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Peco Code 100 three-way point - radius?


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The Peco web site describes the SL-99/SL-E99 as "3 Way Turnout, Medium Radius".  However, in the technical specification section it says that the nominal radius is 610mm, which is the same as the small radius left and right turnouts, and the small radius Y.

 

Putting to one side issues about varying actual radii within a turnout, does this sound right, or has Peco made a mistake in this case?

Edited by ejstubbs
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I think the reality is that one hand is medium radius (ie around 36" / 915 mm) but the other hand is small radius (ie around 24" / 610 mm).  That is, it is effectively a small radius turnout overlaid on a medium radius turnout.  The overall length is the same as a medium turnout with the difference in length between a medium and small turnout (about 40 mm) being the difference between the tips of the two sets of switchblades.

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  • RMweb Gold

The staggered point blades don't reduce the radius of the smaller right hand route by very much.

I measure ~915mm for the left hand route, as expected, and ~800mm for the right.

 

Peco do make mistakes with their stated radii. They sometimes claim the Large turnouts are 60in radius - and that's just silly.

 

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I think the OP is talking about the (almost) symmetrical Code 100 version?  It takes seven and a half of them to get round 90 degrees (as you'd expect given the stated 12 degree turnout angle), but the radius of the resulting continuous turn (as plotted by XTrackCad) is actually 41 inches (1050 mm), give or take a smidge.  Which is larger than the stated radius of the medium turnout - but a similar turn made up of the mediums overlays the 3-ways exactly.  I suppose "nominal radius" is the radius of the curved bit?  Which is much less useful when planning .....

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40 minutes ago, Chimer said:

I think the OP is talking about the (almost) symmetrical Code 100 version?

 

Correct, I am (per the thread title, in fact).

 

Unfortunately Peco themselves seem to be confused between the code 100 and the code 75.  This was their answer when I posed the question to them by e-mail:

 

Due to the design of this turnout, the left hand route would be a nominal 24" radius, with the right hand route of a slightly larger nominal radius being nearer to 36".

 

:mad:

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2 hours ago, ejstubbs said:

 

Correct, I am (per the thread title, in fact).

 

Unfortunately Peco themselves seem to be confused between the code 100 and the code 75.  This was their answer when I posed the question to them by e-mail:

 

Due to the design of this turnout, the left hand route would be a nominal 24" radius, with the right hand route of a slightly larger nominal radius being nearer to 36".

 

:mad:

 

That weasel word, "Nominal", is their "get out of jail free" card...

 

Edited by Harlequin
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I've always understood "nominal radius" to mean the radius of the circle you'd get if you connected a bunch of them together one after the other.  Much as Chimer said, in fact.  It is useful for planning purposes - however, I don't think the computer-based planning packagaes can necessarily be relied upon to have the figures precisely correct.  To be fair, I do get a similar result with AnyRail as Chimer did with XtraCAD, giving a nominal radius of ~1050mm for both the three-way and the medium right-hand turnout.  Oddly, though, 15 of the three-way gives me fractionally more than a full semi-circle, while 15 of the right-hand turnout gives we almost exactly the same fraction less than 180°.  Go figure...

Edited by ejstubbs
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Whilst I haven't done it for the 3 way points, like others I've found it useful to make up a circle of the unit in question in a CAD program (SCARM is my favoured medium) and measure across it. Like the OP, I find that the units don't necessarily connect up perfectly, even where the manufacturer's nominal spec says they should. I figure it doesn't really matter as, in reality, it would be very unlikely that sufficient turnouts would ever be connected together that the discrepancy would become significant. 

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18 hours ago, ejstubbs said:
19 hours ago, Chimer said:

I think the OP is talking about the (almost) symmetrical Code 100 version?

 

Correct, I am (per the thread title, in fact).

Here is the data for a Code-100 3-way turnout according to the 3rdPlanIt layout software:

2020-09-19_130507.jpg.cff7cfc891857db61334adc3c8d928f4.jpg

 

Ignore the 'cost' field. That has to be entered by the User ...

Does any of this disagree with other software? I hope not, as I've used it to design my layout.

 

Ian

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