Templot Club Archive 2007-2020                             

topic: 849printed bisect of frog angle
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posted: 29 May 2009 20:03

from:

jeckardt
 
Beaverton - Oregon USA

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I am finally to the point of actually using a Templot template to build my first two custom turnouts. 

As I am sitting here filing the v-rail angles and trying to get the rails to fit together properly, I realize that it would be very helpful to have a "construction line" bisecting the the frog, extending maybe 2-3 centimeters on either side of the v-rail.  Sure, I can (and did) hand draw this onto each of the printed templates, but it would be nice to have an option to have Templot do that for me accurately.

Joe

posted: 29 May 2009 21:00

from:

Nigel Brown
 
 

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Joe

There are various approaches to producing the V. I think what you're doing is filing both rails at half the angle so that placed side by side they produce the required V? If so there are alternative, rather easier and possibly more accurate methods. E.g. File one rail to a point using the same angle as that required for the crossing. Do the same for the other rail but on the other side. Slide the filed bit of the latter down the first rail until the point reaches the end of the filed bit of the first rail. You now have the required V, with just one rail providing the point of the V, the other sitting further back. That's the principal. There are some refinements which are a good idea, aimed at getting the web of the rail extending to the point, rather than to one side of it.

cheers
Nigel

posted: 29 May 2009 21:34

from:

Jim Guthrie
 
United Kingdom

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Joe,

There was a thread just over a year ago covering this very subject where Martin gave a description of an excellent way to construct a crossing nose.

topic 359

Jim.
Last edited on 29 May 2009 21:35 by Jim Guthrie
posted: 30 May 2009 10:54

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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jeckardt wrote:
As I am sitting here filing the v-rail angles and trying to get the rails to fit together properly, I realize that it would be very helpful to have a "construction line" bisecting the the frog
Hi Joe,

You can create such a bisector line by means of a partial template overlaid.

Create a turnout with half the crossing (frog) angle in degrees and use its track centre-line as the bisector. That means doubling the unit angle for an approximate result (i.e. for a 1:6 (#6) frog you need to create a #12 frog), then adjust with F5 to get an exact result through the F.P. marker. (Or do your own trig thing :) -- half of RAM 1:6 is RAM 1:12.083)

Put the peg on the D.P. (CTRL-3) before you begin, and set track centre-lines only to remove the rails and timbering. Set any angle for F5.

I have made a scruffy bit of Jing video showing that (wait for it to load, mouse-over it for the controls, pause it to drag the slider to any frame):



The video shows a straight turnout for clarity, but it all works equally well for a curved turnout (creating a curved bisector line).

Having done all that, it is really much better to construct vees in the prototypical fashion, as explained by Nigel and Jim. The vee rail in the main road is solid rail (called the point rail), and the vee rail in the turnout road is spliced into the side of it (called the splice rail). Jim provided the link to a topic where I have made some diagrams showing that. Here it is again:

 topic 359 - message 2078

regards,

Martin.

posted: 1 Jun 2009 13:44

from:

David R
 
Hatfield Heath - United Kingdom

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Please add this to my "wish list" as, in many designs, the crossing chairs are perpendicular to this bisecting line and not aligned with the timbers -- the prototype then didn't need left and right-hand versions of the crossing chairs.

And if the chair outlines were also included then we'd know if we needed 12" or 14" timbers to accommodate all the fixings.

Dave R


posted: 1 Jun 2009 14:32

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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David R wrote:
Please add this to my "wish list" as, in many designs, the crossing chairs are perpendicular to this bisecting line and not aligned with the timbers -- the prototype then didn't need left and right-hand versions of the crossing chairs.
Hi Dave,

For bullhead track, I think you can replace "in many designs" with "always". :) I can't think of any BH crossing chairs which were handed.

If you change to the "equalized" styles of timbering in Templot, the timbers are aligned to the half-angle, and you can align the chairs to the timber edges. If you are using "square-on" timbering instead, you could overlay a duplicate template showing only the equalized timber centre-lines when printing a construction template. This would give you guide marks for the chairs.

I will look at adding such "chair-alignment" marks on the square-on timbering option -- thanks for the suggestion. :)  

And if the chair outlines were also included then we'd know if we needed 12" or 14" timbers to accommodate all the fixings.

Templot's printouts show only the rail and timber positions, without any chairing detail. There is too much prototype variation in chair patterns to make this practical -- you need to refer to your chosen prototype.

For a guide to the common REA chair types and positions, detailed templates can be downloaded and printed from the Exactoscale web site, and scaled to any size. See:

 message 4620


chairing_patterns.gifchairing_patterns.gif
regards,

Martin.

posted: 1 Jun 2009 22:32

from:

jeckardt
 
Beaverton - Oregon USA

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Martin Wynne wrote:
You can create such a bisector line by means of a partial template overlaid.

Thank you, Martin, that will work.  The video was most helpful.

I'll also study the alternate method of building the v-rail, although it seems to require creating a sharp bend in the rail... something I'm not convinced I can successfully do with code 250 rail.

Regards,

Joe



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