EM wheels on 18.83mm track

[Martin Wynne]

Following some discussion on RMweb, here are some suggested dimensions for running unmodified EM wheels on 18.83mm gauge track:

Code: Select all

Track Gauge:        18.8mm MIN
Check Gauge:        18.0mm MIN
Crossing Flangeway:  0.8mm - 0.85mm
Check Span:         17.2mm MAX

Wheel Width:         2.0mm MIN
Back-to-Flange:     18.0mm MAX

Back-to-Back:                    17.3mm MIN
 RP25/88 wheels (0.6mm flange):  17.4mm MAX
    EMGS wheels (0.5mm flange):  17.5mm MAX


I have now added this to the list of gauge/scale pre-sets in Templot, with the name EM4 (18.8mm gauge, 0.8mm flangeway). In the next program update:



Check rail chairs for 0.8mm flangeway are available from C&L -- see: http://www.finescale.org.uk/index.php?r ... ct_id=3938

The 0.8mm flangeway is narrower than a rail-width, so retains the "P4 look" while accommodating the thicker EM flanges.

Unlike ordinary EM, this standard is not suitable for widened RTR wheels (RP25/110).

regards,

Martin.

[dal-t]

Brave move, well done. The flak should be interesting ...

[Jol Wilkinson]

Let confusion reign!

[Martin Wynne]

Brave move, well done. The flak should be interesting ...

Thanks, but I don't understand what is brave about it?

I put things in Templot which I think will be helpful to modellers. There has been some recent discussion about this subject so I thought it would be helpful to have some relevant numbers in Templot. No-one is under any obligation to take the slightest notice.

regards,

Martin.

[Noel]

Purely as a matter of logic, specifying minimum figures implies a need to specify maxima as well. Otherwise, in theory, you could end up with nonsense results such as a check gauge wider than the track gauge. In practice, none of this matters much unless suitable track building gauges are available?

Noel

[jayell]

I think there is enough confusion about standards already without adding a hybrid EM/P4 one to the mix. EM plus P4* should be enough variety for modellers who want a more accurate track width than 00.

I'm not sure what the current EM standards are but it used to be 18.00mm guage with EM Society wheels (those are the ones I have lurking in one of my 'bits boxes' from 30? years ago).

*18.83mm guage with P4 wheels from the likes of Alan Gibson, I am assuming that S4 standards are more or less defunct

John

[Martin Wynne]

Purely as a matter of logic, specifying minimum figures implies a need to specify maxima as well.

Hi Noel,

This is not the case because all the dimensions are interdependent.

For example the check gauge is specified only as a minimum because it cannot go larger than the maximum crossing flangeway plus the maximum check span.

Likewise the check span is specified only as a maximum because it cannot go smaller than the minimum check gauge minus the maximum crossing flangeway.

The track gauge does not have an upper limit, otherwise you cannot apply whatever gauge-widening is needed on very sharp industrial curves. Perhaps I should have added:

Track Gauge: common-sense mm MAX.

This system of interdependent max and min dimensions is the best way to specify track standards. For years it was used by the NMRA for all their standards and everything made perfect sense and worked. A few years ago they changed to having a target figure and a +/- tolerance for every dimension, and now you can find lots of anomalies and inconsistencies in their published figures.

Note that the published P4 standards also specify either a max or a min but not both (apart from the mysterious max on the check gauge):

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

regards,

Martin.

[jim s-w]

I do like the EM4 title. I called it EMwide when it was discussed on here. The fact is its not EM and it's not P4. It uses one standard for one critical aspect and another for the other one. As such if you are going to call it one or the other you have as much right to call it EM as P4 (I wonder if there's an element of snobbery in choosing p4?)

At the end of the day, the track is p4 but the stock on it is out of gauge EM.

There were claims made that still have been unproven. 100% reliability. Well since neither EM or P4 layouts can claim that, a mish mash of both clearly can't either.

The track doesn't need adjusting. I offered to run some of this stuff on BNS at scaleforum years ago. It was declined.

As we found with our test tracks. If you don't have any pointwork, standard EM runs on p4 track too!

Cheers

Jim

[Martin Wynne]

At the end of the day, the track is p4 but the stock on it is out of gauge EM.

Hi Jim,

EM4 track is not P4 track. The check gauge and crossing flangeway have been adjusted for a better match to the thicker EM flanges. It also runs RP25/88 wheels, which is not the case with P4 track.

As far as I know no-one is yet using EM4. But I have put the dimensions in Templot so that those who want to try it can plan ahead. For a "regular-pattern" V-crossing in Templot the crossing flangeway affects the lead length, so it is important to have the flangeway gap set up correctly when track planning.

regards,

Martin.

[jim s-w]

True Martin.

But you are confusing a theoretical standard that you have, for the want of any other description, just made up. With the practical experiences of those who claim they have successfully used em wheels on 18.83mm track (clue is in the title).

Cheers

Jim

[Martin Wynne]

But you are confusing a theoretical standard that you have, for the want of any other description, just made up.

Hi Jim,

Read my first post in this topic -- "here are some suggested dimensions..."

Everything in Templot was made up by me. Some folks find it useful, but no-one is obliged to take the slightest notice of any of it.

regards,

Martin.

[grovenor-2685]

Jim,
While I agree that Martin W has just made up EM4 and has not suggested otherwise, the thread title here is explicit, 18.83 is only the nominal gauge and does not of itself specify the flangeway standards used which could be P4, S4, EM4 or any other one cares to invent. True that Martin G aka Crichel Down and the other author in MRJ specified track P4 standards for their experiments with non-standard wheels but Martin W is suggesting something else
Keith

[jim s-w]

[

Everything in Templot was made up by me. Some folks find it useful, but no-one is obliged to take the slightest notice of any of it.

regards,

Martin.

I would hope nothing in templot is made up by you Martin. I understood it to be based on prototype practice and established standards.

Cheers

Jim

[Martin Wynne]

I would hope nothing in Templot is made up by you Martin. I understood it to be based on prototype practice and established standards.

If only it was that easy.

[martin goodall]

I am bound to say that Martin Wynne’s suggested new dimensions do seem to be a rather pointless exercise, not least because they would involve adopting a whole new set of standards, whereas those of us who use EM wheels on P4 track are using existing manufactured components, and existing track and wheel standards. All we do is to run EM wheels by manufacturers such as Ultrascale, KM and Alan Gibson set to a back-to-back of about 17.7mm (give or take a gnat's whisker) (i.e the back-to-back setting you get if you use one of the original Studiolith P4 BB gauges) on P4 track. It definitely does work. And so I for one don't propose to attempt to mess about with these new standards which Martin Wynne has (rather mischievously) proposed.

Martin Wynne and Bill Bedford (among others) seem to have got very steamed up about what name should be given to the use of EM wheels on P4 track. I have coined the name "Coarse-scale P4" for it, which clearly irritates the purists (and is, of course, intended to do so).

As I have pointed out ‘in another place’, when we use EM wheels on P4 track, it is an inescapable fact that the track remains 'P4' (it complies with the recommended P4 dimensions - there is no need to 'tweak' or adjust it in any way) and so there seems to be no reason why it should not still be described as 'P4', although that is really only just a short-hand way of identifying it.

I have never regarded myself as modelling "in 00" or "in P4" or anything else. I just make models - and I don't care what label you care to apply to them. But, purely for identification (and for a bit of devilment), I will continue to describe this particular mix of standards (i.e. EM wheels running on P4 track) as "Coarse-scale P4". If anyone objects to that, then frankly that’s their problem.

[Martin Wynne]

All we do is to run EM wheels by manufacturers such as Ultrascale, KM and Alan Gibson set to a back-to-back of about 17.7mm (give or take a gnat's whisker) (i.e the back-to-back setting you get if you use one of the original Studiolith P4 BB gauges) on P4 track. It definitely does work.

Hi Martin,

The P4 check gauge is 18.15mm min. If you set wheels to 17.7mm back-to-back the maximum flange thickness which can be relied on to run reliably in all possible track formations is 0.45mm (i.e. 18.15 - 17.7 = 0.45). Flanges thicker than this risk hitting the nose of the vee when crossing the flangeway gap.

It is next to impossible to get definitive information about the flange thickness of manufacturers wheels, or agreement about how it should be measured, but none of them have ever published a flange thickness as thin as 0.45mm other than for P4 wheels. The Ultrascale web site currently says "What tyre profile comes closest to the RP25 standard? The nearest is our 00/EM profile, which is close to the RP25/88 specification."

For RP25/88 wheels the published flange thickness is 0.025" = 0.63mm, which is a lot more than 0.45mm. See: http://www.nmra.org/sites/default/files ... 009.07.pdf

Now I know you are going to say that it all works fine, and I believe you. But if so it is doing so by the skin of its teeth, and in my view can't be relied on always to work with future wheel production, or in all possible track formations. I wouldn't like to be the one who persuaded someone to build P4 track with the promise that they will be able to run EM wheels on it when it is finished.

Against that I have suggested some dimensions properly matched to EM wheels (and RP25/88 wheels) which I am confident will always give good results for those who want to use EM wheels on 18.83mm gauge track. I see no reason to apologize for doing so -- no-one is under the slightest obligation to use or take any notice of them. I have given them a name (EM4) which clearly isn't P4, to underline the difference and avoid confusion.

regards,

Martin.

[Jol Wilkinson]

Martin (Goodall),

you clearly believe it is okay for you to follow your own modelling path and then consider it appropriate to set to have a poke at those that wish to follow a different route, i.e. use the S4 Society's published track and wheel standards.

Could you explain why?

Jol

[LesGros]

Hi Jol,
There is a clue in MG's earlier post:

... Martin Wynne and Bill Bedford (among others) seem to have got very steamed up about what name should be given to the use of EM wheels on P4 track. I have coined the name "Coarse-scale P4" for it, which clearly irritates the purists (and is, of course, intended to do so)...

a bit tiresome innit?

[Terry Bendall]

a bit tiresome innit?

It is indeed. P4 wheels on P4 track, and using the agreed P4 standards work. There is no need for anything else.

Terry Bendall

[jayell]

It is indeed. P4 wheels on P4 track, and using the agreed P4 standards work. There is no need for anything else.

And in my (humble) opinion EM is not really relevant these days except for people who are already committed to that standard, anyone new to finescale modelling would be better off using P4 standards from the outset.

John

[Colin Parks]

Speaking as one who is starting out in P4 and has yet to get anything running but has plans to build a P4 exhibition layout:

I've been reading though the online argument back and forth on this subject, both here and on RMweb. I've also been reading my recent copies of the S4 News (and MRJ 234). One thing that stands out to me is that a lot of people have trouble keeping P4 wheels on P4 track: One correspondent in the S4 News letters section recently wrote that he had attended an S4 event (unspecified) where six out of eight layouts did not perform to a reasonable standard. This letter in turn had been prompted by a comment in the previous issue where the writer had spent an hour watching a layout "and nothing fell off". There are more accounts articles, reports and comments alluding to persistent problems with derailments on P4 layouts.

Granted, there are always going to be derailments on model layouts from time to time - whatever the scale/gauge and for various reasons. I managed to reduce the number of incidents where things came off the track to five times in nine exhibitions on my 00 layout (they were not wheel-profile or back to back measurement related). None of what I have read is inspiring me with confidence that I can make P4 work. Taking all the comments that I have read on to consideration, the problem seems to be rooted in the scale depth of the wheel flanges. Yes, under-gauge track is also quoted as a potential cause of trains coming off the rails as well.

There are P4 layouts which do, by all accounts achieve good running. These seems to be of the permanently installed type or ones where the wheels are fine-tuned to the layout.

I have always loved the look of P4 layouts, with their track work that looks like real track and wheels ditto. Trouble is, for me, there is more to building layouts than having them looking realistic in digital photos. Martin Goodall's solution seems to provide those of us who cannot maintain tolerances to two decimal places with some hope of reliable running on P4 track.

For me, if the running of my layout is not good then it's a been a waste of time building it.

Colin

[billbedford]

I can see the day when, after there's been a rash of hybrid P4/EM layouts on the circuit, that people will realise that the size of wheel flanges has very little bearing on whether models stay on the track or not. It seems to that there is a lot of people seeing what they want to see and the use of circular arguments, i.e. "It is obvious that deep are going to be a Good Thing(TM) therefore smaller flanges are not going to work as well"

Now here's a radical thought; Maybe the number of derailments, at least on mature layouts, can be put down to nothing more technical than a lack of driving skills........

[Martin Wynne]

It is indeed. P4 wheels on P4 track, and using the agreed P4 standards work. There is no need for anything else.

Hi Terry,

That's a strange choice of words.

In the grand scheme of things there is no "need" to build a model railway at all.

Your post has caused me to be seized with the intention to create "004" and add it to Templot -- using P4 wheels on 16.5mm track.

Martin.

[Andy W]

There are lots of P4 layouts that run extremely well - St Merryn etc. There are also many OO and EM layouts that don't. It's surely not the gauge that is often the problem - it's the building/maintenance etc that needs examining.

[Colin Parks]

I can see the day when, after there's been a rash of hybrid P4/EM layouts on the circuit, that people will realise that the size of wheel flanges has very little bearing on whether models stay on the track or not. It seems to that there is a lot of people seeing what they want to see and the use of circular arguments, i.e. "It is obvious that deep are going to be a Good Thing(TM) therefore smaller flanges are not going to work as well"

Now here's a radical thought; Maybe the number of derailments, at least on mature layouts, can be put down to nothing more technical than a lack of driving skills........

Sorry Bill,

All the evidence suggests that flanges do have an influence on whether model trains stay on the track.

But if you read my post carefully, I mention that the derailments on my layout were specifically unrelated to the wheel dimensions and settings. To be clear, two of my 'public' derailments were caused by a misalignment of the fiddle yard traverser, one by a bent coupling dropper wire fouling the points and two were the result of badly fitted (by me) Bachmann automatic couplings on wagons levering an adjacent vehicle off the track. There were a few other incidents at exhibitions involving operator errors and one short circuit caused by heat expansion closing an insulation gap - but nothing fell off on those occasions!

What has been said in the article MRJ234 and also by Martin Goodall is that poor running was eliminated by use of wheels with deeper flanges. Or are you saying that both these people suddenly drove their trains with much more skill once they had changed their wheels?

Colin