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On the topic of switch sizes...
 Moderated by: Herb Kephart
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 Posted: Fri Sep 23rd, 2016 03:35 pm
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Scott G
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Guys,

What is the deal with switch sizes. I was able to figure out that the smaller the number the sharper the switch diverts the train, but I couldn't really find any good information about how this all relates to min radius. In fact the article I read said "radius doesn't apply the same to switches", which left me puzzling, if I want a min radius of 18 and an ideal radius of 22 what size switches should I be using.

Looking for some sage advice from this group - if anyone know this stuff please lay it on me. Many thanks!

Scott

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 Posted: Fri Sep 23rd, 2016 05:24 pm
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Herb Kephart
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OK-

Believe it or not, with the exception of some industrial trackage, all railroad switch frogs are STRAIGHT for a short distance, even on the curved track.

So, if you extend the angle of the two straight lines of the frog rails a distance, then take a arbitrary distance from the point of the frog, and measure the distance that the two lines have diverged you have the dimensions of that angle.
Let's show a very simplified version of that process.
Go to a point where the lines have spread 1 foot. Measure from here, back to the frog point. Let's say it is 6 feet. You are looking at a #6 switch.  Not all that complicated, right?

I have hand laid my own track, since the dawn of time (almost) and have always built the diverging rail of a frog in a curve. This because in the early daze, I didn't know about this both rails straight stuff, but mostly because I was building trolleys, and with the sharp curves they use going around street corners, etc., the real track is that way. Since, I have built some railroad track, and I do the same, as 99% of the time model curves used are far, far sharper than the prototype would use in the same situation--and to my eye, It makes the curves more ''flowing''



Now some of you will say ''they aren't switches, they are turnouts''. Call the darn things anything you like--I'm tired of fighting that battle, Call frogs -- toads. See if I care

Herb



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 Posted: Fri Sep 23rd, 2016 05:36 pm
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NathanO
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The problem in model railroading is there are 'prototype' style turnouts and 'curved' turnouts.

The prototype style model turnouts are numbered like the real ones taking into account the length verses offset for the diverging route and so not have a true radius.

In HO scale Atlas sells what they call 'Snap' turnouts that do have a radius that matches the curved track they sell. So do some others in HO and other scales.

Nathan

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 Posted: Fri Sep 23rd, 2016 06:08 pm
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Helmut
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In prototype practice, there are straight and curved frogs. The curved ones are used only when absolutely necessary and are preferably found in industrial trackage where space is at a premium and sharp curves prevail. Herb's masterpiece is a very good example. Not to forget the exact model of CNJ's Bronx Terminal. For a given turnout no. and length the radius of a curved turnĂ³ut will always be greater than that of straight turnout. You can have a #4 with 18" and with 22" radius in e.g. H0 depending on the frog type. Look at NMRA's website for the standards - there's the whole nomenclature of turnouts explained.

Last edited on Fri Sep 23rd, 2016 06:11 pm by Helmut



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 Posted: Fri Sep 23rd, 2016 08:47 pm
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Scott G
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Thanks Herb for that info and for the amazing turnout you built. It's beautiful, I wish I had those skills. I'll be using off the shelf turnouts. I feel a lot smarter now guys thanks for the education.

Nathan the turnouts I was using on the plan seem to be curved on the switches, I guess that's pretty common.

Helmut I've seen that model before that one turnout is insane, I think it's the main reason he modeled the terminal! :)

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