coachmann Posted January 12, 2011 Share Posted January 12, 2011 I think Trix came in with a compromise 'H0' scale of 3.8. With todays manufacturing techniques and finer tolerances, true H0 is probably possible from the plastic RTR people, but of course reality tells us "Why should they".... Eighty years of '00' on the scapheap overnight? The toy train buyers would not fully appreciate what H0 was all about and no doubt would end up mixing items from two scales. Not just trains but buildings as well. Then what about the after-market guys and all their kits, track and what-not? As David says...... Please don't raise that one again! Link to comment Share on other sites More sharing options...
Jol Wilkinson Posted January 12, 2011 Share Posted January 12, 2011 You can't scale clearances, so the works won't fit. (This applies to 4mm too. Ask anyone who works in P4.) David, can you explain that for me. While there can be clearance issues (usually with outside valve gear/cylinders)in P4, 00 also creates problems with cab splashers and interiors not to mention bl**dy great cutouts in boilers with over wide splashers to cover the wheels. Overscale flanges also cause problems. I have found it is actually easier to design an etched loco kit for P4 than 00. Cast kits may however be different due to the thickness of items like splashers. Jol Link to comment Share on other sites More sharing options...
craigwelsh Posted January 12, 2011 Share Posted January 12, 2011 That comment on scaling clearances probably needed a disclaimer saying it referred to plastic RTR where you would need wider wheels and plastic thickness splashers due to material limitations and much sloppier tolerances. P4 is quite tight at times because you are scaling clearances and they are rather small in 4mm scale but they can work when correct scale components are used. I agree with Jol about P4 being easier to design for at times, i'm playing with a proper tank wagon chassis at the moment and you'd have to compromise the framing arrangement for 00 wheels. Link to comment Share on other sites More sharing options...
bertiedog Posted January 12, 2011 Share Posted January 12, 2011 The one killer with all attempts to tighten up scale appearance is the common use of splashers on British Locomotive designs, only P4 works, and even there most materials for the superstructure are over scale thickness, by a tiny amount. HO is not a cure to UK modellers, Continental HO and US HO is not exact scale, nearer , but not exact, and they barely have to deal with superstructures like splashers, which some continental makers like Roco and Marklin etc., do, by moving the splashers out of scale position by over a foot in scale terms! If we changed to HO would you accept a T9 440 with the outside of the splashers move outwards by about foot? It would be that much when modern HO wheel width , plus clearance , plus plastic thickness is added up. With OO we have a scale body from Hornby, and it can be converted to exact scale on P4. An HO one with typical changes to the body and splashers that the RTR makers apply would leave a model un-convertible to exact HO. So although the system of using 4mm on the wrong track seems crazy, it actually works for UK outline models, allowing toy makers products to be converted to closer scale use, something US modellers are unable to do for instance, you cannot take a US RTR and simply turn it to Protoscale 3.5, but in the UK we can change Hornby and Bachmann to scale versions in P4. Stephen. Link to comment Share on other sites More sharing options...
Il Grifone Posted January 12, 2011 Share Posted January 12, 2011 David, can you explain that for me. While there can be clearance issues (usually with outside valve gear/cylinders)in P4, 00 also creates problems with cab splashers and interiors not to mention bl**dy great cutouts in boilers with over wide splashers to cover the wheels. Overscale flanges also cause problems. I have found it is actually easier to design an etched loco kit for P4 than 00. Cast kits may however be different due to the thickness of items like splashers. Jol It's not my statement (I believe it belongs to R.C. Ormiston-Chant - hope I got that right. Apologies if not.). Basically, as I understand it, it refers to all clearances, from bearings upwards - really down to the atomic level). We expect our models to work with slop in the mechanisms of a similar level to that on the prototype (they would seize if scaled down). Sharper than scale curves require extra sideplay usually obtained by narrower than scale frames (I believe I am correct in saying than a BR standard has two inches of clearance behind the driving wheels, which is more generous than most - There's more wobble than that in some commercial chassis I've seen). My reference to P4 was in no way intended as critiicism - more the contrary - and I was thinking of outside cylinders and valve gear. The various bodges required in 00 I'm well aware of - the standard ½" frames being one of my unfavourites. Trix Twin (possibly the best/worst example of 'coarse scale') was variously described as 3.5mm to 4mm to the foot depending which piece of literatue you read. At best flexible in scale, the buffers measure 23mm* between centres. With the advent of the late 50s Trix scale models, they settled on 3.8mm. The scale was still flexible, though less so, and the buffer centres still 23mm. (Rivarossi used the same scale for their European models, but set their buffers at the H0 20mm , calling their models H0 to confuse the issue. (Mixing Lima and Rivarossi Italian models looks ridiculous as a result - In the nineties Rivarossi switched to 1/87.) * Measured on the tender of a TTR compound (she looks like a compound, bears the numbers of compounds (41062 and 1168 ), but keep her away from photos or, worse, drawings of the prototype). Some rolling stock is even wider! Link to comment Share on other sites More sharing options...
bertiedog Posted January 12, 2011 Share Posted January 12, 2011 The narrower frames in OO and in HO allow more side movement and this must be added to the clearances behind an over scale splasher, it is all interrelated, as I said before with a 440 like a Southern T9 with flush sided splashers, where do you expand the body to allow for it, you can't in HO or P4 if it is to go around corners.. OO does answer the problem, scale bodies on undersized chassis, it does work even if undesirable to purists, who can take the scale body and convert the chassis to exact scale. Try doing that to a Marklin or Rivarrossi steamer, it is near impossible as the makers have stretched and altered the body to allow for the splashers and boiler clearances, you cannot convert most HO RTR to a Proto scale version, without considerable re-construction, but you can take most 4mm OO RTR, and convert the chassis quite easily. Stephen. Link to comment Share on other sites More sharing options...
rjstott Posted July 2, 2011 Share Posted July 2, 2011 I've alway thought that the difference had more to do with pracaticality than anything else. Hence wheel flanges are larger to keep the trains on the track, thicknesses of materials are what is necessary to avoid unde flexing and obviously you get the detail that you pay for. Is this a fair summary? Link to comment Share on other sites More sharing options...
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