martin goodall wrote:To take up Ian White’s point, railway modelling could be said to be the art of compromise. No one set of standards (not even P4) is perfect.
Finescale 00 is one alternative, as Paul Townsend has pointed out. Another possible compromise is the one I have adopted – using EM wheels (spaced out to the P4 back-to-back gauge) on P4 track. I am not the only Society member who has adopted this expedient. It still necessitates some adaptation of rolling stock to accommodate the wider gauge, but compensation or springing can largely be eliminated, and this greatly simplifies the conversion of RTR stock.
Answering the original question, this forum is for whatever contributors want to write about, but its most useful role is to share practical tips and advice on a wide variety of model-making topics.
Julian Roberts wrote:Martin - what is the flange thickness of EM wheels? I've often seen in your interesting posts you don't 'do' measurements of less than 0.1mm. So maybe you don't know.
Having no answer, unsurprisingly given my question was only put about an hour ago, from Martin Goodall, I've been looking for the Flange Thickness (EF) of EM wheels on the internet. The EMGS website doesn't seem to have its Track and Wheel Standards on the public part - maybe it does in the members area - if I could remember my Login. (PS I've just seen Jol's naughty step message to me and downloaded the link, but that doesn't show the Flange Thickness, thanks all the same Jol.)
As always, Martin Wynne to the rescue: http://85a.co.uk/forum/view_postx.php?post_id=567
The NMRA RP25/110 flange thickness is 0.8mm max which easily clears a 1.0mm flangeway, as for DOGA Fine. Romford/Markits and Alan Gibson wheels have thinner flanges, corresponding to RP25/100 and RP25/88 respectively.
So he said on 10th August 2007. I regard Martin W as the only person around who actually understands all the issues. Maybe he will annihilate the ideas I'm putting in this post later today...
So what is the NMRA RP25/88? Here's the NMRA table that comes up on a Bing search.
Let's assume Martin Goodall and others are using Alan Gibson wheels. The flange width for the Alan Gibson profile for 00/EM wheels, RP25/88 is given as .025" which is 0.635mm.
Judging by the absence of any agreement with my saying this on the thread discussing Back to Back - see viewtopic.php?f=8&t=1764
- I don't know if everyone - or anyone - understands that the BB plus one flange mustn't exceed the Check Gauge or a derailment is likely on the crossing of a turnout.
17.67 plus 0.635 is 18.305mm. The P4 Check Gauge is 18.15mm. So the BB of these EM wheels needs to be reduced to 17.52 to properly clear a crossing V.
But there also seems to be a total incomprehension that there's absolutely no harm in making the BB less than 17.67 even with P4 wheels, apart from the increased sideplay which worries some people, and the lack of adherence to the standards, at which people look in wonder as if they are Holy Writ.
How do I know? Because accidentally, through using a BB gauge that I didn't know was not made properly and in fact gave a BB of around 17.60, and then pressing too hard, I have several locomotives that work perfectly and never derail with a BB in the mid 17.50's, and one with a BB of 17.47 on its front wheels. But the difference to many people's locos is that they are made as heavy as possible and the compensation UNequalized to give more weight on the front or rear wheels which are the guiding ones - as per my articles in Snooze 199 and 200.
Gauging EM wheels to 17.52 seems to me to offer a recipe for the possibility of having a decent collection of rolling stock such as short wheelbase wagons and bogie coaches that won't need compensation or whatever (though I won't apply this to locos). Possibly thereby I may have the time to build a layout in my retirement which beckons. Anyway I'm going to try this out on the Bachmann LMS guards van I bought yesterday at the Glasgow Model Rail exhibition.
I have come in for a lot of stick for talking about minute numbers on this Forum. I make no apology for doing so on this thread. There seems to be an idea that we shouldn't talk in any detail about things for fear it will put people off. That reminds me of people trying to suck me into the church youth group when I was a kid by trying to make it sound fun. Luckily the 'fun' offered had no attraction for me whatever, not being the least bit interested in sport type activities. Later I found the real message of the Gospel considerably more attractive. In my opinion, what puts people off P4 modelling is the idea promulgated by some that it is easy. Following this gospel, they make trackwork without understanding the issues, and put on rolling stock (with P4 wheels) without proper suspension, and, of course, it doesn't work properly. Yes, maybe 80% or 90% of the time, but not really reliably. Personally I'm not happy with anything less than 100% reliability of trains staying on the track. When the issues are properly understood, the time involved making something that works properly is not a lot greater, and there is then no track "tweaking" which is what is endlessly done to try to improve dismal running.
I'll stand back and watch the bombs falling in my direction for what will be seen as shock horror HERESY
By the way the absolute minimum BB is the Check Span, 17.47. But there should be some clearance over this, normally 0.1. So a reliable minimum BB would be 17.57. So EM wheels will not be ideal at all. But the deeper flanges must explain why they don't derail on crossings in people'sometimes normal use at 17.67. A BB of around 17.55 will be the compromise I will try to find.