[Accrs-o] O Scale Dimensions

[ACCRS O Scale list]

 Steve,    Here's a link to NMRA standards for track centers---it's diff depending on era and of course if tangent curve or not ----https://www.nmra.org/sites/default/files/standards/sandrp/pdf/rp-7.1_tangent_track_centers_and_clearance_diagrams_2019.01.pdf
Tony--  Our O scale is 1/48.  The British use a a 7 MM scale that is close to 1/43.  It's the track gauge that is a mess in "O"scale ---a real rabbit hole.    The short is that a wrong gauge was used back in the 20's - 30's that was rounded up to inch and a quarter from the correct 1/48 scale (1.25 inches actually scales 5 feet instead of 4foot 8 &1/2 " ) . various attempts have been made to correct this by changing the scale or the gauge or both,  What has been pretty much settled on is US O scale = 1/48 and 1.25 " gauge for most models and a smaller group that does "Fine scale" or "Proto 48"  that is 1/48 with a gauge of 1.177 min -1.203 max .   I'll PM you because your model drawings need a longer explanation.   (And you other guys, No, I don't want to argue about it or be better informed. --add smile emoji here)
JJ    On Monday, November 8, 2021, 10:11:14 AM PST, ACCRS O Scale list <accrs-o at mail.accrs.org> wrote:  
 
 I am working on a plan for a small O scale layout.  Could someone remind me what the distance between track centers and what the vertical clearance should be?  I have been using 4 inches for both.
Steve Bull
On Mon, Nov 8, 2021, 10:04 AM ACCRS O Scale list <accrs-o at mail.accrs.org> wrote:

Message From: Tony Long  tony.long at outlook.com


I have a question on O scale measurements and wanted to check with others.

 

 

Conversion – what is the correct conversion for 2 Rail 1:48 scale.  I’ve seen it listed as 1:43.5

 

 

Using that then the spacing between rails for 4’ – 8.5” comes to 32.99 millimeters.   I don’t have any two rail O scale track here to check that.     Is that correct?    Using 1:48 comes to 29.90 millimeters. 

 

Millimeters is what I want to sketch with.

 

 

 
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Message From: Steve Bull  sbullfox at gmail.com

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