Society Gauge Widening Tool

Discuss the prototype and how to model it.
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grovenor-2685
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Re: Society Gauge Widening Tool

Postby grovenor-2685 » Thu Aug 04, 2016 4:39 pm

However, this begs the question of whether all P4 wheel manufacturers actually use the same profile; I seem to remember the suggestion elsewhere in this Forum that this was not entirely true.

Well, if they are different enough for it to matter then they don't comply with the P4 standards!

That would be great Keith - can you alert me/us when you have done so?

Not before the end of the month I'm afraid, just about to take off for a while.
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Re: Society Gauge Widening Tool

Postby grovenor-2685 » Thu Aug 04, 2016 4:50 pm

Personally I don't see what the problem would be with choosing something nearer to the real thing,

Anyone is free to do just that, Ray Hammond, Bill Richmond and a few others did just that from an early date.
Provide an opportunity and there will always be someone to grab it. The current P4 standards document details the adjustments needed to get to exact scale. It steps you up one more level in care and attention to detail with the modelling, more hair needed in your shirt etc.
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Re: Society Gauge Widening Tool

Postby Julian Roberts » Fri Aug 05, 2016 8:45 am

Allan Goodwillie wrote:Hi Julian,


On Grayrigg I did have to install a check rail on one of the inner mainline curves to cope with the bigger engines and as you know I can get my A4 around the inner circuit. Mike's Cardean did not have any outside cylinders to foul the bogies. I had to do a bit of grinding, not seen from most angles, of the back of the cylinders just to make it happen.

I remember one time looking forward to seeing Ian Middleditch's Duchess run on Grayrigg. Ian is better known for his beautiful GSWR locos, but he had put together a beautiful kit version of the Duchess just to have as a display. You could even see through the centre of the middle axle as per prototype! It ran beautifully along the straight, but disappointingly would not go around the curves, even on the outer circle, unless the front bogie was removed. It was intended as a glass case model anyway.

My good friend Bob Hetherington who has also brought up his Stockton and Darlington locos from time to time also found that they would not go around the corners on Grayrigg without trying to climb the rail. Again this is no condemnation of Bob's wonderful locomotives, it is just that they were built to greater exactitude than mine with less sideways travel built into the chassis than I have in my 2-8-0's and 4-6-0s. I think Bob's minimum point is a 10 on his own layout. In fact I think he is busy replacing them with a couple of 12s at the moment.


One thing I might add is just a comment on the perception of curves. Grayrigg can only be seen from the inside of the layout and curves seen from the inside never seem so bad just due to the straight on angle you are looking at them from. The impression the layout gives is that of a proper main line. It is now more than twenty years old and has lots of experimental features - some of which have been very successful, others less so, but what a lot I have learned from building it. I am putting all of this into practice on my new layout/s so we will see what comes of that in the next few years, if I am spared. I have been heavily involved with both modelling groups for years as you know and feel that I can take more of a back seat as there is plenty of talent around in both groups and I may get more time to do my own thing.



Hi Allan

Sorry to reduce all your interesting points and discussion to my totally banal level! :geek: : did you put in gauge widening on the curves on Grayrigg? As I recall you use the Protofour Mark 2 track gauge, not the triangular Mark 1 version. So you have to put in the 0.2mm washer for curves - but did you, were the curves on Grayrigg sufficiently sharp for you to decide to do that? - Do you remember?! What is the minimum radius on Grayrigg?

I am banging on about all this, sorry that everyone must think I am bonkers, it's because I still don't fully understand it. Gauge widening won't help a Duchess go round an A4 point, I think, but I wonder whether it might make just a wee bit of a difference for some of the locos you mention here on your layout?

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Re: Society Gauge Widening Tool

Postby grovenor-2685 » Fri Aug 05, 2016 9:29 am

Gauge widening won't help a Duchess go round an A4 point, I think, but I wonder whether it might make just a wee bit of a difference for some of the locos you mention here on your layout?

Gauge widening is related to the fixed wheelbase so not really of relevance to Pacifics and such. The worst case locos are usually 0-6-0s with long fixed wheelbase, 16'6" for Midland/LMS even more for a few others. Also 8 & 10 coupled locos of course.
With Pacifics the fixed wheelbase is usually shorter and the limitations come from the need to allow overscale side swing on bogie and pony to get round sharp curves, gauge widening only has a marginal effect on this.
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Re: Society Gauge Widening Tool

Postby Julian Roberts » Fri Aug 05, 2016 8:27 pm

grovenor-2685 wrote:
Personally I don't see what the problem would be with choosing something nearer to the real thing,

Anyone is free to do just that, Ray Hammond, Bill Richmond and a few others did just that from an early date.
Provide an opportunity and there will always be someone to grab it. The current P4 standards document details the adjustments needed to get to exact scale. It steps you up one more level in care and attention to detail with the modelling, more hair needed in your shirt etc.
Regards


Just to briefly say (PS this ends up not very brief) Keith that I wasn't meaning moving away from any of the other P4 standards, i.e. BB, Crossing Flangeway etc. I am not wanting to go the same way as Ray Hammond. I am not that expert. What I meant was, I don't see the problem with choosing a minimum radius nearer the real thing and working out the necessary gauge widening from that.

I don't know if you understand what I mean. I'll just expand the quote you took

If one looks at any of the graphs drawn to show the gauge widening tool, it is obvious that the gauge widens gradually to a point where it exceeds the prototype's 0.25mm maximum. All that varies is when it hits that point, which would imply the minimum radius possible. The P4 curve on the graph hits its arbitrary maximum of 0.22 at 528mm, which would have been I expect the same or similar to EM. 0.22mm I assume to reflect the narrower BB of P4. Personally I don't see what the problem would be with choosing something nearer to the real thing, and, if one really must make very sharp curves, widening more than 0.22 or 0.25 for that matter - after all there is about 1.5mm to play with before the wheels fall between the rails. But that would be unprototypical...

A prototypical widening tool would be a little less than 45mm, and would hit the prototype maximum widening at about 3' 3", more or less the same as Will L's chosen minimum radius. If I built a bit of track for the Calderside extension using such a tool, there would be no practical difference visually or to the running of anyone's stock, except perhaps a greater reliability of road-holding.


The prototype scaled down section of the Digest 1.2 gives the maximum gauge widening of 3/4" at 5.5 chains, as we all know perfectly well. That's 4' 9". But that surely ? doesn't mean that this is the minimum possible radius curve in prototype or (let's say) Ray Hammond style S4? The real thing then stays at that widening as the curve gets progressively tighter. Well that's not what is needed. We need the widening to go in ratio to the radius, not in steps, just as the triangular tool does, but (what I am suggesting) is a tool that gives the equivalent of the prototype in a curve or ratio in P4. Thus there would be a slightly wider track gauge on curves than at present making it easier for non experts like me to get good results.

0.22 maximum widening is 12% less than the prototype 0.25mm, so far so good. That's the P4 amount of extra tolerance I think, as in the crossing flangeway and BB. Look at the spreadsheet, in my opinion the 45mm tool represents the nearest on them to the prototype if the prototype can be expressed as a ratio or curve. Look at the figures for 1452mm - the 29.75mm tool gives 0.075mm widening, the 45mm tool 0.17. Not 12% difference but nearly 50%. Meanwhile to be pedantic the actual prototype figure is 0.25mm, so the P4 widening is just 33% at that point.

What I am suggesting as a question is that the P4 choice of a minimum curve of 528mm compromises the gauge widening unnecessarily...? The 45mm tool length gives a theoretical minimum prototype radius of 3' 3" or 990mm at 0.25mm. Not a 12% difference but getting on, again, to 50%.

No need for a hair shirt. What I am suggesting would surely be an easier way to get good results - a silk shirt instead of a cotton one? I don't know, I am suggesting it. All I do know is that everyone says that, even in P4 with its narrow BB, undergauge is bad but overgauge is OK; and my experience is that making a turnout, at the diverging road blade even 4 wheel SWB wagons can derail if the gauge is too narrow through the blade, and the reliability gets better the more (within reason) that is filed off the blade gauge surface to get the gauge wider. Starting with a 0.1mm wide gauge before the blades, on both roads, as per Clag http://www.clag.org.uk/switch-traverse.html makes the job easier. I am not talking about derailment at the tips, as that is or may be an issue about the tips themselves, but as the wagon goes through the switch, if that switch is not filed in a proper taper. To err is human, better err on the wide side.

Just to reiterate, I am not talking about going S4. And I do know that people, good modellers, make P4 work well. I am asking if more of us less good modellers may be able to get good results more easily if we junk the trainset minimum radius that is -?- if I am right? - an integral part of the gauge widening standard....? Isn't a minimum of 3' 3" small enough nowadays?

Not before the end of the month I'm afraid, just about to take off for a while.

Regards

Have a good trip!

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Re: Society Gauge Widening Tool

Postby grovenor-2685 » Fri Aug 05, 2016 9:00 pm

Thus there would be a slightly wider track gauge on curves than at present making it easier for non experts like me to get good results.

What actual difficulty are you having with the existing standard using the triangular gauge?
It has worked for me for 49 years, and I did not start out as expert, just followed the P4 Manual and it worked.

I am asking if more of us less good modellers may be able to get good results more easily if we junk the trainset minimum radius that is -?- if I am right? - an integral part of the gauge widening standard....? Isn't a minimum of 3' 3" small enough nowadays?

I don't recall anyone proposing train set radii for P4! General recommendation is usually 4ft, with a bit of care you can manage with less, I have a few bits down to 3'6". Tin Venton on Clutton, I believe uses 3ft.
You seem to be suggesting using both larger radii and bigger gauge widening, its unlikely to do much harm, but I don't see any benefit in it either. P4 has that extra slop in it as compared to exact scaled down dimensions specifically to make it easier for the non-expert, there's no need to go any further But if it makes you feel better that you are using exact prototypiocal gauge widening, there's no reason not to.
Have a good trip!

Thanks, leave in the morning.
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Re: Society Gauge Widening Tool

Postby Julian Roberts » Fri Aug 05, 2016 9:30 pm

I don't recall anyone proposing train set radii for P4!
Yes I agree, what I said seems absurd.

I ought to leave you to pack, and I should reflect more on things you have said before writing any more.

But -

Can you explain what the 0.22mm at 528mm means then in the Digest?

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Re: Society Gauge Widening Tool

Postby Julian Roberts » Sat Aug 06, 2016 2:33 pm

Obviously Keith is now on holiday well away from my irritating questions.

grovenor-2685 wrote:
Thus there would be a slightly wider track gauge on curves than at present making it easier for non experts like me to get good results.

P4 has that extra slop in it as compared to exact scaled down dimensions specifically to make it easier for the non-expert, there's no need to go any further


This is exactly the point: I don't know if Keith understands what I am saying, or if he is saying I am wrong. Surely:

P4 has 12% extra slop built in to it, but roughly half of that extra slop disappears on curves - just when we need it most.

I thought we had done this to death!


Sorry everyone, I know I am being a pain in the arse, but until someone can explain why the Standards say 0.22mm at 528mm for gauge widening I am going to go on popping my head over the parapet to try to understand this business.

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Re: Society Gauge Widening Tool

Postby Will L » Sat Aug 06, 2016 11:31 pm

Julian Roberts wrote:P4 has 12% extra slop built in to it, but roughly half of that extra slop disappears on curves - just when we need it most.

Julian, I think the point you are missing may be that the 12% extra slop is all about the practicalities of making functional point work easier and nothing at all to do with the need for gauge widening. However once you’ve got it, the need for gauge widening is less.

OK if, for the purposes or modelling veracity, you want to replicate prototype exactly then that is your right. But, despite the rhetoric, the P4 standards are not an exact scale reduction of the real railway. They are actually a practical working set, proven over time to work and for the generality of users don’t need the tweaking you suggest.

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Re: Society Gauge Widening Tool

Postby billbedford » Sun Aug 07, 2016 7:41 am

Will L wrote:OK if, for the purposes or modelling veracity, you want to replicate prototype exactly then that is your right. But, despite the rhetoric, the P4 standards are not an exact scale reduction of the real railway. They are actually a practical working set, proven over time to work and for the generality of users don’t need the tweaking you suggest.


If you want modelling veracity, and you want to replicate prototype exactly then surely you should be modelling in S4?
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Re: Society Gauge Widening Tool

Postby Julian Roberts » Mon Aug 08, 2016 12:06 am

Hi Will

Will L wrote:
Julian Roberts wrote:P4 has 12% extra slop built in to it, but roughly half of that extra slop disappears on curves - just when we need it most.

Julian, I think the point you are missing may be that the 12% extra slop is all about the practicalities of making functional point work easier and nothing at all to do with the need for gauge widening. However once you’ve got it, the need for gauge widening is less.

OK if, for the purposes or modelling veracity, you want to replicate prototype exactly then that is your right. But, despite the rhetoric, the P4 standards are not an exact scale reduction of the real railway. They are actually a practical working set, proven over time to work and for the generality of users don’t need the tweaking you suggest.


Hi Bill

If you want modelling veracity, and you want to replicate prototype exactly then surely you should be modelling in S4?


Thanks for your thoughts!

Problem with a Forum is to have to keep repeating myself. No, I am not wanting to go S4 nor replicate the prototype just for modelling veracity, the issue here is completely invisible and totally minute, we are talking here the equivalent of how many angels can dance on a pinhead, a difference of 0.1mm at a curve of 4' 6".

What I am trying to talk about making things easier for ourselves. An equivalent in music is that when there is a very difficult passage with a lot of notes, in their anxiety people tend to rush as they get near the passage, so that means they've got to play them even faster. Music is a bit like the circus, making things look or sound easy that are really very difficult. Practising to perfection is a lot about learning to give ourselves room, or find tiny ways to make it easier.

There is 12% more slop in P4 but about 50% less gauge widening on curves. So we give ourselves more room with one hand, and then take half of it away with the other! Many people here have said they were unaware that it was the case, that the P4 gauge widening is 50% less. Did you know?

Yes lots of people make it work - but I bet there are lots of others who can't, and give up, or try EM flanges etc, that we don't know about. P4 still has an air of mystique about it, as it were the icy mountaintop of 4mm modelling. People like you, Keith, Allan, Tim Venton are master modellers. But one sees lots of references to "running was improved" by such and such a tweak from ordinary mortals! - people are always looking for ways to improve the reliability of running, surely.

As far as I can see by looking at the graph (that originally Alan Turner came up with) and figures, the gauge widening standard is predicated on a toy train minimum radius of 21", from the days 50 years ago when such a curve was more normal in modelling. I wonder if it might have been to do with the EM standard which is 0.2mm at 610mm radius. Their triangular gauge is just 1mm shorter.

But you say it was intentional for the kind of radii we normally work to, 4ft minimum the general recommendation.

The thing about this is, that the gauge widening progressively gets wider as the radius decreases, so a 50% difference is a gradually increasing figure. Meanwhile the 12% extra slop figure stays constant. This means that gradually the P4 slop completely disappears, so that by the time we are down to 4 foot radius the Running Clearance is starting in some situations to be less than the prototype. So, relative to the real thing, as the track curve incresases the rails become tighter and tighter on the wheels.

It is all obvious if you look at the graph - the blue line (for the Society standard) and yellow line (that represents the averaged out prototype) diverge as the radius narrows. Both these lines were made up by Alan - they both require a tiny bit of correction, but the message will hardly change:

Gauge Widening Graph 1.pdf
(104.96 KiB) Downloaded 76 times

I don't know how to convert these files to PDF which would make them visible here - but here are photos of the pc screen

2016-08-08 09.29.03.jpg


The spreadsheet gives numbers:

Gauge widening Spreadsheet.xlsx
(25.24 KiB) Downloaded 62 times


2016-08-08 09.31.32.jpg



I've done some maths from the spreadsheet and the Track and Wheel Standards. Here are some running clearance figures. As BB is expressed as a range (17.67-17.75 in P4, 17.87-17.89 on the prototype) there is an analagous range to the figures:

PROTOTYPE with prototype gauge widening*****************P4 with Society Gauge Widening***************P4 with prototype gauge widening
Straight track: 0.18 - 0.2***************************************0.28 - 0.36****************************************0.28 - 0.36
8 foot curve: 0.283 - 0.303*************************************0.325 - 0.405*************************************0.383 - 0.463
4 foot curve: 0.3844 - 0.4044**********************************0.3694 - 0.4494***********************************0.4844 - 0.5644

Edit: As these numbers go out of place on my mobile phone here are the figures handwritten as a table, which I don't know how to do on a pc:

Running Clearance in P4.jpg




[Well I don't know if my maths is correct. Example: For P4 straight track 18.83 - 17.67 (BB) - 0.8 (flanges x 2) = 0.36. Or with 17.75 BB the result is 0.28] [Prototype at 4 foot: 18.83 + 0.2044 (widening for 45 mm tool) = 19.0344. Minus BB 17.87 and two flanges 0.38 each = 0.4044. Or with BB 17.89 the result is 0.3844)]

The P4 BB, using prototype gauge widening, would keep the Running Clearance comfortably above that of the prototype.

Obviously a wider gauge of, for example, 0.1mm at 4' 6" is hardly going to make a vast difference. Of course it doesn't mean you can do without adequate sideplay, compensation or springing, all the things necessary for proper running. But might it be a tweak (and no more) that the generality of users could benefit from? It doesn't imply any criticism of any other aspect of the standards - at least not as far as I know.

Things have come on a lot in this hobby in the last 50 years. People always argue against change on the grounds that things are perfectly good as they are. Increasing the length of the triangulation would not change anything else at all in the standards. The difference it would make is minute. Not worth the effort of writing this probably...

However, just to return to a bit of sanity and reality, Richard Chown, got back to me (thanks Richard!) with the information that the curves I mentioned, at Carstairs and Cowlairs, are far less sharp than I was expecting - around 10 and a half chains at Cowlairs, more at Carstairs with various other considerations. So these sharp curves being discussed above are way out from being realistic - but that doesn't mean we never use them.
Last edited by Julian Roberts on Mon Aug 08, 2016 8:40 am, edited 2 times in total.

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Re: Society Gauge Widening Tool

Postby Terry Bendall » Mon Aug 08, 2016 7:18 am

Julian Roberts wrote:Yes lots of people make it work - but I bet there are lots of others who can't, and give up, or try EM flanges etc, that we don't know about. P4 still has an air of mystique about it, as it were the icy mountaintop of 4mm modelling.


I don't think there are "lots" of others who cannot make P4 work, but there are certainly some who do give up and some who will try alternatives such as EM wheels on P4 track. I am not convinced that there is an air of mystique about P4. It does work and lots of "ordinary" folks can and do make it work.

Julian Roberts wrote: People like you, Keith, Allan, Tim Venton are master modellers.


I think that these thee gentlemen are far too modest to thank they are master modellers :) but they, and many others have made a success of working to P4 standards. However, Keith, Allan and Tim, and all the other people who have success were not born knowing how to be good modellers, - they learnt it through many years of trying, having success and I expect sometimes failing as well.

Julian Roberts wrote: Music is a bit like the circus, making things look or sound easy that are really very difficult. Practising to perfection is a lot about learning to give ourselves room, or find tiny ways to make it easier.


I often use this analogy when talking to visitors to the Society stand at exhibitions. Skilled musicians, like skilled sports people, and like skilled modellers were not born with those skills - they were developed over many years of practice, developing experience, and sometimes failing. Some years back I was working in a school alongside a less experienced teacher, and supporting his work. I was using a plane to reduce the height of a drawer to fit the space and working round the side and front at the same time. "Gosh" he said, "you are good at that." "I would hope so," I said, "I have been using a plane for 50 years." :)

P4 is not the "icy mountaintop". It is not always easy, but it is a lot easier that it used to be. :)

Julian Roberts wrote:people are always looking for ways to improve the reliability of running, surely.


I don't think this is the case. Improve the running if things fall off - certainly, and if something wobbles or otherwise is not as smooth as it might be, yes again, but once those sort of things are sorted out, leave well along is my view. :)

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Re: Society Gauge Widening Tool

Postby Julian Roberts » Mon Aug 08, 2016 2:24 pm

Hi Terry - thanks for your thoughts.
Terry Bendall wrote:
I often use this analogy when talking to visitors to the Society stand at exhibitions. Skilled musicians, like skilled sports people, and like skilled modellers were not born with those skills - they were developed over many years of practice, developing experience, and sometimes failing. Some years back I was working in a school alongside a less experienced teacher, and supporting his work. I was using a plane to reduce the height of a drawer to fit the space and working round the side and front at the same time. "Gosh" he said, "you are good at that." "I would hope so," I said, "I have been using a plane for 50 years." :)


Yes, quite so - let me amplify my point, I was illustrating one small aspect of that acquiring of knowledge that makes us good at what we do, regarding "giving ourselves room". An example of something different, from the world of sport, was through Graham Obree, the cyclist from near Glasgow. He was convinced the standard bicycle had a bottom bracket (where the pedals are fixed to the frame) that was too wide relative to the distance between his legs where they are fixed to the body at the hips, so he made his own bike from washing machine parts, with a narrower bottom bracket, and went on to smash some Olympic record or other. I don't know if his idea became mainstream. A tiny change to most people; though apparently the cycle trainer David Brailsford talks about getting big results through the accumulation of many tiny improvements.

With his agreement, I attach the thoughts of Richard Chown on the question of gauge widening on model railways, and how much they relate to the real thing - he was a professional PWay man, and is well known as a 7mm modeller hereabouts.

Gauge widening Richard Chown.docx
(125.08 KiB) Downloaded 94 times


I don't know if by S4 he means modellers Scalefour Modellers, or people modelling in S4, but I rather assume the first. It will be seen that he suggests a full 0.3mm gauge widening at 4' 6" - our gauge gives 0.08mm; first and foremost he is explaining what makes a commonsense, flexible and pragmatic approach in the eyes of a pro.

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Re: Society Gauge Widening Tool

Postby Noel » Mon Aug 08, 2016 3:18 pm

Julian, I can't read the posted .docx file on my internet machine as I don't have the software required (Word 2007 or later, from memory) to open it. Can you post it as a .pdf file, please, as this is more generally readable? Alternatively , .txt or .rtf formats may be OK if it is text only.
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Re: Society Gauge Widening Tool

Postby Armchair Modeller » Mon Aug 08, 2016 3:35 pm

The critical bit seems to be this

"We build our track on bases that continue to shrink. We force our rails into position before securing them – C&L chairs for instance are plastic and intended to hold the rails at some version of the correct 1:20 inclination, so when we remove the gauge they tilt together on release. The plastic sleepers of Peco 0 gauge shrink over the years, even more when exposed to sunlight. Nor should we kid ourselves that our work has second figure decimal accuracy. I know that the track that I lay, no matter how carefully, for reasons some of which are beyond me, tends to finish tight to gauge. And it’s not just me.
It would seem sensible therefore to lay your track generally slightly wide to gauge, I would suggest 0.15 mm (There were people working to 19mm gauge decades ago.) As S4 curves tend to be a minimum 4’6” radius that puts them at a full size 110 metres, implying that they ought to be laid at least 0.2 wide, I would suggest 0.3 mm on the curve, but still no more than 0.15 in the switch. This on any layout on which you intend to run six- or eight- coupled locomotives and/or they have bogies. Tighter curves than that, in a dockyard perhaps, should not need more, so long as you are using short four-wheeled locomotives and stock. You might need to experiment to find what works. On Allendenac S7 locos needed to negotiate 1100 radius on a wye. I modified a roller gauge by adding a 1mm thick washer – that’s adding 43.5mm full size. It works. I had to transition the changes."


The whole premise is based on the idea that model track shrinks when we have built it, so you have to widen the gauge to allow for this. Does track really still shrink, or is this just an historical problem that we need not worry about any more?

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Re: Society Gauge Widening Tool

Postby Julian Roberts » Mon Aug 08, 2016 4:07 pm

Hi Noel
Sorry technology is at its limit in my case, all I know is how to take these photos of the screen and upload that way. Hope it might be legible...

2016-08-08 15.33.11.jpg


2016-08-08 15.33.43.jpg

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Re: Society Gauge Widening Tool

Postby RobM » Mon Aug 08, 2016 4:16 pm

With compliments.......... :thumb
Gauge widening Richard Chown.pdf
(200.3 KiB) Downloaded 69 times

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jon price
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Re: Society Gauge Widening Tool

Postby jon price » Mon Aug 08, 2016 5:10 pm

I have been following this theoretical discussion with some interest, and although it has been characterised at some point as a bit of an "angels on a pinhead" discussion I would be interested to hear the advice of the venerable masters when it comes to a practical application.

My layout fatures the entrance to Connah's Quay from the Buckley Railway. The track curves tightly and is stated in the reference material to have a minimum radius of 3 chains, or 195 feet. The locos which ran down into the docks were an 0-6-2ST heavily modified and ancient No6, originally built by Sharp Bros for the Manchester and Birmingham Railway in 1846; and an 0-6-0T No8, built by Sharp Stewart in 1880 specially for the Buckley. The 0-6-2 had a coupled wheelbase of 10'11", driving wheels of nominal 4'3, and a total wheelbase of 18'6"; the 0-6-0 had a coupled wheelbase of 15'6", and driving wheels of 4'8". My locos will have the correct wheelbase, and wheel diameters within half an inch less than the prototype. In practice my tightest curve will be a 4.5 turnout at 682mm radius or 170 scale feet as a 5 turnout at 859mm or 212ft is too large.

My question is what guage widening do I need on this section, and more importantly how do I go about achieving it? In addition the curve had a check rail. Which of the two possible P4 checkrail spacings should I use for this?
Connah's Quay Workshop threads: viewforum.php?f=125

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Re: Society Gauge Widening Tool

Postby Paul Townsend » Mon Aug 08, 2016 8:33 pm

Noel wrote:Julian, I can't read the posted .docx file on my internet machine as I don't have the software required (Word 2007 or later, from memory) to open it. Can you post it as a .pdf file, please, as this is more generally readable? Alternatively , .txt or .rtf formats may be OK if it is text only.


Microsoft offer a free download plugin that enables reading of .docx files on older machines with Word using .doc file format

Julian Roberts
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Re: Society Gauge Widening Tool

Postby Julian Roberts » Mon Aug 08, 2016 11:02 pm

Jon

In the light of all that I've been thinking about here - that's the sort of juicy question that all these graphs and numbers might help with...or maybe the venerable masters will have an opposite view?!

Thanks to Rob and Paul. Armchair, after a pause for thought, if there are any questions specifically for Richard I will contact him after a week or so.

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Will L
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Re: Society Gauge Widening Tool

Postby Will L » Mon Aug 08, 2016 11:42 pm

Julian Roberts wrote:With his agreement, I attach the thoughts of Richard Chown on the question of gauge widening on model railways, and how much they relate to the real thing - he was a professional PWay man, and is well known as a 7mm modeller hereabouts.


I'm not sure this adds anything to your argument Julian, as the issue that appear to concerned him were
1. on the prototype, tenancy for locos to spread the track on sharp curves, which thanks to "the physics doesn't scale issues" I promise you does not apply to our models
2. on the Model a tenancy for plastic track to shrink, which if it does apply to the track you are laying, is an argument for laying over gauge everywhere but is not the same as adding gauge widening on curves.

I don't know if by S4 he means modellers Scalefour Modellers, or people modelling in S4, but I rather assume the first.


Your assumption is incorrect, as S4 has a very particular meaning. S4 is an exact scaled down version of prototype track, with the "compromise for the sake of practicality" in the P4 standers removed (e.g. the 12% variation from scale BtoB that has been bothering you). S4 is practised by a very few determined soles, who take the "getting it all right" mantra very seriously and who are indeed likely to be bothered by a failure to replicate the degree of gauge widening used on the prototype. If P4 is hair shirt, S4 includes much more of the sort self mortification beloved of medieval christen monastics.

jon price wrote:My question is what gauge widening do I need on this section, and more importantly how do I go about achieving it? In addition the curve had a check rail. Which of the two possible P4 checkrail spacings should I use for this?


And the answer, which unfortunately Julian doesn't seem happy with, is that it depend how much lateral flexibly you allow on the middle driving axle. The exact scale-ness of wheel and wheels matters little, what really counts for a 6 coupled loco is how much side play is possible on the middle driving axle.
Exactly how much flexibility you can build in depends on the design of you chassis, (i.e. the width over the chassis sides and how much more room is taken up by your horn block/axle barring assemblies. If you can get enough in so that the Versine (see Keith posting here) is fully accommodated then no gauge widening will not be necessary and you loco will run reliably round curves with no gauge widening.

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Re: Society Gauge Widening Tool

Postby Julian Roberts » Tue Aug 09, 2016 8:46 am

Hi Will


Your assumption is incorrect, as S4 has a very particular meaning. S4 is an exact scaled down version of prototype track, with the "compromise for the sake of practicality" in the P4 standers removed (e.g. the 12% variation from scale BtoB that has been bothering you). S4 is practised by a very few determined soles, who take the "getting it all right" mantra very seriously and who are indeed likely to be bothered by a failure to replicate the degree of gauge widening used on the prototype. If P4 is hair shirt, S4 includes much more of the sort self mortification beloved of medieval christen monastics.


I do understand the difference between P4 and S4. I am a P4 modeller. But sometimes people confusingly abbreviate the Scalefour word (which, as in the phrase "Scalefour Modeller" normally, though not necessarily always, means P4 modeller) to S4; as this also means the different exact "S4" prototype standard there is always the likelihood of ambiguity.

The 12% doesn't bother me, it's great, it makes it easier. The thing that bothers me is, not invisible exact gauge widening, but all too visible and far from prototypical derailments.

I'm not sure this adds anything to your argument Julian, as the issue that appear to concerned him were
1. on the prototype, tenancy for locos to spread the track on sharp curves, which thanks to "the physics doesn't scale issues" I promise you does not apply to our models


Of course. But what Richard says there seems to me the exact issue - the fact that physics doesn't scale issues means:
Model trains are light. They will not force the rails apart if gauge is tight, they will just climb


(and therefore be likely to derail.)

And the answer, which unfortunately Julian doesn't seem happy with, is that it depend how much lateral flexibly you allow on the middle driving axle. The exact scale-ness of wheel and wheels matters little, what really counts for a 6 coupled loco is how much side play is possible on the middle driving axle.
Exactly how much flexibility you can build in depends on the design of you chassis, (i.e. the width over the chassis sides and how much more room is taken up by your horn block/axle barring assemblies. If you can get enough in so that the Versine (see Keith posting here) is fully accommodated then no gauge widening will not be necessary and you loco will run reliably round curves with no gauge widening.


I wrote already, yesterday

Of course it doesn't mean you can do without adequate sideplay, compensation or springing, all the things necessary for proper running.

- by which I meant adequate sideplay for whatever curve you have as your minimum

Jon

If you find that Will's recipe is all that is necessary for what works, hallelujah, I will be very happy, the angels may be dancing on their pinhead too but we won't need to count them.

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Will L
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Re: Society Gauge Widening Tool

Postby Will L » Tue Aug 09, 2016 4:33 pm

Julian Roberts wrote:The 12% doesn't bother me, it's great, it makes it easier. The thing that bothers me is, not invisible exact gauge widening, but all too visible and far from prototypical derailments.


Agreed you have said that several times and perhaps I should have been taking more notice, but it may be that attaching it to a worry about running problems cause by the lack of gauge widening that has caused the protracted nature of this thread.

IMHO gauge widening is the very least of the problems that leads to inconsistent running and derailment issues. When you do have a vehicle which needs gauge widening/or more internal flexibility, you will find it reliably wont go round the corners that are too sharp for it.

The common reasons why running reliability comes out patchy is down to more common place problems like,
    wheel sets not running true and/or out of gauge,
    track imperfections and level irregularities which may well not be obvious to the eye and
    the prevalent view that suspension systems are not really necessary on short wheel base wagons.
I know that some will take exception to that last one, but it is also the reason why EM wheels have been suggested as a palliative. Without some form of suspension, any irregularity in the track means that any 4 wheeled wagon is likely to be running on three wheels only. Should the 4th wheel be over the outside rail on a curve, you are entirely reliant on the flange to stop it carrying strait on, and the flange depth will have been reduced by the amount of clearance between wheel tread and rail. Hence give it a bit more flange and it is less inclined to fall off. Which wheel is off the ground will depend, among other things on coupling and buffering forces, so, sometimes all will be well and others there will be problems. Track irregularities sufficient to cause this are quite hard to eliminate on even supposedly entirely level track, and are implicit in some things we may want to include like changes in gradient, or the use of super elevation.

Do keep in mind that poor running very rarely has a single cause, so finding and fixing a variety of issues is the norm. Its the guys who are good at that consistently who produces layouts that run well.

Terry Bendall
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Re: Society Gauge Widening Tool

Postby Terry Bendall » Wed Aug 10, 2016 6:37 am

Will L wrote:The common reasons why running reliability comes out patchy is down to more common place problems like, wheel sets not running true and/or out of gauge


I would add:

wheel sets not being parallel to each other or not square t0 the solebars;
build up of dirt or glue or varnish on the tread of the wheel (don't ask how but I have seen it happen. :) )
suspension systems not set up correctly - i.e sprung axle boxes not moving freely enough or having the same amount of vertical movement.

Will L wrote:Do keep in mind that poor running very rarely has a single cause, so finding and fixing a variety of issues is the norm.


Very true and the finding needs patience and care.

Terry Bendall

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Allan Goodwillie
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Re: Society Gauge Widening Tool

Postby Allan Goodwillie » Wed Aug 10, 2016 8:02 am

:D I concur with both Will and Terry. I am hoping that when the starters group get down to layout building then we will look at this very thing. When the East Group were first building Burntisland, like all the entries to the competition we were working against the clock. My usefulness to the group was that I had already built an exhibition layout in P4 at the Melrose Model Museum which had to run 7 days a week 7hours a day without someone constantly operating it - so it had to run well.

I was given the job of technical advisor - maybe just so that if it all did not work then there would be someone to blame, or more charitably, someone who would step in and say the "buck stops here" and gently sort it out. Frankly Burntisland although built and put together at first ran like a pig.

It took six weeks with me working on it in my garage to bring it up to scratch and I am pleased to say it worked well in its baptism of fire at Scalefourum. There were all manner of things wrong, but I am not going to go into that now although Will and Terry have touched on some of them. After we had won the competition I stepped down from my role, but Burntisland has continued to grow until it is the present size. Not all my suggestions were taken up as final decisions were taken by the committee and there are some things I think we should have done differently, but all in all it has been and continues to be a very interesting, inspiring and at times challenging project to have been part of.

In the starters section I hope to cover where things might go wrong when building layouts and how to sort them and will put together all the good ideas people have come up with over the years and point our starters towards them.


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