Slide Rule to convert dimensions scale to scale?

[Porkscratching]

I recall a post somewhere on the forum, not particularly recently, suggesting use of a slide rule to make simple conversions or take dimensions from one scale to another..

For instance, I would like to take dimensions from a 7mm to the ft. model or drawing, and convert them with as little maths as possible to 10mm to the ft. scale... Now it was suggested this could be done by simply setting a slide rule and reading off the result..this sounds like it'd be ideal... Any idea how you'd do this ?.

If it's a "goer" I can doubtless get a slide rule off evilbay for pennies !

Also are all slide rules marked the same ?

[ikcdab]

Slide rules, now there's a thing...I can't think how a slide rule would do this...

But an excel spreadsheet would do the job very easily indeed. 

Or just write a list on a bit of paper....

[Porkscratching]

I really don't want a computer or online based thing, I'm looking for some physical solution that will sit in front of me on a bench!

I could of course at length write a chart with some salient points on it, just that the slide rule thing sounded great, maybe i misunderstood..

[jcm@gwr]

I use scale rules, they are available in 2mm, 4mm and 7mm.

 

[meil]

16 minutes ago, Porkscratching said:

 some physical solution that will sit in front of me on a bench!

 

A calculator?

[dhjgreen]

For nostalgia's sake I bought slide rule at an antiques centre for £6 (last used one 40 years ago).

 

For your example, set 10 below the 7, use the cursor to read off against the dimension you require.

 

In my photo, 10 ft reads off as 14.3 ft

 

Edit: all sliderules will be similar, this one has some complicated scales for engineering calculations.

Edited August 18, 2019 by dhjgreen

[ikcdab]

try the attached....

Untitled-1.pdf

[rdr]

here's an easy way to do it with a calculator.

 

Take the measurement, let's say it's 100mm in 7mm scale, then divide it by 7 and then muliply it by 10

100 divided by 7 x 10 = 142.857

[Porkscratching]

Thanks all, so much for your rapid replies, that's great.

The one with the slide rule certainly was what the person before was getting at but not clearly explained in the way you did 

I'll print that little scale chart off too ( several times! )

Also handy to have rdr's equation to be able to work it out if needs be.

The scale rules again sound useful but do I imply they don't do one in 10mm ?... I'll be using that scale too..  

[jonny777]

26 minutes ago, rdr said:

here's an easy way to do it with a calculator.

 

 

 

Here is an easy way to do it without a calculator. 

 

In 7mm to the ft scale 2ft is represented by 2x7 = 14mm, 2ft 6in is represented by 2.5x7 = 17.5mm, 3ft is 3x7 = 21mm, and so on....

In 10mm to the ft scale 2ft is represented by 2x10 = 20mm, 2ft 6in is represented by 2.5x10 = 25mm, 3ft is 3x10 = 30mm, and so on....

 

It is called arithmetic - something we old geezers learned at primary school. 

[Porkscratching]

Yep, arithmetic, we did that too, unfortunately it wasn't my best subject..!

[Porkscratching]

1 hour ago, ikcdab said:

try the attached....

Untitled-1.pdf 1.32 MB · 9 downloads

I've got a print this in front of me on bench right now, just the job !.

..If I see a slide rule cheap I'll get one too, at least I'll look like i know what I'm doing..

[Bernard Lamb]

4 hours ago, dhjgreen said:

For nostalgia's sake I bought slide rule at an antiques centre for £6 (last used one 40 years ago).

 

 

Edit: all sliderules will be similar.

 

Unless you use an Otis King.

I used one for over thirty years. For nostalgia's sake I suppose I ought to get hold of one again.

Bernard

[jcm@gwr]

5 hours ago, Porkscratching said:

Thanks all, so much for your rapid replies, that's great.

The scale rules again sound useful but do I imply they don't do one in 10mm ?... I'll be using that scale too..  

 

To be honest, I don't know! I would hope that they do, 10mm is hardly an obscure scale!

But once you know the 'real' size, you can easily convert to 10mm, just multiply by 10! 

[Porkscratching]

I'll certainly check out the various scale rules, as you say 10mm is a fairly well used scale and you'd think they'd cater for it !

As they do seem to have a use in all this, I got a British Thornton slide rule from ebay a bit earlier for a fiver, so be interesting to have a play with that too, thanks to dhjgreen for the hints on how to apply it..!

[jonny777]

6 hours ago, Porkscratching said:

Yep, arithmetic, we did that too, unfortunately it wasn't my best subject..!

 

 

You might think yourself lucky, because in my day we had questions such as this - 

 

 

Sally has one pound seven shillings and sixpence three farthings. 

 

How much money would she have to give to each of her two brothers in order that they all had an equal amount of cash? 

 

Once we mastered that at the age of 9, most things seemed easy -

 

 (until we reached topological spaces about 10 or 11 years later). 

 

 

[rab]

6 hours ago, Porkscratching said:

Yep, arithmetic, we did that too, unfortunately it wasn't my best subject..!

Wasn't it one of the 3Rs, Reading, wRiting and aRithmetic

[Hroth]

13 minutes ago, jonny777 said:

Sally has one pound seven shillings and sixpence three farthings. 

 

How much money would she have to give to each of her two brothers in order that they all had an equal amount of cash? 

 

Surely Sally would feel hard done by if she had to share it with her brothers!

 

9 shillings tuppence and one farthing each.  And they say multiplication tables are unfashionable....

(And that pounds, shillings and pence are difficult to deal with!)

[Porkscratching]

Not much kop at riffmatic rab....but I woz ok at the weedin' an rightin'...

Edited August 18, 2019 by Porkscratching

[Hroth]

7 hours ago, dhjgreen said:

For nostalgia's sake I bought slide rule at an antiques centre for £6 (last used one 40 years ago).

 

For your example, set 10 below the 7, use the cursor to read off against the dimension you require.

 

In my photo, 10 ft reads off as 14.3 ft

 

Edit: all sliderules will be similar, this one has some complicated scales for engineering calculations.

 

Looks like a British Thornton* to me.

 

We started with log tables, progressed to sliderules and then one day, there was a small box on the teachers desk with glowing numerals, and a numeric keypad.  He said "This is the future, you'll never have to worry about sliderules again..."

 

As well as the BT which I still have, I've a cute little circular one that I picked up when a stationers shop was closing down.

 

* Perhaps not, or maybe a more upmarket one, the cursor is a bit fancier in your photo!

 

Edited August 18, 2019 by Hroth

[Porkscratching]

4 minutes ago, Hroth said:

 

Surely Sally would feel hard done by if she had to share it with her brothers!

 

9 shillings tuppence and one farthing each.  And they say multiplication tables are unfashionable....

(And that pounds, shillings and pence are difficult to deal with!)

Course the brothers would find Sally's conned them, as the farthings wont be accepted after 1960..

[Porkscratching]

2 minutes ago, Hroth said:

 

Looks like a British Thornton to me.

 

We started with log tables, progressed to sliderules and then one day, there was a small box on the teachers desk with glowing numerals, and a numeric keypad.  He said "This is the future, you'll never have to worry about sliderules again..."

 

As well as the BT which I still have, I've a cute little circular one that I picked up when a stationers shop was closing down.

 

Apparently they still use a circular type of slide rule in aircraft, presumably as a navigation aid or back up ?

[Hroth]

2 minutes ago, Porkscratching said:

Course the brothers would find Sally's conned them, as the farthings wont be accepted after 1960..

 

If the brothers can't work it out for themselves, she could do some appropriate rounding in her favour.  I'd assume that the poor benighted siblings were stuck in a 50s timewarp if the initial stake included a trio of farthings.

[Porkscratching]

Lucky them, wish I could join 'em.!

[Hroth]

11 minutes ago, Porkscratching said:

Apparently they still use a circular type of slide rule in aircraft, presumably as a navigation aid or back up ?

Apparently an "E6B", very special purpose!

 

https://en.wikipedia.org/wiki/E6B