Back to Back wheel Measurements

Finally got myself some calipers, and want to check my wheels...
what is the correct measurement for my OO, standard Hornby settrack?
I've heard 14.2mm to 14.5mm, though this was for Code 75 track.
As I understand it, it will depend on the radius of your tightest curve, and the clearance of flangeways (on the points)
As you will be using Hornby set track, then the flangeways are going to be pretty wide, so that shouldn't be an issue.
What will affect the setting is the radius of your tightest curve. Radius 1 is very tight, so will need a narrower gauge to allow reasonably free running, so 14.2 would possibly be a good starting point.
If you're on radius 2, or even better radius 3, then 14.5 would be the better measurement.
However, I stand to be corrected.
Ian J.
the DOGA website suggests 14.4mm. Does this sound about right?
Prepare to becorrected. ;-)
Assuming that all the wheels of a model railway collection are not all the same, (DMUs only?) then the correct dimension is from one flange face to the opposite flange back. This is a bit difficult to measure in a single operation with a pair of calipers. That dimension is however 15mm. The flange thickness _should be_ 0.5mm giving 1.0mm of play between flange faces and rail heads at correct gauge.
So, if your flanges are 0.5mm thick (width) then the correct back to back is 14.5mm If your flanges are thicker than 0.5, which is quite likely, then you need to reduce the 'back to back' measurement by an equal amount, but not to a dimension less than 14.2mm.
However, if you are running "finescale" wheels and trackwork, whch you almost certainly are not if you're asking the question then my answer will be totally wrong and an argument of many eons and harsh words will result. Whatever, my dimensions allow me to operate NEM, NMRA and British wheels on the same tracks without problems.
PS - you will never get your wheelsets perfectly to gauge, but +/-0.1mm of the above will be fine =8^)
Regards, Greg.P.
That should work well for most currently produced wheelsets.
Regards, Greg.P.
For Hornby and Peco Set track 14.4mm is going to be to wide for many wheels. Do what Greg suggested before and measure your wheel flange thickness. As you have calipers you can measure the check face to check face dimension of the set track. For older models with deep fat flanges a minimum wheel back to back dimension of 14.00mm should work for set track. However before accepting these numbers see my web page for a XL spread sheet that does the sums for track standards. Measure your set track check face to check face dimension, Use a check gauge of 15.0mm for set track. Get the track numbers to be close to your measured track numbers then you can play around with your back to back dimensions to get the best values. I must stress these numbers are for Peco and Hornby set track only and are not suitable for the other Peco turnouts.
Terry Flynn
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