14mm Gauge Standards
I note that a set of standards, copied from NG&I REVIEW issue 14 are published in the
'Files' section for this group.
These were tentative, and a revised set of standards, based on experience, have been
part of the RCL 'Product Handbook' (page T14) for some time. A copy, together with
an explanation of the way the dimensions work to make reliable turnouts is attached,
as a PDF.
These standards are derived from the old British Railway Modelling Standards Bureau
(BRMSB) document 'Standard Dimensions'. When, in the 1980s, I was developing
proper wheels for 7mm scale narrow gauge rolling stock, the best commercial profile
available was (and remains) that for 'EM'. I took the BRMSB dimensions for EM
(18.00mm gauge), deducted 4mm as appropriate and made a few slight adjustments
in the light of experience.
The 'EM' profile, as made by Alan Gibson, Maygib etc., represents a profile (in 7mm
scale) part way between the Festiniog Railway 'Coach' and 'locomotive' wheel profiles
as drawn in 'Vignes Atlas'. The flange is a little overscale, but not as much as
Romfords. With regard the latter, the 'RP' is not, if I understand Mark Arscott of
Romford correctly, 'Recommended practice (NMRA) but stands for 'Romford Profile'. It
follows NMRA RP-25 standards to an extent, but should not be considered
interchangeable with that profile.
The Romford wheels are entirely at home, however, with my modified standards -
note that recent i.c. loco kits use solid turned nickel silver wheels made for us by
Romford. The trick is getting the back to back measure correct.
I have a small layout built using these standards, with three turnouts (see recent
issues of NG&IRM REVIEW). All the stock have EM profile wheels, machined in steel,
those on the locos being polished out to aid current collection. none of the rolling
stock has any additional weight. Rakes of six skips can be propelled at the top speed
(a scale 20mph) through turnouts without any fear of derailment. The 'trick' is solely
one of keeping to the standards and not deviating. Additional reliability comes from
having locos and stock where the overall lengths and wheelbases are near identical.
The 'Rugga' chassis helps too, as the ends are rounded.
non-industrial prototypes, with varying lengths, wheelbases etc., will always be more
difficult to resolve in terms of good running. Mixing disparate prototypes is another
cause of problems, in the real and model world.
Please bear in mind that I developed these standards to ensure my range of 7mm
scale, 14mm gauge kits worked reliably, given that no set standards existed at the
time of development. I have always felt that, for 'larger' two-foot gauge equipment, a
development of the NMRA standards for 'On2' would be more appropriate.
Roy C Link
