Metric / Imperial conversions

[mzetati]

What is it with you guys? Don't you have a calculator lying on your workbench?

Want the decimal equivalent of 39/64? Just divide 39 by 64
Want to convert 6 mm to inches? Just divide 6 by 25.4
Want to convert 3.5 inches to mm? Just multiply 3.5 by 25.4

I have a couple of 'Euro' converters I bought purposely: I set the 'currency' conversion factor to 25.4 to see the metric result as soon as I key in the Imperial value digits.
Works with "39/64=" too!! ;D

Marcello

 

[jonesie]

i have to agree with marv.go to the dollar store and buy some dollar calculators and just do the conversions so you have exact number and then round off if you need to.it is as fast and simple as finding the right chart. iwill take a print and convert all the numbers before i start a project. just my thoughts jonesie

 

[mklotz]

Yes, go to the dollar store. But don't buy a cheap four function (add, subtract, multiply, divide) calculator for a dollar. Instead, buy a cheap scientific calculator for $5. That way you can throw away your trig tables since all those functions are built in, as are the conversions between decimal and deg.min.sec angles. Most of them can do fractional calculations directly (as, 3/4 + 1&7/16 = 2&3/16) and convert the result to decimal with the push of a button.

And for David, the OP, who can't cope with "long strings of odd digits", scientific calcs have built-in formatting functions that can be set to automatically round the display to any number of decimals.

 

[Lew Hartswick]

Yea Marv. If only those cheep ones used RPN I'd have one every where I sit down.
...lew...

 

[mklotz]

Yea Marv. If only those cheep ones used RPN I'd have one every where I sit down.
...lew...

Oh come on, Lew. If you're clever enough to use RPN, you're clever enough to retrain yourself to use algebraic.

 

[Maryak]

Whose a Hewlett Packard fan then ;D ???

Best Regards
Bob

 

[mklotz]

Whose a Hewlett Packard fan then ;D ???

I, enter, am.

The calculator program I wrote (it's on my page) is RPN and includes a few features that HP left out.

 

[boxcarmj]

Fast & Easy -- http://www.kbismarck.com/weights.html

 

[Lew Hartswick]

Whose a Hewlett Packard fan then ;D ???

Best Regards
Bob

Me!! It's the ONLY kind to have.
Who needs an = sign? And especially to re-enter a solution to part of a problem to
do the next step. BAH!
...Lew...

 

[Swede]

Am I the only Imperial guy who almost never uses fractions? In my head, they're all decimal. 0.250, 0.500" etc . 1 inch is divisible by 10, 100, and 1,000 just like a mm or cm.

The usual grumbling from Metric guys is "those fractions are a pain to work with." Yes they are, but why bother with them? As model guys, we rarely work with feet, only inches. And there are 1,000 of our favorite "units" per inch. I don't know if this is making any sense. I don't think 9/16ths, I think 0.562", or 0.500" or whatever.

That said, I've never had problems working on Metric plans. Especially if you have a DRO, it is child's play. About the only thing I have trouble with is a mental "rule of thumb". I can visualize what a 0.100" cut looks like in my head, but not so well when using mm. ???

 

[Tin Falcon]

I am with you swede i can easily convert fractions to decimals most of the time in my head. I also convert ounces to pounds regularly (I am a scale mechanic) we have two weight kits one the small weights are decimal pounds the other fractional ounces.Tell me that is not confusig at times. You would be surprised or not the number of folks that have no idea how to convert ounces to decimal pounds. Easy for a machinist who is used to converting inches in 1/16ths to decimal inches or the other direction.
I also worked in a steel fabrication shop for about a year. the lead guy in the shop had been a dentist. Yeah not kidding. smart guy 4.0 average all the way through medical school . but he needed a construction calculator to add and subtract fractions. I did it in my head then checked with soap stone on steel.

Tin

 

[lazylathe]

I grew up on metric and have a hard time figuring out fractions....

Just a story now:

I went to Home Despot to get some plywood cut for my bench.
I whip out my diagram with measurements on it and they are in cm.
I tell the guy i need four bits cut to 98,5 X 85,5.
He looks at me and tells me the sheets of plywood are not big enough for my measurements!! :big:
When i tell him they are cm's he pulls out his tape measure and asks if he can convert to the nearest 1/16th.
Confused the heck out of me!!!
Even though his tape measure had inches and cm's on it he could not do the measurement in cm's!

It was quite a fun evening!!

Andrew

 

[Tin Falcon]

Andrew when I was in high school in 19XX there was a big push on metric . the us was converting to metric and metric had to be taught and learned in school . Edmund scientific had kits with metric measuring tapes and other aids for learning metric. So I learned metric. I used metric for engineering classes and chemistry in college.
I admit metric makes more sense in most cases. but I still live and breathe imperial measurements for the most part.
Tin

 

[Lockstocknbarrel]

Hey Tin,
You must be as old as me. ;D..I remember when 342434 was just an amassing measurement then they added...ABCD :bow:
But now Metrics have come along it does not seen the same.
But I must admit using metrics to measure a flat surface that man is deserving of knighthood.

 

[Swede]

I do believe that metric is, overall, a superior system. When you look at prints for a steam engine, you see the dimensions like

<-- 5 -->

Or

<------------ 3.2 --------->

And you rarely need to mess with hundredths of a mm, since 0.1mm = 0.004"

It makes for a clean and logical layout of components. But in the end, I guess yo use whatever you grew up with. It's interesting that the USA switch to metric decades ago failed so badly. I suspect it was because we had billion$ if not trillion$ of $$ worth of Imperial machinery, tools, etc. Entire industries, giant factories, were all inch, like the factories that pump out imperial fasteners by the thousands of tons annually.

 

[Russel]

As I understand it, a thousandth of an inch (0.001”) is a tolerance that can be machined and a ten thousandth (0.0001”) is a tolerance that can be precision ground. So, imperial measurements kind of falls into place for machining. I know this isn't carved in stone, but it is a fair rule of thumb.

Unless I'm machining something that doesn't need accuracy, I usually machine to a thousandth of an inch. A thousandth of an inch in millimeters is kind of an odd number, at least for me, 0.0254mm. Machining to a tenth of a millimeter is a little course, 0.1mm = 0.0039”, and machining to a one hundredth of a millimeter is a little to fine 0.01mm = 0.00039”.

 

[greenie]

A thread that is 3 years old has surfaced once again, amazing, eh.

Russel, have you read the third post of this thread, if not, here it is again.


-- "OK, here's another way of doing the conversion and it's real easy too, it is not 100 % dead nuts spot on, but it's that close it actually works.


0.040" = 1.00 mm

0.020" = 0.50 mm

0.010" = 0.25 mm

0.004" = 0.10 mm

0.002" = 0.05 mm


It's so quick and easy to do any converts from either Mongrel to Metric, or the other way round, it gets you that close, then it's out with the appropriate micrometer and you can then get it dead nuts spot on.

The machinery I work with, lathe and mill, are all graduated in Metric and to get it converted to Mongrel, well it's just a "chunk of urine" doin' it this way

OK, the purist are gunna shoot this lot down, just 'cause it aint 100% dead nuts spot on, all I'm sayin' is, give it a go and see how easy it is to do the converts.

regards greenie - "



Instead of trying to remember all those little numbers, just make them into these 'full numbers' and it actually works.

Easy as falling of a wet log, eh.

regards greenie

 

[AussieJimG]

Life for the imperial guys would have been much easier if the micrometers etc. used octal (at least up to 1 inch). Then 0.1 = 1/8", 0.01 = 1/64 and so on.

The fractions are all basically binary: 1/2, 1/4, 1/8 and so on. The crazy part is converting to decimal on the dials.

Of course once you get over 1 foot, you are on your own. Or as Bernd says: You can't fix Stupid.

Jim

 

[Peter.]

I can't convert the fractions to decimals in my head - but I know the 1/8th sizes by learning them rote, anything more than that and I grab a calculator. I just bought a couple of hundred imperial taper-shank drills, but I do all my work in metric. Do I care? Nope - I just measure them with a caliper - same as the metric ones I have. Some of them make great tapping-size drills.

 

[terryd]

I am with you swede i can easily convert fractions to decimals most of the time in my head. ...........
Tin

It's really easy to convert fractions to decimal and to metric if you require, what is more difficult is multiplying or dividing fractions without converting. Try dividing 3 7/8 by 1 9/16 ???

T