martin goodall wrote:Just to clarify a couple of points.
Thanks for the extra clarification. I don't think that it persuades me to change (back) as P4 works for me as a "package" but could I tease out one or two more points for the sake of full understanding?
martin goodall wrote:First, my track is built to P4 standards. Flangeway and check rail clearances are all within P4 tolerances; they have not been adjusted in any way to accommodate the EM-profile wheels. I can run P4 rolling stock on my layout, and I still have some vehicles which have P4 wheelsets, but I am currently working my way through them substituting EM wheels set to P4 back-to-back gauge, just to get that little bit of extra reliability that the deeper flanges of EM wheels give you. (They are only 0.25mm = .010 ins deeper, but it seems to make all the difference.)
You mention that the only difference is the flange depth. Does this mean that all of your wheels are replacement EM wheelsets, from Alan Gibson, Exactoscale and the other usual suspects?
That would make a big difference to how they go through flangeways as it would already be finescale flanges compared to OO dimensioned ones. The point that I'm making is that in effect you are approaching EM from the finescale end, rather than the approach that can be done with EM of pulling the OO wheelsets out to the EM B2B. Of course, I still don't believe that the EM profile would deal well with prototypically inset or tram (I'm typing this from Amsterdam, so I have plenty of examples outsode of just how shallow the rail grooves are) track, but that is probably not on your layout.
If you're using finescale EM wheelsets, do you know how the tyre width differs, if at all, from the P4 Standard?
martin goodall wrote:As regards a name for this 'bastard' standard, I thought of EMF, but that has been used before and meant something else, so I call it "Coarse-scale P4"! It is P4, because the track, as I have said, is exactly to P4 standards; it is just the wheel profile that's different.
I'm not sure that the name conveys exactly what you mean, because P4 describes the (rail+wheel) package as a whole but I see where you are coming from. A similar sort of thing to the seven-millers that have Coarse and Fine versions of "O", leaving aside the ScaleSeven fraternity as well.
martin goodall wrote:Where the use of EM-profile wheels really comes into its own is in converting RTR rolling stock to run on P4 track. Its quick, it's easy and it works. That, of course, is where we came in - in suggesting answers to the query posed by Julian Roberts. I can't help feeling that some of the other solutions that have been suggested are consderably more time-consuming and certianly a lot less easy than mine, even though they may be intellectually more satisfying.
I think that what you have given is a very different answer to the same question. It isn't just the intellectual satisfaction, or the complexity involved. It is that in simple terms, one is P4 and one isn't
Yours is a pragmatic solution for your own needs. It's not a quick solution to a P4 RTR conversion, but an alternative approach using 18.83 track. It gives a different result - and that's not said as criticism, by the way. If it works for you, it's a GoodThing(tm).
One aspect of your approach is that it is backwardly compatible. If a friend brings round P4 stock to run on your layout, it would work just as well as on his or her own. If you take your EM-wheeled stock to a P4 layout, it *should* run equally well but it's only your loss if it doesn't, if you see what I mean.
The problem would be if the more lax tolerances built into your EM wheels led to lower standards of track-building that then fell away from the P4 track standards, and consequently stock with P4 wheels wouldn't run on it. I could see this becoming a downward spiral that would (in all frankness) not benefit P4 modelling by having the name associated with it. But the Scalefour Society is only the guardian of the P4 standards. It doesn't own a patent on the specifications, and I don't think that it would want to, given the nastiness that apparently led to thirty years ago!
Yours is an interesting development and, as I said at the outset, not one that I would want to follow personally. But the primary objective of the Scalefour Society is to "promote finescale 4mm railway modelling" and that does not explicity exclude EMF, EM, OO or whatever. To misquote Voltaire, "I disapprove of what you model, but I will defend to the death your right to model it. "
All the best,