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still can't figure out scale measurements

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  • Member since
    January, 2019
  • From: Phillipsburg,NJ
still can't figure out scale measurements
Posted by NewB71 on Saturday, April 20, 2019 1:15 PM

I am soon going to be building a new truck and I still can't figure out how the hell to convert like inches to mm or the other way around. Is there an easy way to do this:? Thanks Bob

  • Member since
    March, 2012
Posted by AstroDad on Saturday, April 20, 2019 2:27 PM

Hi Bob,

Assuming your are building for enjoyment and not some super-over-the-top contest, for 1/25 scale, 1 inch real life is just about 1mm in scale. To my eye works fine for 1/24 scale as well. And easy to remeber 1inch=1mm

  • Member since
    February, 2016
Posted by Plowboy on Saturday, April 20, 2019 2:45 PM

That's why the metric system sucks. One inch equals 25.4 mms. On short measurements up to around ten scale inches, you can do one inch equals one mm. Anything above that, your measurements will be off. Even at ten, the measurement won't be accurate. But passable. I do it old school and take the full scale measurement and divide by the scale I'm building. Much simpler for me.

  • Member since
    February, 2008
  • From: Auburn KY
Posted by jonesmarc on Saturday, April 20, 2019 4:37 PM You can do your conversions with this tool

  • Member since
    January, 2005
  • From: Canberra, Australia
Posted by aussiemuscle308 on Saturday, April 20, 2019 7:56 PM

That's why the metric system sucks.

no, that's because you are converting to an out of date stupid British (not U.S) system. You can't quickly calculate stuff unless you're brilliant at maths. you just have to learn by rote to remember the next size up or down. for metric, you just need to count.

eg, i've got a 6mm drill that's a bit too small. next size up is 7mm, easy. what's the next size up in imperial? a diameter is 10mm, the center point is 5mm, easy. what's the center point of a 5/16"? i have no idea!

to OP, i use the above conversion calculator, or just a desktop calculator to divide from the real size by 25.

My Flickr:

  • Member since
    January, 2019
  • From: Phillipsburg,NJ
Posted by NewB71 on Saturday, April 20, 2019 10:27 PM

Thanks for the replies and hints and I agree the metric system sucks. Thank god we don't go to the  British system of money,that would really suck.

  • Member since
    January, 2019
  • From: Burleson, TX. Grew up in Pittsburg and Whitehouse TX
Posted by ModelTexan1 on Saturday, April 20, 2019 11:23 PM
You kind of answered your own question when you stated the center point of a 10mm diameter is 5mm. You mentally divided it by 2 to get the center based on the radius. Same thing holds for English measurements. The center for 5/16 inch diameter is half, or 5/32. (to divide, you simply multiply the denominator by 2). Most rulers marked in Metric and English will have both mm and 32nd markings.
  • Member since
    May, 2005
  • From: Central U.K.
Posted by hayes on Sunday, April 21, 2019 5:37 AM

There seems to be a lot of confusion & a lack of facts here. The "stupid" British system of measurement is exactly the same as the American system - INCHES whether in decimal or fractional form. The British system of money that "sucks" is the same as the American system - i.e. 1 Dollar = 100 cents, in the UK 1 Pound = 100 pence & has done for over 50 years.

The easy way to do scale conversions is, as has been suggested, buy a scale conversion ruler - or - use a calculator by dividing the full size (1:1) measurement by 25 to get the scale (1:25th) measurement. If you want that in millimeters multiply the answer by 25.4, as Plowboy said. If the full size (1:1) measurement is in millimeters divide by 25.4 & then divide that to get the scale (1:25th) measurement in inches. Simple. 

  • Member since
    August, 2015
  • From: Hamptonville, NC
Posted by TarheelRick on Sunday, April 21, 2019 6:47 AM

I have a 6 inch and a 12 inch ruler that has SAE measurements on one edge and Metric on the other.  I have found recently that using the metric side I can get more accurate measurements, especially when fabricating.  What drives me nuts is working on a lawnmower, my Ford Ranger, or any other late model piece of equipment and finding a mixture of SAE and Metric fasteners.

I build models because I can't afford the real thing!

  • Member since
    April, 2007
Posted by ford57bucket on Tuesday, April 23, 2019 1:26 PM

I have an app that is called Model Scaler.

don;t throw that away,i can use it!

  • Member since
    April, 2008
  • From: West Virginia
Posted by gramps-xrds on Tuesday, May 14, 2019 9:26 AM

I don't use metrics at all. Their not acurate. I prefer decimals. One inch is .040 in 1/25th scale. One ft. is .480. For me it's just so much easier this way.

Bill AKA Gramps


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