nswgr1855

There is a GNR atlantic RTR from Bachman and Hornby also did a RTR GNR N2 , so the market for GNR is there. Do a GNR roof and you have a near enough solution for a 7 car train behind my Stirling. Terry Flynn.

I used the semi elliptical description to describe the GNR roof style to distinguish it from the simple cured roof Hattons will be doing. Yes the GNR roof is fairly flat on top but is made of of more than one curve, and noticeably different to the simple curve variety. I personally would be happy to use the generic wagon if it has the correct roof profile, the paint job should give the illusion of correct paneling. If Hattons does 3 roof profiles, then at least most of the range would look right from a distance. Terry Flynn.

From the evidence supplied the proposed models are not accurate enough for coaches with non simple arch roofs, as the different roof shapes are easily observed from a distance. Yes it will cost more in tooling to do 3 roof shapes, but if Hattons decide to do this I am sure the market is big enough, even if the price is increased to cover the extra cost. Terry Flynn.

No doubt they are close enough to some 4 and 6 wheeler coaches for a couple of companies. Unfortunately they are diabolically inaccurate for the GNR 4 and 6 wheel prototypes that I have seen photographs of. I'm not talking about a few inches or a rivet or 2 missing, but a totally different roof and paneling type. The roof is easily seen as inaccurate from 2m away. I would also suggest a semi elliptical roof would be more accurate for GWR and NB prototypes as well. Terry Flynn.

I am prepared to pay more for a GNR style roof, and more again for accurate models. I may not go ahead at the moment and purchase these, because for GNR they will look wrong from 2m away. Unfortunately, when a supplier produces low cost inaccurate repaint models, it increases the risk of doing higher priced accurate RTR models. Terry Flynn.

Thank you for your reply about the wheels. I am always prepared to pay more for an accurate model. Terry Flynn.

I'm no expert at UK prototype, but from the limited photographs I have seen of GNR 6 wheelers, they have a semi elliptical roof shape. This is a significant visual difference, easily seen from a distance. Yes it would cost more to have a second roof shape and ends tooled, but if Australian suppliers can supply RTR carriages of complete NSWGR train sets where most cars are different. Im sure the economics is good enough for a second roof shape in the much larger UK market. I would also have expected most of these early non bogie carriages to have spoked wheels. Terry Flynn.

Hello Nick, I have done the experiments in H0 a couple of years ago so my layout grades would not be to steep for the trains I wanted to run. My results will be relevant to 00. I tackled the problem from a slightly different perspective. Firstly I made the assumption all wagon weights were proportional to their length. I use the Australian Model Railway Association Mass standard http://amra.asn.au/standards/ I measured what I call the coefficient of rolling resistance of my wagons by using the inclined track method, that is inclining a piece of track with a wagon on it and measuring the incline when the wagon starts to roll. There is a large difference measured between different wagons. I only use pin point axles and bearings which are usually free rolling. The value I picked was the largest typical value of 0.02. Like you I measured the coefficient of friction of my locomotives using an inclined plain. I wanted the worst case so for calculation purposes I used the lowest value, 0.2 which was on track with a small amount of oil, which I use for improving electrical contact. From these values you can calculate easily the maximum train mass that can be pulled on flat straight track by a given locomotive mass which works out at train mass =10 times locomotive mass. Experiments confirmed this. Measuring curve friction is more difficult and to confirm by experimentation. Over may years I have tried to do the experiments on different layouts with Helices. The problem is the radius, grades, locomotive and wagon variables are hard to control. Any way I came up with a rough rule of thumb for layout design to compensate for the curves on grades, and that is multiply the prototype grade by 1.75,(1:40 becomes 1:70) If you want to run prototype length trains up to 2700mm long on typical H0 model railways using curves down to 900mm radius. Conversely going the other way, a 1:40 grade on your layout is like having a 1:23 prototype grade. DCC will make no difference to pulling power other than if it can control the motor better at low speeds. What will make a difference is wheel tire material. Generally harder materials used for model railway wheels have a lower coefficient of friction but are preferably used due to lower electrical contact resistance and less dirt pickup. Also what makes a big difference is if all the loco weight is on the driving wheels. If you have non powered bogies with inside plain bearings, that is the formula for a poor pulling model. These models tend to have traction tires in order to pull enough. Cheers, Terry Flynn.

I know many here will not be much need for the use of an air compressor sound on your model UK steam locomotives, but I will ask the following any way. How do I get to make the air compressor noise to automatically start when my locomotive comes to a stop. Is it something to do with CV 158? Thanks for any help, Cheers, Terry Flynn.

A group of modelers who built a NSW Proto87 exhibition layout have now reverted back to various more popular easier to build H0 standards. My prediction is Andy will be the only builder to 00-P. Cheers, Terry Flynn.

Hi Martin, Every dimension that I have used in this subject has been properly calculated to account for practical tolerances for k crossings unlike the G0G standard and various add on standards using the G0G wheel standard. My sensible advice is to use the AMRA recommended fine tolerance wheel and track standard. You have now highlighted another problem with the current 31.5 mm gauge '0-MF standard'. If you use the 28.6mm max check span for the 31.5mm 0-MF standard, (the same check span as the AMRA standard coincidently), then you need to work to a tolerance of only 0.033mm, to maintain the correct check gauge through a K crossing. No gauge is built to the exact size, so the tolerance of the gauge also needs to be factored into the standards calculations. 0.033mm is not a practical track laying tolerance and a tolerance not achievable using simple non clamping roller gauges. The fact is using simple roller gauges, there is clearance between the gauge and rail. Some track could end up slightly under the check gauge of 30mm. Most wheels should be just under the maximum check gauge limit, not a problem however if a wheel is on the limit, usually a good flange profile will hide the track under check gauge issue, no derailment, just a slight bump in this case. This means we do not have a design that is 100%, just mostly OK. For other cases the check span can be over the specified amount to around 28.7mm, not a problem if you keep your wheel back to back around 29mm. This results in a fairly tight wheel back to back tolerance of 29.0mm to 29.2mm for flanges up to 0.8mm wide. The problem with the 31.5mm 0-MF standard is where is a complete copy of the standard? Without this document modellers and manufacturers will do their own thing, some adjusting one way, and others the other. It’s clear the K crossing case was not properly considered in the development of this fairly new track gauge. The G0G wheel standard is incorrectly toleranced, Consider the following, your maximum wheel back to back is calculated from the formula, check gauge - maximum flange width. Thus 30mm check gauge - 1mm wide wheel flange = 29mm wheel back to back. The problem is the G0G minimum back to back is 29mm also, thus you have an impractical 0mm tolerance to work to. This is probably why the G0G track check gauge is 30.25mm. (Older versions of the standard used 30mm). This excessive difference adds to the wide flange way in this standard. The AMRA standard on the other hand allows for a greater range of fine scale wheels to operate on track built to the AMRA fine tolerance standard, with less wheel drop compared to G0G fine scale track. The AMRA standard sticks with the traditional UK check gauge of 30mm. It is best to use the same value for both track and wheels. As a bonus the AMRA standard includes the dimensions to make the track roller gauges. Terry Flynn http://www.amra.asn.au/finewheeltrack.pdf

Martin, In order to have smooth running with 0-MF turnouts, you need to keep your wheels within a back to back of 29.0mm to 29.2mm for a 0.8mm wheel flange thickness. If the wheel flange thickness is 0.9mm, then your wheel back to back needs to be 29.0mm to 29.1mm. If your wheel flange is 1mm wide, the G0G maximum, we see a problem with the G0G wheel standard as the result is no variation in the wheel back to back. In an earlier post you have identified the wheel drop issue with the G0G wheel and flangeway. Considering the G0G wheel back to back issue, you need to be extra careful which wheels you use if you go with the 0-MF standard. My recommended solution is the AMRA fine tolerance standard, which allows a larger range of wheel back to back and is full compatability with the G0G fine wheels. In fact 0-MF can be compatable with the AMRA standard. Note the minimum track gauge in the AMRA standard is 31.5mm. The flangeway sizes recommended in the AMRA standard are not compulsory. They are the best compromise I could come up with between looks and ease of manufacture for K crossings, considering the real worlds variation in wheels and desirable wheel rail clearances. Crossing V's with check rails are easy to get right compared to K crossings. The NSW crossing V's I see these days are sharp, compared to your UK example. The blunt bit is only about 10mm wide. The crossing V's do wear, causing a noticable bump, but interestingly, the wear causing the bump is not at the tip of the V. These are not cast one piece crossing V's so it might have something to do with movement of the various bits. Cheers, Terry Flynn.

Hi Martin, The dimensions I have recommended for finescale O gauge do not result in significent wheel drop if the wheel width is above the G0G standard 3.5mm minimum. Is a 3.4mm wide wheel a scale 7 example?. In Australia some of our 0 gauge 'finescale' wheels use NZ made wheels, which have a slightly wider flange compared to the Slaters wheels. Thicker flanges requires the wheel back to back to be set to a tighter tolerance, hence the recommended AMRA values allowing for wheels with a smaller back to back value to work without clearance issues. The AMRA standard ends up at 1.6mm to 1.7mm flangeway using 31.7mm to 31.8mm track gauge (The original 0 gauge,1.25"=31.75mm) and works for all crossings. Sharp crossing V's are common in NSW so having the minimum wheel width =2 x the maximum flange way is OK on paper. The blunt UK crossing V will not produce a noticeable wheel drop using the AMRA flangeway maximum of 1.7mm. I estimate the wheel drop for the extreem case here is less than 0.2mm for a 21mm diameter wheel on a 1:9 crossing. My point is you do not need to be as accurate compared to the 1.5mm flangeway option in building your track, nor do need to be as accurate setting wheel back to backs. Also the wider track gauge and flange ways in the AMRA standard allows for curves through the crossing without extra gauge widening, which could be a problem with the smaller 31.5mm track gauge. In conclusion using the original '0' gauge of 31.75mm (AMRA fine tolerance standard) you get easyer to build finescale track and a wheel back to back that can have a variation of around 0.1mm. Much easier to get right compared to the G0G fine and 0-MF 31.5mm gauge alternatives. I doubt the visual difference would be noticed except in close up photographs designed to see a difference. It's 100% compatible with existing G0G wheels and Slaters fine scale wheels. Terry Flynn

Hi Martin, I am sure you will find prototype manufacturing drawings that use the =/- tolerance convention which means exactly the same as the maximum minium alternative method of expressing the allowable size range of an object. Note the AMRA standard I wrote uses the maximum and minimum convention, but I was critised on a Aussie news group for this, claiming modellers and manufacturers could not work out nominal values easily. I have no trouble determinimg the tolerance range that complex model track needs to be built to because I have put all the relevent sums into an XL spread sheet to get the relevent sizes. Are you sure the crossing flangeway is 1.5mm maximum. I would think using the construction method of using a 1.5mm metal shim, you get a 1.5mm minimum flangeway in practice. Yes how accurate you build your track is determined by the variation in wheel sizes. Using my spread sheet, the closest I get is as follows. If you limit your wheels to a 28.9mm minimum back to back you can have your maximum check face to check face at 28.7mm, resulting in flangeways between 1.44mm to 1.51mm, track gauge 31.51mm to 31.58mm for a K crossing. To be honest, I you are happy working to these tolerances you might as well build to scale 7 dimensions. If I was building 0 gauge track, I would design my track for a easier to build wheel back to back range, (down to minimum back to back of 28.8mm), and work to the easier tolerances in the AMRA fine tolerance standard. Same check gauge 30mm, easier to build within tolerance with only a slight increase in flangeway gap. By the way I like the improvements in Templot 2. Cheers, Terry Flynn.

I always question and I have a problem with any track 'standard' that does not include tollerances for complex trackwork. According to my figures and observations you need to work to with an accuracy of around +/-0.025mm if you want to have complex trackwork with crossing K's using the 31.5mm minimum track gauge, 1.5mm flangeway combination. For O gauge a more practical solution is the AMRA Fine tolerance standard, with nonimal recommended dimensions of 31.75mm track gauge and 1.65mm flangeways. A tolerance of =/- 0.05mm is allowed. The AMRA standard is on the associations webpage. http://www.amra.asn.au/standards.htm Terry Flynn.