--- In [email protected], Talmadge C 'TC' Carr <group_list@...> wrote: > The Proto idea is 'scale the real thing' and uses a wheel profile that matches this ideal. I think you need to add a rider to that, TC, so that it reads 'scale the real thing as far as is possible'. The laws of physics do not change, and when scaling things down some factors reduce in a linear fashion (1:64), some in a square fashion (1:4,096) and some in a cubic fashion (1:262,144 [!]). Add to this the fact that a tolerance of, say, 0.0005" on the model scales up to 0.032" (more or less 1/32") on the prototype (and I am not claiming that I can work to such tolerances!) and some pragmatism is required. If everything was scaled down perfectly, then the model would bind up solid. I am also ignoring the fact that most of us have sharper curves than the real thing scaled down. However, a prototype wheel profile, track standards, and ideally rail section are all possible, but the latter is desirable rather then essential. How do I know? Because I have worked to such standards in UK outline for nearly a third of a century, and others have done so for even longer. The key benefit is that the standards have all been ironed out on the real thing, and scaling it down by dividing is a straightforward process provided allowances are made for such things as greater rigidity of track and frames on models compared to the real thing. All this really means is that a bit (not much - 0.010" is frequently enough) of extra side-play is required on the wheelsets where there are more than 2 axles in a frame, e.g. six-wheeled trucks, ten-wheelers, and so on. Through the 1970s and into the 1980s (and it still rumbles on) there was an awful amount of acrimony and mis-understanding in the UK railway modelling hobby as a consequence of claims that total scale reduction of the prototype was required, and that this could only be achieved by working to ultra-fine tolerances. This is arrant nonsense: a few gauges and a consistent tyre (or at the very least, flange) profile with controlled side-play (reduce it as much as is feasible where it is not needed, make it no bigger than necessary where it is required) means that Proto:XX modelling is no more difficult than producing decent scale models to other standards: the same level of care and consistency of application are required. I would hope that we can all avoid that by learning from other people's experience. Even laying snap track on the carpet for a train set requires a certain amount of care, to ensure that rail joiners are correctly aligned in vertical and horizontal planes. Modelling is just about taking the care into all areas of things, including getting details and paint schemes correct, and Proto:XX modelling is just about taking it a little bit further, but at the end of the day, we still need running fits for axles in axle boxes, and so on. Some of you may ask why bother with Proto:64. The answer of course, is that if you are happy with "code 110"-based NMRA/NASG standards, then carry on. However, if you like to make your models that bit more accurate, and want to get closer to how the real thing moves and operates, then Proto64 solves a lot of problems, for there is less play in the wheel/track standards, so equipment will roll and couple better. The turnouts also look better, and equipment runs more smoothly through them. Finer standards do, though, create a few other problems - essential items have to be "just-so" and not "nearly-so", and of course a large section of the hobby is hostile to such approaches. In S you can - with a little rough riding in NMRA standards and very rough riding in the coarse standards - run your equipment on non-Proto layouts, preferably not through turnouts facing the direction of traffic. The reverse is not possible, in theory at least. In practice, I have run an OMI GP38-2 with code 110 wheels on scale track. The springing on the wheelsets and also the bogie pivots meant that the loco dealt with the narrow flangeways by simply climbing up over them. The loco itself did not rock, roll or fall off. That requires soft springing and a certain amount of weight, and was also possible because the bogie wheelbase was longer than the guard rails. Not sure it would work with a freight car! It depends on what you want from the hobby, but an accurate track gauge is an accurate track gauge no matter what the track standards, and an inaccurate one should not be used. With a single tyre profile, Proto:64 modellers can simply set the wheels using a back-to-back gauge, knowing that the check gauge - which is the most important part of the whole thing - will automatically be correct. The same cannot be said of other standards, unless they are adhered to rigidly: if you wish to run code 88 wheel sets on (for want of a better description) "code 110 compatible" track, then you need an extra back-to-back gauge, and in any case one is better advised to use a Proto:64 wheel profile ( more width to the tyre) set to the correct check gauge. As far as I can see, Proto:64 means being more careful with the modelling, but otherwise is a lot simpler than other standards, as everything is pre-defined by applying the scale ratio to the real thing, allowing for engineering tolerances.
Simon Dunkley
