Which gauges for track construction?

Discuss the prototype and how to model it.
John Palmer
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Re: Which gauges for track construction?

Postby John Palmer » Mon May 07, 2012 1:41 am

Keith and Russ, that’s much appreciated.

I had missed the advice in the Exactoscale instructions about gauge widening, but now note that they only advise this for radii of less than 1500mm – about 5.7 chains – at which point they recommend GW of +0.2 or +0.3mm and use of check chairs with the wider (0.8mm) spacing.

To achieve gauge widening through a crossing the conventional technique would appear to be to fix the stock rail to the wider gauge and rely on the check chairs with 0.8mm spacing to set the check rails to CG. Presumably, however, it would be feasible to reverse the procedure by gauging the check rails to CG and relying upon their 0.8mm spacing to set the associated stock rail to a widened gauge. Any reason to prefer one approach over the other?

I can see the merit in an increase in the BB setting and had been toying with the idea of taking this course anyway, assuming my skills permit it.

doktorstamp
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Re: Which gauges for track construction?

Postby doktorstamp » Mon May 07, 2012 5:44 am

In response to Danny's question of what should could be included on a FAQ.

1. Recommended gauges to buy, and why they are necessary. Perhaps with a financial inducement in the form of a discount for newcomers :D

2. Links to track construction on the net

3. Rewheeling, again with links to information on how to etc.

4. Locomotive sprung suspension, with links that will allow the newcomer to decide for himself, although the merits of the various systems (choices) open to them need to be highlighted (objectively) by a knowledgable person with no axe to grind.

5. Engineering principles, basic; these are covered in the digest; it should be exemplified, in the nicest possible way, that they are required reading, even if appearing somewhat soporific initially.

These I feel, and this list is no way exhaustive, are the principle hurdles that a newcomer to P4 has to deal with. It is to be hoped that in their previous 00 incarnation they acquired a skill set of some sorts beyond unpacking the latest life's-not-worth-living-without-this.

They are listed in no priority.

regards

Nigel

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grovenor-2685
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Re: Which gauges for track construction?

Postby grovenor-2685 » Mon May 07, 2012 8:24 am

So, essentially what is needed is a "P4 Manual/Scalefour Digest" and a links page.
What do you see as the deficiencies of the ones we already have and which all new members are pointed at?

Perhaps this needs a new topic.
Regards
Keith

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LesGros
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Re: Which gauges for track construction?

Postby LesGros » Mon May 07, 2012 9:01 am

grovenor-2685 wrote:So, essentially what is needed is a "P4 Manual/Scalefour Digest" and a links page.
What do you see as the deficiencies of the ones we already have and which all new members are pointed at?
Perhaps this needs a new topic...


I think Keith makes a valid point, that there is a valuable information source existing online. On the other hand, the recent crop of forum posts do seem to have a common thread; the problem(s) faced by the beginner to Scalefour, and those extending their interests into new areas. The kind of questions such as: where do I find...? What is the best... ? What is the latest thinking on... ?
I am sure I am not alone in having remembered a bit about the content of a useful posting but then not being able to find it without a time consuming, and sometimes fruitless search. The in-house search facility can help, but has its limitations, especially if the searcher does not know enough to ask the right question.

Perhaps the solution is an A to Z Glossary, with links to relevent fora, supplimented by a "beginners to P4" FAQ with new navigation links in the header bar above.

In any case, a new thread on how best to help the newcomer could be useful to make a start on making things easier for everyone.
regards
LesG

The man who never made a mistake
never made anything useful

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Bigfish
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Re: Which gauges for track construction?

Postby Bigfish » Mon May 07, 2012 11:17 am

What a very interesting discussion this has turned into! I'd be happy to contribute some thoughts from a newbie's perspective to a thread on "helping newbies find their way round" - I'm in London at the moment, not home in Nottingham, so will do when I get back. BTW some of us (well me anyway) don't have any "00 experience" either! I've decided to regard this as a bonus ie no baggage! The next best thing after joining the ScaleFour Society has been turning up to our Nottingham Area Group meetings where I've met a group of nice chaps with inexhaustible patience. On Saturday the Lady Wife and I spent a charming afternoon trundling up & down the KWVR in Yorkshire, so at least I now understand how a slide chair works! How I envy you chaps who actually saw and remember the Real Thing. 5 minutes looking at a working example sure beats a couple of hours trying to understand the written word!

Alan

allanferguson
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Re: Which gauges for track construction?

Postby allanferguson » Mon May 07, 2012 12:09 pm

John Palmer wrote:Keith and Russ, that’s much appreciated.

I had missed the advice in the Exactoscale instructions about gauge widening, but now note that they only advise this for radii of less than 1500mm – about 5.7 chains – at which point they recommend GW of +0.2 or +0.3mm and use of check chairs with the wider (0.8mm) spacing.

To achieve gauge widening through a crossing the conventional technique would appear to be to fix the stock rail to the wider gauge and rely on the check chairs with 0.8mm spacing to set the check rails to CG. Presumably, however, it would be feasible to reverse the procedure by gauging the check rails to CG and relying upon their 0.8mm spacing to set the associated stock rail to a widened gauge. Any reason to prefer one approach over the other?

I can see the merit in an increase in the BB setting and had been toying with the idea of taking this course anyway, assuming my skills permit it.


I lack the theoretical knowledge of many of the contributors here, but I did ponder, on a pragmatic basis, the issue of gauge widening and check rails when I first aquired these things.

It seems to me that the purpose of a check rail at a crossing is to prevent the wheelset taking the wrong road. So as long as it fulfils that purpose it doesn't matter how far across it pulls the wheelset away from the crossing, so long as it doesn't interfere with the wing rail (i.e. within the limit set by the flangeway gap).

Am I wrong?

On the other matter raised here, many of those who come new to P4 modelling are also new to railway modelling, which is a very wide subject indeed, but perhaps difficult to separate out.

Allan F

Strandline
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Re: Which gauges for track construction?

Postby Strandline » Mon May 07, 2012 8:14 pm

I must admit that being a complete newbie, with no prototype, modelling or engineering experience of any kind, this thread just makes me wonder what on earth I am doing! However, with patience and the wide knowledge available here I am sure that one day I will have a working model. The layout may take a little longer... :)

Still, I do have some sleepers, chairs and rail, together with a couple of turnout kits, so will be making a start on a (straight) length of test track next week. Be prepared for questions...
Brian,
Sussex-by-the-sea

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Will L
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Re: Which gauges for track construction?

Postby Will L » Mon May 07, 2012 8:53 pm

Strandline wrote:I must admit that being a complete newbie, with no prototype, modelling or engineering experience of any kind, this thread just makes me wonder what on earth I am doing!...


Plenty enough good modellers started in the same place. Join your area group, read all the information you can get, never be totally satisfied with your work but be prepared to stop when its good enough and aims for improvement next time.

Will

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Russ Elliott
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Re: Which gauges for track construction?

Postby Russ Elliott » Mon May 07, 2012 9:39 pm

allanferguson wrote:It seems to me that the purpose of a check rail at a crossing is to prevent the wheelset taking the wrong road. So as long as it fulfils that purpose it doesn't matter how far across it pulls the wheelset away from the crossing, so long as it doesn't interfere with the wing rail (i.e. within the limit set by the flangeway gap).

Am I wrong?

No. But if you were a 50g vehicle on a diverging path of a turnout whose wheelset was approaching a checkflare at a modest 20smph, where would you prefer the rear face of the wheel to strike the flare: A, B or C?

checking.png
checking.png (8.43 KiB) Viewed 8885 times

allanferguson
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Re: Which gauges for track construction?

Postby allanferguson » Mon May 07, 2012 10:08 pm

[No. But if you were a 50g vehicle on a diverging path of a turnout whose wheelset was approaching a checkflare at a modest 20smph, where would you prefer the rear face of the wheel to strike the flare: A, B or C?

You are absolutely right, of course, and if I had a 50 ton vehicle with 50 passengers aboard they would know the answer too, I don't doubt!

However my passengers have never complained, and I'm dealing with the inaccuracies of model back to backs, wheel wobble, and track gauge. (I don't make them inaccurate, sir, they just happen that way!)

And my trains don't come off the track (at that crossing, anyway -- they do elsewhere, but that's a different story).

Allan F

wally

Re: Which gauges for track construction?

Postby wally » Tue May 08, 2012 10:17 pm

I think we are beginning to get confusion between what happens on the "real" railway and the model with regard to this subject.

Over twenty years spent trying to maintain trackwork on a preserved line (with a small budget compared to the main line) I have learnt the most important track dimension is what is being called here the check gauge, when used on S & C work, this does stop the wheels or - more embarrasingly - one single axle from going the wrong way as a train passes over the crossing!

The use of gauge widening on plain track will normally be instead of a check rail and then only on the larger radius work running at higher speeds, checks will be used on slower, tighter, curves especially when passenger carrying vehicles are being accomodated.

The discussion regarding wheels striking the check lead in is somewhat ambiguous as in normal (prototype) use the inclination of the rail and coneing of the wheels leads to the axle centering between the rails and neither the front or rear of the flange comes into contact, indeed this is the cause of the rail head flattening and the formation of the distinctive mushroom on the gauge corner of old rail, if there was regular contact this would be automatically worn off and the rail would not require grinding and reshaping.

Unfortunately, along with time, mass cannot be modelled at a smaller scale and some of the theoretical practices of the big train set cannot be used on our models. Compromise must be made to ensure good running and a blind eye turned to some of the more complex aspects of the prototype.

Perhaps there comes a point when "accuracy" will only needlesly confuse the newcomer.

Wally

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Will L
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Re: Which gauges for track construction?

Postby Will L » Tue May 08, 2012 10:54 pm

wally wrote:...The discussion regarding wheels striking the check lead in is somewhat ambiguous as in normal (prototype) use the inclination of the rail and coneing of the wheels leads to the axle centering between the rails and neither the front or rear of the flange comes into contact, indeed this is the cause of the rail head flattening and the formation of the distinctive mushroom on the gauge corner of old rail, if there was regular contact this would be automatically worn off and the rail would not require grinding and reshaping.

Unfortunately, along with time, mass cannot be modelled at a smaller scale and some of the theoretical practices of the big train set cannot be used on our models...


Now that is interesting I knew that mass doesn't scale, but that particular implication hadn't occurred to me.

Will

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Bigfish
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Re: Which gauges for track construction?

Postby Bigfish » Mon May 28, 2012 7:18 pm

I've now acquired a set of gauges, triangular and rolling, and many thanks to all of you for your advice.

Unfortunately the Stores is currently out of stock of checkrail gauges, and without one of these I think I may be a bit stuffed!

I wondered if anyone either knows when stocks might appear, or might even have an unwanted spare they'd be willing to sell me?

Cheers

Alan

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grovenor-2685
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Re: Which gauges for track construction?

Postby grovenor-2685 » Mon May 28, 2012 7:49 pm

Unfortunately the Stores is currently out of stock of checkrail gauges, and without one of these I think I may be a bit stuffed!

I think we mentioned above somewhere that you can manage without one of these for the time being. If using P4 Track Co check rail chairs it doesn't help much anyway, if soldering etc you can get by OK with a track gauge and flangeway gauge.
Do some trial builds while you wait.
Regards
Keith

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Bigfish
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Re: Which gauges for track construction?

Postby Bigfish » Wed May 30, 2012 7:31 pm

Thanks Keith. I'm going to build my first "P4 plank" using C&L components, gluing chairs to ply sleepers with butanone ie I'm not soldering. I've put a post in the "Private wants" section to see if anyone has a spare check gauge - so far, 54 views and no offers! Fingers crossed.

Cheers, Alan.

craig_whilding
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Re: Which gauges for track construction?

Postby craig_whilding » Wed May 30, 2012 7:47 pm

Bigfish wrote:Thanks Keith. I'm going to build my first "P4 plank" using C&L components, gluing chairs to ply sleepers with butanone ie I'm not soldering. I've put a post in the "Private wants" section to see if anyone has a spare check gauge - so far, 54 views and no offers! Fingers crossed.

Cheers, Alan.


Alan Gibson sells check gauges too, its only a .68mm wide piece of metal anyway though how accurate it is im not sure.

You wont need one if gluing chairs anyway unless you are making up your own crossings.

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grovenor-2685
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Re: Which gauges for track construction?

Postby grovenor-2685 » Wed May 30, 2012 8:24 pm

Craig,
The 0.68 strip is the "Flangeway gauge", the "checkrail gauge" that is oos is the one for setting the check rail from the opposite rail, which is usually the crossing nose. As in this pic. Image
(I see the straight flangeway guage is also out of stock but the round one is available and does the job).

Regards
Keith

PS Alan, you might find this useful, even using plastic chairs, all the rail parts are the same.
http://www.norgrove.me.uk/points.html

craig_whilding
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Re: Which gauges for track construction?

Postby craig_whilding » Wed May 30, 2012 8:38 pm

Ah sorry, that one is a bit more useful.

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Bigfish
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Re: Which gauges for track construction?

Postby Bigfish » Thu May 31, 2012 8:19 am

Keith, many thanks, the link to your turnout construction page is exceedingly helpful and I shall study it carefully!
I have followed up the Alan Gibson reference, and have just enquired about availability of gauges. Very glad to have discovered the AG catalogue too!
My package of bits from C&L arrived this morning, so the prospect of actually making something is getting nearer. On track construction I am proceeding slowly past a calling-on signal operated by my guru Howard :)

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Bigfish
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Re: Which gauges for track construction?

Postby Bigfish » Sat Jun 02, 2012 10:09 am

My check gauge & flangeway gauge arrived this morning from Alan Gibson, so I've got a full set and I'm good to go! Many thanks to everyone who took the time to provide advice on this thread.
Cheers

Alan

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Martin Wynne
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Re: Which gauges for track construction?

Postby Martin Wynne » Sun Apr 05, 2015 8:56 pm

Russ Elliott wrote:The prototype, where all flangeways are set to 1.75", has no recognition of the concept of CG.

I'm resurrecting this topic because I have just come across the above statement.

It is not correct -- the prototype makes special chairs with wider flangeways for use where there is gauge widening. The 4ft-6.3/4in CG dimension (check rail gauge) is well known and referred to as such. Here is a scan from BRT3 of 1964.

Image

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

John Palmer
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Re: Which gauges for track construction?

Postby John Palmer » Mon Apr 06, 2015 12:59 am

Interesting. Presumably the 'special chairs' referred to in the red boxed paragraph are the check chairs that set the check rail at a greater distance from the stock rail than normal? The impression given is that maintenance of a 4' 6.75" CG has primacy over maintenance of TG where gauge widening is to take place. That seems to raise the implication that where gauge widening is to be applied at a common crossing, the appropriate construction method is to set the check gauge relative to the crossing nose, leaving it to the special check chairs to introduce the gauge widening being sought. It was this possibility that prompted the question I posed in my 7-5-2012 01:41 post above.

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Martin Wynne
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Re: Which gauges for track construction?

Postby Martin Wynne » Mon Apr 06, 2015 4:01 am

John Palmer wrote:Presumably the 'special chairs' referred to in the red boxed paragraph are the check chairs that set the check rail at a greater distance from the stock rail than normal? The impression given is that maintenance of a 4' 6.75" CG has primacy over maintenance of TG where gauge widening is to take place. That seems to raise the implication that where gauge widening is to be applied at a common crossing, the appropriate construction method is to set the check gauge relative to the crossing nose, leaving it to the special check chairs to introduce the gauge widening being sought.

Hi John,

Yes. The check gauge is the most important dimension in constructing a crossing -- the check rails are always set from the opposite running rail. Some modellers like to fix the check rails first for this reason, adding the running rail afterwards. The actual width of the check rail gap is not important. Here's some info which I have posted many times on other forums, for 00 modellers new to trackbuilding, but it applies equally for P4.

Image

A is the check gauge. It is the most critical dimension in pointwork. If this dimension is too small, wheels running from left to right can hit the nose of the vee and very likely derail, or at least bump. If this dimension is too large, the wheel backs will bind or jam on the check rail. To make sure it's correct, the check rail is set using check gauge tools. For 00-SF and 00-BF this dimension should be 15.2mm. You can use the same check gauge tools for both these standards (they are both running the same wheels).

B is the crossing flangeway gap. It's also important. If this dimension is too small, the wheel backs will bind or jam on the wing rail. If this dimension is too large, the gap in front of the nose of the vee will be too wide, and the wheels may drop into it with a bump. This gap is set using a small piece of metal shim called a crossing flangeway gauge shim. For 00-SF it should be 1.0mm thick. For 00-BF it should be 1.3mm thick.

C is the track gauge. It shouldn't be less than the specified dimension, but it can be wider. It is often widened on sharply curved track to ease the running of long-wheelbase vehicles. The track gauge is normally set using roller gauge tools, or alternatively using a 3-point gauge tool, which automatically widens the track gauge on sharp curves. For 00-SF this dimension shouldn't be less than 16.2mm. For 00-BF it is normally 16.5mm.

D is the check rail gap. The width of this gap doesn't matter a damn, providing it is wider than the wheel flanges. It's whatever you end up with after setting A and C correctly. But where the check rail is combined with a wing rail in complex formations (i.e. in parallel-wing V-crossings) it must be the same as B. This means that it is not possible to have gauge widening through such formations, such as a tandem turnout.

regards,

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

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grovenor-2685
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Re: Which gauges for track construction?

Postby grovenor-2685 » Mon Apr 06, 2015 9:07 am

None of which should be news to any of us considering that it is all published here, http://www.scalefour.org/history/p4gauges.html
Regards
Keith

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Martin Wynne
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Re: Which gauges for track construction?

Postby Martin Wynne » Mon Apr 06, 2015 9:57 am

grovenor-2685 wrote:None of which should be news to any of us considering that it is all published here, http://www.scalefour.org/history/p4gauges.html

But written of course before the advent of functional plastic check rail chairs. Perhaps it needs updating to emphasize that when using these chairs it is the check rail which should be set using the gauge tools, not the running rail. The track gauge to the running rail is determined by the chair, not by using the track gauge tools.

With the existence of the two different standards, P4 and S4, and recent discussions about using EM wheels on P4 track, it must seem to beginners that the P4 standards are nearly as confusing as those for 00.

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


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