Templot Club Archive 2007-2020                             

topic: 1225Minimum Radius
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posted: 31 Aug 2010 09:20

from:

RichardTP
 
United Kingdom

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Hi everyone

1st of all I'm very new to Templot so forgive the idiots question.

I am building my 1st O gauge layout, I have printed out a simple A5 turnout (straight) and a minimum radius of 49.5ins is quoted, the turnout looks to have a much larger radius than this, certainly 5 ft and C and L quote 6.6 feet approx for the radius.

Can you please explain

Thanks

Richard

posted: 31 Aug 2010 10:36

from:

Nigel Brown
 
 

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Hi Richard

As you will have noticed, the turnout road is a complex mix of curves and straights; the minimum radius is the sharpest of these curves. The other radius sometimes quoted is the substitution radius, which is what you would have if you replaced the whole turnout road with a curve of constant radius. The substitution radius is the larger, and is intended as an aid to producing the overall design. The minimum radius is intended to give you an idea of whether your stock might have trouble running through the turnout.

Cheers
Nigel
Last edited on 31 Aug 2010 10:37 by Nigel Brown
posted: 31 Aug 2010 10:41

from:

RichardTP
 
United Kingdom

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Hi Nigel

Thanks for that, not simple is it! So presumably if you want to try and maintain a 6foot minimum radius you have to go up to a B6, almost just to play safe

Richard

posted: 31 Aug 2010 12:18

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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RichardTP wrote:
So presumably if you want to try and maintain a 6foot minimum radius you have to go up to a B6, almost just to play safe
Hi Richard,

Welcome to Templot Club.

It's not necessary to go all the way to B-6 to get above 6ft radius. Changing to a 9ft-type straight switch instead of the A switch, and a generic type V-crossing instead of regular, gets you to 73.9" radius at 1:5.5 RAM crossing angle. This turnout isn't significantly longer than the A-5:

2_310702_310000000.png2_310702_310000000.png

These are for 0-MF gauge (31.5mm track gauge).

In truth, A-5 is an unsatisfactory size, it is too far below the natural angle for an A switch (A-7), resulting in a short sharp length of turnout radius. You can see that changing to an older straight type of switch makes a much gentler space-saving design. You don't have actually to build it as a loose-heel switch, you can simply use the same geometry but for a flexible switch. The NER did this, so it's not necessarily unprototypical.

For more information, see also:

 message 6572

 message 4271

 http://www.templot.com/martweb/gs_realtrack.htm

regards,

Martin.

posted: 31 Aug 2010 14:46

from:

RichardTP
 
United Kingdom

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Hi Martin

Thanks for your replies, I want to make track construction as simple as possible so will be using C and L pieces, so will I have to go to a B6 if I don't use an A5.

Can I ask another question please. Can I use imperial measurements! I would prefer to have inches on the left and bottom of the screen instead of mm's is there an option for this.

Thanks

Richard

posted: 31 Aug 2010 16:06

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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RichardTP wrote:
will be using C and L pieces, so will I have to go to a B6 if I don't use an A5.
Hi Richard,

Using C+L components you can build an A-6 turnout, which actually has an easier radius than a B-6 (but a sharper switch deflection, so it won't take much curving) of 75.6" like this:

2_311050_130000000.png2_311050_130000000.png

Note that using C+L switch blades you can also build 9ft and 12ft straight switches, because the planing angle for those is the same as for A and B switches respectively (1:24 and 1:32 deflection).

Can I ask another question please. Can I use imperial measurements! I would prefer to have inches on the left and bottom of the screen instead of mm is there an option for this?

Yes. Which version of Templot are you using? In 091c you have a range of pre-set spacings in addition to the ability to set any spacings you wish.

See above screenshot -- pad > pad grid options > menu options.

in 074b it's pad > pad grid options > grid spacings... menu item, and you must set the units and spacings manually.

When entering data which Templot asks for in mm, you can enter inches instead by prefixing the number with a letter i. So entering i10 means 10 inches and Templot will convert it to 254mm for you.

There are several other prefix letters you can use, see the help notes on the data-entry dialog.

regards,

Martin.

posted: 31 Aug 2010 16:18

from:

RichardTP
 
United Kingdom

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Hi Martin
Thanks again, your answers are a big help. I need to have another play around tonight. Templot is clearly a brilliant programme, but a massive amount to learn!

regards

Richard

posted: 31 Aug 2010 21:35

from:

Alan Turner
 
Dudley - United Kingdom

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To get the most out of Templot you have to take the trouble of understanding something of real track-work.

I think this is the biggest mistake that people generally make. Unlike the toy train track-work that Anyrail or Xtrax produce Templot is about modelling real track-work.

Alan

 

posted: 1 Sep 2010 23:06

from:

Bill Fay
 
 

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Alan Turner wrote:
To get the most out of Templot you have to take the trouble of understanding something of real track-work.

I think this is the biggest mistake that people generally make. Unlike the toy train track-work that Anyrail or Xtrax produce Templot is about modelling real track-work.

Alan

 
A bit chicken and egg really. I came to Templot with minimal knowledge of track-work geometry. However I have learnt (and am still learning) some of the basics as I have progressed with Templot and enjoyed doing so. What I would dearly love is a book or website that could educate me on the topic without having to have a degree in mathematics to understand it - oh and preferably GCR orientated :D

Bill

posted: 2 Sep 2010 14:44

from:

Phil O
 
Plymouth - United Kingdom

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Bill Fay wrote
A bit chicken and egg really. I came to Templot with minimal knowledge of track-work geometry. However I have learnt (and am still learning) some of the basics as I have progressed with Templot and enjoyed doing so. What I would dearly love is a book or website that could educate me on the topic without having to have a degree in mathematics to understand it - oh and preferably GCR orientated :D

Bill
Hi Bill

Have a look at this previous topic and the links it may help

topic 1169

Cheers Phil

posted: 2 Sep 2010 16:03

from:

Jim Guthrie
 
United Kingdom

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Bill Fay wrote: 
What I would dearly love is a book or website that could educate me on the topic without having to have a degree in mathematics to understand it - oh and preferably GCR orientated :D
Bill,

It's worth trying to get a copy of "British Railway Track: Design,  Construction and Maintenance" published by the Permanent Way Institution.  This is the bible used by professional railway men.   The older the version,  the more information you get about bullhead track.  My edition is the 1956 one and it has bullhead and flat bottom information.   There are several chapters of mathematics applied to P&C design but it is surprisingly basic mathematics which you should be able to understand if you have got to "O" level :-)

I've just had a look in Abebooks and there are several copies available - going back to the 1943 edition - the prices might be a bit of a shock :-)

Jim

posted: 2 Sep 2010 18:42

from:

Bill Fay
 
 

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Phil O wrote:
Hi Bill

Have a look at this previous topic and the links it may help

topic 1169

Cheers Phil

Phil, Thanks I will have to dig around. Bill


posted: 2 Sep 2010 18:48

from:

Bill Fay
 
 

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Thanks Jim,

I will put that on my list - looks useful. The trouble (and one of the pleasures) with this hobby is that the more you learn the more there is to learn - if you see what I mean.

Bill

Jim Guthrie wrote:
Bill Fay wrote: 
What I would dearly love is a book or website that could educate me on the topic without having to have a degree in mathematics to understand it - oh and preferably GCR orientated :D
Bill,

It's worth trying to get a copy of "British Railway Track: Design,  Construction and Maintenance" published by the Permanent Way Institution.  This is the bible used by professional railway men.   The older the version,  the more information you get about bullhead track.  My edition is the 1956 one and it has bullhead and flat bottom information.   There are several chapters of mathematics applied to P&C design but it is surprisingly basic mathematics which you should be able to understand if you have got to "O" level :-)

I've just had a look in Abebooks and there are several copies available - going back to the 1943 edition - the prices might be a bit of a shock :-)

Jim


posted: 3 Sep 2010 09:59

from:

Andy B
 
 

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You can get Part 3 of "British Railway Track. 7th edition" which specifically covers Bullhead track new from the PWI at £36 (incl postage I think). Whilst this may not cover the detail differences of the pre-grouping companies that may be found in the 1st & 2nd editions (which I've never seen, so can't confirm their content), it does cover all the terminology and much more as an aid to understanding Templot.

Go to http://www.permanentwayinstitution.com/ and click on 'Publications'.

If I get time, I'll put the chapter headings on here over the weekend, so you'll have a better idea of its content.

Andy

posted: 5 Sep 2010 18:29

from:

Bill Fay
 
 

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Andy,
Thanks for the pointer. Yes a look at the chapter headings would be useful.
Bill

posted: 5 Sep 2010 20:49

from:

R A Watson
 
 

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Bill,

Before buying the later book (also refered to as "the Bullhead Suplement") you may like to consider that it is written to cover mainly modern B H track, which is mostly London Underground applications, and is not too helpfull for those working on older prototypes.

Perhaps for a greater overview you should go for one of the earlier books recommended above.

Wally

 

 

 

posted: 5 Sep 2010 23:05

from:

Bill Fay
 
 

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Wally,

Thanks for the allert.

Bill

posted: 11 Sep 2010 08:22

from:

Andy B
 
 

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Andy B wrote:
You can get Part 3 of "British Railway Track. 7th edition" which specifically covers Bullhead track ........

If I get time, I'll put the chapter headings on here over the weekend, so you'll have a better idea of its content.

Andy


Apologies - didn't manage it until now.

The book has 5 sections, plus 23 pages of Glossary and several appendices (60 pages). There are references all the way through to pre-grouping practice - e.g Appendix 3 gives dimensions of GWR, LMS, LNER and SR switches.

Section 1 - Plain Line (36 pages); Rails, rail joints, fishplates (incl insulated), expansion allowance, check rails in plain track, sleepers & sleeper spacing, chairs, keys, chair fastenings, ballast, life of P-W materials, measuring wear of rails

Section 2 - Switches & Crossing (52 pages); Introduction, switches, switch planing, switch checking, common crossings, flexible wing or spring crossings, standard leads, obtuse crossings, fixed diamonds & switch diamonds, single & double slips, 3-throw turnouts, tandem turnouts, scissors crossovers, timbering, measurement of unit angles, 2-level junctions, trap points & sand drags, catch points, chairs, switch operating mechs, switch heating, layout S&C work.

Section 3 - Modern Practice - Plain Line (20 pages); generally an expansion of section 1, with reference to continuously welded rail, modern sleepers, chairs & fasteners, etc.

Section 4 - Modern Practice - Switches & Crossings (16 pages); generally an expansion of section 2.

Section 5 - Examples of Bull Head Track (31 pages); all photos with brief descriptions / explanations

Hope this helps.

Andy



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