# Metric to american



## Brento (Jul 25, 2018)

Has anyone done any project from books like these? My issue is all of the projects are in metric and id like to convert into american. I was curious if its easier to convert everything to american at known nominations or just make the part to the actual conversion from metric.


----------



## Tony Wells (Jul 25, 2018)

That would depend largely on the complexity of the project and your design/engineering talents. That is, if you mean taking 10mm from print and subbing in 3/8"(0.375).

I'd probably convert the drawings to SAE/Imperial. Have done so for few commercial jobs. Just have to convert the tolerances too.


----------



## jocat54 (Jul 25, 2018)

Never done any from the books--but it's pretty easy to convert metric to imperial (25.4mm=1"). Think that's what I would do.


----------



## savarin (Jul 25, 2018)

Why not follow the rest of the wold and use metric then you can just follow the projects as is.
My lathe is imperial but all my projects are metric so its no real problem. and seriously, Americans actually do use the metric system and have done so for years, you just divide an inch into 1/10ths, 1/100s, 1/1000s instead of a millimeter.
I use both systems and would just transcribe the measurements to the system I wanted. If done exactly and not to the nearest equivalent there should be no problems.


----------



## Brento (Jul 25, 2018)

There is alot of complex parts so the best thing is to maybe just convert to us to measure with my instruments but in the end keep dimensions the same.


----------



## Bi11Hudson (Jul 25, 2018)

I have been working with the metric system for more than 50 years building and modifying scale models. H-O trains....
The scale is 3.5mm to 1.0 foot. The end result is that I work as easily with the metric system as with imperial. Although imperial is what I grew up with, metric is somewhat easier. The important thing is to "get comfortable" with metric measurement. Most of my construction experience is with imperial. The machine work is maybe 30-70 metric.

A few years ago, I built an electric powered bicycle. The doner(?) was a late model Schwinn, made in China. So all the additions I made were done in metric. With few exceptions, such as I don't have metric keyway broaches. Had to finagle that. A three wheeler arrangement, it worked out well.

A few dimensions to get comforteble with:
25 mm is a fuzz less than an inch (25*.4*mm=1 inch)
1 mm is 0.03937 inch (roughly 40 thou)
10 mm X 1.5 thread is so close to 3/8-16 TPI you need to measure cose to find the difference.

With little expenditure, you can tool up for metric. A good metric caliper or micrometer along with the conversion factors for imperial leadscrews will yeild good metric measurements. On the other hand, conversion to imperial is just a matter of converting all the measurements, to the above listed factors. The bicycle mentioned was done in metric to make everything one system, no half and half, no two sets of wrenches, et al. My model building is done to imperial, because I must interact with others that have no grasp (nor want) of metric. Go for it, Dude. By whatever system is easiest for* you*. 
Bill Hudson​


----------



## T Bredehoft (Jul 25, 2018)

Brento said:


> in the end keep dimensions the same.



That's probably your best bet. Perhaps more work, but won't cause any problems.


----------



## Brento (Jul 25, 2018)

Bi11Hudson said:


> I have been working with the metric system for more than 50 years building and modifying scale models. H-O trains....
> The scale is 3.5mm to 1.0 foot. The end result is that I work as easily with the metric system as with imperial. Although imperial is what I grew up with, metric is somewhat easier. The important thing is to "get comfortable" with metric measurement. Most of my construction experience is with imperial. The machine work is maybe 30-70 metric.
> 
> A few years ago, I built an electric powered bicycle. The doner(?) was a late model Schwinn, made in China. So all the additions I made were done in metric. With few exceptions, such as I don't have metric keyway broaches. Had to finagle that. A three wheeler arrangement, it worked out well.
> ...


Thank you Bill perhaps once i get more into this hobby and some free cash i will pick up a metric micrometer or 2 all of my instruments are in imperial which is the only reason why im asking for opinions.  I have found metric to be easier for drawings myself but due to everything in imperial through my last 3 jobs its hard to tool up on it without a good reason for it.


----------



## Hoover (Jul 25, 2018)

I am a machinist/ fabricator in new product development for one of the US power sport companies.
The company is global so everything is designed in metric.
The funny thing is that quite often when I convert to inches (I just can't think metric) dimensions convert to a nominal standard size.
It seems like a lot of parts are designed in US, converted to metric, then I convert back.


----------



## Bi11Hudson (Jul 25, 2018)

That makes good sense. For conversion factors, multiply any dimension in millimeters by 25.4. In centimeters, you can multiply by 10 and then convert. For decimeters, by 100 then convert. The result will be in inches. Run out 3 or 4 decimals and round it as fits. Some places it matters, some it doesn't. That's essentially what I do with my models. 

As an aside, I picked up a metric micrometer on eBay a while back for 3 or 4 bux. They paid shipping... It took 3 weeks plus to get here and I'm not sure how accurate it is. But I was getting it as a standby tool anyway. If I measure a 12mm shaft at 12.02mm, that's close enough for what I do.


----------



## Brento (Jul 25, 2018)

Ill keep that in mind thanks Bill. Just a question how wide does a set of metric micrometers measure? Equivalent to a 0-1?


----------



## Superburban (Jul 25, 2018)

Does anyone have a chart as to what American threads are close enough to metric threads?


----------



## RJSakowski (Jul 25, 2018)

Bi11Hudson said:


> That makes good sense. For conversion factors, multiply any dimension in millimeters by 25.4. In centimeters, you can multiply by 10 and then convert. For decimeters, by 100 then convert. The result will be in inches. Run out 3 or 4 decimals and round it as fits. Some places it matters, some it doesn't. That's essentially what I do with my models.
> 
> As an aside, I picked up a metric micrometer on eBay a while back for 3 or 4 bux. They paid shipping... It took 3 weeks plus to get here and I'm not sure how accurate it is. But I was getting it as a standby tool anyway. If I measure a 12mm shaft at 12.02mm, that's close enough for what I do.


Bill, I believe that you meant to say divide by 25.4 to convert mm to inches.  I multiply by ,3937 to convert to inche.  If a rough calculation is OK, .4 works.  I work with both but becuase my measurement tools are Imperial, I convert almost everything to inches


----------



## RJSakowski (Jul 25, 2018)

When I did layouts with a scribe and ruler, designing to nice round numbers was more or less a necessity.  Nowadays, with CAD, DRO's, digital calipers, and CNC's, round numbers aren't as important.  A consideration as to whether to design in metric or Imperial.  In the U.S., Imperial measured stock is readily available while metric stock is not.  In the rest of the world, metric stock is the most common one.  Also true for fasteners.  Here, you can find metric fasteners but usually they are more expensive.


----------



## Brento (Jul 25, 2018)

Well what i may do is keep everything metric but convert to imperial to make the part but when i have to use metric fasteners i will engineer it to be imperial fasteners.


----------



## Tony Wells (Jul 26, 2018)

RJ......I think you meant multiply by 0.03937 for mm to inch. Left out a zero

In general I like Metric, but I'm pretty well instrumented up for Imperial, plus some machines are cross-dialed, and some have DRO that speaks Metric. Too late in life to start buying a bunch of Metric instruments. Of course, some (the digital stuff)  is bilingual.


----------



## Boswell (Jul 26, 2018)

I have a couple of digital tools that work great both ways. I particularly like my Mitutoyo Solar powered calipers. I also have a 0-1" digital micrometer but I pretty much only use it when I need to do Metric. I much prefer my mechanical micrometers because I don't have to search for batteries every time I need it.


----------



## Mitch Alsup (Jul 26, 2018)

I interchange metric and Imperial all the time.

Al you need is a calculator and 1 constant:: 25.4.

Imperial ince = metric mm / 25.4
metric mm = Imperial inch * 25.4

10mm = 10 / 25.4 = 0.393700
1 inch = 1 * 25.4   = 25.4 mm


----------



## Dave Paine (Jul 26, 2018)

You can always get an inexpensive handheld calculator and convert dimensions as needed.

Sharp metric conversion calculator at Staples


----------



## Brento (Jul 26, 2018)

I have a machinest calc pro which is very sophisticated that i dont remember the button sequence to figure things out.


----------



## Dave Paine (Jul 26, 2018)

Brento said:


> I have a machinest calc pro which is very sophisticated that i dont remember the button sequence to figure things out.



That calculator is indeed sophisticated.    I looked at the User Guide.   Easy to set for entering Imperial or Metric, but converting is not so easy, it is part of the Conversion menu.

The Staples calculator and others like it would be far simpler to convert between Imperial and Metric.  I may have to get one for myself.   I have an HP32 calculator which does all sorts of functions, but no Imperial to Metric, other than my entering 25.4/ or 25.4*.


----------



## pontiac428 (Jul 26, 2018)

I interchange systems and don't have a preference, I just work with it. 
My machine scales and leads are in inches, but the cutting tool does not have a preference, it just cuts. 
You want to build something of a given size, then build it.  The units of measurement are inconsequential.
Conversion factors are ratios, and ratios are proportions.  We could convert to a different number base or work from log-10, either way  we'd be watching some dimensional value and working towards it, cut by cut.
I am not trying to sound trite, it's just a number!

Edit:  Microsoft Excel is your friend.


----------



## Bi11Hudson (Jul 26, 2018)

I seem to have stepped in it big time here*...* A calculater is nice*...... *if you're in a class. I prefer to have things where I can convert in my head, a pencil & paper at worst. Ya never know when the batteries will give out. And most times, I don't need an answer to 5 decimal places in imperial. I do use 5 places for a mm because the numbers are easy to remember. Point03937... Pi is 3point14159 Just the way my memory works. I take the measurement of a* ...*motor shaft with an imperial caliper. If it is 0.079~, it's a 2mm. If it's 0.092+, it's 3/32". In either case, it will work, just a matter of what type of coupling to use. Or what size fuel line. Or whatever I happen to be using for that install. 

I have a number of project books, some from the U.S., some from England, and some for pure metrics. Some very old, some recent. The only place I have any trouble is with English fasteners (Whitworth) and pipe fittings. What's called British Standard. But that's just a matter of a different method of measuring. I don't use the English systems very often, so must brush up on them when I have a project from that area. But you've got to watch the English. They started out imperial and converted to metric only recently. Sometimes the systems get a little mixed up. As in both systems side by side. A shaft 2 inches long by 1.5mm diameter. Ya got to think, 2X1/16", more or less. Or 50mmX1.5 if you're trying to stay metric all the way. If the shaft fits into something, can the something be reamed to 1/16. Or is it just to stand off something.

Most metric micrometers read to 25mm, or just a whisker fuzz under 1.0 inch. Making an imperial leadscrew cut (true)metric threads requires a 127/120 conversion gear. If you backtrack the numbers, the 127 gear is to convert 25.4 to a solid number, one without a partial remainder. The most important factor is to get comfortable with the idea of a *fuzz and if it's important*. A cylinder/piston/rings of any larger size won't matter that much. A shaft, especially a small one, fitting into a bearing, will. It's one of those calls you must make for yourself based on what the book says. The book you have posted is for machine parts. Take a dovetail cross-slide. The angle is important but will be the same, imperial or metric. The width (distance between) may be metric, but a fuzz too full won't really matter because of the gib and setscrews to adjust it. If it calls for 25mm, make it an inch. That's what I was refering to for you to make the call. And the worst case: As a hobbyist, if your call* isn't *right, ya make it again, watching the dimensions a little closer. 

I'm not trying to denigrate one system under the other here. I'm only trying to give a little insight into the process of making a conversion from one to the other. I responded to a post the other day regarding need vs want. You *need* a set of manual calipers and a feeler guage. Anything else is a *want,* or time saver. Chew on that for a while.

Bill Hudson​


----------



## Bi11Hudson (Jul 26, 2018)

Quote:
Bill, I believe that you meant to say divide by 25.4 to convert mm to inches.  I multiply by ,3937 to convert to inche.  If a rough calculation is OK, .4 works.  I work with both but becuase my measurement tools are Imperial, I convert almost everything to inches 

Answer:
That is for centimeters;
A millimeter is 0.03937" (40 thou)
A centimeter(10mm) is 0.3937" (400 thou)
A decimeter(100mm) is 3.937" (4 inches)
A meter(1000mm of course) is 39.37" (40 inches)

I prefer the multipliers rather than the divide process. Usually I don't consider rods, yards, feet, whatever. Unless I'm doing construction work. Most times, under 20 feet I stick with inches and fractions. To a sixteenth, as a rule. It's a matter of what fits best. When I am *survey*ing something, I measure in feet and tenths(possibly 100ths) of a foot. I have a tape measure with 10 "inches" per foot. A lot of fun with a helper that can't read a tape that well. I have another tape with 12 inches per foot, but in *tenth*s of an inch. Used to setup a machine where I *used* to work.

Bill Hudson​


----------



## RJSakowski (Jul 26, 2018)

Tony Wells said:


> RJ......I think you meant multiply by 0.03937 for mm to inch. Left out a zero
> 
> In general I like Metric, but I'm pretty well instrumented up for Imperial, plus some machines are cross-dialed, and some have DRO that speaks Metric. Too late in life to start buying a bunch of Metric instruments. Of course, some (the digital stuff)  is bilingual.


Yes, I did  I know better!  Thank you Tony & Bill for catching it.  Muscle memory makes running the conversion almost automatic.  
I am going to chalk it up to the late hour and the half a snifter of brandy.  Anyway, that's my story and I'm sticking to it.


----------



## Tony Wells (Jul 26, 2018)

We all do it from time to time......


----------



## BenW (Jul 26, 2018)

Brento said:


> Ill keep that in mind thanks Bill. Just a question how wide does a set of metric micrometers measure? Equivalent to a 0-1?


Metric mikes are ususally 25mm travel, so same as imperial ones. 

Sent from my SM-G930F using Tapatalk


----------



## P. Waller (Jul 26, 2018)

If the engineer is thoughtful they will dual dimension each drawing in inch and millimeters like so.
This is from one of todays jobs.




Same customer and same assembly but this one is not dual dimensioned as above, this part is mostly in whole 1/16s of an inch, go figure.
Simply use a calculator to convert and write the inch numbers next to the metric numbers as I do, I do this 6 days per week 52 weeks per year.
As mentioned the international standard is 25.4
It does not get any simpler than that.


----------



## Brento (Jul 26, 2018)

What is your rule for rounding up when converting the metric to inches.


----------



## royesses (Jul 26, 2018)

Brento said:


> I have a machinest calc pro which is very sophisticated that i dont remember the button sequence to figure things out.



I have the machinistcalcpro2. On it I enter a number then inch. Then tap mm and it converts the displayed number to metric. Tap inch again and it converts back to inch.  Do the reverse to convert to inch. I don't know if your version is the same. I also have a calculated industries conversioncalc plus that does this and many other conversions including torque units.

Roy


----------



## P. Waller (Jul 26, 2018)

Brento said:


> What is your rule for rounding up when converting the metric to mm?


I do not round in either direction, it is normally obvious what the designers intention is by the tolerance call out for each dimension.
If a bore dimension is .625" +.001 -.000 the intention is a diameter that under no circumstances be less then .625".

If you are concerned about the 4th decimal place you can already make parts in tenths and need not be asking questions here, a grinding forum would be a better place for such questions.


----------



## randyjaco (Jul 26, 2018)

I just don't understand why this country refuses to go metric. The imperial system is archaic. We are just being Luddites on this issue. It is time we bite the bullet and made the change. The vast majority of our manufacturing companies could do it over night, if it weren't for there current inventories. 
Randy


----------



## Brento (Jul 26, 2018)

P.Waller i just ask bc some measurements like 4mm converted is .1574803. The book of drawings in metric does not have any tolerances. Since my work is all mainly imperial im new to converting everything over and not sure what type of tolerance i should use when converting. Should i round the conversion to the nearest tenth? I guess im asking for your opinion.


----------



## P. Waller (Jul 26, 2018)

Brento said:


> P.Waller i just ask bc some measurements like 4mm converted is .1574803. The book of drawings in metric does not have any tolerances. Since my work is all mainly imperial im new to converting everything over and not sure what type of tolerance i should use when converting. Should i round the conversion to the nearest tenth? I guess im asking for your opinion.


Do you use machines that have graduated dials that resolve to 7 decimal places?
If the answer is yes you are in the wrong forum, if no they are like most hobby machines that are graduated in .001" divisions, ask yourself this question, "Self, how do I remove a 7th decimal inch (1 millionth) amount of material with a 3 decimal reading machine". The short answer is that you can not do so. It is likely that you could not measure it if you did manage to do so.

If the tolerance call out is +-.002"  then you have .002" on either side, if the tolerance is 3 decimal places this means that in this example .0029" is acceptable as it is not .003"

Very simple, in your example above I would call that .157"

If the drawings that you are working from have no tolerance on the dimensions then someone dropped the ball, do not try it.


----------



## Brento (Jul 26, 2018)

Ok thank you. Exactly what i wanted to hear. I still have my machines in storage but ik the SB lathe is dials and my mill does have read out.


----------



## P. Waller (Jul 26, 2018)

Brento said:


> Ok thank you. Exactly what i wanted to hear. I still have my machines in storage but ik the SB lathe is dials and my mill does have read out.


Much like "digital calipers" many DROs use 4 decimal displays, do not expect this sort of accuracy in use.


----------



## Winegrower (Jul 26, 2018)

One of the best uses for even the cheapest DROs on a mill or lathe is to set mm or inches.   I feel sorry for anyone with his calculator trying to hit 0.4863 by reading the dials.


----------



## RJSakowski (Jul 26, 2018)

Brento said:


> What is your rule for rounding up when converting the metric to inches.


The precision to which you carry out conversions depends very much on what the requirement represented by the dimensions are.

A metric dimension may be listed as 22 mm but unless otherwise stated, I assume 22.00 mm which would be .8661".  If that 22 mm is the i.d of a bearing to be a light press on a shaft, you better be working to four decimal places.  On the other hand, if that 22 mm is the diameter of a crank handle, I would probably round it off to 7/8".

I carry all my calculations out to four decimal places.  I know that bothers some people but I am used to dealing with it.  Most of my work is done to thousandths so the extra decimal place helps to prevent stack up errors.  An example would be  10 holes .5002" apart.  If I round to .500" and start machining holes, by the tenth hole, I would be .002" out

Bear in mind that virtually all of my design work is for my own use.  I am aware of what the functional requirements are and what kind of machining accuracy is required to meet the functional needs.  If I were designing in collaboration with others and cimmunicating with those responsible for executing the design, as I did in my professional life, it is a totally different ball game.


----------



## cvairwerks (Jul 27, 2018)

randyjaco said:


> I just don't understand why this country refuses to go metric. The imperial system is archaic. We are just being Luddites on this issue. It is time we bite the bullet and made the change. The vast majority of our manufacturing companies could do it over night, if it weren't for there current inventories.
> Randy



DoD is pretty much the reason. They are the 600 pound gorilla in procurement. Going metric would necessitate a clean break in procurement and stocking. The public would freak out finding out that they would be spending billions on setting up, qualifying and then stocking metric hardware for the various programs. Then think of the logistics of having to handle both systems, in the same maintenance units, until all the imperial equipment was transitioned out. For some things, the equipment is in use for 40+ years...


----------



## philip-of_Oregon (Jul 27, 2018)

I'm a Visual sort of guy, It helps me if I ~SEE~ rather than read or hear.

Upon buying my New *PEC* 6 inch scale, I had the typical choices, so I bought their Imperial/Metric scale.

It does 1/64", and inches decimal (100 per inch) then side two has Metric ( @ 0.5mm for 2 (or 4) CM, then the rest in 1.0mmm Plus CM's.  The Fourth scale is (IIRC) 1/32 . I use this 6" scale for most of my work, as it is nitrided a "Gold" color and is plain easy on the eyes.

Using the Metric Side, even when DOING Imperial Work helps me "keep" them relatively "together" in my mind.

Note: the Company *Incra Rules* is my "Go To Ruler" for All Wood Working, and has been since 1989. their thin Stainless Steel is perforated so a .5mm Pencil will fit perfectly, the ends have a removable "Tee Square" that can slide so either top scale or bottom scale is "On Edge" with the Tee. 

They Provide 1/16, 1/8, 1/4, etc. line markings & holes then, With a Unique system in the center of their Scales, (a series of Diagonal Holes Marked +/- ) one can Accurately Draw LINES to 1/64 inch Plus whatever inch distance from the scale.

They even have a 3X4 inch X/Y Plotter "scale". As Well as a Special Order for a Metric Based Scale Sized to the equivalent nearest Inch length say 75X100 instead of 3X4. 

I do not work for, NOR Receive $$$ for "endorsing" their Products, I simply pass the information On as an Avid User.

As my STANDARD Pencil in my shop is a Metric .9 Milimeter lead, I once took the time to increase the holes in one scale to .9mm, But that is a Lot of work, you gotta be just a bit OCD to "do That" ! ! ! ! ! 

philip, Oregon is dry this week, Next week Fall will start!


----------



## RJSakowski (Jul 27, 2018)

IMO, we don't go metric for the same reason that we clung to an antiquated television technology; legacy products.  It took an act of congress to change  to digital television, along with a government givaway of two converters to any household that requested them.  We invented cell phone technology, along with CMDA protocols while the rest of the world has GSM protocols which make our CMDA phones useless when we travel abroad.  

We developed an entire infrastructure over the period of 200 years base on Imperial measurement.  While this isn't as important for consumables and short lifespan products, when it comes to long lifespan products like housing, Making repairs to or remodeling a 40 year old house would be a nightmare if the building supplies were all metric..  Probably the biggest legacy  issue is the citizenry itself.  We could very easily convert to Celsius for temperature.  Most of the modern thermostats are already selectable. for C or F.  If the TY stations and Weather Channel made the switch, it would relatively easy to train the populace to accept Celsius.  And 110ºF does sound better as 43ºC

Most, if not all, of our durable goods manufacturing has gone metric already.  The medical industry and the scientific community have been metric for as long as I can remember.  I had been introduced to metric measurement  over fifty years ago and have used both on a regular basis ever since. So what's left?  For the most part, popular acceptance.

With learning a foreign language, it takes a fair amount of time to think in the language rather than translating from our native tongue.  The same is true for Americans dealing with the metric system.  When we look at 4", we don't see 10 cm; we have to mentally do the conversion.  When we get to the point of thinking in mm,  kg,  and liters, we will have converted.


----------



## Dave Paine (Jul 27, 2018)

There was an act for the US to adopt the metric system signed by Gerald Ford in 1975.

Metric conversion act Wiki page


----------



## Bi11Hudson (Jul 27, 2018)

This one truely seems to be significant. It's like I said in an earlier post, "I stepped in it big time". So, I guess I should add this: We, as Americans, have had access to the metric system for a while. My studies indicate that the metric system was well supported by Thomas Jefferson. Just following the war of 1812*... ... *The concept was declined by the U.S.Congress because we (the States) were still mostly trading with England and wanted the maximum compatible system of measurement. With that in mind, standing with the imperial system as technology advanced has caused us to become seriously dependant on the "English" imperial system of measurement. If we had gone metric then, it would be a non-issue. Might also have helped during WW 1 and 2, using foreign made parts as "git by" repairs.

If I may bring your attention to the Ford Mustang II, from the late '70s if I recall correctly. The one that had a four cylinder engine*... ...* There were some 14 fasteners (bolts) holding the water pump to the timing cover. Six of those were 1/4-20, the others were M6X1. Caused no end of trouble for mechanics of the time, most of whom considered metric to be one step away from Martian. Especially as they were mixed. Drop one wrench and look around for that "odd one" size.  Then grab the 7/16 again.

Then, a while back, the English opted for the metric system. *Almost *like a plot to leave us in the U.S. hanging on to an archaic system trying to catch up. It's like anything else, "Follow the money". Yeah, I'm waxing a little "salty" here. It's early and I'm not awake yet.

*To digress*; and it's not "off topic", although does come close. Someone had asked about a "conversion" chart on screw sizes, imperial to metric. For what it's worth, I am currently in the process of building such a chart of the smaller sizes. It is for my own gratification, so may contain some empty slots. And will contain some archaic machine screw sizes and threads that haven't been used for many, many years. Mostly as a curiosity, to satisfy my own desires rather than needs. I will post it when I have it far enough done to make sense.

Machine screws are a curiosity themselves. Starting with Size 0 at 0.060"X80TPI, about 1.5mmX0.5. Mighty close there. Then stepping by 0.013", damn near *1/3*mm. Another curiosity, why not some other stepping. And, if you look at a Nr6-32 TPI, it's 3.5mmX0.8 (to 4 decimal places) an almost true metric thread. But that's why it is "in progress". Many of my models are (were) built in Japan. Which, for years, was half imperial and half metric. Go figure*.. ... *What caught my attention is the size Nr14. 1/4" is 0.250"X20, Nr14 is 0.242"X24 and M6X1 is 0.236"X25.4. Curious* ... ...*

Bill Hudson​


----------



## Dave Paine (Jul 27, 2018)

The US did come close to adopting the metric system in the days of Thomas Jefferson - if not for some pirates.  I found this an interesting read.

Pirates hijacked the Americas using the metric system.


----------



## jdedmon91 (Jul 27, 2018)

randyjaco said:


> I just don't understand why this country refuses to go metric. The imperial system is archaic. We are just being Luddites on this issue. It is time we bite the bullet and made the change. The vast majority of our manufacturing companies could do it over night, if it weren't for there current inventories.
> Randy



Not that simple. The investment in measuring tools alone would cost a fortune. The company I retired from just made the outside the US use decimal system. We have returned product that came from the Mexican plant and photos of the measurements were in decimal. 


Sent from my iPhone using Tapatalk


----------



## uncle harry (Jul 27, 2018)

Dave Paine said:


> That calculator is indeed sophisticated.    I looked at the User Guide.   Easy to set for entering Imperial or Metric, but converting is not so easy, it is part of the Conversion menu.The Staples calculator and others like it would be far simpler to convert between Imperial and Metric.  I may have to get one for myself.   I have an HP32 calculator which does all sorts of functions, but no Imperial to Metric, other than my entering 25.4/ or 25.4*.



I occasionally use a digital caliper having both metric & Imperial capability as a converter .  Kind'a like using a slide rule, slip it to a position close to the 
desired value on the engraved scale on it's length & then "tune" it to the metric or imperial digital value in question. Then hit the alternate system button for the conversion.


----------



## savarin (Jul 27, 2018)

If you blame the English for the imperial system you are stuck with why are your gallon and fluid ounces so different? (serious question)


----------



## RJSakowski (Jul 27, 2018)

savarin said:


> If you blame the English for the imperial system you are stuck with why are your gallon and fluid ounces so different? (serious question)



We originally used the same system of weight and measures as the British.   In 1824, the British Weights and Measures Act redefined the pint and therefore the gallon and the fluid ounce which was then the standard throughout the British Empire.  We continued to use the old British system of weights and measures as we were no longer part of the British Empire.

A question back at you.  We have a saying "the pint's a pound the world around" which is true for the American pint which contains 16 fluid ounces and weighs close to 16 ounces which is a pound.  However the British pint contains 20 fluid ounces. How come?


----------



## Nogoingback (Jul 27, 2018)

Just buy a set of Mitutoyo calipers: they'll do the math for you by pushing the button.


----------



## savarin (Jul 27, 2018)

Damn you young man you made me search for an answer
https://www.quora.com/Why-is-an-American-pint-of-beer-smaller-than-a-British-pint


----------



## RJSakowski (Jul 28, 2018)

Just think, before the internet and Google it would have been the subject of an all night discussion in an Irish pub.  That is, after all, how the "Guinness Book of World  Records" got started.


----------



## higgite (Jul 28, 2018)

If you can tell time with a clock that isn't metric, what's the problem with measurements that aren't metric? You metric guys are just lazy, that's all there is to it. 

Tom


----------



## Dave Paine (Jul 28, 2018)

RJSakowski said:


> We have a saying "the pint's a pound the world around" which is true for the American pint which contains 16 fluid ounces and weighs close to 16 ounces which is a pound.



I went to school in the UK, our saying was "A pint of pure water weighs a pound and a quarter, a gallon of water weighs ten pounds"

I did like Savarins link about how the US and UK fluid ounce changed.

It is interesting that the UK has generally gone metric, except for beer still being sold in pints and speed in mile/hr.


----------



## RJSakowski (Jul 28, 2018)

higgite said:


> If you can tell time with a clock that isn't metric, what's the problem with measurements that aren't metric? You metric guys are just lazy, that's all there is to it.
> We also measure angles in degrees, minutes, and seconds.  This apparently goes back to antiquity, predating the ability to divide time into minutes and seconds by more than a thousand years.
> Tom





Dave Paine said:


> I went to school in the UK, our saying was "A pint of pure water weighs a pound and a quarter, a gallon of water weighs ten pounds"
> 
> I did like Savarins link about how the US and UK fluid ounce changed.
> 
> It is interesting that the UK has generally gone metric, except for beer still being sold in pints and speed in mile/hr.


Also milk although on recent trips I seem to recall the canned beer and milk are now dispensed in ml.  They probably won't be successful in changing a pub pint though as changing the size to 500 ml would serve 68 ml less beer.


----------



## hman (Jul 30, 2018)

One of the complications (difficulties?) I've frequently read about is the need to replace fasteners with the nearest equivalent size in "the other" system.  Bill Hudson just posted a very nice screw size chart, showing Imperial (number) and metric fastener sizes, all sorted by major diameter.  
https://www.hobby-machinist.com/threads/machine-screws-inc-archaic-sizes.71735/
Download the PDF.  It should be pretty helpful when converting.


----------



## Bi11Hudson (Jul 30, 2018)

If I may: The chart referred to was for my own purposes, my own uses. There are a number of holes where metric and imperial thread "pitch" and TPI are not listed. The conversions there are for younger eyes than mine. Feel free to fill it in, long as you post the updated version*!*

I also would like you to take note of the many *archaic* imperial sizes that have not been used for many years  Nr 14 VS 1/4-20 for example. We have stabilized(?) the industry to the point that many of those sizes are now obsolete. From 5/0-160 to 6-32 are still fairly common, especially in "optical" sizes or applications. Those larger are today figured by even numbers such as 6,8,10, &12. Anything larger is figured in fractions. While *my* tap sets have Nr 12, I haven't seen them recently. My interest in the odd sizes is pure purely academic. So far*... ...* But, I do like old machinery.

One other point I'd like to bring to your attention: *Rounding*... As stated above, by several folks, rounding is fine in some applications. And doesn't matter in others. Many of the conversions done with that chart came out to 7 or 8 places. At the 4th place, if it was 50 or less, it was rounded down. 51 was rounded up. Most measuring instruments stop at 3 places. Rarely at 4. That's my reference point. Your's may be tighter. Any metric conversion is liable.

Bill Hudson​


----------



## hman (Jul 30, 2018)

Thanks for clarifying, Bill.  I was assuming that, by giving the link to your post instead of reproducing the chart, people would read what you said and use the information with due care.  But we all know what value to give "assumptions."

Nevertheless, you've provided some useful information.


----------



## warrjon (Aug 3, 2018)

Being an Aussie I mostly work in metric but I have a couple of imperial mics incase I need to work in imperial, so I don't have to keep converting. I was almost in high school when Australia converted from imperial to metric so use both.


----------



## bollie7 (Aug 5, 2018)

As another aussie I was in high school when we officially went metric. That was 1972. What is interesting is that 15 years ago TV's were sold by metric screen sizes ie 106cm, these days we have gone back to TVs in inch sizes. More than likely that is because most tvs come from China and the USA is China's biggest market. What is even more interesting is the kids here who will talk in feet and inches, even though they have never been taught that in school. If you ask them to show you approx how long an inch or a foot is, most of them haven't got a clue. Why is that? Well I reckon its because most the TV shows and movies they have been brought up on are of USA origin.
Then you have the weight of newborn babies, for some weird reason grannies can't understand the weight of a baby in grams. No it has to be in lbs and ounces. Yet they have no problem buying a couple of Kg's of meat at the butcher or 500 grams of butter. The funniest thing of all with this is most of these grannies these days were still in school when the country went metric. Go figure.
Now, when you go to buy self drilling screws at our big hardware store the size is mm for length and gauge for dia. huh?? Gauge hasnt been used here for 40 + years. I dont get why they just cant give the dia in mm as well. Talk about confusing. It just goes on and on. 
Peter


----------



## Brian Hutchings (Aug 5, 2018)

Quote 'Talk about confusing'. Well yes it is and it would be a lot better to stick with inches and ounces.
I started work at a company making Imperial sized engines but then they got a license to make a French engine (stolen from the Germans) that was all metric.
The company set up a department to make these engines and equiped it with metric tools and drawings.
Much later, Ted Heath (Prime Minister) announced that England WOULD go metric, to which I and many others took exception. I always ask for Imperial measurements when buying loose goods but I know what the meric equivalent is and it's surprising (perhaps not) how many time a rip off is attempted.
Brian


----------



## Bi11Hudson (Aug 5, 2018)

*O.T.,* sorta. Still regarding measurements*; *mostly a rant*.*

My house is old. Not just old, but *old*. Built in *18*86, best I can figure from the deed and documentation. It consists of 2X4 walls. In the original  part, the 2X4 is 2+ by 4+ red pine. In the additions, from before 1913, a 2X4 is 1-7/8 by 3-7/8. In more modern updates, post depression era, a 2X4 is 1-5/8 by 3-5/8. In my era, since 1975, that 2X4 is now 1-1/2 by 3-1/2. When I was updating the electrical system, ca. 1975-6, I had trouble drilling through some of the old lumber. When I started doing carpenter and finish restoration, I had to purchase a (current)2X6, and then plane it down to get a (true)1X5 for an older wall. Since both sides were exposed, shims wouldn't work.

With that in mind, what's wrong with metric measurement for lumber?  Except that metric standards are smaller still. An example would be in plywood.  Yes, it's still 4 ft by 8 ft. But nominal U.S. standards are getting harder to find. 1/2" CDX, sheating grade, is now sold as 15/32 inch. Close, but it is still 12 millimeter. A fuzz under 15/32. In many cases, it doesn't matter.  In my case, I had to compensate when I made some esoteric repair. Another shim... ... I suspect, if truth be known, the really modern 2X4s are *metric*, just sized to look like 1-1/2 X 3-1/2.

I could rant for hours on the subject of reducing the sizes (and quality) of lumber.  But why should I raise my blood pressure worrying about it.  Just move to metric sizes, it can't be any more complex than what I deal with in reduced planed sizes. When you are building new, it doesn't come up.  Only when a cheap old buzzard like me gets involved.

Bill Hudson​


----------



## f350ca (Aug 5, 2018)

ah but Bill, the new wood is stronger, so a 1 1/2 x 3 1/2 stud will carry the weight of the old 2x4

Greg


----------



## Bi11Hudson (Aug 6, 2018)

In a pig's patootie.


----------



## Brian Hutchings (Aug 6, 2018)

Quote"In a pig's patootie. "

Hello from the old country Bill. That's a very colourful (colorful) phrase and I think I can work out its meaning but could you explain anyway?
Brian


----------



## uncle harry (Aug 6, 2018)

Bi11Hudson said:


> *O.T.,* sorta. Still regarding measurements*; *mostly a rant*.*
> 
> My house is old. Not just old, but *old*. Built in *18*86, best I can figure from the deed and documentation. It consists of 2X4 walls. In the original  part, the 2X4 is 2+ by 4+ red pine. In the additions, from before 1913, a 2X4 is 1-7/8 by 3-7/8. In more modern updates, post depression era, a 2X4 is 1-5/8 by 3-5/8. In my era, since 1975, that 2X4 is now 1-1/2 by 3-1/2. When I was updating the electrical system, ca. 1975-6, I had trouble drilling through some of the old lumber. When I started doing carpenter and finish restoration, I had to purchase a (current)2X6, and then plane it down to get a (true)1X5 for an older wall. Since both sides were exposed, shims wouldn't work.
> 
> ...



I have  sympathy since my house was built in 1888 & added to in 1903. I also identify with the "cheap old buzzard" moniker.


----------



## Bi11Hudson (Aug 6, 2018)

In response to "furriners"(Brian), colo*u*rful is the correct spelling. The dropping of a character is a matter of what I call "lazy tongue". Shortening of a words spelling to make it easier to say. That's one source of where regional accents come from.
     The term "pig's patootie" is one of many expressions using a "socially acceptable" version of bovine excrerment without using the normal "bulls#!t". It's meaning, in this case, is that the contributor was making a facetous comment agreeing with, but dulling the edge, of my rant. But in a way acceptable to monitoring.
      The original purpose of this column was to help with a "beginner's" trouble with the inperial versus metric measurement systems. It digressed into a dispute regarding what and why that what was being used. My rant was making a parting shot at that why, and my standing on the subject.
      I agree with the original poster, with a few years experience to back up my technique for solving it. By using carpentry references, I could be more clear to "some" machinists. Especially those in a beginners position. Having worked in maintenance my whole life, I have almost as much experience in carpentry as electrical / electronics.
      Adding machining as a maintenance man is a difficult profession to describe. When I make a part, it is "to fit", not a designer's replacement part. It usually works, while it may, or *may not*, be right by the original design. That's where a moniker I sometimes use comes from. I make it to work, not to be right. You may recognise the word*... ...*

Bill Hudson
Master Artificer, Ret​


----------



## hman (Aug 6, 2018)

As I recall the story, the "original" 2x4 was rough sawn, and actually 2" by 4".  Then they started to smooth/plane the surfaces.  This reduced the dimensions, to around 1 ⅞ by 3 ⅞, or even 1 ¾ by 3 ¾.  How we got to the current size is a mystery to me.

Plumbing is another example of nominal sizes not agreeing with actual.  There's absolutely no dimension of ½" anywhere on or around nominal ½" pipe.  As I recall, pipe was originally sized by its internal diameter.  But early pipes were pretty thick walled, and the OD of "½ inch" pipe was what it is today, with fittings' IDs sized accordingly.  As better pipe materials became available, the OD was kept the same (for backwards compatibility), but the ID was increased by having thinner walls.

[PS - I seem to recall that European pipe fittings used the ISO system.  Don't recall how nominal and actual sized compared. Perhaps our cousins from across the pond would care to offer some enlightenment.]

I do agree that the metric system is worth adopting.  But I also see that it will be a tough and long-winded transition, given the huge installed base of "stuff" that we have.  Bill Hudson and Uncle Harry are just two examples of the gyrations and inconvenience of changing standards, that are bound to become almost universal.


----------



## Bi11Hudson (Aug 6, 2018)

This thread seems to have missed that* left at Albequerque*. I won't try to restore it*... ...* It seems to have a mind of it's own.  My father was a timber man in the early depression years. Working in a sawmill much of the time.  What he taught me about lumber... , well now-a-days what is sold for "A" rate material, was in his day, culls. A knothole did't exist, much less a scrap of bark. That fed the fire at the boiler house.

      To respond to the above comment;  In the late 19th century, lumber was cut such that a 2X4 was a "little" full, so that after the planer mill, it was a true 2" X 4".  As time wore on, it was cut to the finished size and then milled when needed.  Then the costs kept increasing so the lumber was reduced in size to try to compensate.  Follow the money*...*

I would remind you that Birmingham, Ala. did not exist in 1870. It is a city that arose where two railroads crossed. The whys and wherefores of the history of the area have been dug through and (mis)quoted for years. One has to piece together many tidbits of information to make sense of it. The more recent histories (since 1945) are left of the mark by a considerable amount.

That said, my house was built with cut (square) nails, when this area just opened up.  Lumber sizes were of an early transition from balloon construction to early stud wall construction. I have collected many books on the subject of residential construction for the simple reason of understanding what I was cutting into. That was important, considering the changes in lumber sizes over nearly 100 years.

The references to pipe sizes I will buy, until proven wrong. Not very likely, it sounds good to me.  But for lumber sizes, I have the word of many old timers in the business. Many older than Pop, and that's going some. (1906) 

The bottom line is that I trust my structures to support the weight of my "small" machines. I certainly wouldn't put them in a more modern building. I would want 4 inches(or more) of concrete below them. I was employed by a pipe foundry in the '70s where the shops were floored with wood a foot thick. It was devised during the first world war to fabricate munitions. The idea that if something was dropped, it wouldn't spark. 

The building is long gone, originating in 1886, by the initials scratched in the original footings.  Such lumber doesn't exist these days, although a stand of it was found on an Army base a few miles east of here. But is guarded by an old man with a shotgun to prevent cutting. The floor of the "shell shop" was made of short pieces about 6X6 inches tampted into the red clay of the area. Machines were bolted down with molten lead in drilled holes with the machines fitted over. But then, they were larger machines. Lathes with ways 20 feet long, and the ungodly swing of 5 feet. Just a little above jeweler's work, they were. Maybe came from a shipyard, who knows?

And as a parting shot, I *didn't* miss that left in Albequerque. I was paying attention when I was there in 1969, on old US Rt 66. I-40 was being graded, but traffic was still on Rt 66. All I remember about that trip was the loss of a bearing in my alternator, no money, and a limit on time. So, I fixed the bearing on the side of the road. That makes my rambling machinery related, I guess.


----------



## P. Waller (Aug 6, 2018)

Brento said:


> Ok thank you. Exactly what i wanted to hear. I still have my machines in storage but ik the SB lathe is dials and my mill does have read out.


You still don't get it, I suspect that you have no method of measuring a diameter of .8661417 +.00000001/ -.00000000", if you can not measure it you can not do it.
Most drawings made by a well schooled engineer will have dimensions like so, in inches for example 1.000" will tell you that the part must be within .000", there may be a callout of +-.0005 which is .001" overall. A metric drawing will have a dimension such as 22.00 MM.
If you receive a drawing with all inch dimensions to 4 decimal places or a metric drawing with all dimensions to 3 decimal places, run away.


----------



## Brian Hutchings (Aug 7, 2018)

Many thanks for the 'patootie' explanation Bill, I was nearly right in my guess as to what it was but I thought it was where it came out of rather than what came out!
I have to disagree about "colour or color" though. I have an English Patent dated 1858 that states that the Patent copy drawings are "not colored"
Apparantlly, some idiot in Victorian times thought that the English language would be more elegant if it was more like French, soo he went about adding totally unnecessary letters. The original spellings were identical to the American ones because they were originally English brought over by settlers.
In response to the query about European plumbing fittings by 'hman', yes, they are an ISO standard but most European countries use British Standard Pipe Threads but they don't call it that!
If English plumbers need to do work on older houses they take a trip to France, Belgium or The Netherlands (Holland) and get what they need at much reduced prices!
Brian


----------



## Bi11Hudson (Aug 7, 2018)

Brian;
Again I will say you are correct. It is where it comes from, not what comes out.  In this reference though, it is a crude but reasonably polite way of saying the person is full of it.


----------

