Fixing "00" Turnouts for "modern" "00" drifting Standards

[Andy Reichert]

Since exploring what was hoped for in achieving so called "finescale" in "00" wheels and trackwork, it's become clear that the idea of "00" being to 4mm scale, but conveniently able to run on standard HO 16.5 mm gauged track, has drifted over the years and now has passed into a form of variable degrees of non-conformity with the original concept.

 

Note I'm not talking about any cosmetic and non functional aspects. I.e Sleeper size, sleeper spacing, rail height and type, rail fixings, etc. But I would like to list and evaluate the possibilities for having UK RTR and otherwise constructed models run on track work that is made to a single simple specification, and can be adapted and/or mixed from the types available commercially, without major skill being involved. 

 

Since I'm an engineer I prefer to work solely with numbers and avoid the allure of unsubstantiated and un-measurable marketing claims, that can so easily list wondrous "pros" and avoid or obscure the associated "cons".  Numbers don't lie as the saying goes. In track work, like all forms of engineering, there is usually no free lunch.  Nor do the laws of physics bend or disappear if shouted down, even by a majority chorus of "but it works on my layout".  Usually 80% of anything appears to work well enough 80% of the time. That's why children's toys sell, but rarely please more critically observant and/or intolerant adults or last into adulthood.

 

Finally I'm living 8 hours behind the UK, so my response to others postings and comments will be considerably behind, if I'm replying to UK based postings that end up far back in the list. So please bear with me if I seem to be slow in getting round to answering a particular point.

 

But to give everyone something to think about for the next 24 hours, here's a simple question.

 

"What track and wheel dimensions do your really have to change to make "00" turnout flange ways (Crossing and check) narrow enough and symmetrical to carry Ordinary RTR, modern narrow RTR and/or kit wheels safely over the crossing vee gap?" 

 

Andy

 

 

 

 

[Andy Reichert]

Here's one idea I'd like to ask for comments on. At 16.5 mm gauge exactly,  it is possible to set both flange ways to almost 1mm, providing the back to back of all wheel sets is adjusted accordingly. e.g

 

 

 

I've taken the dimensions from the NMRA HO standard, so many RTR vehicles may comply.

 

Andy

[martin_wynne]

Hi Andy,

 

The UK DOGA-Fine standard specifies 1.0mm flangeways on 16.5mm min track gauge:

 

 http://www.doubleogauge.com/standards/finescaletrack.htm

 

It is essentially "EM minus 1.7mm".

 

RTR wheels need to be widened to 14.7mm max back-to-back for DOGA-Fine. For Romford/Markits kit wheels the back-to-back needs to be 14.8mm max. Markits supply some 0.3mm spacing washers for their 14.5mm axles for this purpose.

 

The DOGA-Fine kit wheel profile is essentially the same as EMGS, and the back-to-back for those wheels is 14.9mm max:

 

 http://www.doubleogauge.com/standards/finescalewheels.htm

 

Some kit wheels for 00, such as Alan Gibson, are supplied pre-set to this standard. (And need the back-to-back reduced for use on 00-SF. They are too narrow for use on 00-BF or DOGA-Intermediate.)

 

Turnout kits for DOGA-Fine with multi-slot roller gauges are available from C&L:

 

 https://www.clfinescale.co.uk/online-store/4PK-POINT-KITS-ALL-SIZES-4-MM-SELECT-FROM-OO-EM-P4-p128200474

 

Many users discard those gauges and build them instead using 00-SF gauges (also available from C&L), so that their RTR models will run unmodified.

 

They can't be built to 00-BF or DOGA-Intermediate because they include pre-assembled V-crossing assemblies having 1.0mm flangeway.

 

cheers,

 

Martin.

Edited December 17, 2019 by martin_wynne
typo

[Andy Reichert]

Just in case you missed what the diagram shows:

 

Just the ordinary HO standards have always supported the use of (almost) 1mm flange ways to run all RTR and kit HO standards vehicles, even those with (naughty) narrowed wheels.

 

If I've made a mistake with numbers, please let us know.

 

Andy

[Philou]

Might I suggest that the dimensions shown in the plan be provided in good old fashioned metric units? 00 is 4mm/ft and 00/H0 gauge is 16.5mm after all !

 

Cheers,

 

Philip

 

BTW Seasons Greetings over there.

[Andy Reichert]

E

4 hours ago, Philou said:

Might I suggest that the dimensions shown in the plan be provided in good old fashioned metric units? 00 is 4mm/ft and 00/H0 gauge is 16.5mm after all !

 

Cheers,

 

Philip

 

BTW Seasons Greetings over there.

Happy Xmas to all back in the u k

I will be back on a usable computer later in January Andy

[Andy Reichert]

 

 

Here is a quick upload of my way back working drawing for HO with almost 1mm flange ways. Sorry about the 4 decimal places - I just multiplied the "inches" table by 25.4.

 

Rounded mm figures for the HO Standard are in the table below

 

 

I'll try and clean things up later, but as is, it seems to demonstrate that even just the idea of an "HO-SF" to get 1mm flange ways for regular HO is completely redundant. 

 

Andy

[Andy Reichert]

The whole point and necessity of a model railway "standard" is that it is a set of dimensions that ensure 100% interchangeability and 100% perfect running through its turnouts.  It doesn't matter whether the standard is "coarse" or "fine" or prototypical. They all should work perfectly or they aren't a standard. The problems arise if and when, someone "breaks" a standard by changing one critical dimension (or its tolerance) and not also correctly altering all the others necessary to compensate and create a new 100% working standard.  Even if it then works OK, stuff created to a new standard generally isn't interchangeable with stuff built to its predecessor.

 

So there is no such thing as better running for one standard over another.  If there are running problems, then the fault is normally failure to adhere to the standard by inaccurate construction, or substitution of a non-standard compliant component, or something breaking or moving out of it's correct alignment.

 

Andy

 

[Dungrange]

On 31/12/2019 at 22:40, Andy Reichert said:

 Rounded mm figures for the HO Standard are in the table below

 

 

I'll try and clean things up later, but as is, it seems to demonstrate that even just the idea of an "HO-SF" to get 1mm flange ways for regular HO is completely redundant. 

 

I may not be understanding the table above, but it seems to imply that the HO standard permits a flange-way gap of between 0.89 mm and 1.27 mm with a recommended figure of 1.22 mm.  The problem is that if you were to construct a turnout of 16.50 mm gauge with 0.89 mm flange-way gaps, then you'd need a back to back dimension greater than 14.72 mm to allow a wheel set to pass through, so since this is greater than the maximum back to back figure in the above table, that would imply that these tolerances don't all work together properly.

 

Looking at it another way, if you were to set the track gauge to the minimum figure of 16.48 mm and the back to back at the maximum figure of 14.61 mm then the flange-way gap would have to be at least 0.94 mm to produce a working turnout, not the 0.89 mm quoted above.  This is the minimum that could be achieved, but only if the gauge is at the minimum end of the tolerance range and the back to back dimension at the maximum end of the range.  Ideally you would not design operation based on values at the extreme end of the tolerance spectrum.

 

However, even the recommended figures don't seem to align.  Surely the recommended value for the flange-way gap plus the recommended value for the check gauge should be equal to the recommended track gauge?  1.22 mm + 15.42 mm = 16.64 mm, which is not the 16.54 mm quoted.

 

To me these figures seem to be inconsistent or incorrect.  Furthermore, most UK ready to run stock does not seem to come with a recommended back to back dimension of 14.55 mm - I think a distance of nominally 14.4 mm (not sure what tolerance) seems to be the norm, which while within the above range, seems to be very close to the lower bound figure.

[martin_wynne]

24 minutes ago, Dungrange said:

I may not be understanding the table above

 

Hi David,

 

The NMRA dimensioning makes no sense at all and is best just ignored. Similar inconsistencies and incompatibilities can be found in all the other NMRA scales.

 

The dimensions should be either a Minimum, or a Maximum, but not both because they are all interdependent. For some sensible dimensions to use with the actual RTR models available in the UK, see:

 

 https://4-sf.uk/dimensions.htm

 

Notice that the dimensions are all minimum or maximum, but not both.

 

For some historical perspective on this, see: https://4-sf.uk/history.htm

 

cheers,

 

Martin.

[Andy Reichert]

Thanks to those just joining. I'm 8 hours behind, and It's getting late to reply properly, to the comment above, so I'll be back sometime late tomorrow, UK time, other manufacturing priorities permitting.

 

Andy

[PatB]

A brief precis of the development of 4mm scale wheel and track standards here. https://xkcd.com/927/

[Dungrange]

On 31/12/2019 at 22:40, Andy Reichert said:

 I'll try and clean things up later, but as is, it seems to demonstrate that even just the idea of an "HO-SF" to get 1mm flange ways for regular HO is completely redundant. 

 

I don't agree with the above statement, but I do agree with the one below.

 

12 hours ago, Andy Reichert said:

The whole point and necessity of a model railway "standard" is that it is a set of dimensions that ensure 100% interchangeability and 100% perfect running through its turnouts.

 

A 'proper' standard should define a series of target dimensions and a set of tolerances or acceptable variance on these target dimensions.  It really doesn't matter whether the target dimension is a maximum, minimum or intermediate value.  However, anyone claiming to work to a particular standard should be targeting the target (or recommended) dimensions and I would argue that anyone who consciously targets a dimension to be anything other than the stated target dimension is not actually working to that standard.  Therefore, if the NMRA HO recommended flange-way gap is 1.22 mm, then anyone consciously targeting a different figure (say 1.00 mm) is not working to the NMRA HO standard.  A 1.00 mm flange-way gap may lie within the acceptable tolerance levels of the NMRA HO standard, but that is not the same thing.  If a different target value is being pursued, then the modified standard should, I believe, have a different name.

 

What I would expect is that if it were possible to manufacture a turnout and wheel set exactly to the recommended figures (ie with a tolerance of +/- 0.00 mm) then all of the dimensions should work together perfectly and it seems that the NMRA HO 'standard' does not meet this basic requirement and as such I'd consider it to be a 'flawed' standard and one that is in need of modification.  It would therefore be more accurate if the title of this thread where changed to 'fixing the flawed NMRA HO track standards for use with 00'.

 

For example, ignoring the tolerances (which are required simply because it is impossible to consistently manufacture items to an exact dimension) the following should always hold.

 

Track Gauge (16.54 mm) = Flange-way Gap (1.22 mm) + Check Rail Gap  (15.42 mm) = 16.64 mm = FAIL (Error = 0.10 mm)

Track Gauge (16.54 mm) = Flange-way Gap (1.22 mm) + Span (14.15 mm) + Flange-way Gap (1.22 mm) = 16.59 mm = FAIL (Error = 0.05 mm)

 

As you've said previously, the numbers don't lie: the NMRA HO standards are flawed.

 

This therefore means that all manufacturers who are purportedly following the NMRA HO standard are not necessarily all following exactly the same standard because the NMRA HO standard is clearly flawed.  Should a manufacturer target getting the track gauge and flange-way gap right and accept lower values for the check rail gap and span, or should they target the track gauge and span and get narrower flange-ways, or another of combination of dimensions?  It is clearly impossible to meet all of the NMRA recommended values. Ultimately, the errors and inconsistencies in the NMRA HO standard are reasonably small, and therefore the values that must deviate from the recommended values (depending on the priorities of an individual or manufacturer) will generally still lie within the quoted tolerances, but clearly the NMRA HO standards need to change if we are to achieve the dream of 100% reliability and 100% interchangeability.

 

13 hours ago, Andy Reichert said:

They all should work perfectly or they aren't a standard. The problems arise if and when, someone "breaks" a standard by changing one critical dimension (or its tolerance) and not also correctly altering all the others necessary to compensate and create a new 100% working standard.

 

I agree with this and the NMRA HO standard clearly doesn't work perfectly.  To get it to work, one or more of the NMRA recommended values has to be ignored.  There is also a difference between changing a critical distance and changing a tolerance.   If a standard is properly written, then I should be able to tighten all tolerances and still have 100% compatibility.  However, the same doesn't hold if I change the critical dimensions.

 

12 hours ago, martin_wynne said:

The NMRA dimensioning makes no sense at all and is best just ignored.

 

The problem is that I'm interested in how Peco have interpreted the what seems to be a flawed NMRA standard for their North American HO scale code 83 track range.  I'm aware of 4-SF and have a set of 00-SF track gauges from C&L, which I intend to use to hand build turnouts on the scenic part of my layout.  However, I was hoping to use a number of Peco's North American Code 83 points in the fiddle yard and want to know if these are compatible.

 

From 4-sf.uk the Check Rail gap is specified as a MINIMUM of 15.2 mm and with the NMRA HO standard specifying a range of 15.37 mm to 15.6 mm, this would seem to be okay. The Span is specified as a MAXIMUM of 14.25 mm and with the NMRA HO standard specifying a range of 14.10 mm to 14.20 mm, this would also seem to be okay.  Obviously the flange-way gap is greater under the NMRA HO standard, but then so to is the track gauge, so I don't see that as an issue.

[martin_wynne]

2 hours ago, Dungrange said:

A 'proper' standard should define a series of target dimensions and a set of tolerances or acceptable variance on these target dimensions.

 

Hi David,

 

I think you have mixed up a manufacturing drawing with a track standard.

 

A manufacturing drawing typically shows a target dimension and the allowed tolerances on it. Each manufacturer will create their own drawings based on their equipment and processes, which are unlikely to be the same as another manufacturer's drawings.

 

Their object being to create a product which is in compliance with the published standard. That is the purpose of a standard -- to test whether a product is in compliance, not to specify how it should be manufactured.

 

You cannot test whether a component meets a "target" dimension. You can only say whether a dimension falls within the limits specified by the standard. It follows that a standard cannot include target dimensions. This seems to be where the NMRA have got in a complete muddle.

 

Often dimensions are interdependent so that only a maximum or minimum is needed.

 

For example consider a check rail in 4-SF. The standard says it cannot be closer to the opposite rail than the 15.2mm minimum check gauge. There is no specified maximum. But as it moves further away, it will hit another limit -- the maximum limit on the check span. So its position is fully controlled, despite having only one limit directly specified.

 

Double-dimensioning by giving everything both maximum and minimum limits inevitably leads to anomalies, confusion and errors. Triple-dimensioning by including a "target" dimension in what is supposed to be a "standard" is just a nonsense.

 

What the NMRA have published is not a track standard but a manufacturing drawing. One that seems in any event to be flawed, and one which I doubt any manufacturer would actually want to use.

 

cheers,

 

Martin.

[Andy Reichert]

16 hours ago, Dungrange said:

 

I may not be understanding the table above, but it seems to imply that the HO standard permits a flange-way gap of between 0.89 mm and 1.27 mm with a recommended figure of 1.22 mm.  The problem is that if you were to construct a turnout of 16.50 mm gauge with 0.89 mm flange-way gaps, then you'd need a back to back dimension greater than 14.72 mm to allow a wheel set to pass through, so since this is greater than the maximum back to back figure in the above table, that would imply that these tolerances don't all work together properly.

 

Looking at it another way, if you were to set the track gauge to the minimum figure of 16.48 mm and the back to back at the maximum figure of 14.61 mm then the flange-way gap would have to be at least 0.94 mm to produce a working turnout, not the 0.89 mm quoted above.  This is the minimum that could be achieved, but only if the gauge is at the minimum end of the tolerance range and the back to back dimension at the maximum end of the range.  Ideally you would not design operation based on values at the extreme end of the tolerance spectrum.

 

However, even the recommended figures don't seem to align.  Surely the recommended value for the flange-way gap plus the recommended value for the check gauge should be equal to the recommended track gauge?  1.22 mm + 15.42 mm = 16.64 mm, which is not the 16.54 mm quoted.

 

To me these figures seem to be inconsistent or incorrect.  Furthermore, most UK ready to run stock does not seem to come with a recommended back to back dimension of 14.55 mm - I think a distance of nominally 14.4 mm (not sure what tolerance) seems to be the norm, which while within the above range, seems to be very close to the lower bound figure.

 

Before getting into other dimensions, please be aware that the flange way width (FW) only refers to the gap between the wing rail and the frog vee. There are no flange way gaps  (plural). The gap between the stock rail and the check rail is not given a name. as it is the difference between the implemented check gauge and the implemented track gauge, and therefore a derived value.

 

Andy

 

 

[martin_wynne]

26 minutes ago, Andy Reichert said:

it is the difference between the implemented check gauge and the implemented track gauge, and therefore a derived value.

 

That's true.

 

However:

 

The gap between the stock rail and the check rail is not given a name.

 

is not true in prototype terms. It is called the Check Flangeway, and is referenced in relation to the special check rail chairs provided for use where there is gauge-widening -- which requires the check flangeway to be increased by the same amount. See BRT3 page 68.

 

cheers,

 

Martin.

[Andy Reichert]

As Martin has said,  the set of dimensions of a Standard are interrelated. That means that the value of each dimension does not necessarily stand alone for it's entire tolerance range, and may be limited by the actual values of other other dimensions it may be conditional on. Exceeding such condition limits will usually give illegal values, but that does not mean that the Standard is flawed. Just that the conditions have not been properly followed.

 

If you have not already done so, I suggest you and all others interested read through the excellent Scalefour Society P4 Track and Wheel Standards Digest, with particular reference to the conditional relationships 1 thru 7 at the end. It can be downloaded from the website, or accessed on-line at:

 

http://www.clag.org.uk/p4standards.html#table1

 

If you still find a flaw in the NMRA HO Standard, then please post it.

 

Andy

 

 

5 hours ago, Dungrange said:

 

I don't agree with the above statement, but I do agree with the one below.

 

 

A 'proper' standard should define a series of target dimensions and a set of tolerances or acceptable variance on these target dimensions.  It really doesn't matter whether the target dimension is a maximum, minimum or intermediate value.  However, anyone claiming to work to a particular standard should be targeting the target (or recommended) dimensions and I would argue that anyone who consciously targets a dimension to be anything other than the stated target dimension is not actually working to that standard.  Therefore, if the NMRA HO recommended flange-way gap is 1.22 mm, then anyone consciously targeting a different figure (say 1.00 mm) is not working to the NMRA HO standard.  A 1.00 mm flange-way gap may lie within the acceptable tolerance levels of the NMRA HO standard, but that is not the same thing.  If a different target value is being pursued, then the modified standard should, I believe, have a different name.

 

What I would expect is that if it were possible to manufacture a turnout and wheel set exactly to the recommended figures (ie with a tolerance of +/- 0.00 mm) then all of the dimensions should work together perfectly and it seems that the NMRA HO 'standard' does not meet this basic requirement and as such I'd consider it to be a 'flawed' standard and one that is in need of modification.  It would therefore be more accurate if the title of this thread where changed to 'fixing the flawed NMRA HO track standards for use with 00'.

 

For example, ignoring the tolerances (which are required simply because it is impossible to consistently manufacture items to an exact dimension) the following should always hold.

 

Track Gauge (16.54 mm) = Flange-way Gap (1.22 mm) + Check Rail Gap  (15.42 mm) = 16.64 mm = FAIL (Error = 0.10 mm)

Track Gauge (16.54 mm) = Flange-way Gap (1.22 mm) + Span (14.15 mm) + Flange-way Gap (1.22 mm) = 16.59 mm = FAIL (Error = 0.05 mm)

 

As you've said previously, the numbers don't lie: the NMRA HO standards are flawed.

 

This therefore means that all manufacturers who are purportedly following the NMRA HO standard are not necessarily all following exactly the same standard because the NMRA HO standard is clearly flawed.  Should a manufacturer target getting the track gauge and flange-way gap right and accept lower values for the check rail gap and span, or should they target the track gauge and span and get narrower flange-ways, or another of combination of dimensions?  It is clearly impossible to meet all of the NMRA recommended values. Ultimately, the errors and inconsistencies in the NMRA HO standard are reasonably small, and therefore the values that must deviate from the recommended values (depending on the priorities of an individual or manufacturer) will generally still lie within the quoted tolerances, but clearly the NMRA HO standards need to change if we are to achieve the dream of 100% reliability and 100% interchangeability.

 

 

I agree with this and the NMRA HO standard clearly doesn't work perfectly.  To get it to work, one or more of the NMRA recommended values has to be ignored.  There is also a difference between changing a critical distance and changing a tolerance.   If a standard is properly written, then I should be able to tighten all tolerances and still have 100% compatibility.  However, the same doesn't hold if I change the critical dimensions.

 

 

The problem is that I'm interested in how Peco have interpreted the what seems to be a flawed NMRA standard for their North American HO scale code 83 track range.  I'm aware of 4-SF and have a set of 00-SF track gauges from C&L, which I intend to use to hand build turnouts on the scenic part of my layout.  However, I was hoping to use a number of Peco's North American Code 83 points in the fiddle yard and want to know if these are compatible.

 

From 4-sf.uk the Check Rail gap is specified as a MINIMUM of 15.2 mm and with the NMRA HO standard specifying a range of 15.37 mm to 15.6 mm, this would seem to be okay. The Span is specified as a MAXIMUM of 14.25 mm and with the NMRA HO standard specifying a range of 14.10 mm to 14.20 mm, this would also seem to be okay.  Obviously the flange-way gap is greater under the NMRA HO standard, but then so to is the track gauge, so I don't see that as an issue.

 

[Siberian Snooper]

It's all very well setting the track standards, but until you get all the manufacturers to construct wheel sets to conform to your track standard you might just as well whistle 'Dixie ' .

 

Every UK manufacturer builds their wheel sets to different standards and  those of us over here a have found that constructing track to 16.2 mm gauge with a 1mm flange way gap 'V' crossing to wing rail produces a significant improvement in running, without recourse to changing each and every wheel set.

 

Please let me know when you have managed to get every UK manufacturer to make their wheels to the same standard, if I live that long.

 

 

[DCB]

The oldest OO track I have ever used was post WW2 Hornby Dublo 3 rail,  It was a code 100 system designed in conjunction with Hornby Dublo wheels and provided very smooth running over point gaps. Even at 15" Radius.   It did this by having a cast crossing Vee which provided support for the flange as the tyre ran through the gap. Peco used a similar rail section on streamline code 100  but did not use the flange support preferring to allow the large flanges on Triang etc stock pass through.

There is little wrong with Hornby dublo wheels running trough Peco code 100 points, but the coarser or finer the wheels the worse they run and Hornby wheels supplied as spares at best clatter through the gaps, or simply derail.

You will never get all manufacturers to adopt a common standard but you can adopt a standard flange depth and fill in the flangeways to a standard depth so the wheels move across smoothly.  You can narrow flangeways but best of luck getting a common back to back, even my Romford/Markits wheels vary by about 0.5mm, even the ones which don't wobble and Hornby, well plus minus 1mm is good for loco wheels.

All you need is a few strips of polystyrene, a digital vernier caliper, oh and a lathe.

[Andy Reichert]

Thanks for actually answering my OP original question.  I don't know if anyone has applied the S4 Society Standards test conditions to check it, but of it passes those it should be OK, if rather drastic for those who prefer commercially available track.  

 

Andy

 

26 minutes ago, Siberian Snooper said:

It's all very well setting the track standards, but until you get all the manufacturers to construct wheel sets to conform to your track standard you might just as well whistle 'Dixie ' .

 

Every UK manufacturer builds their wheel sets to different standards and  those of us over here a have found that constructing track to 16.2 mm gauge with a 1mm flange way gap 'V' crossing to wing rail produces a significant improvement in running, without recourse to changing each and every wheel set.

 

Please let me know when you have managed to get every UK manufacturer to make their wheels to the same standard, if I live that long.

 

 

 

[Dungrange]

3 hours ago, Andy Reichert said:

Before getting into other dimensions, please be aware that the flange way width (FW) only refers to the gap between the wing rail and the frog vee. There are no flange way gaps  (plural). The gap between the stock rail and the check rail is not given a name. as it is the difference between the implemented check gauge and the implemented track gauge, and therefore a derived value.

 

Okay, I'll accept that the Check Flange-way (the distance between the stock rail and the check rail) is a derived distance.  However, I still think that the Flange-way width (the distance between the wing rail and the common crossing) and the Check Flange-way (the distance between the check rail and the stock rail) should nominally be the same dimension on a straight piece of track: the only reason that I would expect them to differ is because there will be variances in the distances upon which it is derived from during manufacture or intentionally through the application of gauge widening.

 

However, working with the NMRA recommended distances we have:

 

Track Gauge (16.54 mm) - Check Rail Gap  (15.42 mm) = 1.12 mm.  Why therefore would the recommended Flange-way Width be 1.22 mm, but the Check Flange-way derived from use of other NMRA recommended distances give 1.12 mm?

 

3 hours ago, martin_wynne said:

I think you have mixed up a manufacturing drawing with a track standard.

 

A manufacturing drawing typically shows a target dimension and the allowed tolerances on it. Each manufacturer will create their own drawings based on their equipment and processes, which are unlikely to be the same as another manufacturer's drawings.

 

You might be right, but for example, the Double O Gauge Association standards (http://www.doubleogauge.com/standards/finescaletrack.htm)  appear to state a target dimension and a tolerance, albeit in this case it seems to be a one way tolerance - ie all of the target distances appear to be minimum values but are permitted to be a specified fraction of a millimetre more.

 

The Double O Gauge Association standards also highlight that at the nominal (or minimum) values, the Check Flange-way and the Flange-way Width are the same size (in this case 1 mm).  I would have expected the same from the application of the recommended values in the NMRA standards.

 

4 hours ago, martin_wynne said:

Their object being to create a product which is in compliance with the published standard. That is the purpose of a standard -- to test whether a product is in compliance, not to specify how it should be manufactured.

 

You cannot test whether a component meets a "target" dimension. You can only say whether a dimension falls within the limits specified by the standard. It follows that a standard cannot include target dimensions. This seems to be where the NMRA have got in a complete muddle.

 

Okay, this is potentially where the problem lies.  I agree that you cannot test compliance against a "target" dimension.  Therefore for the purposes of Quality Control, you need to define criteria against which something is going to be considered as meeting the requirements of a standard.  It appears that the NMRA have decided that the acceptance criteria should always be defined by a range: a minimum value and a maximum value.  As long as the measured dimension lies within the specified range then the manufacturer can claim compliance with the NMRA standards.  However, what you are saying in relation to 4-SF standards is that only one of these criteria is actually necessary (either the minimum or maximum) with the other criteria being limited by the acceptability of a different dimension.

 

However, the criteria used for acceptance of compliance with a standard is not necessarily the same as the nominal design value.  That is the nominal figure that manufacturers should try to manufacture their products to, which is no doubt the reason why there is also a target value.  Therefore, the inference is that manufacturers should try to produce track to a track gauge of 16.54 mm, but any track with a gauge between 16.49 mm and 16.79 mm is considered to be compliant with the NMRA HO standards.

 

Obviously I can see why three numbers have been specified by the NMRA, but I agree that it would be much simpler to specify either a maximum or minimum as appropriate.

 

4 hours ago, martin_wynne said:

What the NMRA have published is not a track standard but a manufacturing drawing. One that seems in any event to be flawed, and one which I doubt any manufacturer would actually want to use.

 

This would therefore seem to explain the "drift" in standards.  If the claimed standard is inconsistent, then it explains why many UK manufacturers seem to ignore it and use their own.

[Andy Reichert]

1 hour ago, DavidCBroad said:

The oldest OO track I have ever used was post WW2 Hornby Dublo 3 rail,  It was a code 100 system designed in conjunction with Hornby Dublo wheels and provided very smooth running over point gaps. Even at 15" Radius.   It did this by having a cast crossing Vee which provided support for the flange as the tyre ran through the gap. Peco used a similar rail section on streamline code 100  but did not use the flange support preferring to allow the large flanges on Triang etc stock pass through.

There is little wrong with Hornby Dublo wheels running trough Peco code 100 points, but the coarser or finer the wheels the worse they run and Hornby wheels supplied as spares at best clatter through the gaps, or simply derail.

You will never get all manufacturers to adopt a common standard but you can adopt a standard flange depth and fill in the flangeways to a standard depth so the wheels move across smoothly.  You can narrow flangeways but best of luck getting a common back to back, even my Romford/Markits wheels vary by about 0.5mm, even the ones which don't wobble and Hornby, well plus minus 1mm is good for loco wheels.

All you need is a few strips of polystyrene, a digital vernier caliper, oh and a lathe.

 

Agreed, although generally you only need to fill the last 20% of the vee gap towards the vee. I incorporate that for the  3D "Printed" Nickel Silver coarse scale crossings I supply for HO, ("88-Safe Frogs") so that the popular but non-compliant narrower code 88 wheels run smoothly too.  However, Martin prefers recommending gauge narrowing and the extra work of making whole hand built turnouts, even if they are "squiggly" if connected to ordinary 00 flex track.

 

Andy

[martin_wynne]

4 minutes ago, Dungrange said:

Okay, I'll accept that the Check Flange-way (the distance between the stock rail and the check rail) is a derived distance.  However, I still think that the Flange-way width (the distance between the wing rail and the common crossing) and the Check Flange-way (the distance between the check rail and the stock rail) should nominally be the same dimension

 

 

Hi David,

 

Yes they should. In fact in some situations they must be the same. For example it is not unusual see a crossover fitted with parallel-wing V-crossings, so that the wing rail on one V-crossing is extended to become the check rail on the other V-crossing:

 

 

 

In such a situation it is clear that the crossing flangeway and check flangeway must be the same. Many complex track formations are designed on the assumption that the flangeways are symmetrical. By definition this means that gauge-widening is not permitted through them.

 

I can't speak for the DOGA standards.

 

Bear in mind that just because a standard is published, it doesn't mean that it is necessarily correct or sensible.

 

cheers,

 

Martin.

[martin_wynne]

33 minutes ago, Andy Reichert said:

Martin prefers recommending gauge narrowing and the extra work of making whole hand built turnouts, even if they are "squiggly" if connected to ordinary 00 flex track.

 

Hi Andy,

 

Please don't put words into my mouth. I have never recommended "gauge-narrowing" in any shape or form. The correct gauge for 00-SF is 16.2mm. It is NOT a narrowed version of something else. It is a gauge in its own right, derived by subtracting 2.0mm from the current EM standards. What the other 00 or H0 standards happen to be is irrelevant.

 

Modellers are obviously free to use whatever plain track they prefer. Often 16.5mm flexi is a sensible choice where there are sharp curves needing gauge-widening. For a smallish mostly straight or gently curved layout, I have suggested that modellers using 00-SF might prefer to hand-build 16.2mm plain track.

 

Hand-built turnouts are not "extra work". For many they are the whole point and purpose of a finescale layout, to enable the track to be modelled on the prototype in the same way as the rest of the models. And to allow the creation of bespoke track formations matching the prototype, or best fitting the available space.

 

cheers,

 

Martin.

Edited February 19, 2020 by martin_wynne
typo

[Andy Reichert]

8 minutes ago, martin_wynne said:

 

Bear in mind that just because a standard is published, it doesn't mean that it is necessarily correct or sensible.

 

cheers,

 

Martin.

 

My point exactly.  Established proven Standards usually come from a recognised Society, and/or if for commercial interchangeability, from multiple manufacturers who between them demonstrate and manufacture matching wheeled vehicles, wheels and track specifically for, and named for, that Standard.