 05:01 PM »
METRIC is easy just like the money here in USA.

10 penny = 1 dime
10 dime = 1 dollar
100 dollar bill = 1 100 dollar bill

I never could see where the confusion is here.

Online DeformedTree

  • Posts: 561
Re: Metric measures
« Reply #29 on: April 05, 2019, 05:17 PM »
When I take a measurement of, say 62.6 cm on my tape measure, I write down 626. There's no chance I could ever think I might have meant 626 cm, same as you don't mistake 6 inches for 6 feet. When I have to use a tape measure again to transfer the measurement, I add in one decimal point and it's 62.6 again.

The simple fact is that millimeter based measuring devices are not common and often not practical for the kinds of distances we need (in the sense that the numbers won't fit in a sensible way). But you can easily read a cm based tape measure as a millimeter based one that just has numbers every tenth millimeter and a larger mark every fifth.

Life would just be easier to have a truly mm tape measure, then you wouldn't be going back and forth.   But look at my example I gave above.  It's not that one is going to think one or the other. It's about when you go to mark things and get screwed up in the way I described above, it's very easy to do. It's just an oddity that tape measures show in cm (generally), yet nothing else does.  Machines with readouts are inches/mm , same for calipers and a lot of other measurement tools.  Drawings are in mm, etc.  Why does one thing in the whole system report in cm.  I'm sure a lot of it is people who make the tapes just go with it because all the other tapes before did it.  I like rule 2 printed right on the tape of the fastcap tape "remove the opportunity for mistake from the process".

Offline demographic

  • Posts: 501
Re: Metric measures
« Reply #30 on: April 05, 2019, 05:26 PM »
When I take a measurement of, say 62.6 cm on my tape measure, I write down 626. There's no chance I could ever think I might have meant 626 cm, same as you don't mistake 6 inches for 6 feet. When I have to use a tape measure again to transfer the measurement, I add in one decimal point and it's 62.6 again.

The simple fact is that millimeter based measuring devices are not common and often not practical for the kinds of distances we need (in the sense that the numbers won't fit in a sensible way). But you can easily read a cm based tape measure as a millimeter based one that just has numbers every tenth millimeter and a larger mark every fifth.

There may be a misunderstanding about how I do this but thats basically what I do.
I have a tape that reads in cms and I automatically convert to mms straight away, I never ever write down a size in cms.
Any apprentice I have gets trained to do the same so they can give me a size to cut something to or vice versa without having to explain it too much 170 always means 170mm, none of this 170 cms stuff.
They are on my tapes but as far as. e using them is concerned they only exisf in theory, never as a spoken or written size.

Furthermore, on the sites I see using cms marks someone out as being a possible chancer, that's in the UK though, when I was working in France a few years ago and went into a builders merchants asking for a 600 concrete lintel they looked at me like I was crazy because they work in cms so it would be six metres long.


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Offline Alex

  • Posts: 6079
Re: Metric measures
« Reply #31 on: April 05, 2019, 05:37 PM »
The cm-kg-s system is obsoleted for m-kg-s and or mm-kg-s.

Cm is not an SI unit, and the scientific community must use SI units. But do you think a carpenter is a scientist?

On tolerances, I'm not sure where you were taking issues. 

You said in engineering everything is measured in whole millimeters. I gave the example of tolerances to show engineers works with decimals constantly. It's the norm. Because of tolerances.

It comes down to things being the right scale, and that's why mm are so nice.

Exactly, and cm is precisely the scale that relates most to humans. If your girlfriend ask you the size of your pee pee, do you say 150 mm? No. 15 cm.  [wink]

But there is no reason to use cm, we don't talk in cm, we don't design in cm, standards/specs for things aren't in cm.  So it comes down to why inject something in there for no reason.  Stuff is generally listed/talked about in  mm and m.   

We don't talk in cm? We talk in centimeters ALL the time. Constantly, every day. We just can't shut up about them. But of course we're inhabitants of metric country. What do we know.  [tongue]

switch to mass for a moment,  we work in grams and kilograms.   Sure kg may be a bit big of a unit for  some things, and gram may be a bit to small for things, but we stick to gram and kg,  we don't don't randomly decide to use centigrams.  If you bought a scale and it read out in centigrams, sure it works and yes you can convert easy enough. But will a person make mistakes, you bet and often.

It is just a matter of habit. You can't relate how people talk about mass to how they talk about size. Size and distance is a much more occuring measure for people than weight is.  So for weight we're happy using the two most common units, grams and kilos. For size, and distance we use four. Millimeters, centimeters, meters and kilometers. Your gf will not ask you how much your pee pee weighs, just how long it is.

PS, if there's anything in my post our beloved moderators can't live with, just PM me and I'll erase your concern.  [embarassed]

Offline Cheese

  • Posts: 6377
Re: Metric measures
« Reply #32 on: April 05, 2019, 05:56 PM »
I try to stick to one unit of measurement to reduce possible confusion and more importantly error. So for me it’s millimeters or inches. 

And even for 2x materials and boards, I still use inches up to about 12 foot. It’s just easier to remember 139 3/8” than 11’ 7 3/8”. Especially if you’re trying to remember 2 different measurements at the same time.

So for me cm is just another distraction. My Starrett scales and Woodpeckers scales are all in inches or mm. That’s the way God wanted it...[poke]
« Last Edit: April 06, 2019, 09:09 AM by Cheese »

Offline Jiggy Joiner

  • Posts: 750
Re: Metric measures
« Reply #33 on: April 05, 2019, 07:59 PM »
In the UK, some old die hard trades work in feet and inches, and they end up making mistakes, and costing themselves money when wrongly converting. They are too stubborn to learn the metric system but, hey, each to their own.

The majority of trades over here work in metric, and most of those in millimetres. A lot of the public (non trade) people use CM's as they were probably taught it at school, and feel after a measurement goes past 9mm they have to use CM's, and after 100 CM's they start stating metres etc, etc.

Most aspects of construction use millimetres, joinery companies, replacement window and door companies all work in millimetres.
Most bricklayers, and plumbers do too, and many suppliers.

Although as I mentioned last time this came up.
Some shops sell in LBs & oz as well, as or instead of grams and kilograms. Then of an evening, we might call a taxi, to take us to the pub, on the way to the pub, the taxi gets low on fuel, the driver is in a rush but, observes the 30mph speed limit, and pulls into the petrol station, and puts 25 ltrs of petrol into the cab. Then proceeds to the pub, when we arrive, we pay in pounds Sterling (decimal) money.
We get to the bar, and I order a well deserved pint of beer for me, and a white wine for Mrs Joiner. Outside is a shellfish stool, he's selling prawns, how much I ask? do you want a pint, or a kilo? says the stall holder.

Simple really  [big grin] [tongue]

Online DeformedTree

  • Posts: 561
Re: Metric measures
« Reply #34 on: April 05, 2019, 09:02 PM »
The cm-kg-s system is obsoleted for m-kg-s and or mm-kg-s.
Cm is not an SI unit, and the scientific community must use SI units. But do you think a carpenter is a scientist?

Why would it matter,  the idea is one system to rule all. 

Quote

On tolerances, I'm not sure where you were taking issues. 

You said in engineering everything is measured in whole millimeters. I gave the example of tolerances to show engineers works with decimals constantly. It's the norm. Because of tolerances.


I think you mis-read or something.  Engineering is certainly not in whole mm.  The point I was making that when designing in metric/mm things work out very nicely that almost nothing is ever going to go below a whole mm outside of tolerances and such.  I wasn't saying the resolution of the engineering world is 1mm units.   If you have a part,  your going to not likely to have a dimension like 95.5mm on it, you will probably be 95 or 96.   In the inch world we don't get such a niceness as you really can't design much if you never go sub 1". 

Quote

It is just a matter of habit. You can't relate how people talk about mass to how they talk about size. Size and distance is a much more occuring measure for people than weight is.  So for weight we're happy using the two most common units, grams and kilos. For size, and distance we use four. Millimeters, centimeters, meters and kilometers. Your gf will not ask you how much your pee pee weighs, just how long it is.

PS, if there's anything in my post our beloved moderators can't live with, just PM me and I'll erase your concern.  [embarassed]

Yeah, it is habit.  Being pro-cm is a bit like those who are pro-inch.  Definitely you live in an area that speaks in cm,  even without talking to you I am use to the regionalism with cm.  I know there are pockets in Europe were they are commonly used.  I've had co-workers from Europe, some spoke in cm, some did not. But they generally learn to move on from cm because else where as has been mentioned by myself and others it's either inches or mm. Also living in country that is stuck with inches I know all too well the issues that come up with cm.  If you try to convince people of the value of the metric system, a centimeter is seen as just a different sized inch, it's different but doesn't help them any any way, it's just different.  Those who bash usage of the metric system use the silliness of a cm as part of their case.  But also it's what confuses people.  When I have got people to remove cm from their mind and just use mm and m, the system comes around to them a lot easier.  Nothing they will measure in general usage will matter sub mm, now it starts to make sense, no more decimal place for the most part.  And from a human perspective mm is great.  a mm is about as small as a person is going to notice by looking.  If your laying stuff out, between your pencil mark, and some fudge in tools, marking, etc. You will probably get the mark plus/minus 1mm.  This works out just fine, if your building stuff, you generally stop at around 1/8th or 1/16th of an inch. So that error in your marking is well within "good enough".  If you do need to go finer, .1mm is great for folks to comprehend because of the similarity to paper.  People have a sense on the thickness of paper, you can't really see it, but you can feel it. Much below that, folks can't really feel very much.  So it's a good bottom threshold for people to keep their head around.  Other folks I have known have commented along the same lines that once they gave up on cm, and started thinking mm, they came around to the whole thing.

For sure if you grew up in a world like you did with cm as the conventional unit, it will seam fine and you won't see the issue with it. Again it's not different than those who see inches and fractions as being fine and being natural and making sense.  Or to leverage another topic we have had, it's like wanting to stick to 110V (the centimeter of electricity) power.  Why go all 240V, when 110V and 240V work perfectly well together  [wink] .

You get North America to go 230V, and the rest of the world can worth on freeing the Netherlands from the centimeter  [big grin]

Offline Bob D.

  • Posts: 1266
Re: Metric measures
« Reply #35 on: April 05, 2019, 09:48 PM »
I think you're all making a mountain out of a mm.    :)
-----
It's a table saw, do you know where your fingers are?

Offline Alex

  • Posts: 6079
Re: Metric measures
« Reply #36 on: April 06, 2019, 01:43 AM »
But they generally learn to move on from cm because else where as has been mentioned by myself and others it's either inches or mm. Also living in country that is stuck with inches I know all too well the issues that come up with cm.  If you try to convince people of the value of the metric system, a centimeter is seen as just a different sized inch, it's different but doesn't help them any any way, it's just different.   

Nobody is moving on from cm. There are no issues with cm. Where do you get these ideas? Certainly not in places that actually use metric. Conversion between mm, cm and m is done all day without effort or confusion.

The scientific community made the SI system to avoid confusion because their high end applications required more clarity in cross-communication. But the scientific community is just a very small percentage of the world, and for the vast majority that are the rest it doesn't matter.

Those who bash usage of the metric system use the silliness of a cm as part of their case.

Who bashes the metric system? That 5% of the world population still living in the imperial age? Yeah, good case.

Funny how those who don't use the metric system find 500 reasons what wrong with it, but those who actually use it don't think twice about it.
« Last Edit: April 06, 2019, 01:47 AM by Alex »

Offline Sanderxpander

  • Posts: 381
Re: Metric measures
« Reply #37 on: April 06, 2019, 01:48 AM »
When I take a measurement of, say 62.6 cm on my tape measure, I write down 626. There's no chance I could ever think I might have meant 626 cm, same as you don't mistake 6 inches for 6 feet. When I have to use a tape measure again to transfer the measurement, I add in one decimal point and it's 62.6 again.

The simple fact is that millimeter based measuring devices are not common and often not practical for the kinds of distances we need (in the sense that the numbers won't fit in a sensible way). But you can easily read a cm based tape measure as a millimeter based one that just has numbers every tenth millimeter and a larger mark every fifth.

There may be a misunderstanding about how I do this but thats basically what I do.
I have a tape that reads in cms and I automatically convert to mms straight away, I never ever write down a size in cms.
Any apprentice I have gets trained to do the same so they can give me a size to cut something to or vice versa without having to explain it too much 170 always means 170mm, none of this 170 cms stuff.
They are on my tapes but as far as. e using them is concerned they only exisf in theory, never as a spoken or written size.

Furthermore, on the sites I see using cms marks someone out as being a possible chancer, that's in the UK though, when I was working in France a few years ago and went into a builders merchants asking for a 600 concrete lintel they looked at me like I was crazy because they work in cms so it would be six metres long.
So actually you use cms all the time and convert to millimeters anf back without even thinking about it. And the order of magnitude between them is so great that even when your workmates were used to speaking in centimeters the situation was quickly resolved because they realized you couldn't possibly mean that.

I think we really do the same thing, I don't understand the "issue" with centimeters as you've just demonstrated there is none.

Offline Jiggy Joiner

  • Posts: 750
Re: Metric measures
« Reply #38 on: April 06, 2019, 06:15 AM »
I much prefer to work in millimetres and have no reason to include centimetres.
I’ve also noticed that when discussing measurements with clients, suppliers and architects, all is just fine until somebody introduces cm’s or mtrs into the conversation.
Usually lots of mumbling and placing of decimal points follow.

I remember when decimalisation was first introduced, many weren’t interested and said why change? Then apart from because we are getting more involved in the EE, being given as a reason, we were also told for accuracy.
It was banded around that a millimetre was a very small and precise measurement, that could be split if required but, mainly because of how everything was derived from a single millimetre, up in multiples of 10’s, 100’s 1000’s etc, to very large measurements.

On Monday morning I have to go and quote a job, it’s a small extension with a couple of roof lanterns, and some large either sliding, or bi folding glazed doors to the rear and side.
I am meeting the client and a roofer there, I bet the only person who won’t be talking in millimetres, will be the client.


Online DeformedTree

  • Posts: 561
Re: Metric measures
« Reply #39 on: April 06, 2019, 11:51 AM »
I much prefer to work in millimetres and have no reason to include centimetres.
I’ve also noticed that when discussing measurements with clients, suppliers and architects, all is just fine until somebody introduces cm’s or mtrs into the conversation.
Usually lots of mumbling and placing of decimal points follow.


Yup, have had meetings where the one person uses cm and throws people off, especially if you are in a country that defaults to inches.  When you work on stuff that is always different and generally doesn't have a baseline to work from to have an idea how big the thing someone is talking about it, it gets very confusing.  If you work on the same stuff all the time, that is always more or less the same size, it's going to be less confusing.

Online DeformedTree

  • Posts: 561
Re: Metric measures
« Reply #40 on: April 06, 2019, 12:35 PM »
But they generally learn to move on from cm because else where as has been mentioned by myself and others it's either inches or mm. Also living in country that is stuck with inches I know all too well the issues that come up with cm.  If you try to convince people of the value of the metric system, a centimeter is seen as just a different sized inch, it's different but doesn't help them any any way, it's just different.   

Nobody is moving on from cm. There are no issues with cm. Where do you get these ideas? Certainly not in places that actually use metric. Conversion between mm, cm and m is done all day without effort or confusion.

The scientific community made the SI system to avoid confusion because their high end applications required more clarity in cross-communication. But the scientific community is just a very small percentage of the world, and for the vast majority that are the rest it doesn't matter.


I think you are still missing the original point I brought up.  It's not that one can't convert between cm and mm easily, obviously that is extremely simple. It's when you make a mistake such as what happens with a tape measure.  If you are going to mark 1106mm , you look at the tape that you have pulled out past a meter and see "106" you mark it because it is what you are going for.  You're not thinking that you just marked 1060mm. You are now 54mm off, this isn't because you don't know a cm is 10mm.  Typical metric tapes don't have markings set up as you would expect. If they aren't going to just count from 0mm up to how many mm it goes to, you are expecting a repeat, such as ever meter, it counts from 0mm again and works back up to 999mm and then repeats after the next meter mark. The fastcap tape keeps counting up in 100mm increments, so 100mm, 500mm, 1300mm, etc.  Every 100mm the marks reset and count from zero up to the next 100mm.  It works like you would expect a tape to work.   If you need 923mm,  you see (900), and then advance to (20) go 3 more ticks, you find the mark the same way we speak number NineHundred, Twenty, Three.  On a cm tape you are going to 92 and then going 3 marks more. It's not natural, we don't say NinityTwo-Three to say 923.  A proper mm tape works the way we speak, which is key.  We say Eighteen, not  One-Eight.


Offline Michael Kellough

  • Posts: 4165
Re: Metric measures
« Reply #41 on: April 06, 2019, 12:43 PM »
I much prefer to work in millimetres and have no reason to include centimetres.
I’ve also noticed that when discussing measurements with clients, suppliers and architects, all is just fine until somebody introduces cm’s or mtrs into the conversation.
Usually lots of mumbling and placing of decimal points follow.


Yup, have had meetings where the one person uses cm and throws people off, especially if you are in a country that defaults to inches.  When you work on stuff that is always different and generally doesn't have a baseline to work from to have an idea how big the thing someone is talking about it, it gets very confusing.  If you work on the same stuff all the time, that is always more or less the same size, it's going to be less confusing.

Reminds me of my first encounter with CM.

Winter of ‘78-‘79, installing the premier exhibition of Cy Twombly’s suite of ten paintings titled “Fifty Days at Iliam”. Cy flew in to supervise from Rome, Italy (where he’d been living for the past twenty years) and was asking for the distance between the last two canvases. I told him “thirty two inches” (from memory) and he scowled and said “don’t give it to me in inches. Give it to me in sin timitters”. He grew up in Lexington, Virginia. About the paintings.

Offline demographic

  • Posts: 501
Re: Metric measures
« Reply #42 on: April 07, 2019, 03:13 AM »
This Youtube vid is worth a watch regarding the metric system .

Online DeformedTree

  • Posts: 561
Re: Metric measures
« Reply #43 on: April 07, 2019, 09:22 PM »
I watched that now, wasn't expecting it to hit on so many things I have gone thru.  The stuff starting at 5min in on centimeters is spot on.  His stuff on rulers is spot on. This was from around 2014 it sounded, but he's right, I think the fastcap tape is the only mm tape you can find in the US.  Even to get my other cm tapes I had to find them online. He mentioned the Japanese company, I have bought stuff from them for the very reason.  I have bought some of their stuff in a local store.  I actually found some dual tapes (yes dual is terrible like he mentions) at a local shop that supports trades. I asked if they had any that were just metric, he said they don't but mentioned how people ask for them all the time. Which drives me mad, people ask for them all the time yet you don't carry any, of course the issue might be they just don't have a good source for them.

His pseudo-inch comment is spot on and what I mentioned before.  If you do dual scale, or cm, you will never get change.  And really we need mm tapes to be at every store.  I keep one at work simply because the excuse not to do something in mm once was that there are no tape measures in metric, so I keep it there waiting for that again.  I'm forced to work with inch and metric for work, and the excuses for not using metric are endless and of course has a large age dynamic. The host on the video summed up how younger folk in the country generally feel.  As he touches on in the video, mm have been with us in this country for a long time.  People have been making excuses not to change for a long time and I've heard a ton of them. Oh, we probably shouldn't go down the "ton" discussion.

I'll have to look to see if his longer presentation is online.  I'm sure he removed stuff.  The stuff on decimals leaves out the key part for folks to understand that people can do  97+15  way faster than they can 9.7+1.5   you think it's the same, but it's not, the human brain just doesn't do decimal places well. Also curious if he talks about all the places we do use metric, which is just as important, that a lot of the US is metric, it's just hidden to most folks. Showing people it is all around them is a big help to getting acceptance.

Offline Cheese

  • Posts: 6377
Re: Metric measures
« Reply #44 on: April 09, 2019, 10:26 AM »
This is referencing a recent thread I did on machining an MFS support bracket.




This is how I make sense of items when both metric and imperial dimensions are needed.
In this case, the metric sized angle is sold by the inch.  [eek]  So both metric and imperial dimensions are used for the part. The wooden support block is a 2 x 6 so imperial dimensions are used. The slotting and the spacing between the slots will all be done on the MFS so it's back to metric. And even though M5 fasteners will be used in the slots, the only aluminum cutting router bit I could find was 7/32" in diameter so it gets thrown in the mix.  [big grin]

If I wanted to duplicate this job in 3-4 years, it's easier to just look at the drawing with the native dimensions and realize what items I used at the time. If every dimension is changed to metric or imperial, there's just a lot of confusion as to what individual items were used. 

It may not be everyone's panacea, but it works for me.



Online DeformedTree

  • Posts: 561
Re: Metric measures
« Reply #45 on: April 09, 2019, 10:07 PM »
Fairly standard practice.   Our rule is you keep the part what it was. So if it's an inch designed part, you model it and put it in cad as an inch part.  If it was metric, you keep it metric.  The system adjust.  Of course that doesn't mean nominal hole patterns and such work out.  Bigger issue is when someone comes along and wants something all one system (always inch), so now records like you have will be messed up because something is now all sorts of funky numbers.  Too many people convince themselves that if you take something designed in mm, and re-model/document it in all soft converted inches that it is the same thing.  So we end up with a lot of metric things modeled in inches.  Bearings are a big hang up of mine. Almost all bearings are metric and basically always have been.  But where I work they will document them in inches because some folks/customers want to pretend metric doesn't exist.

What you show is no different than me modeling up something metric, but I need an inch based threaded hole.  It will be a metric drawing, but the hole called out can be 1/4-20 UNC , it is what it is.  And sure enough you will have people argue you can't do that and want the part redesigned in inch, and then the system it goes into redesigned in inch, so so everything is all the same system.

Like you show with your slot. Most metric prints I've ever made when it comes to thru holes, or fillets, and the like are often going to be converted inch values simply because of drills and mills that are on hand.  This is changing though.  If your only making a single part and having a small shop make it, your not going expect them to go get a metric drill or mill, though really at this point they have them, it's just the collective mind thinking places don't.

The issue is when people don't understand these things and you have stuff where lets say it was designed in metric.  Now in the US all information on it gets converted to inches because that's what people do.  Do you know if the hard or soft converted, did they make a mistake in conversion, etc.  You start getting all these back and forth conversions with no idea how much rounding happened each time, even worse is someone throws fractions in there.  Or they dual dimensioned something and you have no idea which is the native unit.  Stuff can get out of whack in a hurry.  I don't like inches, but if something was designed in inches, keep it that way.  Same for metric stuff.  I hate trying to find stuff in the US that you know was made in say Europe and all the information in the US shows not just inches, but fraction inches.  Now you have no idea what you are working with.  I wouldn't be surprised if the same happens in Europe, something from the US comes over and the documentation gets converted to mm and becomes non-sense.  Like with Festool stuff, you end up having to go to the UK sight to figure things out.

Metric angle sold by the inch, yup, sounds right.  People just can't get on with the program.  Much like one of my favorites, plywood with "18mm" printed right on it and the store doing it's darnedest to call it some fraction or just 3/4, they just can't bring themselves to labels it 18mm, and even worse is they decide it's 3/4, and then to be "helpful" they call it 23/32, and then from there they convert to decimal inch and then convert that to metric and now you have 18.256mm plywood.....magic!

Offline MikeGE

  • Posts: 27
Re: Metric measures
« Reply #46 on: April 11, 2019, 05:41 AM »
I do not have any metric measures and will be building the newest Ron Paulk workbench. His newest plans are only in metic. What specific metric measuring products would you suggest the not only cover this project, but will be nice to have I the future?

I apologize for straying from the current discussions, but whichever product you choose, be consistent with it.  I use several BMI 2m folding Class II steel rules and a Hultafors Class I 8m tape.

Prior to buying these, I had several folding wooden rules and assorted 2m and 8m tape measures scattered around the shop and garage.  Prior to building out my basement shop, all cutting was done in the garage.  I would measure what I needed in the basement with one device, then go to the garage and measure for the cut with another device.  None of the boards I was cutting in the garage were fitting, and it took me a while to figure out what the problem was.  The problem was worse when I was cutting boards to measure when the measurements were taken by someone else and passed to my by email or over the phone.

The "aha" moment hit me when I consolidated all of my measuring devices and compared them for consistency over two meters.  Out of eight items, none were the same at two meters, and only three were the same at one meter, or as close as my aging eyes could determine.  The variance over two meters was 4mm.  This is likely good enough for carpentry or brick laying, but not for cabinet making.  I tossed all but one tape measure (it lives in the center console of my truck) and bought the BMI and Hulfators. 

Offline Jiggy Joiner

  • Posts: 750
Re: Metric measures
« Reply #47 on: April 11, 2019, 06:35 AM »
I noticed yesterday that any drawings we send to suppliers, or they to us, are in mm’s and often the mm’s aren’t even stated. Instead it’s common to see something like 3645 x 2150. Or, W: 2350 H: 2200 etc. Mtr’s are rarely mentioned unless something is over 10mtrs in size. Cm’s aren’t mentioned or indicated anywhere.

So, we’re in the mm only persuasion  [thumbs up]

Offline travisj

  • Posts: 363
Re: Metric measures
« Reply #48 on: April 15, 2019, 12:22 PM »
I do not have any metric measures and will be building the newest Ron Paulk workbench. His newest plans are only in metic. What specific metric measuring products would you suggest the not only cover this project, but will be nice to have I the future?

I apologize for straying from the current discussions, but whichever product you choose, be consistent with it.  I use several BMI 2m folding Class II steel rules and a Hultafors Class I 8m tape.

Prior to buying these, I had several folding wooden rules and assorted 2m and 8m tape measures scattered around the shop and garage.  Prior to building out my basement shop, all cutting was done in the garage.  I would measure what I needed in the basement with one device, then go to the garage and measure for the cut with another device.  None of the boards I was cutting in the garage were fitting, and it took me a while to figure out what the problem was.  The problem was worse when I was cutting boards to measure when the measurements were taken by someone else and passed to my by email or over the phone.

The "aha" moment hit me when I consolidated all of my measuring devices and compared them for consistency over two meters.  Out of eight items, none were the same at two meters, and only three were the same at one meter, or as close as my aging eyes could determine.  The variance over two meters was 4mm.  This is likely good enough for carpentry or brick laying, but not for cabinet making.  I tossed all but one tape measure (it lives in the center console of my truck) and bought the BMI and Hulfators.
One of the first things I remember learning from my grandfather was to only have one tape measure out for a project.  Put the rest away in a  drawer/box so you aren’t tempted to grab a different one.

As to metric measuring devices.  I have some Woodpeckers items that I like and a few of the Fastcap tapes (blue 32mm, yellow combined metric/imperial, and grey storypole).  I use the yellow combined one often to get a quick conversion.  I switched to woodworking in metric, but I still think in imperial.


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