Thread: Metric / Imperial relationship reference

Originally Posted by Lappa

They mainly do high performance including drag, circuit etc. Most of their high performance engine parts are still imperial as they mostly come from the US

Not that I doubt you, but in US catalogues I've seen router bits sizes like 15/64 (which is 6 mm in our language) and thus suspect that many US dimensions are really the nearest 64th or thousandth equivalent to a metric size.

Any imperial measurement, either decimal or fractional, can be expressed in a metric decimal equivalent. It is often the case that a metric measurement cannot be accurately expressed as an imperial fraction.

There are now only 2 countries in the world that hang on to the imperial system of measurement. The United States, and Myanmar. Make of that statement what you will.

At the end of the day, a measurement is just a number. It's just about positioning it, repeating it, filling it, etc.

Cheers

Originally Posted by ian

Not that I doubt you, but in US catalogues I've seen router bits sizes like 15/64 (which is 6 mm in our language) and thus suspect that many US dimensions are really the nearest 64th or thousandth equivalent to a metric size.

I wouldnt call 5.953mm 6mm.. sure it's close, but it's not the same.

It's the same as people saying 9/16 is the same as 14mm it's not, it's 14.28mm, as many a damaged bolt or nut can attest to.
Same goes for 7/16 vs 11mm, 1/2 vs 13mm, 3/4 vs 19mm etc. As a I work on new through to vintage, I have sets of metric, imperial, and Whiteworth/ BSF. Makes for an expensive tool kit with some tools being used once in a blue moon, BUT I have then so I dont have to improvise with the incorrect fitting tools.

A man after my own heart, use the right spanner for the job not one that is close.
Unfortunately we seem to be drifting off the original post of a helpful chart that was put together to assist himself and others should they wish to use it.

Originally Posted by Treecycle

A man after my own heart, use the right spanner for the job not one that is close.
Unfortunately we seem to be drifting off the original post of a helpful chart that was put together to assist himself and others should they wish to use it.

This made me chuckle. I've come to realise that any initial post is really just a starting prompt to get people discussing something. I noted after the first several posts that most people either just skimmed my post, or went straight to the chart with little consideration for why I actually created it.

I'm fine with that, I just sat back and enjoyed the ride

Originally Posted by Lappa

I wouldnt call 5.953mm 6mm.. sure it's close, but it's not the same.

Same goes for 3/4 vs 19mm etc.

??

I seem to recall that the <2 thou difference is less than the allowed tollerance

I know exactly what you mean about YouTube videos. As soon as they talk imperial, they might as well speak in Latin. Except Latin still has some relevancy.

I just switch off mentally when they talk imperial and watch it for the concept or inspiration. Not for any details. Then if I do a project based on those ideas I have to design it myself. Which leads me to incorporate 'improvements' so I end up with something quite unique anyway.

What frustrates me more is new tools being expressed in imperial. Why should I pay for new and get something from the last millennium?


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Originally Posted by DaveVman

What frustrates me more is new tools being expressed in imperial. Why should I pay for new and get something from the last millennium?

it might be my age, but what is the problem?

the only tools where the width is important are chisels and grooving / rebating blades (and those router bits used to create grooves and rebates)
and in that case you want your chisel and grooving blade to be the same width so that they work together.

As I said above, parts need to fit -- they don't need to be some exact measurement. The wood doesn't care -- nor do your fingers or eyes.

Originally Posted by DaveVman

What frustrates me more is new tools being expressed in imperial. Why should I pay for new and get something from the last millennium?

Or if you're particularly perceptive you could do what I did, and buy a tape measure, get home and discover that it's metric on one edge and imperial on the other. And as per the rules of fate, my most oft used edge is the one with imperial measurements.

So now I grab my wife's tape (the one she bought) instead.

Originally Posted by ian

it might be my age, but what is the problem?

OK - so this is not directed at you but to illustrate what just part of issue is. Quite frankly the following are the thoughts that are going through my head during these transactions and I bet that 95% of people under 60 and outside USA/UK are the same, even though we usually don't express them. (I feel sorry for Canadians to be honest).

For just one example, if I am going to lay down 4 figures of my hard earned cash on a new machine then why would someone try to tell me it's capacity in units from pre-roman times?

<scenario>

"Please buy this 8 inch jointer.."

- What the F*&^ is 8 inches??????
- Don't answer that because I don't give a flying rat's rear end what it is. Why would I?

- Listen, I am the customer. It is not my job to go away and research ancient history and translate that to something meaningful. That is your job. It is called marketing. Look it up. It's another one of those innovations that occurred over the last 1,000 years that you seem to have missed.

- Just how good can this machine be given that it appears to have come out of some archeological dig site? What happens when I need a part for it made in the current century?

</scenario>

......Yeah I could go on and on with the sarcasm on this topic - but you get the idea.

eight inch = two syllables
two hundred and three point two millimeters = waaaaaaaaaay too many syllables!

gimme a 8be4 sheet of mdf.
gimme a twenty four hundred by twelve hundred sheet of mdf.

It's good to be able to speak in imperial. I imagine it would be good to be able to speak another language as well, but since I speak English I just assume everyone else does too

Some of you guys must be having conniptions at the way I mix imperial and metric in the dust forum.

I can think and work fine in both systems but its interesting that I tend to favour one system over other in certain situations mainly because I can think slightly faster in a particular system for different apps. e.g. Imperial for DC air flow rate, flow speeds and pressure, whereas for other fluids I tend to think in metric.

For Timber I tend to think in imperial, but metal it's metric.

Because I often work on older machines I have to work in imperial but where I'm refurbishing something that was originally imperial, if I can I tend to use metric replacements.
A lot of what I do uses recycled materials so quite a few of my projects end up being a mix.
If I'm working on a project and look in my fasteners drawer for metric bolts but don't have enough of those but I have enough imperials I will use those.
All 4 of my chainsaw mills are made using a mix of metric and imperial bits.

It's similar for language, when I see things like an apple or a truck the first descriptor words that come into my head are from my mothers italian dialect that we used as kids.

Originally Posted by Kuffy

eight inch = two syllables
two hundred and three point two millimeters = waaaaaaaaaay too many syllables!

Except to some extent this is a fallacy of conversation.
It should be manufactured to 200mm or 20cm. We're metric.
Which means its 7.874015748 inches.
Give me two hundred mils = 3 words
over seven inches eight hundred and seventy four thousands of an inch = 11 words any day.

See what I did there?



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Originally Posted by DaveVman

OK - so this is not directed at you but to illustrate what just part of issue is. Quite frankly the following are the thoughts that are going through my head during these transactions and I bet that 95% of people under 60 and outside USA/UK are the same, even though we usually don't express them. (I feel sorry for Canadians to be honest).

For just one example, if I am going to lay down 4 figures of my hard earned cash on a new machine then why would someone try to tell me it's capacity in units from pre-roman times?

<scenario>

"Please buy this 8 inch jointer.."

- What the F*&^ is 8 inches??????
- Don't answer that because I don't give a flying rat's rear end what it is. Why would I?

- Listen, I am the customer. It is not my job to go away and research ancient history and translate that to something meaningful. That is your job. It is called marketing. Look it up. It's another one of those innovations that occurred over the last 1,000 years that you seem to have missed.

- Just how good can this machine be given that it appears to have come out of some archeological dig site? What happens when I need a part for it made in the current century?

</scenario>

......Yeah I could go on and on with the sarcasm on this topic - but you get the idea.

Dave, chrissakes man, settle down before you have an apoplexy! Regardless of how you feel about Imperial measurements, those that can converse in both systems are much better off - just like spoken languages. Full stop, end of section.

In your case it would prevent you having to get so wound up about an advert. Apart from that there are some really useful measurements in Imperial, such as a foot or two, an inch or two, and a few others. Obviously you can't comment on how useful they are because you don't know what they are.

Here's another example: I can converse with people who only know one system or the other - which includes you - and with equal ease. Imperial-only people will not die off for another 25 years or so, and you may not even make it that long......

Now I do say that the Metric system is where it's at, particularly for spreadsheet use, and other logical applications. Where Imperial really falls to bits is in the fractions of an inch - even though I can correctly identify them with a gap between my fingers. (Yes, I'm another who was at high school in the 70s when we changed over - AND had all the GREAT music). We don't have to get into the silliness of Rods, Perches, Furlongs, Chains etc etc etc. My favourite STOOPID Imperial measure is a CWT aka Hundredweight which wasn't a hundred weight at all - it was 112 "lbs" (which somehow means pounds).

See? You really didn't know how cumbersome Imperial was, didja?

No need to get so excited though, it does have it's useful characteristics.