EM wheels on P4 track

[jim s-w]

Dont you find that if you set up P4 with the same care and attention that works fine too? Theres a chance that the extra tweaks you have done to get EMwide to work would have paid off in P4 too.

I really don't think the depth of the flange is actually that relevant, as most of the interaction is at the root of the flange anyway. I have seen 00 models on well laid track dive off into the ballast and if 00 can come off with their rollercoaster style wheels then the flange cant really be that relevant. Many people have run P4 though stupidly tight curves at equally stupid speeds and it stays on, the differences you mention are surely the same as the difference between clean and dirty wheels.

Cheers

Jim

[martin goodall]

Dont you find that if you set up P4 with the same care and attention that works fine too? Theres a chance that the extra tweaks you have done to get EMwide to work would have paid off in P4 too.

Funnily enough, the same thought occurred to me only the other day. There are quite a few P4 modellers who think their track will be fine if they build it with the P4 gauges, but as some of us have discovered - it ain't necessarily so. Checking with a roller gauge afterwards is essential, and any tight spots need to be eased out to ensure the track really is 18.83mm gauge (or wider), and not 18.75 or whatever.

P4 wheels, because of their slightly under-gauge back-to-back setting, have plenty of room to 'hunt' on P4 track, and this may disguise slight narrowness in the track gauge, but this gauge narrowing can still cause problems, as can the slightly under-gauge back-to-back setting itself (see Ray Hammond's 1976 aricle to which I referred earlier, which led him to develop "Scale Four" as a refinement of P4).

I must re-test those vehicles that I have not yet converted to "Coarse-scale P4" to see if they now run faultessly after all. Nevertheless the fact remains that my coaches and wagons fitted mainly with Kean-Maygib EM wheels regauged to P4 back-to-back (17.7mm on the old Studiolith BB gauge I use) run very happily everywhere on the P4 track on my layout, which is entirely unmodified - other than easing out any tight spots where the gauge was found on checking to be less than 18.83mm.

It is interesting that in the course of this discussion, the two arguments which have been deployed against the use of fine-scale EM wheels on P4 track are precisely the same as the arguments which die-hard adherents of 00 and EM gauge threw at P4 in the early days - (1) it won't work; and/or (2) it's unnecessary.
I have proved to my own satisfaction that it does work. As to whether it is necessary or not, I believe that the extra depth of flange (even though it is no more than 0.25mm or 10-thou), and also the extra thickness of the flange at the flange root (an extra 0.1mm, or 4-thou) are an advantage.

In my experience (which now includes more than 35 years of model-making to P4 standards), vehicles fitted with P4 wheels definitely need some means of adapting themsleves to minor variations in rail level, even if this consists only of some slop in the axle-boxes. P4 wheels held rigidly in place in the underframe cannot be relied upon to run around the layout without derailing sooner or later; whereas EM-profile wheels similarly fitted don't seem to need this extra assistance to keep them on the rails. This is the big attraction to me of using EM-profile wheels. It eliminates the need for compensated suspension or springing, and that represents a substantial saving of time in completing rolling stock to run on the layout.

[martin goodall]

After the discussion in this and related threads (especially those contributions discussing the actual dimensions involved), I began to wonder whether I might after all be wrong, and so I decided to check the relevant dimensions. I also double-checked the wheels on the converted stock on my layout and did some more testing to see if I could discover exactly how the rolling stock was behaving (and why).

The first thing I discovered was that the EM wheel flanges are slightly wider than I had originally thought – about 0.65mm rather than 0.5mm. This means (on paper at least) that the measurement over the treads ought to be marginally wider than the track gauge. (0.65 + 17.7 + 0.65 = 19)

But careful examination of the Kean-Maygib wheels (14mm steel disc and 12mm steel 3-hole disk) and observation of their behaviour on the layout showed that they were definitely running on their treads, and did not have their flanges hard up against the rail head (although obviously very close). The Alan Gibson wheels (12mm 8-spoke with plastic wheel centres) were not quite so free-running as the Kean-Maygib wheels, but they too proved to be running on their treads, and did not seem to have an effective flange width any greater than the Kean-Maygib wheels.

Was my track over-gauge? Gauge widening was, of course, automatically built in on curves when the track was constructed, but on the straight track a few random measurements with the vernier gauge showed that it was only marginally over the minimum 18.83mm figure, but then I expect your track is too, except where it is slightly tight to gauge in one or two places. (I had already ironed out these tight spots when checking my own track at an earlier stage in my experiments.)

Might the wheels actually be running on the outer face of their flanges? My examination of the wheels and observation of their behaviour on the layout did not indicate this. If any of the wheels had been running on the outer faces of their flanges, I would have expected the flanges to ride up over the top of the rail-head and derail, but this has never happened. There are no signs of distress when running.

The only bumps and jumps with these wheels occurred at an early stage, before I had eased out the few tight spots, where the track had proved to be marginally below the 18.83mm minimum. It never happens now.

I did find that a couple of wagons slowed down when passing through the crossings of one or two turnouts. It seemed that the check-rails were acting like retarders in a hump yard. This turned out to be the result of these wheels being set a bit too tight on the back-to-back gauge. Very slight adjustment, so that the insides of the tyres were ‘a comfortable interference fit’ over the BB gauge soon cured that problem. It had nothing at all to do with these wheels having an EM profile; the same thing would happen with P4 wheels if you set them too tight to the BB gauge.

[I have not yet fitted any EM (or EMF) loco wheels, and must complete the first loco conversion to see how this will work. But experience with carriage and wagon wheels does not suggest that I should expect any problems. No Pacifics or other exotic beasts are involved.]

So my further investigations were somewhat inconclusive. On the one hand, the theorists would appear to be right, if you simply take the actual dimensions and do the calculations - on paper, what I have done can’t work. Yet in practice it does work - I just can’t figure out why.

In practical terms, I shall just carry on using the Kean-Maygib steel wheels, and (where there is no alternative) also Alan Gibson wheels - I don’t think their slightly less smooth running has anything to do with the P4 track/EM wheel profile combination; it only relates to the ease with which they roll, not to any misbehaviour on the track.

[jim s-w]

Hi Martin

do you have any P4 stock you can run through the trackwork to see if it gives you problems. I am beginning to wonder if an EMwide wagon might actually be a benefit as a rolling test vehicle, especially when looking for tight spots. Especially as you mention they have more resistance when they find one. I might still have some EM wheels knocking around somewhere

Cheers

Jim

[martin goodall]

Hi Martin

do you have any P4 stock you can run through the trackwork to see if it gives you problems. I am beginning to wonder if an EMwide wagon might actually be a benefit as a rolling test vehicle, especially when looking for tight spots. Especially as you mention they have more resistance when they find one. I might still have some EM wheels knocking around somewhere

Cheers

Jim

I still have a fair number of vehicles with P4 wheels. They have never revealed any problems with the track, although (as seems to happen with P4 stock) there was the occasional unexplained derailment, which I attributed to the miniscule P4 flanges.

Bear in mind that P4 wheels set up to the usual P4 standards have a running clearance of about 0.33mm, so they are unlikely to detect minor variations in track gauge. The few tight spots on the layout, where track was marginally below the minimum 18.83mm gauge only showed up when EM-profile wheels were used, because the running clearance is much less (in fact a negative value if the figures are to be believed!). It was at that point that I acquired a P4 roller gauge to check the track gauge more scientifically. It showed up more tight spots than had been discovered through the use of EM-profile wheels. These were easily adjusted (my track is 'Brook Smith' soldered assembly using the traditional 2mm rivets).

So the EM-profile wheels were slightly less sensitive to tight spots in the track gauge than the P4 roller gauge. A bump or jump could be seen when a wheelset enountered some of these tight spots (although the wheels never derailed), but not all of them. Incidentally, I found no such tight spots in any of my turnouts; they were all on plain track. I think I would still rely on a roller gauge rather than a wheeled vehicle for this purpose.

The 'tightness' through a couple of check rails was an entirely different problem, and as I pointed out, it had nothing to do with the use of EM-profile wheels. It is what will happen if you set any wheelset (including P4 wheels) too tight on the BB gauge. This is a point mentioned in the literature. If a wheelset is a push fit over the BB gauge, it is too tight. It should slide over the gauge easily, but without any slop - what I referred to as ‘a comfortable interference fit’. Another point which is not widely appreciated is that only the tyres should go over the gauge; one should not push the whole wheelset into the crook of the elbow, so that the axle goes right into the corner of the gauge. If you do that you will be measuring the space between the backs of the wheel-centres, which may not be the same as the back-to-back measurement between the backs of the tyres.

[Russ Elliott]

Martin - I've experienced a sort of parallel to your situation, in that I've got some undergauge K&L flexi on Somersham, between 0.15mm and maybe a tad more undergauge. I like to set my (P4) wheels BB at 17.8mm, so with conformant flange widths of 0.35mm to 0.4mm, I'm looking at over-flange distances of between 18.5mm and 18.6mm. The upper end is still just within running tolerance on the undergauge track, although uncomfortably so. I suspect in my case there maybe some tighter spots, and I wouldn't be surprised if some vehicles weren't very close to riding on their flange faces, given that our wheels are very rarely wobble-free. Fortunately, the worst of the undergauge is on a very gentle curve.

With respect to your theoretical 'non-fit' of 0.65mm flange widths set at a BB of 17.7 on a 18.83mm minimum TG, I would say that measuring EFs accurately is very difficult, and it is also difficult to see if treads are sitting snug on the railhead top. If your EFs really are 0.65mm, then clearly something doesn't quite add up. I note from the indicative EM tyre profile (on the EMGS site) the objective EF seems to be within a 0.5mm to 0.55mm range, and that the BB setting and measurement is made complex (I would say unnecessarily so) by the presence of the 5 degree chamfer on the rear face of the flange. Having said that, I do not know whether that drawing is being used in earnest, and obviously you are in the best position to judge and measure the actual wheelsets you have.

The other reason I have a doubt about your 0.65mm EF, notwithstanding your BB easing over checks, is the ability to get such an EF through a P4 CF. In effect, you are looking at a near interference fit, even for a wheelset guaranteed to be at a true perpendicular to the track. Very few of us have that luxury in the vicinity of a crossing, and I don't suppose you have either. Again, if your EFs really are 0.65mm, there's only one way such a tyre can go when traversing a P4 CF at anything more than 0.5 degree off the perpendicular (for a 36mm wheelbase, that's equivalent to about 1900mm radius), and that's upward. Your 0.55mm deep EM flanges no doubt save you in the vertical direction as you have reported, but I can't help feeling you could be running on an overall set of tolerances in the lateral plane a lot tighter than most Scalefourers usually find necessary.

[martin goodall]

Russ - You may have hit on the answer. I was quoting a 0.65mm flange from dimensions given by Iain Rice, but I had previously been under the impression that the EF dimension of EM-profile wheels was in fact 0.5mm or thereabouts, which would give me a theoretical running clearance of 0.13mm.

As you say, measuring the flange thickness is alsmost impossible, and like you I don't really believe that my wheels are wider than than the gauge of the track - they are obviously running with the flanges between the rails, rather than on top!

[rjh]

Russ - You may have hit on the answer. I was quoting a 0.65mm flange from dimensions given by Iain Rice, but I had previously been under the impression that the EF dimension of EM-profile wheels was in fact 0.5mm or thereabouts, which would give me a theoretical running clearance of 0.13mm.

As you say, measuring the flange thickness is alsmost impossible, and like you I don't really believe that my wheels are wider than than the gauge of the track - they are obviously running with the flanges between the rails, rather than on top!

Martin,

Taking your second point first, I have been experimenting with a rig to try and derive a reasonably accurate value for the "Effective Flange Thickness" of a wheelset. Results so far are reasonably promising and I hope to post some notes on this shortly.

Taking your first point second, about quoting flange widths, I read your article in the recent Scalefour News No.170 and found something odd regarding flange width in that, so I have submiited the document below as a "Letter to the Editor", intended for publication.

Regards, Rodney Hills

--------------------------------------------------------------------------------
Dear Sir,

"Scalefour News" No.170 (Dec 2010) includes, on page 24, an
article by Martin Goodall entitled "Wheel and Track Standards".

In it the author asserts that "..,in theory, both the orthodox P4
wheel settings and the S4 settings can exceed the minimum
specified check gauge in each case.".

He states:
"Min P4 check gauge = 18.15mm"
"Min S4 check gauge = 18.26mm"
"Max P4 flange + max P4 BB = 0.425 + 17.75 = 18.175mm
Max S4 flange + max S4 BB = 0.425 + 17.91 = 18.335mm".

He does not specifically cite sources for his numbers above,
but the two diagrams in the article are labelled as extracts
from "Digest Sheet 1.2", which can be found here:
http://www.scalefour.org.uk/downloads/P4-standards.pdf

Were Mr Goodall to extract the numbers for his P4 calculation
from this document, he would get:
Min P4 check gauge = 18.15mm
Max P4 flange + max P4 BB = 0.40 + 17.75 = 18.15mm

This P4 sum does NOT exceed the value of the check gauge
dimension.
What are these max 0.425mm flanges?

In the case of S4, both the info in the P4 document (q.v.)
and in Ray Hammond's article in Scalefour News No 11,
Feb 1978 give different figures for S4 min check gauge,
max flange and max BB respectively.

Perhaps Mr Goodall could cite the sources of all his figures,
please?.

This specific inter-relationship twixt wheelset and track
is Condition 2 of 6 and is discussed in the Digest 1.2
section entitled "Technical derivation of P4 track and wheel
standards".

Yours sincerely,
Rodney Hills
6255
5 December 2010
======================================================

[martin goodall]

The following text is extracted from a note I have sent to the Newsletter Editor, and I think it probbaly answers the point raised by Rodney Hills :-

Brian Morgan has kindly drawn my attention to a small error in my short piece in N/L No.170. The figure of 0.425mm which I quoted for the maximum (worst-case) effective flange width (EF) resulted from my having mis-read a reference to manufacturing tolerances in Brian’s contribution to N/L No.169. The passage in question reads “Unfortunately the EMGS do not tolerance their dimensions but one could assume that it would vary +/- 0.025mm, the same tolerance on P4 wheels”.

What I failed to understand was the figures in brackets which then followed, which I now realise were intended to refer to the P4 tolerance – “(but P4 is +0.05 / - 0)”. On re-reading this passage, I realise that Brian was referring here to the stated parameters of the P4 EF dimension, i.e. 0.35mm – 0.4mm. Thus the tolerances are within those two dimensions, and I was under a misapprehension in adding a further tolerance of 0.025mm to produce a ‘worst case scenario’.

This is all really rather academic, because the extra 0.025mm which I inadvertently added to the calculation is a shade under one-thousandth of an inch, and in any event I was not seeking to prove anything, but merely pointing out that you could play about with figures as much as you like, whereas a “suck-it-and-see” approach is my kind of engineering, and to hell with precision measurements and calculations.

Having reviewed both Brian’s original contribution and my own note, I am happy to accept that (in theory at least) the ‘worst case’ figures for P4 do come out just on the minimum P4 Check Gauge of 18.15 mm. For those who enjoy such abstruse points, the recalculated figures for P4 and S-4 respectively are:

Max P4 flange + max P4 BB : 0.4 + 17.75 = 18.15mm
Max P4 flange + max S-4 BB : 0.4 + 17.91 = 18.31mm

That puts the P4 wheelset just on the maximum dimension which is compatible with a minimum P4 Check Gauge of 18.15 mm. Ray Hammond’s S-4 standards specify a wider minimum Check Gauge of 18.25mm, but the calculation shown above still takes this value theoretically over the line by 0.06mm, and as I readily admitted in my earlier piece, my EM wheels set to the P4 BB gauge are theoretically too wide by 0.15mm (0.55 + 17.75 = 18.3mm). However, as I pointed out, neither Ray Hammond nor anyone else who has adopted the “Scale Four” standards has reported any problems, and I have certainly encountered none with my EM wheels set to the P4 BB gauge. So I think we can safely bin the theory and stick to rough-and-ready experimental experience.

The illustrations at the foot of the article were added by the Editor, presumably as an aid to understanding the expressions/abbreviations used.

[David Thorpe]

So I think we can safely bin the theory and stick to rough-and-ready experimental experience.

Experience tends to bear that out. A member of our group reports having purchased an EM Black Beetle motor bogie, intending to put P4 wheels on it. However, as an experiment he set the back to back on the EM wheels to P4, following which he found that it ran happily through all his P4 pointwork (which I have no doubt is built to precise P4 standards).

DT

[rjh]

Experience tends to bear that out. A member of our group reports having purchased an EM Black Beetle motor bogie, intending to put P4 wheels on it. However, as an experiment he set the back to back on the EM wheels to P4, following which he found that it ran happily through all his P4 pointwork (which I have no doubt is built to precise P4 standards).

DT

DT,
Well, that's a very interesting setup.

http://branchlines.blogspot.com/2006/07 ... heels.html
says that Black Beetle EM wheels are RP25/88 profile.

http://www.nmra.org/standards/sandrp/pd ... 009.07.pdf
says that RP25 Code 88 wheels have Flange Width (T) of 0.025 inches.
That's 0.635 mm.

Conside two of those on P4 18.83mm TG track
(2 x 0.635) = 1.27mm.
Subtract 1.27 from 18.83 = 17.56mm

We're all agreed that the standards have P4 back-to-back set at:
Min; 17.67mm Max: 17.75mm

But there's no room in your co-member's setup to stick within that range, is there?

What does his back-to-back actually measure?

Regards, Rodney Hills

[David Thorpe]

What does his back-to-back actually measure?

I've no idea - I'm merely reporting what he has said. However, I have no reason whatever to disbelieve him, any more than he has any reason to say something that isn't true. It strikes me that if it works, then, well, it works.

You appear to be suggesting that these wheels are incapable of navigating P4 pointwork, but that they might do so if set to a non-standard back-to-back?

DT

[craig_whilding]

What does his back-to-back actually measure?

You appear to be suggesting that these wheels are incapable of navigating P4 pointwork, but that they might do so if set to a non-standard back-to-back?
DT

I'd have thought a narrow b2b would just cause the wheelset to smack into check rails and create more issues. More likely i'd have thought that your member has regauged the wheelsets using a normal P4 b2b and that if there isn't slop in the check gauge then the wheels are just riding up the flanges a bit when going through crossings.

Ideally someone would need to fit one of those wireless hd cameras to their stock watching the wheelset as it negotiated the trackwork to have some idea of what happens though I don't think you could get one that has a high enough frame rate!

[martin goodall]

You may not be entirely surprised to learn that, employing my "suck-it-and-see" philosophy, I tried out some RP25.88 profile wheels (Black Beetle from Australia as supplied by Branchlines) reset to P4 back-to-back.

They seemed to run OK on P4 track - BUT on closer investigation it turned out that they were in fact running on the sides of their flanges. What alerted me to this was the fact that a coach fitted with these wheels, while it sailed happily through P4 pointwork rapidly acquired a list to starboard (or port), as the wheels hunted about without the treads of the tyres being able to sit down on the rail-head.

So RP25.88 wheels won't run on P4 track, whereas those with the orthdox EM profile will.

You do at least have the comfort of knwig that this statement is not mere theory, but is the result of actual experiment and fairly thorough testing on the layout.

(P.S. Anyone want to buy some RP25.88 wheels? One careful owner. Very low mileage.).

[martin goodall]

A further point arising from the two most recent exchanges :

If you set any wheels (even coarse-scale 00 wheels) correctly to the P4 BB gauge, then it is absoutely impossible that they could have any problem with check rails or wing rails, etc. because by definition they are correctly set to the P4 BB setting and so will have no reason to climb over check rails, etc.

Where the problem will occur (if you are going to get a problem) is on the outside of the flange, i.e. at the interface between the outside of the flange and the head of the running rail. If the flange is too thick to go through P4 flangeways, it will knock against the running rail or try to climb up it (as the RP25.88 wheels I mentioned a few moments ago did - although they never actually de-railed, just hunted about and imparted a noticeable list to the vehcile under which they had been fitted.

Modern EM wheels (as supplied by manufacturers such as Ultrascale or Kean Magib) have flanges which are slim enough to go through P4 pointwork without any problems, but coarser flange profiles will bump, grind, climb up the head of the running rail and quite possibly de-rail (as you would expect).

For some reason everyone seems to assume that any clearance problems are likely to occur on the backs of the wheels, which is precisely the opposite of what occurs in practice if you try using wheels which are simply too 'fat' to go through the P4 flangeway clearances.

[David Thorpe]

They seemed to run OK on P4 track - BUT on closer investigation it turned out that they were in fact running on the sides of their flanges. What alerted me to this was the fact that a coach fitted with these wheels, while it sailed happily through P4 pointwork rapidly acquired a list to starboard (or port), as the wheels hunted about without the treads of the tyres being able to sit down on the rail-head. So RP25.88 wheels won't run on P4 track, whereas those with the orthdox EM profile will.

Thanks for this, Martin - I should have realised that you would have tried it! Anyway, I've advised the person concerned of your comments and he accepts that his was not an exhaustive test - basically he wanted to check that the Beetle worked and do a little bit of running in. In any event, he ran it through several of his points and it seemed to work. He did not, however, look closely at the relationship between the wheel tyres and the railhead, and is therefore quite happy to take what you say as read.

Early in the new year he's going to bring it along to one of our meetings and will try it on another member's layout - I'll report back then!

DT

[andrew jukes]

A few late comments on this strange discussion.

Exactoscale wheels are 1.67mm wide (carriage and wagon) and 1.83mm wide (all loco wheels). We think there are quite a few advantages in using correct scale dimensions and very few disadvantages.

Quite correctly, it has been pointed out that, allowing for the blunt nose, wheels that are 1.67mm wide do not quite meet the criterion for continuous support with crossing flangeways that are 0.68mm wide. The question is, how much does this matter?

It is easy to forget that the wheel tread, at the point of contact with the rail head, is parallel to the rail. As you move forward or backwards from the contact point, the gap between the tread and the rail head grows - but initially quite slowly. Doing the sums, I reckon that a 12mm diameter wheel running over a 2mm gap between rail ends (an extremely crude rail joint!) will dip down a maximum of less than 0.1mm. A large driving wheel (say 28mm diameter) will drop less than 0.04mm. That’s perhaps why it is so much more important to get rail ends at exactly the same height rather than worrying overmuch about the gap (except that anything over 0.5mm, to me, looks bad).

Applying this to common crossings, I would take with a pinch of salt Martin Wynne’s concern that the Exactoscale wheels are 0.03mm too narrow for use with 0.68mm crossing flangeways. Perhaps someone would care to do the sums for the amount of dip in the (unusual) worst case where the back of the flange is rubbing against the wing rail.

On The P4Track Co. turnouts, we have aimed to set our crossing flangeways at 0.65mm (the P4 minimum). This was done as part of the process we have seen since the early days of P4 of trying to reduce unnecessary ‘slop’ in the original MRSG P4 standards - a process which we have supported by providing our standard Back-to-Back gauge at the Society recommended dimension of 17.75mm (compared with the original P4 setting of 17.67mm). Our scale width wheels can also be regarded as part of this trend.

Perhaps this will help Craig to stop worrying about Exactoscale products.

The oddest part of all this discussion is how Martin Goodall seems to think that his finding that some sorts of EM wheel will run satisfactorily on P4 track is conclusive proof that a ‘suck it and see’ approach is the best way of designing engineered products. I suppose when a component on his car fails, he goes round all the car dealers to buy the equivalent part from each of them to see which one works best - somehow the fact that things in the world around us generally work pretty well and can be replaced successfully if required thanks to all the engineering design input that sets tolerances and controls manufacture, has escaped Martin.

Of course I’m not saying that Martin can’t use whatever wheels he likes (though EM rims on near-scale centres look awful), but to attempt to make a general case that ‘suck it and see’ is better than using a properly calculated set of standards is very odd.

Regards

Andrew Jukes
Exactoscale Ltd.

[martin goodall]

Andrew Jukes wrote: “The oddest part of all this discussion is how Martin Goodall seems to think that his finding that some sorts of EM wheel will run satisfactorily on P4 track is conclusive proof that a ‘suck it and see’ approach is the best way of designing engineered products.”

I have never advocated that manufactured products should be designed on a ‘suck it and see’ basis. I am looking at it solely from the point of view of the end user, who may well find that accepting the whole package of standards adopted by a particular manufacturer or designer (originally Studiolith Ltd as manufacturers on behalf of the MRSG as designers) may not give completely satisfactory performance. After all, you are being asked to accept at face value whatever standards the designer and manufacturer have chosen to adopt. Those products may or may not be designed and manufactured to ‘a properly calculated set of standards’ but even if they are, this does not necessarily guarantee totally satisfactory performance in a practical context.

As I have suggested seriatim in this forum, the P4 wheel flange, being almost exactly to scale, is so unforgiving of minor track irregularities or small anomalies in the ride of vehicles (even if fitted with compensated suspension or springing) that occasional derailments are inevitable, even on the most carefully built P4 layout, using the most carefully built P4 rolling stock. Just to take one example, I noted at Scaleforum 2009 that every single layout in the show was suffering intermittent derailments, even though these layouts and the rolling stock which was running on them clearly exhibited the highest level of workmanship and care in their construction. I am aware that consideration is already being given within the Society (quite independent of the views I have expressed) to possible revision of the P4 wheel profile, although I am entirely neutral on that issue, having now adopted the EM wheel profile as a practical answer to the (admittedly infrequent, but nevertheless irritating) problem I had encountered when using P4 wheels.

Designers and manufacturers must necessarily adopt consistent standards in the design and manufacture of their products (whatever those standards might be), but the end user is entirely at liberty to mix and match different products, and to adopt a pragmatic ‘suck-it-and-see’ approach to their model-making. The results will naturally vary depending on the care which the model-maker takes in conducting any such experiments, but there is no need for any manufacturer to feel threatened by such an approach being taken by individual modellers.

[doktorstamp]

As a newcomer to P4 standards I have read this thread with interest: Firstly I have found Martin G's practical experience in combining the standards uplifting. I can see the advantage in having slightly overscale flanges.I suppose this makes me a heretical noviciate

The purist argument fails on two counts; A. because practice has clearly proved the contrary of the theory; B. the theoretical arguments have been selective with the sole purpose of villifying a heretic, who has had, in their eyes, the temerity to pragmatically demonstrate his case.

In the theorectical arguments Newton's three laws of motion have been disregarded,as has the effect of gravity. The pragmatism on the other hand, whilst unfounded scientifically, has been proved by experimentation, and demonstration. I fear it is this last which has proved patently unpalatable to the purists.

So let's instead enjoy our modelling and the hobby.

regards

Nigel

[Tim V]

Unfortunately, Martin has not proved the concept publicly, merely postulated it. Burford is a permanent layout, so we cannot see the layout perform under exacting exhibition conditions.

Perhaps a demo at Scaleforum/the AGM where it can be properly scrutinised by a number of other modellers (step forward Terry)?

[dcockling]

I suppose this makes me a heretical noviciate

Hi Nigel,
Firstly there aren't any heretics; it's a hobby! You and Martin are perfectly entitled to persue your hobby any way you want to, but so are the people that you are labelling as purists and if they want to question or refute what Martin has written they are entitled to do so to without being criticised for doing so. Knowing Martin, he is more than capable of arguing his corner.

I have no problem with the first part of your post, which relates to your opinions and feelings about what Martin has written. What I can't understand is why you then go on to condemn others for disagreeing. Perhaps you're seeing something I'm not, but I'm reading the same thread, and I see people having a discussion on a friendly basis. Your post seems to be doing exactly what you object to the other way round: villifying the purists, who have had, in your eyes, the temerity to pragmatically demonstrate their case. Or perhaps I've just imagined seeing layouts built to P4 standards working well over the years.

So let's instead enjoy our modelling and the hobby

I hope that Isn't shorthand, for "I've had my say, I'm right, don't have the temerity to disagree."

It seems that people who have made their choice to use P4 standards are enjoying their modelling and the hobby, as are other people who have chosen not to. I infer from your comments that you think there's something wrong with people chosing pure P4, they're those awful purists. Why can't they do that? Who is being harmed either by their choice or their advocacy of what they have chosen?

No-one has ever been forced to model to P4 standards if they don't want to, or stopped from using any other standard or combination of standards that they choose.

Users of P4 have been criticised and attacked for over 40 years for choosing and advocating P4 as if their choice has some kind of detrimental effect on, or is in itself an attack on people using other standards; I even noticed some months ago on another forum a number of Scalefour Society members, commenting on this thread in a condemnatory manner, hiding behind the (apparent) anonymity of their usernames, as if they didn't use P4 themselves and weren't members of the Society. Very odd!

As I said It's a hobby and we're all free to do whatever we like, I don't go around condemning people who've chosen EM or 00, or even people who have chosen to mix standards, it's their choice.

All the Best
Danny

[jim s-w]

because practice has clearly proved the contrary of the theory; B. the theoretical arguments have been selective with the sole purpose of villifying a heretic, who has had, in their eyes, the temerity to pragmatically demonstrate his case.

Nothing has been proved at all. People have been selective on both sides. For example my attempts at using em wheels ay p4gauge showed no real improvement but while a lot of rtr vehicles can have proper p4 wheels simply dropped in ( and they work) EMwide wheels don't fit. Having tried it as Martin suggested it's more work for no gain. Of course anyone else that interested can try it and judge for themselves.

Fact remains though, to truly model to p4 standards you have to use P4 standards. You can't just pick and chose which bits of the standard you like. You understand how the p4 society can't really support something that isn't p4 standards but at the same time Martin listed his layout as EM in his mrj article.

Cheers

Jim

[martin goodall]

It is fortuitous that this topic should pop up again. Yesterday, I fitted EM wheels set to 17.7mm back-to-back to two more bogie coaches and four more RTR wagons. They were the standard Kean Maygib EM gauge steel disc wheels, 14mm and 12mm diameter respectively, and they ran through all my points and crossings and round the 3 foot curve on my layout beautifully (without any compensation or springing). This brings to 14 the number of similarly converted bogie vehicles now running on my layout, and I now have some 40+ 4-wheel wagons and other vehicles (a mixture of RTR and Parkside Dundas kits) running on the layout which have been converted in the same way. The wheels in question are what Jim Smith-Wright would describe as "EM wide".

I have fitted three pairs Ultrascale EMF wheels (with 2mm wide tyres) to a GWR tender, but have not yet fitted EMF wheels to any of my locos, all of which are stil running on P4 wheels at the moment. The tender in question has run perfectly happily over all parts of the layout, both when being being hauled and propelled. The flange profile is the same in both cases - it is the tyre width which differs, the standard EM wheel tyres being 2.25mm wide.

I have never set out to 'prove' anything. I just carried out some experiments to see if EM wheels would run on my P4 layout, and (slightly to my initial surprise) I found that they did. My reason for adopting EM wheels, following those successful experiments (especially when converting RTR stock) is that it obviates any need for compensation or springing, so (as far as I am concerned) it represents a considerable saving in time and trouble in adpating these vehicles to run on a P4 layout. Others have reported that they have successfully converted RTR stock using P4 wheels without compensation or springing, but I just felt that the extra flange depth would give more reliable road-holding in these circumstances. I have experienced ZERO derailments.

The description of my layout in MRJ as 'EM Gauge' was an editorial slip, about which Paul Karau was acutely embarrassed, although I found it rather amusing in the circumstances and wasn't in the least bit concerned about it. The fact remains that I still describe my layout as P4, because the track is laid to a minimum gauge of 18.83mm, subject to gauge widening where approriate, and all crossings and flangeways are set strictly to the P4 standards - they have not been tweaked or eased in any way to accommodate EM flanges.

[By the way, I think Jim's "Birmingham New Street" layout is fantastic - truly inspirational modelling. This is shaping up to be one of the great layouts of all time.]

[jim s-w]

Thanks Martin

Do you use dcc at all? I will have a section of the layout at scaleforum if you fancy bringing some stock along for a play.

Cheers

Jim

[martin goodall]

I have not succumbed to the temptations of DCC (yet), so all my locos are analogue-controlled. I am not sure that DCC has any advantages in the case of a comparatively small and simple branch terminus, but I can certainly see the potential of DCC on a layout such as Birmingham New Street - in fact it is the obvious control system to use on a layout of that complexity.

Several people have invited me (or in one or two cases 'challenged' me !) to run my EM-wheeled stock on their P4 layouts, but my stock is fitted with couplings of my own unique design, so won't couple to anything else, and in any event I have always believed in the old adage "Horses for courses", which basically means that rolling stock should be built or adjusted for use on a specific layout. I have seen P4 rolling stock which runs perfectly on its owner's home layout misbehaving when tried out on another layout, even though the 'home' stock on that other layout has never given any problems.

I suppose we could try propelling a rake of coaches (not coupled to the loco, for the reason mentioned above) through the pointwork on BNS at Scaleforum, although I am not sure it would prove anything one way or the other. But irrespective of whether I am able to accept this invitation, I shall very much look forward to seeing the layout at Scaleforum. The photos on this website are mouth-watering.