Templot Club Archive 2007-2020                             

topic: 3680Scissors crossovers
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posted: 28 May 2020 06:29

from:

Graham Long
 
 

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HiI am grappling with making a template for a scissors crossover. I understand there are two types of scissors crossover i.e Scissors 1 and 2. The scissors 1 is more difficult. I am not sure if this means that more difficult to get make template or it is more difficult to make the formation from the template. Could I get clarification?  Are they both prototypical?

posted: 28 May 2020 08:59

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Graham Long wrote:
HiI am grappling with making a template for a scissors crossover. I understand there are two types of scissors crossover i.e Scissors 1 and 2. The scissors 1 is more difficult. I am not sure if this means that more difficult to get make template or it is more difficult to make the formation from the template. Could I get clarification?  Are they both prototypical?
Hi Graham,

In a type 1 scissors crossover the V-crossings on the diamond are in the turnout radius section of each turnout:

2_280306_090000000.png2_280306_090000000.png


In a type 2 scissors crossover the V-crossings on the diamond are in the crossing entry section of each turnout:

2_280306_090000001.png2_280306_090000001.png

colour codes:

2_280441_190000000.png2_280441_190000000.png

Note that the type 2 scissors is shorter with sharper turnout curves, so you may need to use a longer size for the turnouts.

Both types are equally easy to get to this stage in Templot with a few clicks. See below for the basic recipe. The diagrams above are in curved track, but it is the same for a straight scissors.

However, to get beyond this stage to detailed templates with all rail conflicts removed is much easier in a type 2 scissors, because in that case the middle diamond-crossing is an ordinary regular diamond with all crossing angles equal.

In a type 1 scissors the middle diamond-crossing will need to be created from multiple partial templates, and the V-crossing angles will differ from the K-crossing angles.

Both types can be found on the prototype, in all the thousands of scissors crossovers around the world and at different periods.

Both types are equally easy to build, once you have the printed templates. A beginner would likely choose a straight scissors, in which case a type 2 would be a bit easier to build because all the rails in the middle diamond will also be straight.



The basic procedure to create an outline scissors crossover, in curved or straight track, is:

1. start with a turnout of the required V-crossing angle, regular, and TS track spacing centres.

2. tools > make ordinary crossover

3. do > snap to peg

4. tools > make mirror on peg     

5. tools > make ordinary crossover

6. store & background

That works starting with a straight or curved turnout, and gets you all the essential rail alignments.

If you start with an ordinary turnout the above procedure will most likely give you a type 1 scissors, with the V-crossings for the diamond in the turnout curves. However, it is generally easier to create a type 2 scissors, with the V-crossings for the diamond in extended crossing entry-straight* sections on the turnouts.

To do that, start by extending the entry-straight on the first turnout (SHIFT+F11 mouse action -- keep an eye on the turnout radius and increase the turnout size if needed). Then at template > V-crossing settings... , tick this box before making the first crossover:

2_280306_090000002.png2_280306_090000002.png

* entry-straight is the name for that section of a regular V-crossing. It is actually straight only in a straight turnout. In a curved turnout it is curved to the same radius as the main road.



cheers,

Martin.

posted: 29 May 2020 07:21

from:

Graham Long
 
 

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Thanks for information. I have used you recipe to make a template for a scissors crossover on a curve.
I see there are black lines on the template. It appears that the two them indicate the boundary between knuckle and closure rail. If this correct then the tips of the diamond is definitely closer to toe of turnouts. Thus it seems that I have a Scissors 1. I think I will be able to to stop wing rails from interfering with running rail and aligning crossing timbers using the methods use on your making a slip video. How do I make the Vs of the diamond?

posted: 29 May 2020 09:11

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Hi Graham,

If you are making a type 1 scissors I'm assuming you are reasonably experienced in Templot, so I will just summarise the basics. A full scissors video would take me a couple of days to make and I'm a bit busy at present, sorry.

The diamond V-crossings are partial templates extracted from a separately created half-diamond. As a starting point the angles will be half those of the turnouts. i.e. if the turnouts are 1:7, a starting point for the half-diamond would be 1:3.5 .

Run the peg along the turnout stock rail to the intersection (zoom in for accuracy). Using CTRL-4 peg the half-diamond V-crossing in that position. With a bit of care you can do it all with just the one partial template. Use this menu item to set the curving in it:

2_290354_280000000.png2_290354_280000000.png


Then using F9 and F10 alternately, adjust the angle and radius to match the other turnout. Keep the peg on CTRL-4 while doing it.

The main work is adjusting all the check rail flares to clear the wheel backs and still maintain adequate checking of the crossings. It is usually necessary to adjust the flare length before you can adjust the rail length:

2_290357_260000000.png2_290357_260000000.png

That still leaves the underlying turnout rails conflicting through the V-crossing, which can be dealt with by splitting them out on further partial templates in the usual way.

cheers,

Martin.

posted: 29 May 2020 13:38

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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p.s. Graham,

The way to get the K-crossings is to temporarily peg a couple of lengths of plain track onto the CESP positions:

2_290821_410000000.png2_290821_410000000.png


Then adjust the radius in them to fit the opposite CESP positions:

2_290822_510000000.png2_290822_510000000.png

This will average out the difference in radius between the inner and outer main lines.

After which you can do peg/align tools > make diamond-crossing at intersection to create the K-crossings, and then delete the original plain track.

The diamond-crossing won't fit the V-crossings because this is a type 1 scissors, so you can shorten the half-diamonds back (F4) to just the K-crossings.

Then the final tidying up is to split out the partial templates, and shove the timbering.

(For a type 2 scissors, this method would also create the V-crossings.)

cheers,

Martin.

posted: 30 May 2020 06:58

from:

Graham Long
 
 

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Thanks for your help. I am a rank begginer and will have to study and make sense of your explanations. I was only making the templates at this stage to see roughly how much length I would need for this formation whilst making a plan by pencil and paper. I will concentrate on getting my template to one suitable for printing later. Thanks again for your help. I am looking forward to making use of Templot.
Graham



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