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Design for multi-country manufacture - Metric vs. inch stock
14

Design for multi-country manufacture - Metric vs. inch stock

Design for multi-country manufacture - Metric vs. inch stock

(OP)
We are a US company which recently merged with a European company. How do we design 'common' products, when we can't but metric stock economically here, and they can't buy US gage, or fractional, stock there?

We certainly aren't the first in this situation. What do other companies do? Any suggestions appreciated.

Thanks.

RE: Design for multi-country manufacture - Metric vs. inch stock

What do you mean by stock, just 'stock fasteners' or do you mean 'stock material' such as sheet or plate of a certain thickness or both.

On the fasteners issue, I willl say that metric is probably easier to get in the US than Unified is in most other places.

So it may be you have to look at each category and see if one way or the other has advantages.

I'd be interested in seeing what others post as we have some similar issues and haven't yet forged a clear path forward.

 

KENAT,

Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?

RE: Design for multi-country manufacture - Metric vs. inch stock

Although I prefer imperial i'd say stocking metric would be the best course of action since it is more widespread. Uness it is a UK company where you might be more likely to come across imperial sizes.

RE: Design for multi-country manufacture - Metric vs. inch stock

Perhaps you can list what kinds of items you need (either in this thread or in a new one).  You may find that the membership can help you find economical metric items.

RE: Design for multi-country manufacture - Metric vs. inch stock

We had trouble with some metric hardware.  Clevis pins, weld nuts, cap nuts and retainers in particular.  Good luck finding metric structural tubing in the U.S.

My boss likes to point out that the U.S. is one of only three countries that isn't metric, and another of those is Libya.

RE: Design for multi-country manufacture - Metric vs. inch stock

Contrary to what most of the world seems to believe, the United States is not "non-metric".  We are both metric and imperial equally.  Any American engineer under the age of about 60 is utterly bilingual with regard to measurement systems.  You can get virtually any metric part you want here, though they might cost a little more, be a little harder to find, and require the additional purchase of a metric tool.

So, as has been mentioned, it is no big deal to specify metric equipment for use in America, though it might be a bad idea to use imperial elsewhere.

We don't hate the Metric System in America, we just think it's overrated.

Don
Kansas City

RE: Design for multi-country manufacture - Metric vs. inch stock

Oh real minor issue but look out for some screw head types.  North American metric pan-heads are apparantly taller than the rest of the world, it's the Canadians fault apparanly.  Bit me in the proverbial on my first significant project in the States.

eromlignod, I think you may slightly everestimate how 'bilingual' many US engineers are, but certainly agree they're probably more bilingual than anyone except Perhaps Brits, Canadians and maybe a couple other commonwealth places.

I'd almost be more concerned about things like stock material sizes such as scructural tubing, plate etc.

KENAT,

Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?

RE: Design for multi-country manufacture - Metric vs. inch stock

4
TheTick wrote <<Good luck finding metric structural tubing in the U.S.>>
I buy from Parker Steel Company. http://www.metricmetal.com
They have everything metric, no minimum orders, and sales people are very helpful. If you can use short pieces, they sell cut-offs at reduced prices.
Larry

RE: Design for multi-country manufacture - Metric vs. inch stock

Nice!  Thanks.

RE: Design for multi-country manufacture - Metric vs. inch stock

what exactly do you mean with "common products"? Components that can be incorporated in products on both locations or products that can be used "as is" and need not be linked to other machinery? In the latter case you can either use metric or imperial. As i understand it designing is not the problem, but manufacturing. If particular materials in certain sizes are difficult to obtain or costly then manufacture should take place where they are readily available - and perhaps shipping cost then becomes the problem. it is also possible to build a complete metric or imperial unit and equip it with an interface in the other system so it can easy be connected to other machinery.

the automotive industry in europe has put up with such a scheme for years (brakehosecouplings and tapered roller bearins only have become available in metric sizes only in recent years). still engines are sold with a SAE size bell housing flange and trucks with fifth wheels that require an imperial size kingpin....

it all illustrates that in a global world global standards are more then ever needed.

RE: Design for multi-country manufacture - Metric vs. inch stock

Tyre/Tire sizes!!!

A mix of imperial, metric and then a ratio thrown in for good measure.

Does anyone manufacture metric wheel rims?

- Steve

RE: Design for multi-country manufacture - Metric vs. inch stock

All OEM wheels are metric.

RE: Design for multi-country manufacture - Metric vs. inch stock

Metric as in sensible rounded numbers, or just inches converted into the nearest mm equivalent?

- Steve

RE: Design for multi-country manufacture - Metric vs. inch stock

What is a sensible rounded number?

Rim thickness = 3.75 mm ± 0.25 mm
Flange thickness = 5.5 mm ± 0.5 mm
Lug hole diameter = 16 mm ± 0.5 mm

I suppose the wheel width from bead seat to bead seat is "noncompliant" at 216 mm, as is the wheel diameter from bead seat to bead seat (436.6 mm).

The solid model, drawing, calculations, dimensional measurement, and testing are all metric, so I think it is safe to call it metric.
 

RE: Design for multi-country manufacture - Metric vs. inch stock

As I said, it's a sad mix.

- Steve

RE: Design for multi-country manufacture - Metric vs. inch stock

At my last job, making off-road equipment in USA and EU, with some sales in Australia and Asia. This was our approach wherever feasible.

Hydraulic fittings - Imperial, O-ring face seal
--Metric fittings are hard to get and $$$ in North America, whereas imperial can be found in EU and to a lesser extent Asia.

Fasteners - Metric
--Watch the differences in head sizes of cap screws between EU, Japan and North America.
--Many of the large components will be metric anyway (transmission, engine, axles, etc.)

Steel - Try to design with thicknesses which can be interchanged with minimal effect. Make sure the design can accept either, and specify either on the drawing.
--This depends on what you can live with, but <0.005" should be OK.
example: 3mm (0.1181") vs. 11 gage (0.1196")
              6mm (0.2362") vs. 3 gage (0.2391")
              8mm (0.3150") vs. 5/16" (0.3125")
             16mm (0.6299") vs. 5/8" (0.625")

Batteries - designed to accommodate either
-- was a pain, but is doable

Tires - Off-road tires aren't an issue, pretty much the same worldwide.

ISZ

RE: Design for multi-country manufacture - Metric vs. inch stock

(OP)
Sorry for not specifying in the original post.... I was referring to sheet metal, tubing and bar stock. We do use metric fasteners on all our products, as it makes international field service easier. While metric fasteners are, generally, available in the US at a reasonable cost, the sheet and bar stock seems limited. I did recently find Parker Steel (metricmetal.com) and plan to talk to them about stock, but as they are in Ohio I'm concerned about shipping costs for materials. And as we have multiple sheet metal and machine shop suppliers they would all be buying independently in the volumes they need to support our products.
 

RE: Design for multi-country manufacture - Metric vs. inch stock

2
The notion that most US engineers are bilingual is a not true.
Many say so but they do not know what they are talking about.
Unless you are brought up in the metric system from your first day in school, you are not capable of thinking in metric - you are constantly converting, no mater how hard you try. The Obama administration should make the hard choice:" First day in the new school year - all metric!!!Period. No transition over 5 and 10 years - that is a bunch of crap.They will just nickel and dime it to death. If we fail, we will just raise another generation of young people who are practically illiterate,as far as being able to converse with the rest of the world when it comes to engineering and manufacturing. If you need any proof, look at what happened to the conversion of TV to digital. Years of preparation and than- politics.
Yes, it is a handicap for US manufacturing trying to manufacture to metric dim's because materials like sheet and bar sizes are bought at a premium price and if you buy inch sizes you have to machine it down to the next metric size. So anybody out there rooting for the continuation of our present situation is just secretly trying to keep the inch system in place.  

RE: Design for multi-country manufacture - Metric vs. inch stock

I was interested in Kenat's comment about the UK and Canada. Both the UK and Canada have been metric for many years. Having worked in Canada for a long time, the problem in refining and petrochem was that most of the equipment/technology comes from the US and we found that it was imperial units or nothing a lot of the time. Maybe that is changing now. Since relocating back to the UK 2 years ago I now work exclusively in metric (on new plant) although, as Juergenwt said, I constantly convert, especialy when doing things in my head and I want to get a "feel" if something sound's right.
I do think that metric (or SI) is overated although the advantages of 1 global system are obvious.
I did junior school in Imperial, senior school in SI, and unversity back in Imperial. No wonder I am mixed up!

RE: Design for multi-country manufacture - Metric vs. inch stock

I started learning the metric system in fifth grade (1974).  It has been shoved down my throat my entire life.  I know it forwards and backwards and so do all the engineers I have ever worked with (I have been in industry for 22 years).  

I can think in metric all I want.  When I estimate the metric size of an object, I picture a metric ruler in my head, just like I do with imperial.  There is no conversion to it.  I know the temperature in my office right now feels about 22C.  I can pick up an object and tell you approximately how many kilograms it weighs.  What do you want?

...and it's still overrated.

Don
Kansas City

RE: Design for multi-country manufacture - Metric vs. inch stock

We missed a window of opportunity when the steel industry tanked in the 70s.  We should have retooled metric back then.

RE: Design for multi-country manufacture - Metric vs. inch stock

The large multinational companies I have worked for have been all metric but they were in electronics. As many have said it depends what industry you are in and what you need. You are doing the right thing by picking one as a total standard.

There are some things in the US that are sold as inch sizes but made to mm. The best example is plastic sheets and films. Even if custom extruded in the US a 1/4 sheet is really a 6mm sheet. I have also seen this with some Al sheet.

I heard the US military switched to metric for new milspec components. Is this true?

(Ever since the 90s most engineering courses are taught in metric with English units only used where they are tricky like slugs in thermodynamics.)

RE: Design for multi-country manufacture - Metric vs. inch stock


However, please note that most so-called "metric" electronic  components have pin pitches of 1.27mm or 2.54mm spaced at 7.62mm, 10.16mm and so on at standard conversions of imperial fractions, spindles are 6.35mm and panels have 12.7mm holes and these aren't because they're American, many are Japanese, French, German or Chinese, but it is the "Industry Standard" so we all live with it.

Here in the UK, all the aluminium and brass  extrusions we buy are sold in imperial fractional inch dimension for the sections and in multiples of metres for the length! Timber is metric but sheets of ply are so many millimetres thick but still sold in sheets eight by four (feet).

Us old wrinkly's can cope OK, but it's the kids I feel sorry for, they haven't been taught imperial measurments for years now, but all the speed limits are in MPH, road sign distances are in miles with local warnings in yards or fractions of a mile, petrol is sold only in litres, but car mileage is qouted in MPG. Finally, milk and beer is in pints! This is our country's metric policy and I don't see any of this changing much anytime soon!



 

RE: Design for multi-country manufacture - Metric vs. inch stock

"(Ever since the 90s most engineering courses are taught in metric with English units only used where they are tricky like slugs in thermodynamics.)"

I never heard of a slug in thermodynamics, it was all in lbm or kg.  I've seen that in a few old books, but never used in school.  I think it went out of style along with dynes, poises, etc.  Unlike kg-f, bars, calories, and other non-SI units which I still see.

RE: Design for multi-country manufacture - Metric vs. inch stock

2
At my place of work we're moving slowly towards the metric system - one inch at a time.
We're international too, and have had many issues just as described. We make small valve parts from spring steel, and so the difference between 4 thou and 0.1mm is significant in terms of bending stiffness. We've standardized metric as we see this as the long term global direction.  

RE: Design for multi-country manufacture - Metric vs. inch stock

(OP)
gt6racer2

So you use metric stock..

How do you address dimensioning the parts? Do you dimension them in all metric, and shops in the US live with that? Or dual dimension the prints? Or...

What about punched hole sizes? Do you call for standard metric hole diameters? What do US companies do to punch those hole sizes? (Buy metric punches?) Or...

Bob

RE: Design for multi-country manufacture - Metric vs. inch stock

"I never heard of a slug in thermodynamics, it was all in lbm or kg.  I've seen that in a few old books, but never used in school.  I think it went out of style along with dynes, poises, etc.  Unlike kg-f, bars, calories, and other non-SI units which I still see."


"lbm" are strictly bush-league.  Try putting lbm in a formula as simple as F = ma and you'll see what I mean.  The imperial unit of mass is slugs, force is in pounds.

1 lb = 1 slug-ft/s^2

As long as you use slugs for mass you can use all the same simple formulas that you use in metric.

Don

RE: Design for multi-country manufacture - Metric vs. inch stock

After having read the response on metric or inch material and the use of metric vs. imperial I find my point of view confirmed. Confusion, added cost and loss of leadership are only some of the immediate results. My advise to BobVo would be (and I do no know what product he is making and how much material he is using) - stick with metric on all new product. Design and build all tooling for metric product in metric. If not - you will create a big mess for yourself and for your company. It will cost a little more, but you will not sell a product build to imperial standards anywhere but in the US and you will run into big problems when working with your new partner.
The US used to be the leader in machine tools and wrote the book on many standards like tapers, CNC, machine building and design etc. etc.. Unfortunately that is no longer true. Many new Standards being written for ISO seem to have very little US input or am I just plain wrong on this?
It looks to me like most are an exact copy of the German DIN Standard.
  Neglecting our manufacturing sector has changed our society to one more resembling some in the Near East or Mediterranean area where the preferred way of making money is not by engineering and making a product but by buying and selling. Nothing against it - it's the way capitalism works.
However, the results of a free wheeling and unregulated capitalistic society are now coming to haunt us. I am by no means promoting socialism but something needs to be in place to assure that critical industries and skills are still available for future generations.
We have to make sure that one thing is kept under control, and that one thing is "Greed".
We do not need politicians who forever are looking to make sure they do not offend anybody. We need leaders in Washington who can lead and make decisions that are good for the future of the country, even if these decisions are sometimes not very popular.
Otherwise we might es well be governed by a bunch of bureaucrats who than make decisions by plebiscite.
One of these decisions should be to make a final and clear cut to convert this country to metric asap.
And "yes" the US Army is metric - has been for a long time. It was not easy to teach soldiers how to direct Artillery fire and call in adjustments by meters when they where all thinking in feet. But that was in the seventies and now we have GPS.    

RE: Design for multi-country manufacture - Metric vs. inch stock

Don, you can use all the standard formulas with lbm as well, as long as you measure force in poundals.  Where it gets messy is when you want to use lbm for mass and lbf for force - then you need to introduce the dreaded gc. This is (was?) very popular in US chemical engineering texts and has lead to a lot of confusion.

Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com

RE: Design for multi-country manufacture - Metric vs. inch stock

When I was learning physics as a kid, we were taught along the lines that force is proportional to mass times acceleration; pressure is proportional to temperature , current is proportional to voltage (no more examples required).

Then they gave us a consistent unit set.  Brilliant, absolutely brilliant.  I was so thrilled that power and energy from electrical systems was interchangeable with power and energy from mechanical systems.

- Steve

RE: Design for multi-country manufacture - Metric vs. inch stock

2
eromlignod,

   m=w/g

   F=ma=wa/g

   In the English system, you can ignore slugs and just substitute w/g.  Now, you can convert units between inches, feet and millimters to your heart's content, as long as you do not screw up your arithmetic.  Since the Newton is a unit derived from meters and seconds, you have to be disciplined about using meters and seconds as your units in SI calculations.

   Don't forget that the SI system is mks (meters, kilograms, seconds).  Lots of metric types still use cgs (centimeters, grams, seconds).  

   In the English system, slugs are the derived unit.  This is an excellent reason not to use slugs.

               JHG

RE: Design for multi-country manufacture - Metric vs. inch stock

Apologies in advance...

Knowing that BobVo's question has been answered, and that this thread has gone off on a tangent about units and a further tangent about the word "slugs"...

I have to add, that beer is a good way to get rid of slugs.  Whether you drink it, or they do.

 

Patricia Lougheed

Please see FAQ731-376: Eng-Tips.com Forum Policies: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

RE: Design for multi-country manufacture - Metric vs. inch stock

BobVo, some of our parts get dimensioned in mm and I dont' think we have any real problems with vendors not being able to punch the holes etc.

While perhaps not quite as common as inch series, common mm size tools are I believe fairly readily available.

 

KENAT,

Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?

RE: Design for multi-country manufacture - Metric vs. inch stock

vpl, Coors for the slugs, Newcastle for me!

Regards,

Mike

RE: Design for multi-country manufacture - Metric vs. inch stock

The imperial system is based on feet, slugs and seconds.  Force is a derived unit, just like in metric, and is in pounds.

Using pounds-mass is as stupid as using kilogram-force (which you do see sometimes).  As long as you use slugs for mass you can use all the same, simple mechanics formulas as for metric.

How much force does it take to accelerate a 3-slug mass at 15 ft/s/s?  Simple:

F = ma = (3 slugs)(15 ft/s^2) = 45 lbs

What torque results from 20 lbs exerted on a 3-ft lever arm?

T = Fr = (20 lbs)(3 ft) = 60 lb-ft

How much work is exerted when you push on a block with 5 lbs over a distance of 10 ft?

W = Fs = (5 lbs)(10 ft) = 50 ft-lbs

Force is in pounds, torque is in pound-feet, energy is in foot-pounds.  In all of these units pounds are force, not mass.  This is how these quantities are expressed in the engineering world.  When you look at spec. sheets and standard tables, this is what you find, not "pounds and poundals" (how confusing).  Pounds are force.

Don

RE: Design for multi-country manufacture - Metric vs. inch stock

eromlignod,

   Pounds and Kilograms are traditional units, frequently, however improperly, used for mass and force respectively, as you noted.  Slugs and Newtons are derived from force equations involving the traditional units.  If you write an equation with slugs or Newtons, you have to convert all your units into whatever units were used to derive the slugs and Newtons.  If your equations use pounds and kilograms, you can use whatever units you want, although you have to be consistent.  

   I have never seen a mass scale calibrated in slugs.  On a good day, force scales are not calibrated in kilograms and grams.  

   In English units, I almost always use inches as my length units.  I am pretty certain this rules out the use of slugs, which I believe are derived using feet.  I cannot be bothered to look this up.

   I must admit that when I am doing calculations in metric, methodically converting all units to the SI MKS is trivial.  

               JHG

RE: Design for multi-country manufacture - Metric vs. inch stock

(OP)
vpl - With all due respect, my question never did get many useful, on topic' replies... (Thanks to a few participants for the limited 'on topic' replies.)


We quoted metricmetal.com on some sheet stock.. but found they want $247 for an aluminum sheet similar to a .060 sheet our vendor pays $55 for. And $690 for a metric sheet similar to a 16 gage sheet our vendor pays $138 for. At these prices 130 sheets per week of metric sheet metal would obviously drive our costs through the roof. sad  

I'll discuss metic punches with our vendors... (but fear they might be forced to raise part prices to cover the cost of the additional metric tooling.)

Also, as some of our low priced suppliers don't have state of the art presses which can store many more punches than needed, press setup times will increase, as the 'normal' tools in the press will never be the ones we need. sad

BobVo
 

RE: Design for multi-country manufacture - Metric vs. inch stock

eromlignod,

So how do you unite the mechanical and electrical systems.  What are the equivalent imperial units for current and voltage that allow seamless working between the two domains?

- Steve

RE: Design for multi-country manufacture - Metric vs. inch stock

Oops, I sound like I'm goading.  I'm not.  I'm just interested. As I mentioned before, the idea that Volts*Amperes gives the same (W) as N*m/s  thrilled me as a kid.

- Steve

RE: Design for multi-country manufacture - Metric vs. inch stock

BobVo, we don't have large run rates for most our stuff so we're probably already being hammered on set up costs when we buy things 5 or 10 at a time.

We don't buy stock material much ourselves, we rely on the machine shops etc to buy their own.  That said where the 'stock' dimension remains on the part, such as with sheet metal, it's usually inch sizes (or at least AWG).

Our stuff is a terrible mix, we mostly dimension in inches but have quite a few metric threads.  However, every now and then, especially when interfacing with something metric, we have mm drawings.

KENAT,

Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?

RE: Design for multi-country manufacture - Metric vs. inch stock

I took a shot at compiling some sheetmetal equivalents.  Is this roughly what you were looking for?  

Sources for the stock sheet thicknesses were:
http://www.sheetmetalguy.com/sheet_metal_gauge_chart.htm
& http://www.metricmetal.com/products/crsheets.htm

In today's global economy, I think it's a great idea to design so product can be manufactured from the most economical local materials where permissible.  I think I'll start putting a material option on my sheetmetal parts where a precise thickness is not mission critical.

-tg

RE: Design for multi-country manufacture - Metric vs. inch stock

Steve wrote:

"Oops, I sound like I'm goading.  I'm not.  I'm just interested. As I mentioned before, the idea that Volts*Amperes gives the same (W) as N*m/s  thrilled me as a kid."

I wasn't trying to say that the Metric System isn't superior in some ways.  I'm only saying that it's overrated.  The fact that it relates directly to electrical units is nice, but not really that useful.

Power is about the only mechanical/electrical equivalent I ever use.  I just remember that there are 1.356 ft-lb/s in a watt.

Now I'll stop hijacking the thread!

Don
Kansas City
 

RE: Design for multi-country manufacture - Metric vs. inch stock

(OP)
Telecomguy,

I agree that, for the future, designing so metric or gage sheet metal can be used is a smart way to go.

Unfortunately, I expect that if we start looking closely at the current designs we will find places where changing the stock thickness will effect fit and function, for example where functional parts sit on top of sheet metal parts. Or where dimensions are to the 'wrong' side of the part.

It appears worse for bar stock, tubing, etc. For instance we make rollers by pressing a cap into tubing. Tubing diameters here and there are not close, so the cap diameter needs to vary to make a reasonable press fit. How do we design these to simplify the future?

So trying to build a present metric designed product in the US looks like it will require a redesign to tweak dimensions to compensate for material thickness in places. - A task that results in two sets of drawings for us and them. Which leads to other issues, like trying to maintain control of the design. (When you ECO a part how do you know if there is another metric or  inch drawing of a 'similar' part being used overseas?)

When I originally posted I was hoping that there was someone 'out there' who had been through all this and found a simple solution I was overlooking. We haven't found them yet. winky smile

BobVo

RE: Design for multi-country manufacture - Metric vs. inch stock

Bob

This is a little bit more on track: There's another thread in this same forum that's addressing a (somewhat) similar issue in terms of dimensioning on drawing.  You might find it useful:  thread404-233255: Significant Figures On Dimensioned Drawing When Converting Units

Patricia Lougheed

Please see FAQ731-376: Eng-Tips.com Forum Policies: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

RE: Design for multi-country manufacture - Metric vs. inch stock

BobVo,

   I don't know anything about European sheet metal gauges.  I can see two issues with English sheet metal grades.

  1. None of them work out exactly to round inch values.
  2. There are an awful lot of them, and the thickness increments are small.
   On fabrication drawings, you should not call up the English sheet metal grade.  You should call up the thickness, with a tolerance.

   For example, you prepare a drawing showing aluminium sheet metal thickness of 2mm±0.2mm.  English 12 gauge is 2.06mm thick,  placing it well within your tolerances.  My Google search for "sheet metal DIN" reveals this table of German sheet metal gauges.  DIN 13 gauge is nominally 2mm thick.

   Specifying the thickness with a tolerance is the right way to do stuff.

   The dimension with tolerance can probably be achieved by sheet metal gauges.  Thicker plates are a problem, but you can always make your tolerances sloppier.  There is not much difference between 10mm and 3/8" for example.  Does it really matter to your design?  

   The same definitely goes for drills and other tools.  I specify holes with zero positional tolerance at MMC, and a sloppy diameter tolerance, e.g. Ø5.0/4.4mm.  If an English drill or punch does not fall inside this range, you don't have enough English drills and punches.

               JHG

RE: Design for multi-country manufacture - Metric vs. inch stock

"When I originally posted I was hoping that there was someone 'out there' who had been through all this and found a simple solution I was overlooking. We haven't found them yet. "

I guess the 'simple' solution would be to machine everything.  Then all you have to worry about are varying material properties... blllttt

RE: Design for multi-country manufacture - Metric vs. inch stock

(OP)
Alas, simple would have been, c. 1975, when the US congress voted to make the US metric, if we had actually followed through. By now metric would be in place, instead of just 'on the books.'

 

RE: Design for multi-country manufacture - Metric vs. inch stock

2
Unless you are brought up in the metric system from your first day in school, you are not capable of thinking in metric

feel free to speak for yourself... just remember that the kids on the longer bus might have had a different experience.

 

RE: Design for multi-country manufacture - Metric vs. inch stock

BobVo,

   Canada has been officially a metric country since the seventies.   When I went to college, we used English units, and the SI (MKS) system.  I am comfortable with both.  I want nothing to do with CGS units.

   Right now, Canadian architects work in metric, and Canadian contractors work in feet and inches.  

   I am looking at my Machinery's Handbook, Twenty Sixth Edition.  They did not separate the drills between numbered, fractional inch, and metric.  They listed all the drills, in order of size, all in one table, with diameters in inches and millimeters.  I can easily see for example, that if I want to be a tiny, tiny bit above .125" diameter, I need a Ø3.2mm drill.   

               JHG

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