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TEMPLOT 3D PLUG TRACK - To get up to speed with this experimental project click here.   To watch an introductory video click here.   See the User Guide at Bexhill West.

  • The Plug Track functions are experimental and still being developed. Some of the earlier pages of this topic are now out-of-date.

    For an updated overview of this project see this topic.   For some practical modelling aspects of using Plug Track see Building 3D Track.

    The assumption is that you have your own machines on which to experiment, or helpful friends with machines. Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful.

    Some pages of this and other topics include contributions from members who are creating and posting their own CAD designs for 3D printing and laser-cutting. Do not confuse them with Templot's own exported CAD files. All files derived from Templot are © Martin Wynne.
  • The Plug Track functions are experimental and still being developed.

    For an updated overview of this project see this topic.   For some practical modelling aspects of using Plug Track see Building 3D Track.

    The assumption is that you have your own machines on which to experiment, or helpful friends with machines. Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful.

    Some pages of this and other topics include contributions from members who are creating and posting their own CAD designs for 3D printing and laser-cutting. Do not confuse them with Templot's own exported CAD files. All files derived from Templot are © Martin Wynne.

Turnout Radii

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stuart1600

Member
Location
Westmorland
I should emphasise that I raise this issue solely as a matter of idle curiosity........
I'm sure that I read somewhere that there is a series of turnout switch/crossing combinations that produce identical switch and turnout radii, and that the combinations were A7, B8, C10.
But if I try this in Templot, including in near prototype gauges such as S7 and P4, the relevant turnouts are in fact A8, B9, and C12.
Is my memory playing tricks, or my original source incorrect, or is there some reason why Templot is different?
As I say, just idle curiosity....
 
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@stuart1600

Hi Stuart,

To match the prototype in Templot you need to do this:

1. exact scale track gauge, S7, P4, etc.

2. generic (or curviform) V-crossing. Not regular.

That will get you close, but then ideally also

3. convert RAM to CLM crossing angle.

You should then find that the switch radius and turnout radius are very close to equal at REA "natural" turnouts A-7, B-8, C-10 etc. (not GWR).

They won't be exactly equal, because if you look in the REA table of leads, there are slight radius differences between the companies.

If you do all that for a B-8 CLM (B-7.97 RAM) in P4, you get:

switch radius: 2452.0mm (prototype 613ft).
turnout radius: 2456.51mm.

The difference is because the quoted 613ft radius for an REA B-switch is known to be an error. If you calculate it from first principles you get 614ft. If you look at the B-switches in the early FB designs you will see the radius quoted there as 614ft. A can of worms which is all now in the past. :)

614ft = 2456.0mm in 4mm scale.

cheers,

Martin.
 
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