Flange thickness-effect of.

Discussion of model and prototype wheel/rail interaction.
Julian Roberts
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Flange thickness-effect of.

Postby Julian Roberts » Sun Feb 25, 2018 8:46 am

martin goodall wrote:To take up Ian White’s point, railway modelling could be said to be the art of compromise. No one set of standards (not even P4) is perfect.

Finescale 00 is one alternative, as Paul Townsend has pointed out. Another possible compromise is the one I have adopted – using EM wheels (spaced out to the P4 back-to-back gauge) on P4 track. I am not the only Society member who has adopted this expedient. It still necessitates some adaptation of rolling stock to accommodate the wider gauge, but compensation or springing can largely be eliminated, and this greatly simplifies the conversion of RTR stock.

Answering the original question, this forum is for whatever contributors want to write about, but its most useful role is to share practical tips and advice on a wide variety of model-making topics.


Julian Roberts wrote:Martin - what is the flange thickness of EM wheels? I've often seen in your interesting posts you don't 'do' measurements of less than 0.1mm. So maybe you don't know.



Having no answer, unsurprisingly given my question was only put about an hour ago, from Martin Goodall, I've been looking for the Flange Thickness (EF) of EM wheels on the internet. The EMGS website doesn't seem to have its Track and Wheel Standards on the public part - maybe it does in the members area - if I could remember my Login. (PS I've just seen Jol's naughty step message to me and downloaded the link, but that doesn't show the Flange Thickness, thanks all the same Jol.)

As always, Martin Wynne to the rescue: http://85a.co.uk/forum/view_postx.php?post_id=567

The NMRA RP25/110 flange thickness is 0.8mm max which easily clears a 1.0mm flangeway, as for DOGA Fine. Romford/Markits and Alan Gibson wheels have thinner flanges, corresponding to RP25/100 and RP25/88 respectively.


So he said on 10th August 2007. I regard Martin W as the only person around who actually understands all the issues. Maybe he will annihilate the ideas I'm putting in this post later today...

So what is the NMRA RP25/88? Here's the NMRA table that comes up on a Bing search.

Capture NMRA Wheel Profiles.JPG


Let's assume Martin Goodall and others are using Alan Gibson wheels. The flange width for the Alan Gibson profile for 00/EM wheels, RP25/88 is given as .025" which is 0.635mm.

Judging by the absence of any agreement with my saying this on the thread discussing Back to Back - see viewtopic.php?f=8&t=1764
- I don't know if everyone - or anyone - understands that the BB plus one flange mustn't exceed the Check Gauge or a derailment is likely on the crossing of a turnout.

17.67 plus 0.635 is 18.305mm. The P4 Check Gauge is 18.15mm. So the BB of these EM wheels needs to be reduced to 17.52 to properly clear a crossing V.

But there also seems to be a total incomprehension that there's absolutely no harm in making the BB less than 17.67 even with P4 wheels, apart from the increased sideplay which worries some people, and the lack of adherence to the standards, at which people look in wonder as if they are Holy Writ.

How do I know? Because accidentally, through using a BB gauge that I didn't know was not made properly and in fact gave a BB of around 17.60, and then pressing too hard, I have several locomotives that work perfectly and never derail with a BB in the mid 17.50's, and one with a BB of 17.47 on its front wheels. But the difference to many people's locos is that they are made as heavy as possible and the compensation UNequalized to give more weight on the front or rear wheels which are the guiding ones - as per my articles in Snooze 199 and 200.

Gauging EM wheels to 17.52 seems to me to offer a recipe for the possibility of having a decent collection of rolling stock such as short wheelbase wagons and bogie coaches that won't need compensation or whatever (though I won't apply this to locos). Possibly thereby I may have the time to build a layout in my retirement which beckons. Anyway I'm going to try this out on the Bachmann LMS guards van I bought yesterday at the Glasgow Model Rail exhibition.

I have come in for a lot of stick for talking about minute numbers on this Forum. I make no apology for doing so on this thread. There seems to be an idea that we shouldn't talk in any detail about things for fear it will put people off. That reminds me of people trying to suck me into the church youth group when I was a kid by trying to make it sound fun. Luckily the 'fun' offered had no attraction for me whatever, not being the least bit interested in sport type activities. Later I found the real message of the Gospel considerably more attractive. In my opinion, what puts people off P4 modelling is the idea promulgated by some that it is easy. Following this gospel, they make trackwork without understanding the issues, and put on rolling stock (with P4 wheels) without proper suspension, and, of course, it doesn't work properly. Yes, maybe 80% or 90% of the time, but not really reliably. Personally I'm not happy with anything less than 100% reliability of trains staying on the track. When the issues are properly understood, the time involved making something that works properly is not a lot greater, and there is then no track "tweaking" which is what is endlessly done to try to improve dismal running.

I'll stand back and watch the bombs falling in my direction for what will be seen as shock horror HERESY

By the way the absolute minimum BB is the Check Span, 17.47. But there should be some clearance over this, normally 0.1. So a reliable minimum BB would be 17.57. So EM wheels will not be ideal at all. But the deeper flanges must explain why they don't derail on crossings in people'sometimes normal use at 17.67. A BB of around 17.55 will be the compromise I will try to find.
Last edited by Julian Roberts on Sun Feb 25, 2018 8:41 pm, edited 5 times in total.

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grovenor-2685
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Flange thickness-effect of.

Postby grovenor-2685 » Sun Feb 25, 2018 10:49 am

I moved Julian's post here as this should not be lost in "What's the forum for".
The precursors to the above post were
Julian Roberts wrote:I really liked the honesty of your post Ian. My experience of being honest on the Forum is not overwhelmingly positive.
This bit of honest inquiry will probably get me into more trouble.
Martin - what is the flange thickness of EM wheels? I've often seen in your interesting posts you don't 'do' measurements of less than 0.1mm. So maybe you don't know.

Jol Wilkinson wrote:Julian,
"This is the age of the Internet, don't think, just ask".
However, a quick internet search will turn up a link to the EM Gauge Society's pdf download for their EM (and P4) wheel standards. As this is in the public domain I have saved you the trouble and attached it.
EMGS standards.pdf
(219.68 KiB) Downloaded 64 times

So you are on the naughty step for asking someone to put themselves out for your benefit, rather than thinking for yourself!
Jol

PhilipT
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Re: Flange thickness-effect of.

Postby PhilipT » Sun Feb 25, 2018 11:52 am

A couple of quick points:

1 RP25-100 exists only in Romford/Markits - it is not listed in the NMRA table which Julian quotes. It is, in fact, RP25-110 with a wheel thickness of 0.100". It only works satisfactorily on EM trackwork because the root radius of the Romford/Markits flange is less than the NMRA value for RP25-110. If they were to the NMRA RP a wheelset travelling on 18.2mm gauge would be riding on the root radii of the flanges.

2 Effective flange for wheels to the EMGS standard is 0.54mm (determined many years ago by Joe Brooksmith) which are definitely not to RP25-88.

Phil Tattershall

Julian Roberts
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Re: Flange thickness-effect of.

Postby Julian Roberts » Sun Feb 25, 2018 4:44 pm

PhilipT wrote:
2 Effective flange for wheels to the EMGS standard is 0.54mm (determined many years ago by Joe Brooksmith) which are definitely not to RP25-88.

Phil Tattershall


I wasn't claiming any knowledge Phil. If the EF is 0.54 that's still a lot more than P4 EF of 0.35-40.

We've got to have the BB plus one flange a maximum of 18.15. So in this case of a 0.54 flange we need a BB of 17.61 max.

So that's a more comfortable workable area of say 17.55 to 17.61.

Quite a bit less than this magic 17.67. Perhaps people might not get the rough riding through crossings referred to in some subsequent posts on the related thread if they just did the maths.

Julian Roberts
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Re: Flange thickness-effect of.

Postby Julian Roberts » Sun Feb 25, 2018 4:50 pm

grovenor-2685 wrote:I moved Julian's post here as this should not be lost in "What's the forum for".


I'm fine with that Keith but I would have called the topic something like

What is the correct BB for EM gauge wheels on P4 track?

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David Thorpe
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Re: Flange thickness-effect of.

Postby David Thorpe » Sun Feb 25, 2018 5:29 pm

Why is anyone even discussing this? There are perfectly good P4 wheels for P4 track and you know what? They work.

DT

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Colin Parks
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Re: Flange thickness-effect of.

Postby Colin Parks » Sun Feb 25, 2018 5:55 pm

David Thorpe wrote:Why is anyone even discussing this? There are perfectly good P4 wheels for P4 track and you know what? They work.

DT


Well, it is a forum David!

All the best,

Colin

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grovenor-2685
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Re: Flange thickness-effect of.

Postby grovenor-2685 » Sun Feb 25, 2018 7:25 pm

Julian Roberts wrote:
grovenor-2685 wrote:I moved Julian's post here as this should not be lost in "What's the forum for".

I'm fine with that Keith but I would have called the topic something like

"What is the correct BB for EM gauge wheels on P4 track?"

Well you missed your chance when you did not start the topic yourself :)
Besides I would not want to suggest that EM wheels on P4 track is "correct".
Regards

PhilipT
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Re: Flange thickness-effect of.

Postby PhilipT » Sun Feb 25, 2018 8:05 pm

Besides I would not want to suggest that EM wheels on P4 track is "correct".

Fully agree,

Phil

Julian Roberts
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Re: Flange thickness-effect of.

Postby Julian Roberts » Sun Feb 25, 2018 8:18 pm

Keith I didn't start this diversion of the thread "What is the Forum for" into the subject of EM wheels. Martin Goodall did. I was responding to his post. I have edited the opening post of this thread accordingly to include his contribution. However it happened to coincide with something that I had been thinking about arising from the thread "What Back to Back setting do you use?"
David Thorpe wrote:Why is anyone even discussing this? There are perfectly good P4 wheels for P4 track and you know what? They work.

David Thorpe wrote:Why is anyone even discussing this? There are perfectly good P4 wheels for P4 track and you know what? They work.


Hopefully the above explains. And my opening post of this thread which was originally on your thread David. P4 wheels don't work ALL the time unless they are fitted with some sort of suspension. While the subject was discussed ad infinitum in the past I don't remember seeing the point being made that I have made, that the wider flange of an EM wheel demands a reduced Back to Back.

martin goodall
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Re: Flange thickness-effect of.

Postby martin goodall » Sun Feb 25, 2018 8:58 pm

Just to re-cap (as we have moved threads over to this new topic heading, which I see has been changed again since I started writing this contribution to the discussion), I took up Ian White’s point yesterday evening, by suggesting that railway modelling could be said to be the art of compromise. No one set of standards (not even P4) is perfect.

Finescale 00 is one alternative, as Paul Townsend has pointed out. Another possible compromise is the one I have adopted – using EM wheels (spaced out to the P4 back-to-back gauge) on P4 track. I am not the only Society member who has adopted this expedient. It still necessitates some adaptation of rolling stock to accommodate the wider gauge, but compensation or springing can largely be eliminated, and this greatly simplifies the conversion of RTR stock.

Julian Roberts then asked me what is the flange thickness of EM wheels, noting (correctly) that I don't 'do' measurements of less than 0.1mm, and he suggested (again correctly) that maybe I don't know. Even the published EMGS standards (to which Jol Wilkinson kindly provided a link) leave me none the wiser as to this precise dimension.

However, this really doesn’t matter, because I simply established by experiment that ‘modern’ EM wheels, when set to the P4 back-to-back would happily run through the crossing flangeways and check-rails of track built to the accepted P4 settings without any difficulty, and certainly without any derailments.

In effect, I was treating my P4 track as a sort of “Go / No go” gauge. If the EM wheels had given any sort of trouble when tested in this way, that would have been the end of the experiment, and I wouldn’t have pursued the possibility of using EM wheels any further.

There are only two provisos that should be observed when using EM wheels on P4 track, and I mentioned these in another thread in January:

(1) The track gauge must not be less than 18.83mm anywhere on the layout. Don’t assume that because you have laid your track with the usual gauges, it is accurate to gauge – it almost certainly isn’t. (If you use P4 wheels, this isn’t usually a problem, because of the over-generous running clearance built into the P4 standards.)

(2) The EM wheels must be set near enough to the minimum P4 back-to-back gauge (17.67mm). I use an early Studiolith BB gauge, which I measured as 17.7mm. [So this answers the question : What is the correct BB for EM gauge wheels on P4 track?]

If these two points are not observed, you won't get derailments, but the wheel sets may ‘jump’ in places where the track is narrow to gauge, or if the wheelsets have been set to a BB dimension that is wider than 17.7 mm.

With these points in mind, it is entirely unnecessary to speculate as to the precise flange profile of the wheels in question. My approach to all engineering issues is - “Suck it and see.” Either it will work, or it won’t. I found that EM wheels do work on P4 track, and I have never found it necessary to delve into the precise reasons for this, although at least part of the explanation is almost certainly down to the over-generous running clearances that were engineered in to the P4 track standards more than 50 years ago.

I confirm that I do use Alan Gibson wheels, but the wheels I really prefer are Kean Maygib all-steel wheels for carriages and wagons (which I believe may no longer be available), and Ultrascale ‘EMF’ wheels for locomotives. I do not currently have any EM gauge carriage or wagon wheels from Ultrascale, but certainly intend to use them in future, as (like the KM wheels) they run so smoothly.

In line with my “Suck it and see” approach, I did also try out some RP25/88 wheels. They did not derail, but hunted all over the place, due to the flanges running up and down the face of the rail-head. The flanges were just too fat for this application (although no doubt excellent for use in 00 or EM gauge). Just to complete these experiments, I also tried out some Markits wheels, with similar results (and the width of the wheel treads at 2.54 mm, also made it difficult to accommodate these wheels in the available space under the vehicle).

In the course of this discussion, Keith Norgrove observed that he would not want to suggest that the use of EM wheels on P4 track is "correct". I entirely agree. In fact, one does not need to concern oneself as to whether or not it is “correct”. It is merely necessary to satisfy oneself as to whether it works or not. In my experience, it does.

Finally, David Thorpe asked why anyone was even discussing this, because in his view there are perfectly good P4 wheels for P4 track and they work. Well, we have been over that in the past ad nauseam, and there would be no point in going over it all again. I simply felt that the use of EM wheels might prove easier (and, for me at least, more reliable) and would eliminate or reduce the need for springing or compensated suspension. Ultimately, this is entirely a matter of personal choice. If you are entirely satisfied with using P4 wheels on P4 track, and are prepared to do what is necessary to make them work properly, then there is absolutely no need for you to consider any alternative, and you can ignore siren voices like mine.

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Jol Wilkinson
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Re: Flange thickness-effect of.

Postby Jol Wilkinson » Sun Feb 25, 2018 10:12 pm

As an acquaintance has told me several times recently, anther alternative would be Markits wheels on their P4 axles. He claims to have built a loco with these and that they run satisfactorily on a S4 standard layout belonging to one of his friends. You may not be surprised that, not having witnessed this, I am a little sceptical.

And no, it isn't the 1st April.

martin goodall
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Re: Flange thickness-effect of.

Postby martin goodall » Sun Feb 25, 2018 10:23 pm

Like Jol, I am also sceptical about the use of Markits loco wheels.

My experiments with their wagon wheels were unsuccessful. (This came as no surprise, because I did not expect that their profile would be compatible with P4 track standards. But I thought that I should at least give them a fair trial.)

Julian Roberts
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Re: Flange thickness-effect of.

Postby Julian Roberts » Mon Feb 26, 2018 9:24 pm

Martin you have answered very fully, your fluency entirely compensating for the lack of the number I am after, and thank you for that. An email was sent to Colin this morning who answered that the EF of his EM wheels is a commercial confidentiality. Quite understandable probably, there being no published standard unlike with P4 wheels, which I suppose explains the different characteristics Martin finds with the various makes of wheel, as each firm can interpret the drawing as they see fit. I doubt if I can accurately measure the EF at exactly the right place with my cheapo digital Vernier, nor even if I had a posh one, so my post yesterday morning is not answerable in numeric terms, and any further experiment will be done in the same manner as Martin.

Alan Turner
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Re: Flange thickness-effect of.

Postby Alan Turner » Tue Feb 27, 2018 9:21 am

Julian Roberts wrote: An email was sent to Colin this morning who answered that the EF of his EM wheels is a commercial confidentiality.


I don't see how he can justifiably say that as the EF is calculable from the published EMGS standard (See Jol Wilkinson/Grovenor post above). If he is not prepared to say what his is then the conclusion must be that is non-conformant to the published standard.

regards

Alan

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Jol Wilkinson
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Re: Flange thickness-effect of.

Postby Jol Wilkinson » Tue Feb 27, 2018 9:59 am

Perhaps he was too busy to answer - in detail - an email questioning his manufacturing standards/tolerances.

Julian Roberts
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Re: Flange thickness-effect of.

Postby Julian Roberts » Tue Feb 27, 2018 11:47 am

Please enlighten me. While there are plenty of dimensions on the EM wheel drawing Jol kindly provided I can't see an equivalent for the 0.35 of the P4 wheel drawing.

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Jol Wilkinson
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Re: Flange thickness-effect of.

Postby Jol Wilkinson » Tue Feb 27, 2018 11:59 am

Julian,

is the EMGS drawing intended for designing a tool to manufacture wheel tyres?

The P4 wheel profile on the same document doesn't match in drawing style. One issue seems to be the location at which the dimension of .36mm flange width is actually measured, so making it rather irrelevant. In fact, the P4 profile drawing is not really any use, as it lacks several critical measurement setting locations that are on the EM profile drawing.

Jol

Julian Roberts
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Re: Flange thickness-effect of.

Postby Julian Roberts » Tue Feb 27, 2018 1:24 pm

Apologies Jol I'm at work and not able to concentrate here properly. The P4 drawing I was referring to, I should have explained, is that in the Society P4 track and wheel standards. But the Effective Flange thickness 0.35-40mm (tolerance as per the standards) dimension is critical surely you would agree?

Alan Turner
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Re: Flange thickness-effect of.

Postby Alan Turner » Tue Feb 27, 2018 3:56 pm

Julian Roberts wrote:Please enlighten me. While there are plenty of dimensions on the EM wheel drawing Jol kindly provided I can't see an equivalent for the 0.35 of the P4 wheel drawing.


simple enough to calculate it. You have all the data in the drawing.

regards

Alan

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grovenor-2685
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Re: Flange thickness-effect of.

Postby grovenor-2685 » Tue Feb 27, 2018 4:19 pm

simple enough to calculate it. You have all the data in the drawing.

Except the gauge corner radius of the rail.
Regards

Julian Roberts
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Re: Flange thickness-effect of.

Postby Julian Roberts » Tue Feb 27, 2018 5:15 pm

Alan Turner wrote:
simple enough to calculate it. You have all the data in the drawing.

regards

Alan


How? That's way beyond my pay grade!

nigelcliffe
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Re: Flange thickness-effect of.

Postby nigelcliffe » Tue Feb 27, 2018 8:04 pm

Jol Wilkinson wrote:As an acquaintance has told me several times recently, anther alternative would be Markits wheels on their P4 axles. He claims to have built a loco with these and that they run satisfactorily on a S4 standard layout belonging to one of his friends. You may not be surprised that, not having witnessed this, I am a little sceptical.


I have seen some locos built this way. And they do run. But, they are inside valve gear prototypes, with wheels below footplate, or hidden in generous side tanks. Whether they are scale in other areas which are critical to appearance, I can't say, as the locos were far from finished and of prototypes I'm not familiar with.

I'd expect the result to be very wide over the rods and outside valve gear would risk platform strikes. As, not only are Markits wheels very wide, their crankpin system (unless modified) puts the rods a long way out from the wheel faces. Sufficiently bad that Markits EM wheels/axles won't fit under a Hornby K1 2-6-0 without significant modification of the Markits parts. (Full gory details of how to make them fit are available on request).

- Nigel

Alan Turner
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Re: Flange thickness-effect of.

Postby Alan Turner » Wed Feb 28, 2018 8:57 am

grovenor-2685 wrote:
simple enough to calculate it. You have all the data in the drawing.

Except the gauge corner radius of the rail.
Regards


Not knowing the corner radius of the rail would bring the same uncertainty to P4 in just the same way.

regards

Alan

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Jol Wilkinson
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Re: Flange thickness-effect of.

Postby Jol Wilkinson » Wed Feb 28, 2018 10:46 am

Julian Roberts wrote:
Alan Turner wrote:
simple enough to calculate it. You have all the data in the drawing.

regards

Alan


How? That's way beyond my pay grade!


I've done it for you Julian, using the EMGS drawing for their wheel profile standard ( the first and probably only time I'll ever bother with such a calculation). I make it .53mm, measured at the radius point .53mm above the flange bottom. Is that what you wanted or I have misread what you were seeking. ?
Last edited by Jol Wilkinson on Wed Feb 28, 2018 10:51 am, edited 1 time in total.


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