Templot Club Archive 2007-2020                             

topic: 2931Outside slip
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posted: 3 Oct 2016 08:37

from:

Hayfield
 
United Kingdom

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I have been asked to make working drawings from what looks like an Iain Rice drawing, there seems to be an outside slip as well as a 3 way turnout,  the outside slip is at quite an acute angle, please how do I start. Do i make the central crossing first ?

I have done a quick search using outside slip on this forum without any luck, so can anyone give me some pointers please, thanks

John

posted: 3 Oct 2016 11:03

from:

Jim Guthrie
 
United Kingdom

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John,

I would start with the diamond crossing then attempt fitting the two switches so that the radius of the slip road is acceptable and the position of the crossings on the slip road is feasible for building.  You might also have to watch out for where the locations of the hinge points of the switch blades in the four foot so that the blades are long enough to flex.   You might find that you have to make a decision about it becoming half of a scissors rather than an outside slip if things don't work out.

With Iain Rice's plans you might have a wee bit of a fight on your hands since Iain can be a bit optimistic at times. :)

Jim.

posted: 3 Oct 2016 13:06

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Hi John,

As Jim says, outside slips can involve a bit of fiddling about, especially if starting from a CJF or Iain Rice plan. Also in his books Iain incorrectly refers to a half-scissors as an "outside slip", so it may not be entirely clear what he intended.

Yes, start with the diamond-crossing. For an outside slip it will be a short one, typically 1:6 or shorter.

Insert a turnout in the main road of one half-diamond and in the branch track of the other one. Probably you would want it to have a B-switch for a 1:5 outside slip, or a C-switch for a 1:6 outside slip. The V-crossing angle for the turnout doesn't matter at this stage.

do > snap to switch heel on each of them, and then snake them forward into position. Some trial an error may be needed, but a rule of thumb is to have the switch heel roughly mid-way between the vee nose and the vee rail joint, like this:

2_030656_590000000.png2_030656_590000000.png

It's not essential for the switches to be exactly symmetrical* about the diamond, but they need to be within a mm or two.

To create the slip road there are two methods -- the quick way and the other way. :)

1. the quick method:

Revert one of the switches to a full turnout (F4 overall length). Set a curviform V-crossing and extend the turnout road exit (CTRL+F12 mouse action).

Then adjust the V-crossing angle using F9 mouse action (not F5) until the turnout road aligns with the other switch heel. Shorten the turnout road exit (CTRL+F12 mouse action) to fit.

This creates the slip road and one additional V-crossing at the same time. Like this:

2_030746_300000000.png2_030746_300000000.png

If you have got the switch positions about right, the slip road will clear the wing rail ends and break through the diamond legs roughly mid-way between the K-crossings and the V-crossings. The K-crossing check rail is likely to need shortening a bit.

Then repeat for the other switch.

2. the slow method:

Snap a bit of plain track onto one of the switch heels, and adjust the length and curving to fit the other one, in the same way as when adding the slip road on an inside slip, like this:

2_030708_500000000.png2_030708_500000000.png

You then insert curviform V-crossings in the diamond legs in a similar way to when creating a tandem turnout. This method gives you more precise control -- if the diamond-crossing is irregular say, or the whole thing is on a transition curve.

Whichever method you use, some rails will need to be omitted and partial templates split out to remove the conflicts.

*(To get them exactly symmetrical you can create the first half-diamond by putting the peg on split deflection and pegging onto the notch before you start, having reset the notch first if necessary. Then you can create the second switch by making the first one the only member of a group, and mirroring it on X. Then move the whole assembly back into position on your plan. That's a lot of fiddling about.)

regards,

Martin.

posted: 3 Oct 2016 19:45

from:

Hayfield
 
United Kingdom

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Thanks all for the assistance, this is the crazy angle within the plan and the slip curve ends up under 2' radius, any thoughts please.
I do have an old C&L plan in the loft (wrong angle) which may assist with the rails and crossings, but initially just want to know what can be done

Thanks

John
Attachment: attach_2327_2931_Outside_slip_verion_1.box     234

posted: 3 Oct 2016 20:13

from:

Hayfield
 
United Kingdom

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Might be getting a bit nearer with this one
John
Attachment: attach_2328_2931_Outside_slip_verion_2.box     225

posted: 3 Oct 2016 20:23

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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2_031521_070000000.png2_031521_070000000.png

Hi John,

As I suspected when you mentioned Iain Rice, it is not an outside slip at all, it is a half-scissors. The side road does not run through the diamond. There is no way you can add a slip road of any kind to a 1:2.5 diamond-crossing and have a sensible radius.

If you want the turnouts to be the same, they need to be both 1:5.19 RAM angle (half of 1:2.5 RAM). I suggest making them generic V-crossings to ease the turnout radius.

Then you need to snake them close in to the diamond, otherwise you won't be able to check all the V-crossings.

The .box file posted below is just a bare bones. Over to you to adjust all the check rail conflicts, strip out the partial templates, and sort out the timbering. :)

regards,

Martin.
Attachment: attach_2329_2931_john_half_scissors.box     269
Last edited on 23 Mar 2017 21:09 by Martin Wynne
posted: 3 Oct 2016 22:23

from:

Hayfield
 
United Kingdom

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Thanks very much, never knew there was such a thing as a half scissors. Thanks will tidy it up the best I can. Many thanks again

John

posted: 4 Oct 2016 05:52

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Hayfield wrote:
Thanks very much, never knew there was such a thing as a half scissors.
Hi John,

An important distinction between a scissors and a double-slip is in the interlocking. In a scissors both side roads can be signalled to be used at the same time. In a double-slip they can't, whether it is an inside slip or an outside slip.

That's not relevant for a single-slip or half-scissors, but the geometry is the same.

In a conventional scissors of course, the switch deflections are across the diamond, and the side road forms the main road of the turnouts. Here in your example the switch hands are swapped to deflect along the side road, with the main roads across the diamond. So you could argue that it is not a slip or a scissors. But in that case I don't have any other name for it. :?

regards,

Martin.



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