OO-SF tolerances and RTR wheel profiles

[Barry O]

Suggest you try asking @Michael Edgeabout how he builds Oo Fs paintwork. It works very well on Wentworth Junction.. and it does involve a 20p piece..

 

Baz

[polybear]

7 hours ago, PMP said:

There’s no manufacturer shifting goalposts.

There are no agreed industry standards set for Uk 4mm OO gauge wheel profiles. This is why there are significant variations between manufacturers, and even within manufacturers ranges.

 

Agreed - in this context I meant "shifting goalposts" to mean a Manufacturer using a different wheel profile on a new Loco from that previously used (and even between Loco and Tender, as CK has mentioned above).  One asks - "Just why would a Manufacturer do that?" 

In simple terms then in 4mm if you want a "shake the box then play" approach there are very good reasons why Commercial 00 (or DOGA Intermediate) is hard (impossible?) to beat; if however you seek a more accurate/finer/improved/whatever you want to call it appearance (or an attempt to improve running characteristics) then there's 00-sf, EM or P4 - but be prepared for issues as a result.

[polybear]

1 hour ago, Barry O said:

Suggest you try asking @Michael Edgeabout how he builds Oo Fs paintwork. It works very well on Wentworth Junction.. and it does involve a 20p piece..

 

Baz

 

Do you mean 00 Finescale (DOGA Fine)?  Or 00-sf?  The problem here is with a Turnout constructed to the latter standard; I do know that Mike uses 00-sf but I'm not sure if that applies to Wentworth Junction.

 

edit:  I've just measured a 20p piece and it's 1.7mm thick, so I'm intrigued.....

Edited December 17, 2023 by polybear

[Barry O]

1 hour ago, polybear said:

 

Do you mean 00 Finescale (DOGA Fine)?  Or 00-sf?  The problem here is with a Turnout constructed to the latter standard; I do know that Mike uses 00-sf but I'm not sure if that applies to Wentworth Junction.

 

edit:  I've just measured a 20p piece and it's 1.7mm thick, so I'm intrigued.....

It's OO-SF.. just pm him for more details. .

 

Baz

[polybear]

4 minutes ago, Barry O said:

It's OO-SF.. just pm him for more details. .

 

Baz

 

Thanks - I'll do that;  all I can think of is perhaps using it to check the switch blade opening gap?

[PMP]

2 hours ago, polybear said:

 

 One asks - "Just why would a Manufacturer do that?" 

 

It’s a very simple answer, they use different assembly factories, even within the same range. 

 

And no doubt those assembly factories use a variety of third party suppliers for wheels. With no agreed industry standard for OO wheels the assembly factory will specify wheels that meet the customer requirements. That is, in basic terms, they should work through set track trackwork. If they do, job done.

Edited December 17, 2023 by PMP

[Not Jeremy]

5 hours ago, polybear said:

 

Sharp radii will work - but will have a bearing on what Locos can be used; that's why the likes of Hornby etc. give guidance on what curves are suitable for their Loco range.  Just to add to the fun their are other factors that come into play as well, such as side play on wheelsets - which would explain why one kit built 9F might go round 24" curves and another won't.

 

 

Also why you never saw a 9F in Gloucester Docks!

 

Not everything will run round this...

 

 

[LBRJ]

One of the problems with "OO wheels" is that the flange thicknesses can be all over the place; Its not just the back to backs that matter.

 

CLAG have a page on their website, which although obviously aimed at P4 matters, give most of the relevant details far better than I could ever begin to explain away....

[Captain Kernow]

19 hours ago, polybear said:

you mentioned the layout was built to "00 Finescale" track standards; this confuses me a bit because the DOGA 00 Finescale Track Standard has a Crossing Flangeway dimension of 1.0mm (the same as 00-sf) - however this requires a minimum B2B dimension of 14.8mm, meaning RTR Locos etc. would require adjustment.  However, the DOGA Intermediate Standard states a CF of 1.2mm, with B2B of 14.4mm.  Do you recall what dimensions you used for the 00 part of the layout?

 

I have probably misled you when I state 'OO finescale standards'. This is simply a label used by myself and a few other friends modelling to the same standard, back in the day when things like Triang Super 4 and System 6 track were still fresh memories. It really meant the use of SMP chaired bullhead track and hand-built points, more or less to the same clearance standards as a plastic base SMP point kit. Simon (Not Jeremy) will certainly know what I mean by that.

 

I was briefly a member of DOGA, but then again I was also a member of EMGS at the same time (still am, with the latter)...

 

19 hours ago, polybear said:

It should be remembered that one of the main attractions of 00-sf is compatibility with both Kit built wheels (Markits, Gibson etc.) as well as with most modern RTR locos and stock without the need to adjust RTR B2B dimensions from the normal 00 dimensions.  Naturally if some manufacturers start shifting the goalposts with regards to wheel profiles then this may well have an effect.

I agree with Paul (PMP) in that one cannot accuse the manufacturers concerned of 'shifting the goalposts', in that there is no standard, laid down wheel and flange profile for OO...

 

19 hours ago, polybear said:

Finally, you mention that the Turnout causing problems is an A5; I generated one in Templot and the radius comes out at 597mm. 

00-sf is basically EM minus 2mm, meaning the "rules" for EM apply to 00-sf as well; the suggested minimum radius for 00-sf is 750mm on Templot (though this isn't by any means set in stone).  I did note that all the Locos mentioned on your layout thread that had issues were short wheelbase ones though, perhaps with the exception of the Manor - it's not as though you were having issues with Pacifics, 9F's etc.

An A5 turnout is certainly sharp, in the greater scheme of things, but it seemed the best fit for the location on the layout. Some gauge widening was incorporated on the curved sections and all forseeable locos (at the time of testing) were test-run through them.

 

However, mention of the A5 turnouts, the sharpness of the radius through them, check rail clearances etc. etc. is really a red herring to the issue I am raising.

 

Why is this? It's because the wheels of the locos concerned bind (and in one case) derail on plain, straight track, which has been laid to 16.2mm gauge, immediately before the checkrailed area.

 

This is before I even tried to test the locos through the curved sections (what's the point, I think).

 

The b2bs of the 'problem' locos is 14.5mm.

 

The b2bs of 'good' locos is also 14.5mm, but the 'good' locos have an obviously (to the naked eye) thinner flange profile.

 

I agree with Bob (Izzy) that there may also be an issue with the root radius on the locos concerned.

 

As such, it leads me to the conclusion (before anyone has even tried running such locos through actual checkrailed areas) that locos with this wheel/flange profile are incompatible with OO-SF.

 

 

[Captain Kernow]

6 hours ago, polybear said:

Agreed - in this context I meant "shifting goalposts" to mean a Manufacturer using a different wheel profile on a new Loco from that previously used (and even between Loco and Tender, as CK has mentioned above).  One asks - "Just why would a Manufacturer do that?"

As I may have mentioned previously, one of the manufacturers has stated that a future release in their range is being made in a different factory. This information alone makes me hopeful that it won't have the same problems with 16.2mm gauge track.

 

[Captain Kernow]

2 minutes ago, Captain Kernow said:

As such, it leads me to the conclusion (before anyone has even tried running such locos through actual checkrailed areas) that locos with this wheel/flange profile are incompatible with OO-SF.

I'm sure that there cannot be too many modellers modelling to OO-SF standards, compared with the mainstream OO and many of those could also be the kind of person, that is happy to make up an etched chassis and use wheels from the likes of Markits or Gibson.

 

However, in the light of what I have experienced, I cannot now assume that any future new toys that I buy will necessarily be able to run on my layout.

 

[LBRJ]

For anybody who wonders what it was that I was on about a couple of posts ago there is what you may call quite a bit of detail in the link below.

 

CLAG page on the matter

[Jol Wilkinson]

6 hours ago, polybear said:

 

Agreed - in this context I meant "shifting goalposts" to mean a Manufacturer using a different wheel profile on a new Loco from that previously used (and even between Loco and Tender, as CK has mentioned above).  One asks - "Just why would a Manufacturer do that?" 

In simple terms then in 4mm if you want a "shake the box then play" approach there are very good reasons why Commercial 00 (or DOGA Intermediate) is hard (impossible?) to beat; if however you seek a more accurate/finer/improved/whatever you want to call it appearance (or an attempt to improve running characteristics) then there's 00-sf, EM or P4 - but be prepared for issues as a result.

Is OO plagued by a lack of agreed standards, consistently applied? It would appear so.

 

When I modelled in 16.5mm gauge - many years ago - building locos, stock and track, I often had  issues. I put that down to two things, a relative lack of experience and knowledge, coupled with a lack of any OO standards at the time (other than track gauge). When I moved to P4 with its established standards and readily available jigs, etc. I rarely had problems (except for a recent purchase of some P4 Flexitrack which was under gauge). What I learned was that track/wheel standards and compatibility were important. On one  occassion I had a six wheel tender that wouldn't run through established and proven pointwork. It turned out I had been supplied with and fitted a set of OO/EM wheels (which I had set to the correct B2B). 

 

It seems here that while it is possible to apply a set of OO track standards (although there seems to be a variety), you can't know what the RTR manufacturers are doing with their wheels standards.

 

 

[polybear]

27 minutes ago, Captain Kernow said:

The b2bs of the 'problem' locos is 14.5mm.

 

The b2bs of 'good' locos is also 14.5mm, but the 'good' locos have an obviously (to the naked eye) thinner flange profile.

 

I agree with Bob (Izzy) that there may also be an issue with the root radius on the locos concerned.

 

As such, it leads me to the conclusion (before anyone has even tried running such locos through actual checkrailed areas) that locos with this wheel/flange profile are incompatible with OO-SF.

 

 

 

I recall that, when 00-sf started to become known it was suggested (perhaps by Martin Wynne - but I could be wrong as it was a long time ago now) that, with the move away from "Steamroller" wheels to a finer wheel profile by the manufacturers, "most recent RTR Locos should run without the need to adjust B2B dimensions".  Your experiences could perhaps suggest that some Manufacturers have taken a backward step (insofar as compatibility with 00-sf is concerned) on some Locos?  Out of interest, can you measure the relative wheel thicknesses of "good" and "bad" Locos?  This link has some information:

 

https://85a.uk/00-sf/setting_00_wheels.php

[Jeremy Cumberland]

1 hour ago, Captain Kernow said:

Why is this? It's because the wheels of the locos concerned bind (and in one case) derail on plain, straight track, which has been laid to 16.2mm gauge, immediately before the checkrailed area.

Either the flanges are too thick for 00-SF or the back-to-back is too large.

 

Quite honestly, RP25-110 wheels (0.03" (0.76 mm) flange thickness) and 1.0 mm flangeways seems a tough ask. It ought to be possible if the back-to-backs of the wheels exactly match the point dimensions (the aim is to have the back of one wheel on an axle hard up against the check rail and the flange of the other wheel being in the middle of the crossing flangeway), at least if you don't have long rigid wheelbases and tight curves, but the thicker the flanges are, the less scope there is for error or variation. However, flanges that are 75% of the flangeway width - which is what you have with RP25-110 wheels and 00-SF track - seem to me to be pushing it to extremes. Even the prototype only has flanges that are 64% of the flangeway width (1⅛" flanges and 1¾" flangeways).

Edited December 17, 2023 by Jeremy Cumberland

[polybear]

47 minutes ago, Jeremy Cumberland said:

Either the flanges are too thick for 00-SF or the back-to-back is too large.

 

Quite honestly, RP25-110 wheels (0.03" (0.76 mm) flange thickness) and 1.0 mm flangeways seems a tough ask. It ought to be possible if the back-to-backs of the wheels exactly match the point dimensions (the aim is to have the back of one wheel on an axle hard up against the check rail and the flange of the other wheel being in the middle of the crossing flangeway), at least if you don't have long rigid wheelbases and tight curves, but the thicker the flanges are, the less scope there is for error or variation. However, flanges that are 75% of the flangeway width - which is what you have with RP25-110 wheels and 00-SF track - seem to me to be pushing it to extremes. Even the prototype only has flanges that are 64% of the flangeway width (1⅛" flanges and 1¾" flangeways).

 

That would also suggest the DOGA Fine Track Standard would have the same problem as that also has 1.0mm flangeways.

[PMP]

1 hour ago, Jol Wilkinson said:

Is OO plagued by a lack of agreed standards, consistently applied? It would appear so.

 

 

It’s certainly not plagued by it.
 

The specific thrust here is that @Captain Kernow wants to use RTR products on track built to a set of OO society (I presume), specifications for OO-SF.

 

RTR manufacturers don’t use those specifications for their products. OO gauge RTR products are manufactured primarily for set track and streamline types of proprietary trackwork. In my experience from the 1980’s to date, using those types of track systems and unmodified RTR equipment, you rarely get problems. 

[PMP]

1 hour ago, polybear said:

 

"Your experiences could perhaps suggest that some Manufacturers have taken a backward step (insofar as compatibility with 00-sf is concerned) on some Locos? 

Nothing of the sort.

 

RTR models have never been supplied to be specifically compatible with OO-SF.

There’s no backward step, if an RTR release is/was compatible with a set of specifications not used by the manufacturers, it’s purely down to good fortune.

[Dungrange]

16 minutes ago, polybear said:

 

That would also suggest the DOGA Fine Track Standard would have the same problem as that also has 1.0mm flangeways.

 

But the DOGA Fine Track Standards aren't for RP25/110 wheels

 

https://doubleogauge.com/finerscale-wheels/

 

I believe that the closest equivalent to DOGA finescale wheels is RP25/88.

[polybear]

25 minutes ago, PMP said:

The specific thrust here is that @Captain Kernow wants to use RTR products on track built to a set of OO society (I presume), specifications for OO-SF.

 

 

Certainly not the 00 Society (DOGA); the specifications for 00-sf arised thru' discussions and information via the Templot Forum.  Indeed, there are those who took great offence to the use of the "00" part of 00-sf, which is why it's also referred to as 4-sf (though 00-sf probably remains the better known identity).

 

18 minutes ago, PMP said:

RTR models have never been supplied to be specifically compatible with OO-SF.

There’s no backward step, if an RTR release is/was compatible with a set of specifications not used by the manufacturers, it’s purely down to good fortune.

 

I don't ever recall claiming it was - my post read:

 

"Your experiences could perhaps suggest that some Manufacturers have taken a backward step (insofar as compatibility with 00-sf is concerned) on some Locos?"

 

The fact that some Manufacturers appear to have started using wheels of a different width/profile on some models is indeed a backward step insofar as compatibility with 00-sf is concerned, irrespective of the fact that isn't their target audience (they're designed for 00, and always have been).

[polybear]

23 minutes ago, Dungrange said:

 

But the DOGA Fine Track Standards aren't for RP25/110 wheels

 

https://doubleogauge.com/finerscale-wheels/

 

I believe that the closest equivalent to DOGA finescale wheels is RP25/88.

 

It'd be interesting to learn if anyone using the DOGA Fine Track Standard is happily using RTR Wheels?

Certainly there are numerous people using 00-sf (which shares the same flangeway gap of 1mm) with RTR Locos (Eastwood Town, for example).

[melmerby]

I have built a double junction, using the 16.2mm gauges and Templot with a minimum radius of around 36".

Not a single piece of my rolling stock fails on it.

I have items from all the major manufacturers and some minor ones as well as kit built locos and some USA stuff.

In fact it's the smoothest trackwork on my layout, creating less noise than Peco Points as the wheels traverse the (smaller) gaps.

(All B2B are set to 14.5 but the flanges vary greatly)

 

Even the dreadful Hornby Mag Stove R, but with the outer wheels fixed in position doesn't have a problem.

Edited December 17, 2023 by melmerby

[Jeremy Cumberland]

42 minutes ago, polybear said:

 

That would also suggest the DOGA Fine Track Standard would have the same problem as that also has 1.0mm flangeways.

No. The D0GA Fine wheel standard is considerably finer than RP25-110. I haven't found comparative drawings, and I haven't drawn them out side by side myself, but RP25-110 flanges are 0.76 mm from the back of the wheel to the inflection point between the flange radius and the root radius (there is no flange angle, as such). DOGA Fine wheels are 0.686 mm from the back of the wheel to the centre of the root radius. The root radius is 0.152, which probably makes the equivalent of the 0.76 mm dimension in RP25-110 something like 0.55 mm.

 

Quite frankly, RP25 (whatrver code is adopted) does not seem to be designed for narrow flangeways. The root radius is huge, which is great for getting round tight curves, but it makes for very wide flanges relative to their depth. D0GA Fine has slightly deeper flanges than RP25-110, but they are far thinner.

[melmerby]

29 minutes ago, polybear said:

there are those who took great offence to the use of the "00" part of 00-sf,

Why?

As 16.5mm is just one version of 00, there is also a 19 mm version (pity we don't have that!)

[melmerby]

1 hour ago, melmerby said:

I have built a double junction, using the 16.2mm gauges and Templot

Forget to mention, it's code 75 Bullhead track on copperclad sleepers.