Model Railway Forum banner
1 - 3 of 3 Posts

·
In depth idiot
Joined
·
8,271 Posts
... Although I think the engineer in me does feel a little irked as the mismatch of gauge and scale with OO...
You might be even more irked when you perceive the 'variscale' that is the accepted norm for HO steam models.

OO was born out of the necessity to accommodate commercial mechanism parts within the limitations imposed by the UK loading gauge and UK steam locomotive design, most critically the close fitting splashers over driving wheels and the outside cylinders and rods and other components in close proximity to these. The compromise is a constant larger scale, excepting the track gauge.

HO shares the problem of accommodation of the same commercial mechanism parts on steam locos. Even with a larger loading gauge, the larger locos in particular are difficult to produce as working models able to negotiate small radius model railway curves, and the accepted compromise is to move toward 4mm/ft (OO scale) for width around the mechanism. Lima attempted an LMS Crab, and Rivarossi an LMS Royal Scot, and effect is noticeable, as in ugly.

Occasional Japanese and Korean HO brass productions as mentioned above are typically true scale, and the outside cylinder types require scale minimum curve radii, in excess of 1m. Where this all leads if you are sufficiently irked is P4 - true 4mm scale - or P87 - true 3.5mm scale.
 

·
In depth idiot
Joined
·
8,271 Posts
I believe the intention was to increase the selection of components, but this is all being undertaken by volunteer effort; and I would imagine that the present epidemic has only added to the inevitable obstacles to progress.
 

·
In depth idiot
Joined
·
8,271 Posts
However, TTBOMK C&L are still trading and offering P4 track product.

Meanwhile the Exactoscale operation (link post 12 above) offers the somewhat limited range you refer to, as I understand it being run by volunteers? I freely confess to being out of touch since a friend long active in P4 died in 2018.
 
1 - 3 of 3 Posts
Top