I've been searching my HD for anything left over or that was downloaded prior to the 'disaster', anyway I first found MSW some years back and it helped me like you would never believe, in fact I owe my knowledge to THIS SITE!!

 

In return I made this conversion chart, nothing that would set the world on fire but it helped me and I remember a few people showing interest. I've attached a picture of it but I do have the pdf which needs to be printed out at 100% to get the full benifit of the rulers on there, so don't print out using this image or you could find the ruler will be out of scale..

 

UPDATED!!! I've added the PDF file to this post, just print out at 100%, do not scale larger.

 

new-chart_zps919ef985.jpg

Conversion Chart.pdf

robin b, Chuck, jim mclay and 17 others like this

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Thanks Colin that's very useful. I have something similar converting Inches to 1:48 scale millimeters and real size rope circumference to 1:48 scale millimeter diameter. It hangs right in front of me in the works shop as I refer to it very often.

 

Remco

 

post-20-0-59791100-1361109225_thumb.jpeg

 

inch to mm and rope circumfence .pdf

 

 

 

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There are some nice apps to help you with: I use "measures light", but there are plenty of others for free.

 

XXXDAn

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I am sorry but it is probably the engineer in me. To convert any inch measure to millimeter (inch to mm) multiply by 25.4.

To go from mm to inch divide the number by 25.4.

If you want an approximate value drop the .4 and do it in your head. Thus 4 inches is 100 mm (approximately).

 

That number has been in my brain for more than 60 years.

trippwj likes this

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Let me expand a bit on my last post above. But let me start by saying that the metric system is great. It is easy to use and easy to 'visualize' dimensions.

I hate fractional dimensions in the English system. So I usually convert them into the decimal system first. Then it is much easier to visualize how much you are talking about. For example, what is the difference between 13/64 inch and 3/8 inch?

Can you really 'see' how much 13/64 inch is? I can see 3/8 but not 13/64, let alone what the difference is.

Now if you take .375 inch minus .203 inch or .172 inch, I can visualize how much that is. And I can measure it real nicely with my  calipers (it has a dial indicator with markings down to a thousands of an inch). 

 

If I have to convert a dimension of 1 and 13/64 inch to mm I don't use aps, I use my little calculator in the drawer in front of me:
(1+13div64)x25.4 = 30.559 mm. Of course, I would call 30.6 mm being close enough

 

If your model is in 1:48 scale, you take the full scale dimension (let's say twenty feet) and convert it to mm for your model by doing the same conversion on a calculator: 20 x 12 x 24.5 div 48 = 122.5 mm.

 

Finally let me give you another example how poor the fractional system is. If you are working with a line that is 0.50 mm thick and you want to know how much that is in inches, you divide the mm by 25.4 which is 0.020 inch. Now would you convert that to fractions of an inch? I don't think so.The closest I come up with is 5/248 inch, which is ridiculous. 

 

BTW. In 1959 the inch was set to be exactly 25.4 millimeters.  Prior to that, it was set at 39.37 inches per meter. The difference is only 0.0002%, or 2 parts per million. That's something we don't have to worry about. But it is interesting that the inch was set to that value, not the millimeter.

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here is my own converter  I have it in Excel  format and is dynamic so if you ad a new dimension row and add the new dimension in the grey full size column the chart will automatically ad all the numbers in each column.

 

I can only upload a webpage so if anyone want a copy of the file I will happily send you a copy.

 

This chart is easy to modify and it is great to see the information at a glance.

 

comparison of scales for shipmodels.htm

 

Michael

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Thank you very much for both charts. If you have a smart phone or an iPad in your shop there are several conversion apps that you can install for free. I really like the charts myself but there are digital ones out there.

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I printed several copies and pinned them all over my workshop. We chnaged over to the metric system about 40 years ago. So I am used to both systems. The only imperial measurement device i still have is an old boxwood folding rule. Because so many plans and info are in imperial measurement I have to do many conversions.

Thanks for the Chart

marius 

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I realize that some people have trouble using a calculator, but what if you had a situation where the original ship plan calls for a beam that was 9 feet and 10 3/4 inches long? Your model is in a scale of 1 : 90. How do you determine the model length of that beam? Certainly there are no conversion charts for all of those situations.

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Jay,

 

I agree that it is impossible to have conversion charts for everything and everymeasurement, thus:

 

It seems that those people need to learn how to use a calculator and need to know how to look up measurements ... in your example:

9 feet = 9*12 inch ( 1 foot = 12 inch)

plus 10 inch

plus 1 devided by 3 and after that multiplied by 4 (the 3/4")

that value divided by 90 gives the scaled value in inches

the inch value can be calculated to mm multiplying it by 25.4

shorthand:

((9*12)+10+((1/3)*4))/90 =1.325926" (*25.4 = 33.678582 mm)

 

google may come in handy ;)

 

needed to edit as I forgot a ')'

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Thank you Carl. There are times when a few calculations come in handy, rather than to rely on charts. 

 

I, for one, like to put a simple conversion into a simple 'formula', just like you showed.

 

That is not to say that all charts are useless.
I still have a conversion chart above my drill press that converts numeric and alphabetic drill sizes to something I can understand.
Like a number G drill is actually 0.261 inch, or a number 69 drill is 0.0292 inch.

post-246-0-62018500-1365292833.jpg

rtropp and jim mclay like this

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Jay,

 

I agree that it is impossible to have conversion charts for everything and everymeasurement, thus:

 

It seems that those people need to learn how to use a calculator and need to know how to look up measurements ... in your example:

9 feet = 9*12 inch ( 1 foot = 12 inch)

plus 10 inch

plus 1 devided by 3 and after that multiplied by 4 (the 3/4")

that value divided by 90 gives the scaled value in inches

the inch value can be calculated to mm multiplying it by 25.4

shorthand:

((9*12)+10+((1/3)*4))/90 =1.325926" (*25.4 = 33.678582 mm)

 

google may come in handy ;)

 

needed to edit as I forgot a ')'

 

There's an error here:  1/3*4 = 4/3 = 1.333... [3 repeats infinitely]  which does not equal  3/4 = .75

 

The correct equation is ((9*12)+10.75)/90 = 1.319444..." (*25.4 = 33.514888...mm)  [4 and 8 repeat infinitely in the inch and metric conversion answers]

 

The simple keystroke sequence is 9*12=+10.75=/90=

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