P4 vs S4 - Pro's and con's

Discuss the prototype and how to model it.
Knuckles
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P4 vs S4 - Pro's and con's

Postby Knuckles » Fri Dec 04, 2015 7:35 pm

A wee question that may have scope to branch out. I looked where to put this and wasn't sure so I hope here is a good place. Also apologies if it has already been posted somewhere previously. :?

As I understand it, and please correct me if I'm wrong but the difference between P4 and S4 is mainly the flangeway gap size and the back to back settings, correct? I looked at the difference before and in terms of real scale the difference to me looked to be about half a real inch if that, although I'm remembering a long time ago when I looked into the math so again correct me if I'm wrong.

In the early days I looked into it for the obvious reasons of to model P4 or S4 and like most chose to go P4 because...

A) It's apparently easier.
B) More on the market to do so.

I've seen the excellent layout Sheeps Pasture I think the name is in person and I could see the difference with my eyes regarding the flangeway being tighter but haven't seen any other S4 layouts, don't know of any either.
From those of you in the knowledge could you please explain what you consider to be pro's and con's between the two and why anyone would want to go S4 one day considering it seems to be the 'ultimate' answer.

Maybe we could get some good debate and learning out of this, I know not, time will tell.
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Tim V
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Re: P4 vs S4 - Pro's and con's

Postby Tim V » Sat Dec 05, 2015 6:54 pm

To my knowledge, sheep Pasture by Robin Whittle is built to the normal P4 standards.

There are very few layouts built to S4 standards, and even less on the exhibition circuit. Ray Hammond's layout was one, I can't think of any other recent examples.

S4 standards are fine if you can cope with greater radii, otherwise P4 gives the more useful 4' minimum.
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barrowroad
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Re: P4 vs S4 - Pro's and con's

Postby barrowroad » Sat Dec 05, 2015 8:33 pm

Tim, You are correct my Sheep Pasture layout is built to P4 standards.

Robin

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Noel
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Re: P4 vs S4 - Pro's and con's

Postby Noel » Sat Dec 05, 2015 8:59 pm

Tim V wrote:There are very few layouts built to S4 standards, and even less on the exhibition circuit. Ray Hammond's layout was one, I can't think of any other recent examples.


The layout was called Buntingford,

Noel
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Philip Hall
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Re: P4 vs S4 - Pro's and con's

Postby Philip Hall » Sat Dec 05, 2015 11:08 pm

Ray Hammond's prototype for Buntingham was Buntingford. Perhaps the best known large example of S4 standards was the late Bill Richmond's layout in New Zealand.

S4 standards are fine, but there is much less room for error than P4, which is a good reason for sticking to P4. It is much more important that wheels are perfectly true and wobble free, because the increased back to back dimension (with exactly the same wheels as P4) means that there is less play between the wheelsets and the rails. It does look better, because of the slimmer crossing flangeway: exactly to scale.

It is not something I would recommend to anyone other than the most experienced, and even then only to someone well versed in the ways of P4 and who truly understands the ramifications.

Philip

Knuckles
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Re: P4 vs S4 - Pro's and con's

Postby Knuckles » Sat Dec 05, 2015 11:46 pm

Now I feel a right 'tard. Where did I get the impression Sheep Pasture was S4 then? Must have got my wires seriously crossed there. :cry:
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Martin Wynne
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Re: P4 vs S4 - Pro's and con's

Postby Martin Wynne » Sun Dec 06, 2015 12:39 am

Knuckles wrote:Now I feel a right 'tard. Where did I get the impression Sheep Pasture was S4 then? Must have got my wires seriously crossed there. :cry:

Hi Knuckles,

Part of the reason may be the confusing naming. Some traders (including me when I was one) use the designation S4 to mean P4. For example Alan Gibson still does this: "Available in 00 Finescale, EM and S4 Gauges" -- from the current catalogue.

The reason for that is that "P4" and "ProtoFour" were originally trade marks of MRSG/Studiolith Ltd.

For the sake of continuity I'm still doing the same in Templot. Standard P4 is called "S4/P4", and the Ray Hammond variant is called "S4-X" (for "extreme").

Ideally the Scalefour Society would have sorted this out when it was formed, giving the Ray Hammond variant its own more distinct name, but unfortunately it didn't happen.

regards,

Martin.
40+ years developing Templot. And counting ...

Knuckles
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Re: P4 vs S4 - Pro's and con's

Postby Knuckles » Sun Dec 06, 2015 9:16 am

Hmm, maybe that could explain it. Maybe it was listed as an S4 layout instead of a P4 one and I imagined a thinner flange way due to preconcieved expectations. I can't think of any other explanation. Oh well.

Thing is Proto4 technically is Scale4 aswl well because it is a layout modelled to 4mm/1ft scale, and even more so than 00 etc. So by that I guess all P4 layouts could be considered S4.

If this confusion still exists isn't there anything that can be done?

Anyway going back to original topic before I dig my n00b grave any further, If you have an S4 layout can P4 loco's fun on it? Similarly if you have a P4 layout can S4 loco's fun on it (providing the minimum S4 radius is modelled, which is?)

I understand S4 is more for experts which I without question am a long way from, but just thinking to the future how much harder is it and ptoviding curves are not too tight do you get better runnning?

If we all had a mountain of curve space would it be worth doing S4 instead if you hadn't Llrrady amassed a large P4 collection?
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Tim V
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Re: P4 vs S4 - Pro's and con's

Postby Tim V » Sun Dec 06, 2015 10:29 am

Knuckles wrote:Hmm, maybe that could explain it. Maybe it was listed as an S4 layout instead of a P4 one and I imagined a thinner flange way due to preconcieved expectations. I can't think of any other explanation. Oh well.


S4 uses the same wheel profile, I think it's the check rails that are set differently for the wider back to back.

Best not to get worked up about this, the Scalefour Society (and the EMGS) both recommend the use of the standard P4 standards (17.67mm BtoB) and the "standard" gauges.
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grovenor-2685
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Re: P4 vs S4 - Pro's and con's

Postby grovenor-2685 » Sun Dec 06, 2015 10:40 am

Knuckles wrote:Anyway going back to original topic before I dig my n00b grave any further, If you have an S4 layout can P4 loco's fun on it? Similarly if you have a P4 layout can S4 loco's fun on it

See http://www.clag.org.uk/p4standards.html#use-of-4mm-scale-equivalent-dimensions
There is a degree of overlap depending on where in the acceptable range you set your Back to back. P4 BB min is 17.67 while 'S4' Check span max is 17.67, hence a P4 wheelset with a higher than min BB should run on S4 track. The other way round an S4 wheelset with a BB above the P4 max will not be properly guided by the check rails on P4 track so will run most of the time but will not be reliable, especially through complex formations.
(providing the minimum S4 radius is modelled, which is?)

This cannot be defined as it depends on type of vehicle, allowed sideplay in axles, amount of gauge widening in the track etc.
I understand S4 is more for experts which I without question am a long way from, but just thinking to the future how much harder is it and ptoviding curves are not too tight do you get better runnning?

The protagonists always claimed better running :) To work to 'S4' you have to reduce the tolerances and generally take more care in construction of track and stock, IMHO it is this rather than the actual standard that makes a difference. If really interessted go back in the archive and read Ray Hammond's articles.
If we all had a mountain of curve space would it be worth doing S4 instead if you hadn't Llrrady amassed a large P4 collection?

That can only ever be a personal decision.
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newport_rod
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Re: P4 vs S4 - Pro's and con's

Postby newport_rod » Sun Dec 06, 2015 6:30 pm

For what it's worth i built Llanastr to S4 standards and people will be able to see how well/badly it runs at next year's AGM.

Most of my modelling now is for the Newport MRS Little Mill Junction which is being built to P4 standards and, in it's foetal state, will also be at next year's AGM.

See links to both are in the signature below.

Knuckles
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Re: P4 vs S4 - Pro's and con's

Postby Knuckles » Sun Dec 06, 2015 7:13 pm

Ok, many thanks for the responces. Also many thanks for putting up with my myriad of typo's. Touch screen 'phone doesn't help one bit either.
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martin goodall
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Re: P4 vs S4 - Pro's and con's

Postby martin goodall » Mon Dec 07, 2015 8:20 pm

To avoid confusion, I always refer to Ray Hammond's standards as "Scale Four" - the term he has always used himself. (The abbreviation "S4" is best avoided.)

The society adopted the name "Scalefour" (with Ray's consent), because at that time "Protofour" (but not "P4") was a registered trademark, and because the name was still being used by the original Protofour Society.

Unfortunately, the impression was quite inadvertently created that the Scalefour Society was promoting "Scale Four" standards, as a rival to the original P4 standards, but the Scalefour Society has always recommended the original P4 standards, whilst not in any way criticising Ray's "Scale Four" standards, which remain an alternative for anyone who cares to adopt them.

There were never any differences between the Protofour Society and the Scalefour Society as to the recommended track and wheel standards. The Scalefour Society was set up (in Febraury 1976) following the dismissal of the entire Executive Committee of the Protofour Society by that society's proprietors in October 1975, and the consequent suspension of the Protofour Society while its proprietors devised a different means of managing that society's affairs.

The Scalefour Society was set up simply in order to secure reliable supplies of components for model-making to P4 standards in light of the failure of the previous monopoly supplier to deliver the goods, and to ensure that the new society would be democratically controlled by its members, as it has been ever since.

The only difference between the original "P4" standards and the "Scale Four" standards is in the back-to-back setting of the wheels, and in the tightened flangeway and check rail clearances that the wider BB dimension allows. The wheel and rail profiles are identical for both sets of standards.

I appreciate that the majority of members will be well aware of all this, but it may not be so obvious newer members who were not around in the mid-1970s.

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Re: P4 vs S4 - Pro's and con's

Postby Knuckles » Wed Dec 09, 2015 10:13 am

Thanks for the breakdown. There's a lot in that, seems to be a great deal of drama too.
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Re: P4 vs S4 - Pro's and con's

Postby Knuckles » Wed Feb 03, 2016 11:34 pm

Just a quick one.

I have been reading posts here again and read a few times that 17.67mm is the P4 BtoB.

Since day one I have been using a 17.75mm BtoB. I brought the Exactoscale BtoB block on day one and have used it consistently with no issue.

Could you please provide collective opinions on the differences and pro's / con's etc as this new knowledge is concerning me. :/

Thanks in advance if so.
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Philip Hall
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Re: P4 vs S4 - Pro's and con's

Postby Philip Hall » Thu Feb 04, 2016 12:04 am

Knuckles,

The Exactoscale gauge is set to the recommended maximum for P4, 17.75mm. The tolerance is 17.67 minimum to 17.75 maximum, meaning that wheelsets set anywhere between these two figures will behave properly on track built using P4 gauges.
So the gauge you have is just fine, merely set at the the top end. The fact that you have been using it with no issues proves the point.

In reality, the difference between the two figures, 0.08mm, is tiny, no more than the difference between a firm fit and a sliding one. As I have said before, B-B set to the maximum figure is slightly less forgiving of wobbly wheelsets than the lower figure, but there are those who prefer the higher figure, hence the Exactoscale gauge. Many years ago, I decided I would tread the middle path, and had a gauge made up for me at 17.7mm and set wheels to be a good sliding fit on this gauge. In practice I slide the gauge in between the tyre backs, and adjust until it slides in easily.

I really wouldn't worry at all, what you are doing is just fine and it works. All this has been worked out donkeys years ago to save you any of this hassle. What you are doing with the 3D stuff and building a layout is the real modelling!

Philip

Knuckles
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Re: P4 vs S4 - Pro's and con's

Postby Knuckles » Thu Feb 04, 2016 12:44 am

Ok many thanks Philip. :)

I was getting the impression standards were revised or something.

I have a Craftsman Models A5 kit that I am looking forward to building in P4 so the 3D stuff is an addition rather than replacement. Love soldering kits up, 'Fisszzzz' strangly pleasurable..
Completely off topic that but you mentioned it thus the reply.

Ok, many thanks. :)
I'll happily continue with the gauge I have then. It'd be good used as a weapon too!
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Re: P4 vs S4 - Pro's and con's

Postby Horsetan » Thu Feb 04, 2016 10:15 pm

I used Ray Hammond's S4 simply because he let me have a set of gauges for it, and moreover Exactoscale produced a 17.87 back-to-back gauge. If it's there, there's no harm in using it.
That would be an ecumenical matter.

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Re: P4 vs S4 - Pro's and con's

Postby Knuckles » Fri Feb 05, 2016 12:07 am

Sweet. Didn't know you were a full blown S4-er.
What radia do you have and do you have pictures of a layout? Would be nice to see the flangeway difference.
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Re: P4 vs S4 - Pro's and con's

Postby Horsetan » Fri Feb 05, 2016 8:25 am

Knuckles wrote:Sweet. Didn't know you were a full blown S4-er.


In respect of Ray Hammond's back-to-backs, yes.

What radia do you have and do you have pictures of a layout? Would be nice to see the flangeway difference.


I don't have space for a layout here, so I'll have to disappoint you for now. I only have room to build stock. If you do want to try 0.58 flangeway gaps, a spark plug feeler gauge can help you get the right measurement.
That would be an ecumenical matter.

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Re: P4 vs S4 - Pro's and con's

Postby Tony Wilkins » Thu Apr 06, 2017 4:50 pm

Hi Knuckles.
Martin Goodall has explained the history although I always understood that the society chose the name Scalefour to distinguish it from Protofour as they had to find a different name as Protofour was copyright. Since P4 are the recommended standards it seemed logical to refer to the exact scale standards as S4. It is unfortunate, but the seeds of confusion were sown then and remain so today.

There are several S4 layouts around, Ray Hammond has built two, Buntingham and Thursford. My layout Green Street was also built to these standards and so has all the rolling stock I have built including a few locos for Heckmondwike, which was P4. In those days I had to make my own Back to Back gauge although Ray gave me a Crossing Flangeway and Check Rail gauge for his standards. I also believe that Howard Bolton's Layout Minories is built to S4 standards. I am sure he will correct me if I am wrong. There are doubtless others. S4 stock will run on P4 track, but not necessarily the other way round.
The are good technical reasons for the two standards, which I don't propose to go into here. The practical upshot is if you are building a layout with only turnouts, you are unlikely to find any difference between the two standards in terms of reliability. If you are using diamonds then there is a potential problem in P4 with the obtuse crossings due to the wider flangeways increasing the length of the gap between the point rails and wing rails of the obtuse crossing. This risk increases as the crossing angle gets flatter being greatest for 1 in 8 crossings as there is an increased risk that the wheel flange will not be checked throughout its passage across the gap in the running rail. This effect will be worse if the diamond is curved due to sideways pressure on the wheel-set. S4 standards reduce this possibility to a minimum but even the prototype has problems with them at times and has sort to reduce their numbers.
On the down side the S4 wheel-set being slightly wider will make converting stock with limited clearances even worse.
With regard to the minimum radii, I have found little difference between the two in practice.

I have taken two pictures comparing a P4 and S4 1 in 9 common crossing, P4 one at the top.
Tony.
1 in 9 crossing P4.jpg

1 in 9 crossing S4.jpg
Last edited by Tony Wilkins on Thu Apr 06, 2017 5:01 pm, edited 1 time in total.

essdee
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Re: P4 vs S4 - Pro's and con's

Postby essdee » Thu Apr 06, 2017 5:39 pm

Thanks for these images, Tony - I had not realised before, how great the difference is, visually speaking. Hmmm.....

Cheers,

Steve

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Re: P4 vs S4 - Pro's and con's

Postby andrew jukes » Thu Apr 06, 2017 6:45 pm

Tony Wilkins said
S4 stock will run on P4 track
.
While this is what's said in Digest 1.2 (which generally I think of as our bible) I think it is misleading. An S4 wheelset with a 17.87mm BB running through a turnout built to P4 standards i.e. using a check gauge of 18.15mm violates condition 2 of the Digest:

BB (17.87mm) + EF (0.38mm) = 18.25mm i.e. >18.15mm, so the wheelset is likely to conflict with the crossing nose.

What is OK is using P4 common crossing dimensions but with check rails set to the S4 check gauge of 18.25mm. P4 and S4 wheelsets can run happily through a turnout gauged in this way. Condition 5 of the Digest is met as the between checks (over checks, really) dimension is still small enough to accommodate a 17.67mm BB.

Best of course to settle on one consistent set of standards rather than trying to find a workable compromise.

Andrew

Tony Wilkins
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Re: P4 vs S4 - Pro's and con's

Postby Tony Wilkins » Fri Apr 07, 2017 10:04 pm

I would not disagree with Andrews comments as it is obviously highly desirable to choose one set of standards and work consistently to them. Trying to mix and match will not necessarily produce totally reliable results and I would certainly not advocate such practice. This applies to any set of standards regardless of scale. I was merely commenting on my experience with my stock on other layouts.
Tony.

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Russ Elliott
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Re: P4 vs S4 - Pro's and con's

Postby Russ Elliott » Tue Apr 11, 2017 2:13 pm

andrew jukes wrote:An S4 wheelset with a 17.87mm BB running through a turnout built to P4 standards i.e. using a check gauge of 18.15mm violates condition 2 of the Digest: BB (17.87mm) + EF (0.38mm) = 18.25mm i.e. >18.15mm, so the wheelset is likely to conflict with the crossing nose.

Hmmm. 'Conflict' with the crossing nose is a spectrum, and, as the Digest condition 2 points out, a problem is likely to occur only where the value of BB plus a small proportion of EF starts to approach the CG value. My view is that the shape of the flange front, together with dressing of the crossing nose, makes it unlikely that a P4 CG of 18.15mm would give rise to any significant problem. That said, I do agree with you that using a CG of 18.25mm is a more sensible approach if using wheel BBs above 17.82mm.


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